From 83179cd67846fae0e6aea5848c07faaa5d89a1de Mon Sep 17 00:00:00 2001 From: Liao Chang Date: Fri, 24 Jan 2025 09:38:26 +0000 Subject: uprobes: Remove the spinlock within handle_singlestep() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch introduces a flag to track TIF_SIGPENDING is suppress temporarily during the uprobe single-step. Upon uprobe singlestep is handled and the flag is confirmed, it could resume the TIF_SIGPENDING directly without acquiring the siglock in most case, then reducing contention and improving overall performance. I've use the script developed by Andrii in [1] to run benchmark. The CPU used was Kunpeng916 (Hi1616), 4 NUMA nodes, 64 cores@2.4GHz running the kernel on next tree + the optimization for get_xol_insn_slot() [2]. before-opt ---------- uprobe-nop ( 1 cpus): 0.907 ± 0.003M/s ( 0.907M/s/cpu) uprobe-nop ( 2 cpus): 1.676 ± 0.008M/s ( 0.838M/s/cpu) uprobe-nop ( 4 cpus): 3.210 ± 0.003M/s ( 0.802M/s/cpu) uprobe-nop ( 8 cpus): 4.457 ± 0.003M/s ( 0.557M/s/cpu) uprobe-nop (16 cpus): 3.724 ± 0.011M/s ( 0.233M/s/cpu) uprobe-nop (32 cpus): 2.761 ± 0.003M/s ( 0.086M/s/cpu) uprobe-nop (64 cpus): 1.293 ± 0.015M/s ( 0.020M/s/cpu) uprobe-push ( 1 cpus): 0.883 ± 0.001M/s ( 0.883M/s/cpu) uprobe-push ( 2 cpus): 1.642 ± 0.005M/s ( 0.821M/s/cpu) uprobe-push ( 4 cpus): 3.086 ± 0.002M/s ( 0.771M/s/cpu) uprobe-push ( 8 cpus): 3.390 ± 0.003M/s ( 0.424M/s/cpu) uprobe-push (16 cpus): 2.652 ± 0.005M/s ( 0.166M/s/cpu) uprobe-push (32 cpus): 2.713 ± 0.005M/s ( 0.085M/s/cpu) uprobe-push (64 cpus): 1.313 ± 0.009M/s ( 0.021M/s/cpu) uprobe-ret ( 1 cpus): 1.774 ± 0.000M/s ( 1.774M/s/cpu) uprobe-ret ( 2 cpus): 3.350 ± 0.001M/s ( 1.675M/s/cpu) uprobe-ret ( 4 cpus): 6.604 ± 0.000M/s ( 1.651M/s/cpu) uprobe-ret ( 8 cpus): 6.706 ± 0.005M/s ( 0.838M/s/cpu) uprobe-ret (16 cpus): 5.231 ± 0.001M/s ( 0.327M/s/cpu) uprobe-ret (32 cpus): 5.743 ± 0.003M/s ( 0.179M/s/cpu) uprobe-ret (64 cpus): 4.726 ± 0.016M/s ( 0.074M/s/cpu) after-opt --------- uprobe-nop ( 1 cpus): 0.985 ± 0.002M/s ( 0.985M/s/cpu) uprobe-nop ( 2 cpus): 1.773 ± 0.005M/s ( 0.887M/s/cpu) uprobe-nop ( 4 cpus): 3.304 ± 0.001M/s ( 0.826M/s/cpu) uprobe-nop ( 8 cpus): 5.328 ± 0.002M/s ( 0.666M/s/cpu) uprobe-nop (16 cpus): 6.475 ± 0.002M/s ( 0.405M/s/cpu) uprobe-nop (32 cpus): 4.831 ± 0.082M/s ( 0.151M/s/cpu) uprobe-nop (64 cpus): 2.564 ± 0.053M/s ( 0.040M/s/cpu) uprobe-push ( 1 cpus): 0.964 ± 0.001M/s ( 0.964M/s/cpu) uprobe-push ( 2 cpus): 1.766 ± 0.002M/s ( 0.883M/s/cpu) uprobe-push ( 4 cpus): 3.290 ± 0.009M/s ( 0.823M/s/cpu) uprobe-push ( 8 cpus): 4.670 ± 0.002M/s ( 0.584M/s/cpu) uprobe-push (16 cpus): 5.197 ± 0.004M/s ( 0.325M/s/cpu) uprobe-push (32 cpus): 5.068 ± 0.161M/s ( 0.158M/s/cpu) uprobe-push (64 cpus): 2.605 ± 0.026M/s ( 0.041M/s/cpu) uprobe-ret ( 1 cpus): 1.833 ± 0.001M/s ( 1.833M/s/cpu) uprobe-ret ( 2 cpus): 3.384 ± 0.003M/s ( 1.692M/s/cpu) uprobe-ret ( 4 cpus): 6.677 ± 0.004M/s ( 1.669M/s/cpu) uprobe-ret ( 8 cpus): 6.854 ± 0.005M/s ( 0.857M/s/cpu) uprobe-ret (16 cpus): 6.508 ± 0.006M/s ( 0.407M/s/cpu) uprobe-ret (32 cpus): 5.793 ± 0.009M/s ( 0.181M/s/cpu) uprobe-ret (64 cpus): 4.743 ± 0.016M/s ( 0.074M/s/cpu) Above benchmark results demonstrates a obivious improvement in the scalability of trig-uprobe-nop and trig-uprobe-push, the peak throughput of which are from 4.5M/s to 6.4M/s and 3.3M/s to 5.1M/s individually. [1] https://lore.kernel.org/all/20240731214256.3588718-1-andrii@kernel.org [2] https://lore.kernel.org/all/20240727094405.1362496-1-liaochang1@huawei.com Acked-by: Masami Hiramatsu (Google) Acked-by: Oleg Nesterov Signed-off-by: Liao Chang Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20250124093826.2123675-3-liaochang1@huawei.com --- include/linux/uprobes.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index b1df7d792fa1..a40efdda9052 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -143,6 +143,7 @@ struct uprobe_task { struct uprobe *active_uprobe; unsigned long xol_vaddr; + bool signal_denied; struct arch_uprobe *auprobe; }; -- cgit v1.3 From 8ce939a0fa194939cc1f92dbd8bc1a7806e7d40a Mon Sep 17 00:00:00 2001 From: "Peter Zijlstra (Intel)" Date: Tue, 21 Jan 2025 07:23:02 -0800 Subject: perf: Avoid the read if the count is already updated The event may have been updated in the PMU-specific implementation, e.g., Intel PEBS counters snapshotting. The common code should not read and overwrite the value. The PERF_SAMPLE_READ in the data->sample_type can be used to detect whether the PMU-specific value is available. If yes, avoid the pmu->read() in the common code. Add a new flag, skip_read, to track the case. Factor out a perf_pmu_read() to clean up the code. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20250121152303.3128733-3-kan.liang@linux.intel.com --- include/linux/perf_event.h | 8 +++++++- kernel/events/core.c | 33 ++++++++++++++++----------------- kernel/events/ring_buffer.c | 1 + 3 files changed, 24 insertions(+), 18 deletions(-) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 8333f132f4a9..2d07bc1193f3 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1062,7 +1062,13 @@ struct perf_output_handle { struct perf_buffer *rb; unsigned long wakeup; unsigned long size; - u64 aux_flags; + union { + u64 flags; /* perf_output*() */ + u64 aux_flags; /* perf_aux_output*() */ + struct { + u64 skip_read : 1; + }; + }; union { void *addr; unsigned long head; diff --git a/kernel/events/core.c b/kernel/events/core.c index bcb09e011e9e..0f8c55990783 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1191,6 +1191,12 @@ static void perf_assert_pmu_disabled(struct pmu *pmu) WARN_ON_ONCE(*this_cpu_ptr(pmu->pmu_disable_count) == 0); } +static inline void perf_pmu_read(struct perf_event *event) +{ + if (event->state == PERF_EVENT_STATE_ACTIVE) + event->pmu->read(event); +} + static void get_ctx(struct perf_event_context *ctx) { refcount_inc(&ctx->refcount); @@ -3473,8 +3479,7 @@ static void __perf_event_sync_stat(struct perf_event *event, * we know the event must be on the current CPU, therefore we * don't need to use it. */ - if (event->state == PERF_EVENT_STATE_ACTIVE) - event->pmu->read(event); + perf_pmu_read(event); perf_event_update_time(event); @@ -4618,15 +4623,8 @@ static void __perf_event_read(void *info) pmu->read(event); - for_each_sibling_event(sub, event) { - if (sub->state == PERF_EVENT_STATE_ACTIVE) { - /* - * Use sibling's PMU rather than @event's since - * sibling could be on different (eg: software) PMU. - */ - sub->pmu->read(sub); - } - } + for_each_sibling_event(sub, event) + perf_pmu_read(sub); data->ret = pmu->commit_txn(pmu); @@ -7444,9 +7442,8 @@ static void perf_output_read_group(struct perf_output_handle *handle, if (read_format & PERF_FORMAT_TOTAL_TIME_RUNNING) values[n++] = running; - if ((leader != event) && - (leader->state == PERF_EVENT_STATE_ACTIVE)) - leader->pmu->read(leader); + if ((leader != event) && !handle->skip_read) + perf_pmu_read(leader); values[n++] = perf_event_count(leader, self); if (read_format & PERF_FORMAT_ID) @@ -7459,9 +7456,8 @@ static void perf_output_read_group(struct perf_output_handle *handle, for_each_sibling_event(sub, leader) { n = 0; - if ((sub != event) && - (sub->state == PERF_EVENT_STATE_ACTIVE)) - sub->pmu->read(sub); + if ((sub != event) && !handle->skip_read) + perf_pmu_read(sub); values[n++] = perf_event_count(sub, self); if (read_format & PERF_FORMAT_ID) @@ -7520,6 +7516,9 @@ void perf_output_sample(struct perf_output_handle *handle, { u64 sample_type = data->type; + if (data->sample_flags & PERF_SAMPLE_READ) + handle->skip_read = 1; + perf_output_put(handle, *header); if (sample_type & PERF_SAMPLE_IDENTIFIER) diff --git a/kernel/events/ring_buffer.c b/kernel/events/ring_buffer.c index 180509132d4b..59a52b1a1f78 100644 --- a/kernel/events/ring_buffer.c +++ b/kernel/events/ring_buffer.c @@ -185,6 +185,7 @@ __perf_output_begin(struct perf_output_handle *handle, handle->rb = rb; handle->event = event; + handle->flags = 0; have_lost = local_read(&rb->lost); if (unlikely(have_lost)) { -- cgit v1.3 From 8aeacf257070469ff78a998a968a61d0cadc0de3 Mon Sep 17 00:00:00 2001 From: Joel Granados Date: Tue, 18 Feb 2025 10:56:21 +0100 Subject: perf/core: Move perf_event sysctls into kernel/events Move ctl tables to two files: - perf_event_{paranoid,mlock_kb,max_sample_rate} and perf_cpu_time_max_percent into kernel/events/core.c - perf_event_max_{stack,context_per_stack} into kernel/events/callchain.c Make static variables and functions that are fully contained in core.c and callchain.cand remove them from include/linux/perf_event.h. Additionally six_hundred_forty_kb is moved to callchain.c. Two new sysctl tables are added ({callchain,events_core}_sysctl_table) with their respective sysctl registration functions. This is part of a greater effort to move ctl tables into their respective subsystems which will reduce the merge conflicts in kerenel/sysctl.c. Signed-off-by: Joel Granados Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250218-jag-mv_ctltables-v1-5-cd3698ab8d29@kernel.org --- include/linux/perf_event.h | 9 ------- kernel/events/callchain.c | 38 ++++++++++++++++++++++----- kernel/events/core.c | 57 ++++++++++++++++++++++++++++++++++++----- kernel/sysctl.c | 64 ---------------------------------------------- 4 files changed, 83 insertions(+), 85 deletions(-) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 2d07bc1193f3..c4525bae2fe9 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1652,19 +1652,10 @@ static inline int perf_callchain_store(struct perf_callchain_entry_ctx *ctx, u64 } extern int sysctl_perf_event_paranoid; -extern int sysctl_perf_event_mlock; extern int sysctl_perf_event_sample_rate; -extern int sysctl_perf_cpu_time_max_percent; extern void perf_sample_event_took(u64 sample_len_ns); -int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write, - void *buffer, size_t *lenp, loff_t *ppos); -int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write, - void *buffer, size_t *lenp, loff_t *ppos); -int perf_event_max_stack_handler(const struct ctl_table *table, int write, - void *buffer, size_t *lenp, loff_t *ppos); - /* Access to perf_event_open(2) syscall. */ #define PERF_SECURITY_OPEN 0 diff --git a/kernel/events/callchain.c b/kernel/events/callchain.c index 8a47e52a454f..6c83ad674d01 100644 --- a/kernel/events/callchain.c +++ b/kernel/events/callchain.c @@ -22,6 +22,7 @@ struct callchain_cpus_entries { int sysctl_perf_event_max_stack __read_mostly = PERF_MAX_STACK_DEPTH; int sysctl_perf_event_max_contexts_per_stack __read_mostly = PERF_MAX_CONTEXTS_PER_STACK; +static const int six_hundred_forty_kb = 640 * 1024; static inline size_t perf_callchain_entry__sizeof(void) { @@ -266,12 +267,8 @@ exit_put: return entry; } -/* - * Used for sysctl_perf_event_max_stack and - * sysctl_perf_event_max_contexts_per_stack. - */ -int perf_event_max_stack_handler(const struct ctl_table *table, int write, - void *buffer, size_t *lenp, loff_t *ppos) +static int perf_event_max_stack_handler(const struct ctl_table *table, int write, + void *buffer, size_t *lenp, loff_t *ppos) { int *value = table->data; int new_value = *value, ret; @@ -292,3 +289,32 @@ int perf_event_max_stack_handler(const struct ctl_table *table, int write, return ret; } + +static const struct ctl_table callchain_sysctl_table[] = { + { + .procname = "perf_event_max_stack", + .data = &sysctl_perf_event_max_stack, + .maxlen = sizeof(sysctl_perf_event_max_stack), + .mode = 0644, + .proc_handler = perf_event_max_stack_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = (void *)&six_hundred_forty_kb, + }, + { + .procname = "perf_event_max_contexts_per_stack", + .data = &sysctl_perf_event_max_contexts_per_stack, + .maxlen = sizeof(sysctl_perf_event_max_contexts_per_stack), + .mode = 0644, + .proc_handler = perf_event_max_stack_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE_THOUSAND, + }, +}; + +static int __init init_callchain_sysctls(void) +{ + register_sysctl_init("kernel", callchain_sysctl_table); + return 0; +} +core_initcall(init_callchain_sysctls); + diff --git a/kernel/events/core.c b/kernel/events/core.c index 0f8c55990783..45ad0f608349 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -452,8 +452,8 @@ static struct kmem_cache *perf_event_cache; */ int sysctl_perf_event_paranoid __read_mostly = 2; -/* Minimum for 512 kiB + 1 user control page */ -int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' kiB per user */ +/* Minimum for 512 kiB + 1 user control page. 'free' kiB per user. */ +static int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* * max perf event sample rate @@ -463,6 +463,7 @@ int sysctl_perf_event_mlock __read_mostly = 512 + (PAGE_SIZE / 1024); /* 'free' #define DEFAULT_CPU_TIME_MAX_PERCENT 25 int sysctl_perf_event_sample_rate __read_mostly = DEFAULT_MAX_SAMPLE_RATE; +static int sysctl_perf_cpu_time_max_percent __read_mostly = DEFAULT_CPU_TIME_MAX_PERCENT; static int max_samples_per_tick __read_mostly = DIV_ROUND_UP(DEFAULT_MAX_SAMPLE_RATE, HZ); static int perf_sample_period_ns __read_mostly = DEFAULT_SAMPLE_PERIOD_NS; @@ -484,7 +485,7 @@ static void update_perf_cpu_limits(void) static bool perf_rotate_context(struct perf_cpu_pmu_context *cpc); -int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write, +static int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { int ret; @@ -506,9 +507,7 @@ int perf_event_max_sample_rate_handler(const struct ctl_table *table, int write, return 0; } -int sysctl_perf_cpu_time_max_percent __read_mostly = DEFAULT_CPU_TIME_MAX_PERCENT; - -int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write, +static int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); @@ -528,6 +527,52 @@ int perf_cpu_time_max_percent_handler(const struct ctl_table *table, int write, return 0; } +static const struct ctl_table events_core_sysctl_table[] = { + /* + * User-space relies on this file as a feature check for + * perf_events being enabled. It's an ABI, do not remove! + */ + { + .procname = "perf_event_paranoid", + .data = &sysctl_perf_event_paranoid, + .maxlen = sizeof(sysctl_perf_event_paranoid), + .mode = 0644, + .proc_handler = proc_dointvec, + }, + { + .procname = "perf_event_mlock_kb", + .data = &sysctl_perf_event_mlock, + .maxlen = sizeof(sysctl_perf_event_mlock), + .mode = 0644, + .proc_handler = proc_dointvec, + }, + { + .procname = "perf_event_max_sample_rate", + .data = &sysctl_perf_event_sample_rate, + .maxlen = sizeof(sysctl_perf_event_sample_rate), + .mode = 0644, + .proc_handler = perf_event_max_sample_rate_handler, + .extra1 = SYSCTL_ONE, + }, + { + .procname = "perf_cpu_time_max_percent", + .data = &sysctl_perf_cpu_time_max_percent, + .maxlen = sizeof(sysctl_perf_cpu_time_max_percent), + .mode = 0644, + .proc_handler = perf_cpu_time_max_percent_handler, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE_HUNDRED, + }, +}; + +static int __init init_events_core_sysctls(void) +{ + register_sysctl_init("kernel", events_core_sysctl_table); + return 0; +} +core_initcall(init_events_core_sysctls); + + /* * perf samples are done in some very critical code paths (NMIs). * If they take too much CPU time, the system can lock up and not diff --git a/kernel/sysctl.c b/kernel/sysctl.c index cb57da499ebb..4484cdb504c7 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -54,7 +54,6 @@ #include #include #include -#include #include #include #include @@ -91,12 +90,6 @@ EXPORT_SYMBOL_GPL(sysctl_long_vals); #if defined(CONFIG_SYSCTL) /* Constants used for minimum and maximum */ - -#ifdef CONFIG_PERF_EVENTS -static const int six_hundred_forty_kb = 640 * 1024; -#endif - - static const int ngroups_max = NGROUPS_MAX; static const int cap_last_cap = CAP_LAST_CAP; @@ -1932,63 +1925,6 @@ static const struct ctl_table kern_table[] = { .mode = 0644, .proc_handler = proc_dointvec, }, -#endif -#ifdef CONFIG_PERF_EVENTS - /* - * User-space scripts rely on the existence of this file - * as a feature check for perf_events being enabled. - * - * So it's an ABI, do not remove! - */ - { - .procname = "perf_event_paranoid", - .data = &sysctl_perf_event_paranoid, - .maxlen = sizeof(sysctl_perf_event_paranoid), - .mode = 0644, - .proc_handler = proc_dointvec, - }, - { - .procname = "perf_event_mlock_kb", - .data = &sysctl_perf_event_mlock, - .maxlen = sizeof(sysctl_perf_event_mlock), - .mode = 0644, - .proc_handler = proc_dointvec, - }, - { - .procname = "perf_event_max_sample_rate", - .data = &sysctl_perf_event_sample_rate, - .maxlen = sizeof(sysctl_perf_event_sample_rate), - .mode = 0644, - .proc_handler = perf_event_max_sample_rate_handler, - .extra1 = SYSCTL_ONE, - }, - { - .procname = "perf_cpu_time_max_percent", - .data = &sysctl_perf_cpu_time_max_percent, - .maxlen = sizeof(sysctl_perf_cpu_time_max_percent), - .mode = 0644, - .proc_handler = perf_cpu_time_max_percent_handler, - .extra1 = SYSCTL_ZERO, - .extra2 = SYSCTL_ONE_HUNDRED, - }, - { - .procname = "perf_event_max_stack", - .data = &sysctl_perf_event_max_stack, - .maxlen = sizeof(sysctl_perf_event_max_stack), - .mode = 0644, - .proc_handler = perf_event_max_stack_handler, - .extra1 = SYSCTL_ZERO, - .extra2 = (void *)&six_hundred_forty_kb, - }, - { - .procname = "perf_event_max_contexts_per_stack", - .data = &sysctl_perf_event_max_contexts_per_stack, - .maxlen = sizeof(sysctl_perf_event_max_contexts_per_stack), - .mode = 0644, - .proc_handler = perf_event_max_stack_handler, - .extra1 = SYSCTL_ZERO, - .extra2 = SYSCTL_ONE_THOUSAND, - }, #endif { .procname = "panic_on_warn", -- cgit v1.3 From c70ca298036c58a88686ff388d3d367e9d21acf0 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 4 Nov 2024 14:39:13 +0100 Subject: perf/core: Simplify the perf_event_alloc() error path The error cleanup sequence in perf_event_alloc() is a subset of the existing _free_event() function (it must of course be). Split this out into __free_event() and simplify the error path. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Ravi Bangoria Link: https://lore.kernel.org/r/20241104135517.967889521@infradead.org --- include/linux/perf_event.h | 16 +++--- kernel/events/core.c | 138 ++++++++++++++++++++++----------------------- 2 files changed, 78 insertions(+), 76 deletions(-) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index c4525bae2fe9..8c0117bcbdb9 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -673,13 +673,15 @@ struct swevent_hlist { struct rcu_head rcu_head; }; -#define PERF_ATTACH_CONTEXT 0x01 -#define PERF_ATTACH_GROUP 0x02 -#define PERF_ATTACH_TASK 0x04 -#define PERF_ATTACH_TASK_DATA 0x08 -#define PERF_ATTACH_ITRACE 0x10 -#define PERF_ATTACH_SCHED_CB 0x20 -#define PERF_ATTACH_CHILD 0x40 +#define PERF_ATTACH_CONTEXT 0x0001 +#define PERF_ATTACH_GROUP 0x0002 +#define PERF_ATTACH_TASK 0x0004 +#define PERF_ATTACH_TASK_DATA 0x0008 +#define PERF_ATTACH_ITRACE 0x0010 +#define PERF_ATTACH_SCHED_CB 0x0020 +#define PERF_ATTACH_CHILD 0x0040 +#define PERF_ATTACH_EXCLUSIVE 0x0080 +#define PERF_ATTACH_CALLCHAIN 0x0100 struct bpf_prog; struct perf_cgroup; diff --git a/kernel/events/core.c b/kernel/events/core.c index 6ccf363d73cc..1b8b1c8f41ff 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -5289,6 +5289,8 @@ static int exclusive_event_init(struct perf_event *event) return -EBUSY; } + event->attach_state |= PERF_ATTACH_EXCLUSIVE; + return 0; } @@ -5296,14 +5298,13 @@ static void exclusive_event_destroy(struct perf_event *event) { struct pmu *pmu = event->pmu; - if (!is_exclusive_pmu(pmu)) - return; - /* see comment in exclusive_event_init() */ if (event->attach_state & PERF_ATTACH_TASK) atomic_dec(&pmu->exclusive_cnt); else atomic_inc(&pmu->exclusive_cnt); + + event->attach_state &= ~PERF_ATTACH_EXCLUSIVE; } static bool exclusive_event_match(struct perf_event *e1, struct perf_event *e2) @@ -5362,40 +5363,20 @@ static void perf_pending_task_sync(struct perf_event *event) rcuwait_wait_event(&event->pending_work_wait, !event->pending_work, TASK_UNINTERRUPTIBLE); } -static void _free_event(struct perf_event *event) +/* vs perf_event_alloc() error */ +static void __free_event(struct perf_event *event) { - irq_work_sync(&event->pending_irq); - irq_work_sync(&event->pending_disable_irq); - perf_pending_task_sync(event); + if (event->attach_state & PERF_ATTACH_CALLCHAIN) + put_callchain_buffers(); - unaccount_event(event); + kfree(event->addr_filter_ranges); - security_perf_event_free(event); - - if (event->rb) { - /* - * Can happen when we close an event with re-directed output. - * - * Since we have a 0 refcount, perf_mmap_close() will skip - * over us; possibly making our ring_buffer_put() the last. - */ - mutex_lock(&event->mmap_mutex); - ring_buffer_attach(event, NULL); - mutex_unlock(&event->mmap_mutex); - } + if (event->attach_state & PERF_ATTACH_EXCLUSIVE) + exclusive_event_destroy(event); if (is_cgroup_event(event)) perf_detach_cgroup(event); - if (!event->parent) { - if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) - put_callchain_buffers(); - } - - perf_event_free_bpf_prog(event); - perf_addr_filters_splice(event, NULL); - kfree(event->addr_filter_ranges); - if (event->destroy) event->destroy(event); @@ -5406,22 +5387,58 @@ static void _free_event(struct perf_event *event) if (event->hw.target) put_task_struct(event->hw.target); - if (event->pmu_ctx) + if (event->pmu_ctx) { + /* + * put_pmu_ctx() needs an event->ctx reference, because of + * epc->ctx. + */ + WARN_ON_ONCE(!event->ctx); + WARN_ON_ONCE(event->pmu_ctx->ctx != event->ctx); put_pmu_ctx(event->pmu_ctx); + } /* - * perf_event_free_task() relies on put_ctx() being 'last', in particular - * all task references must be cleaned up. + * perf_event_free_task() relies on put_ctx() being 'last', in + * particular all task references must be cleaned up. */ if (event->ctx) put_ctx(event->ctx); - exclusive_event_destroy(event); - module_put(event->pmu->module); + if (event->pmu) + module_put(event->pmu->module); call_rcu(&event->rcu_head, free_event_rcu); } +/* vs perf_event_alloc() success */ +static void _free_event(struct perf_event *event) +{ + irq_work_sync(&event->pending_irq); + irq_work_sync(&event->pending_disable_irq); + perf_pending_task_sync(event); + + unaccount_event(event); + + security_perf_event_free(event); + + if (event->rb) { + /* + * Can happen when we close an event with re-directed output. + * + * Since we have a 0 refcount, perf_mmap_close() will skip + * over us; possibly making our ring_buffer_put() the last. + */ + mutex_lock(&event->mmap_mutex); + ring_buffer_attach(event, NULL); + mutex_unlock(&event->mmap_mutex); + } + + perf_event_free_bpf_prog(event); + perf_addr_filters_splice(event, NULL); + + __free_event(event); +} + /* * Used to free events which have a known refcount of 1, such as in error paths * where the event isn't exposed yet and inherited events. @@ -12093,8 +12110,10 @@ static int perf_try_init_event(struct pmu *pmu, struct perf_event *event) event->destroy(event); } - if (ret) + if (ret) { + event->pmu = NULL; module_put(pmu->module); + } return ret; } @@ -12422,7 +12441,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, * See perf_output_read(). */ if (has_inherit_and_sample_read(attr) && !(attr->sample_type & PERF_SAMPLE_TID)) - goto err_ns; + goto err; if (!has_branch_stack(event)) event->attr.branch_sample_type = 0; @@ -12430,7 +12449,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, pmu = perf_init_event(event); if (IS_ERR(pmu)) { err = PTR_ERR(pmu); - goto err_ns; + goto err; } /* @@ -12440,25 +12459,25 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, */ if (pmu->task_ctx_nr == perf_invalid_context && (task || cgroup_fd != -1)) { err = -EINVAL; - goto err_pmu; + goto err; } if (event->attr.aux_output && (!(pmu->capabilities & PERF_PMU_CAP_AUX_OUTPUT) || event->attr.aux_pause || event->attr.aux_resume)) { err = -EOPNOTSUPP; - goto err_pmu; + goto err; } if (event->attr.aux_pause && event->attr.aux_resume) { err = -EINVAL; - goto err_pmu; + goto err; } if (event->attr.aux_start_paused) { if (!(pmu->capabilities & PERF_PMU_CAP_AUX_PAUSE)) { err = -EOPNOTSUPP; - goto err_pmu; + goto err; } event->hw.aux_paused = 1; } @@ -12466,12 +12485,12 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, if (cgroup_fd != -1) { err = perf_cgroup_connect(cgroup_fd, event, attr, group_leader); if (err) - goto err_pmu; + goto err; } err = exclusive_event_init(event); if (err) - goto err_pmu; + goto err; if (has_addr_filter(event)) { event->addr_filter_ranges = kcalloc(pmu->nr_addr_filters, @@ -12479,7 +12498,7 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, GFP_KERNEL); if (!event->addr_filter_ranges) { err = -ENOMEM; - goto err_per_task; + goto err; } /* @@ -12504,41 +12523,22 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) { err = get_callchain_buffers(attr->sample_max_stack); if (err) - goto err_addr_filters; + goto err; + event->attach_state |= PERF_ATTACH_CALLCHAIN; } } err = security_perf_event_alloc(event); if (err) - goto err_callchain_buffer; + goto err; /* symmetric to unaccount_event() in _free_event() */ account_event(event); return event; -err_callchain_buffer: - if (!event->parent) { - if (event->attr.sample_type & PERF_SAMPLE_CALLCHAIN) - put_callchain_buffers(); - } -err_addr_filters: - kfree(event->addr_filter_ranges); - -err_per_task: - exclusive_event_destroy(event); - -err_pmu: - if (is_cgroup_event(event)) - perf_detach_cgroup(event); - if (event->destroy) - event->destroy(event); - module_put(pmu->module); -err_ns: - if (event->hw.target) - put_task_struct(event->hw.target); - call_rcu(&event->rcu_head, free_event_rcu); - +err: + __free_event(event); return ERR_PTR(err); } -- cgit v1.3 From 6c8b0b835f003647e593c08331a4dd2150d5eb0e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 4 Nov 2024 14:39:15 +0100 Subject: perf/core: Simplify perf_pmu_register() Using the previously introduced perf_pmu_free() and a new IDR helper, simplify the perf_pmu_register error paths. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Acked-by: Ravi Bangoria Link: https://lore.kernel.org/r/20241104135518.198937277@infradead.org --- include/linux/idr.h | 17 +++++++++++++ kernel/events/core.c | 71 +++++++++++++++++++++------------------------------- 2 files changed, 46 insertions(+), 42 deletions(-) (limited to 'include/linux') diff --git a/include/linux/idr.h b/include/linux/idr.h index da5f5fa4a3a6..cd729be369b3 100644 --- a/include/linux/idr.h +++ b/include/linux/idr.h @@ -15,6 +15,7 @@ #include #include #include +#include struct idr { struct radix_tree_root idr_rt; @@ -124,6 +125,22 @@ void *idr_get_next_ul(struct idr *, unsigned long *nextid); void *idr_replace(struct idr *, void *, unsigned long id); void idr_destroy(struct idr *); +struct __class_idr { + struct idr *idr; + int id; +}; + +#define idr_null ((struct __class_idr){ NULL, -1 }) +#define take_idr_id(id) __get_and_null(id, idr_null) + +DEFINE_CLASS(idr_alloc, struct __class_idr, + if (_T.id >= 0) idr_remove(_T.idr, _T.id), + ((struct __class_idr){ + .idr = idr, + .id = idr_alloc(idr, ptr, start, end, gfp), + }), + struct idr *idr, void *ptr, int start, int end, gfp_t gfp); + /** * idr_init_base() - Initialise an IDR. * @idr: IDR handle. diff --git a/kernel/events/core.c b/kernel/events/core.c index ee5cdd692383..215dad53aa1b 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -11914,52 +11914,49 @@ static void perf_pmu_free(struct pmu *pmu) free_percpu(pmu->cpu_pmu_context); } -int perf_pmu_register(struct pmu *pmu, const char *name, int type) +DEFINE_FREE(pmu_unregister, struct pmu *, if (_T) perf_pmu_free(_T)) + +int perf_pmu_register(struct pmu *_pmu, const char *name, int type) { - int cpu, ret, max = PERF_TYPE_MAX; + int cpu, max = PERF_TYPE_MAX; - pmu->type = -1; + struct pmu *pmu __free(pmu_unregister) = _pmu; + guard(mutex)(&pmus_lock); - mutex_lock(&pmus_lock); - ret = -ENOMEM; pmu->pmu_disable_count = alloc_percpu(int); if (!pmu->pmu_disable_count) - goto unlock; + return -ENOMEM; - if (WARN_ONCE(!name, "Can not register anonymous pmu.\n")) { - ret = -EINVAL; - goto free; - } + if (WARN_ONCE(!name, "Can not register anonymous pmu.\n")) + return -EINVAL; - if (WARN_ONCE(pmu->scope >= PERF_PMU_MAX_SCOPE, "Can not register a pmu with an invalid scope.\n")) { - ret = -EINVAL; - goto free; - } + if (WARN_ONCE(pmu->scope >= PERF_PMU_MAX_SCOPE, + "Can not register a pmu with an invalid scope.\n")) + return -EINVAL; pmu->name = name; if (type >= 0) max = type; - ret = idr_alloc(&pmu_idr, NULL, max, 0, GFP_KERNEL); - if (ret < 0) - goto free; + CLASS(idr_alloc, pmu_type)(&pmu_idr, NULL, max, 0, GFP_KERNEL); + if (pmu_type.id < 0) + return pmu_type.id; - WARN_ON(type >= 0 && ret != type); + WARN_ON(type >= 0 && pmu_type.id != type); - pmu->type = ret; + pmu->type = pmu_type.id; atomic_set(&pmu->exclusive_cnt, 0); if (pmu_bus_running && !pmu->dev) { - ret = pmu_dev_alloc(pmu); + int ret = pmu_dev_alloc(pmu); if (ret) - goto free; + return ret; } - ret = -ENOMEM; pmu->cpu_pmu_context = alloc_percpu(struct perf_cpu_pmu_context); if (!pmu->cpu_pmu_context) - goto free; + return -ENOMEM; for_each_possible_cpu(cpu) { struct perf_cpu_pmu_context *cpc; @@ -12000,32 +11997,22 @@ int perf_pmu_register(struct pmu *pmu, const char *name, int type) /* * Now that the PMU is complete, make it visible to perf_try_init_event(). */ - if (!idr_cmpxchg(&pmu_idr, pmu->type, NULL, pmu)) { - ret = -EINVAL; - goto free; - } + if (!idr_cmpxchg(&pmu_idr, pmu->type, NULL, pmu)) + return -EINVAL; list_add_rcu(&pmu->entry, &pmus); - ret = 0; -unlock: - mutex_unlock(&pmus_lock); - - return ret; - -free: - if (pmu->type >= 0) - idr_remove(&pmu_idr, pmu->type); - perf_pmu_free(pmu); - goto unlock; + take_idr_id(pmu_type); + _pmu = no_free_ptr(pmu); // let it rip + return 0; } EXPORT_SYMBOL_GPL(perf_pmu_register); void perf_pmu_unregister(struct pmu *pmu) { - mutex_lock(&pmus_lock); - list_del_rcu(&pmu->entry); - idr_remove(&pmu_idr, pmu->type); - mutex_unlock(&pmus_lock); + scoped_guard (mutex, &pmus_lock) { + list_del_rcu(&pmu->entry); + idr_remove(&pmu_idr, pmu->type); + } /* * We dereference the pmu list under both SRCU and regular RCU, so -- cgit v1.3 From 4baeb0687abf5eca3f7ab8b147c27cce82ec49ea Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 4 Nov 2024 14:39:18 +0100 Subject: perf/core: Merge struct pmu::pmu_disable_count into struct perf_cpu_pmu_context::pmu_disable_count Because it makes no sense to have two per-cpu allocations per pmu. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Ravi Bangoria Link: https://lore.kernel.org/r/20241104135518.518730578@infradead.org --- include/linux/perf_event.h | 2 +- kernel/events/core.c | 12 ++++-------- 2 files changed, 5 insertions(+), 9 deletions(-) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 8c0117bcbdb9..5f293e679ab6 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -343,7 +343,6 @@ struct pmu { */ unsigned int scope; - int __percpu *pmu_disable_count; struct perf_cpu_pmu_context __percpu *cpu_pmu_context; atomic_t exclusive_cnt; /* < 0: cpu; > 0: tsk */ int task_ctx_nr; @@ -1031,6 +1030,7 @@ struct perf_cpu_pmu_context { int active_oncpu; int exclusive; + int pmu_disable_count; raw_spinlock_t hrtimer_lock; struct hrtimer hrtimer; diff --git a/kernel/events/core.c b/kernel/events/core.c index 348a379d4f05..8321b719b6ab 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1219,21 +1219,22 @@ static int perf_mux_hrtimer_restart_ipi(void *arg) void perf_pmu_disable(struct pmu *pmu) { - int *count = this_cpu_ptr(pmu->pmu_disable_count); + int *count = &this_cpu_ptr(pmu->cpu_pmu_context)->pmu_disable_count; if (!(*count)++) pmu->pmu_disable(pmu); } void perf_pmu_enable(struct pmu *pmu) { - int *count = this_cpu_ptr(pmu->pmu_disable_count); + int *count = &this_cpu_ptr(pmu->cpu_pmu_context)->pmu_disable_count; if (!--(*count)) pmu->pmu_enable(pmu); } static void perf_assert_pmu_disabled(struct pmu *pmu) { - WARN_ON_ONCE(*this_cpu_ptr(pmu->pmu_disable_count) == 0); + int *count = &this_cpu_ptr(pmu->cpu_pmu_context)->pmu_disable_count; + WARN_ON_ONCE(*count == 0); } static inline void perf_pmu_read(struct perf_event *event) @@ -11906,7 +11907,6 @@ static bool idr_cmpxchg(struct idr *idr, unsigned long id, void *old, void *new) static void perf_pmu_free(struct pmu *pmu) { - free_percpu(pmu->pmu_disable_count); if (pmu_bus_running && pmu->dev && pmu->dev != PMU_NULL_DEV) { if (pmu->nr_addr_filters) device_remove_file(pmu->dev, &dev_attr_nr_addr_filters); @@ -11925,10 +11925,6 @@ int perf_pmu_register(struct pmu *_pmu, const char *name, int type) struct pmu *pmu __free(pmu_unregister) = _pmu; guard(mutex)(&pmus_lock); - pmu->pmu_disable_count = alloc_percpu(int); - if (!pmu->pmu_disable_count) - return -ENOMEM; - if (WARN_ONCE(!name, "Can not register anonymous pmu.\n")) return -EINVAL; -- cgit v1.3 From 4eabf533fb1886089ef57e0c8ec52048b1741e39 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 4 Nov 2024 14:39:20 +0100 Subject: perf/core: Detach 'struct perf_cpu_pmu_context' and 'struct pmu' lifetimes In prepration for being able to unregister a PMU with existing events, it becomes important to detach struct perf_cpu_pmu_context lifetimes from that of struct pmu. Notably struct perf_cpu_pmu_context embeds a struct perf_event_pmu_context that can stay referenced until the last event goes. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Ravi Bangoria Link: https://lore.kernel.org/r/20241104135518.760214287@infradead.org --- include/linux/perf_event.h | 4 ++-- kernel/events/core.c | 56 ++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 49 insertions(+), 11 deletions(-) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 5f293e679ab6..76f4265efee9 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -343,7 +343,7 @@ struct pmu { */ unsigned int scope; - struct perf_cpu_pmu_context __percpu *cpu_pmu_context; + struct perf_cpu_pmu_context __percpu **cpu_pmu_context; atomic_t exclusive_cnt; /* < 0: cpu; > 0: tsk */ int task_ctx_nr; int hrtimer_interval_ms; @@ -922,7 +922,7 @@ struct perf_event_pmu_context { struct list_head pinned_active; struct list_head flexible_active; - /* Used to avoid freeing per-cpu perf_event_pmu_context */ + /* Used to identify the per-cpu perf_event_pmu_context */ unsigned int embedded : 1; unsigned int nr_events; diff --git a/kernel/events/core.c b/kernel/events/core.c index 773875aaa291..8b2a8c36d124 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1219,7 +1219,7 @@ static int perf_mux_hrtimer_restart_ipi(void *arg) static __always_inline struct perf_cpu_pmu_context *this_cpc(struct pmu *pmu) { - return this_cpu_ptr(pmu->cpu_pmu_context); + return *this_cpu_ptr(pmu->cpu_pmu_context); } void perf_pmu_disable(struct pmu *pmu) @@ -5007,11 +5007,14 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx, */ struct perf_cpu_pmu_context *cpc; - cpc = per_cpu_ptr(pmu->cpu_pmu_context, event->cpu); + cpc = *per_cpu_ptr(pmu->cpu_pmu_context, event->cpu); epc = &cpc->epc; raw_spin_lock_irq(&ctx->lock); if (!epc->ctx) { - atomic_set(&epc->refcount, 1); + /* + * One extra reference for the pmu; see perf_pmu_free(). + */ + atomic_set(&epc->refcount, 2); epc->embedded = 1; list_add(&epc->pmu_ctx_entry, &ctx->pmu_ctx_list); epc->ctx = ctx; @@ -5087,6 +5090,15 @@ static void get_pmu_ctx(struct perf_event_pmu_context *epc) WARN_ON_ONCE(!atomic_inc_not_zero(&epc->refcount)); } +static void free_cpc_rcu(struct rcu_head *head) +{ + struct perf_cpu_pmu_context *cpc = + container_of(head, typeof(*cpc), epc.rcu_head); + + kfree(cpc->epc.task_ctx_data); + kfree(cpc); +} + static void free_epc_rcu(struct rcu_head *head) { struct perf_event_pmu_context *epc = container_of(head, typeof(*epc), rcu_head); @@ -5121,8 +5133,10 @@ static void put_pmu_ctx(struct perf_event_pmu_context *epc) raw_spin_unlock_irqrestore(&ctx->lock, flags); - if (epc->embedded) + if (epc->embedded) { + call_rcu(&epc->rcu_head, free_cpc_rcu); return; + } call_rcu(&epc->rcu_head, free_epc_rcu); } @@ -11752,7 +11766,7 @@ perf_event_mux_interval_ms_store(struct device *dev, cpus_read_lock(); for_each_online_cpu(cpu) { struct perf_cpu_pmu_context *cpc; - cpc = per_cpu_ptr(pmu->cpu_pmu_context, cpu); + cpc = *per_cpu_ptr(pmu->cpu_pmu_context, cpu); cpc->hrtimer_interval = ns_to_ktime(NSEC_PER_MSEC * timer); cpu_function_call(cpu, perf_mux_hrtimer_restart_ipi, cpc); @@ -11925,7 +11939,25 @@ static void perf_pmu_free(struct pmu *pmu) device_del(pmu->dev); put_device(pmu->dev); } - free_percpu(pmu->cpu_pmu_context); + + if (pmu->cpu_pmu_context) { + int cpu; + + for_each_possible_cpu(cpu) { + struct perf_cpu_pmu_context *cpc; + + cpc = *per_cpu_ptr(pmu->cpu_pmu_context, cpu); + if (!cpc) + continue; + if (cpc->epc.embedded) { + /* refcount managed */ + put_pmu_ctx(&cpc->epc); + continue; + } + kfree(cpc); + } + free_percpu(pmu->cpu_pmu_context); + } } DEFINE_FREE(pmu_unregister, struct pmu *, if (_T) perf_pmu_free(_T)) @@ -11964,14 +11996,20 @@ int perf_pmu_register(struct pmu *_pmu, const char *name, int type) return ret; } - pmu->cpu_pmu_context = alloc_percpu(struct perf_cpu_pmu_context); + pmu->cpu_pmu_context = alloc_percpu(struct perf_cpu_pmu_context *); if (!pmu->cpu_pmu_context) return -ENOMEM; for_each_possible_cpu(cpu) { - struct perf_cpu_pmu_context *cpc; + struct perf_cpu_pmu_context *cpc = + kmalloc_node(sizeof(struct perf_cpu_pmu_context), + GFP_KERNEL | __GFP_ZERO, + cpu_to_node(cpu)); + + if (!cpc) + return -ENOMEM; - cpc = per_cpu_ptr(pmu->cpu_pmu_context, cpu); + *per_cpu_ptr(pmu->cpu_pmu_context, cpu) = cpc; __perf_init_event_pmu_context(&cpc->epc, pmu); __perf_mux_hrtimer_init(cpc, cpu); } -- cgit v1.3 From d6834d9c990333bfa433bc1816e2417f268eebbe Mon Sep 17 00:00:00 2001 From: Li Huafei Date: Tue, 22 Oct 2024 03:30:03 +0800 Subject: watchdog/hardlockup/perf: Fix perf_event memory leak During stress-testing, we found a kmemleak report for perf_event: unreferenced object 0xff110001410a33e0 (size 1328): comm "kworker/4:11", pid 288, jiffies 4294916004 hex dump (first 32 bytes): b8 be c2 3b 02 00 11 ff 22 01 00 00 00 00 ad de ...;...."....... f0 33 0a 41 01 00 11 ff f0 33 0a 41 01 00 11 ff .3.A.....3.A.... backtrace (crc 24eb7b3a): [<00000000e211b653>] kmem_cache_alloc_node_noprof+0x269/0x2e0 [<000000009d0985fa>] perf_event_alloc+0x5f/0xcf0 [<00000000084ad4a2>] perf_event_create_kernel_counter+0x38/0x1b0 [<00000000fde96401>] hardlockup_detector_event_create+0x50/0xe0 [<0000000051183158>] watchdog_hardlockup_enable+0x17/0x70 [<00000000ac89727f>] softlockup_start_fn+0x15/0x40 ... Our stress test includes CPU online and offline cycles, and updating the watchdog configuration. After reading the code, I found that there may be a race between cleaning up perf_event after updating watchdog and disabling event when the CPU goes offline: CPU0 CPU1 CPU2 (update watchdog) (hotplug offline CPU1) ... _cpu_down(CPU1) cpus_read_lock() // waiting for cpu lock softlockup_start_all smp_call_on_cpu(CPU1) softlockup_start_fn ... watchdog_hardlockup_enable(CPU1) perf create E1 watchdog_ev[CPU1] = E1 cpus_read_unlock() cpus_write_lock() cpuhp_kick_ap_work(CPU1) cpuhp_thread_fun ... watchdog_hardlockup_disable(CPU1) watchdog_ev[CPU1] = NULL dead_event[CPU1] = E1 __lockup_detector_cleanup for each dead_events_mask release each dead_event /* * CPU1 has not been added to * dead_events_mask, then E1 * will not be released */ CPU1 -> dead_events_mask cpumask_clear(&dead_events_mask) // dead_events_mask is cleared, E1 is leaked In this case, the leaked perf_event E1 matches the perf_event leak reported by kmemleak. Due to the low probability of problem recurrence (only reported once), I added some hack delays in the code: static void __lockup_detector_reconfigure(void) { ... watchdog_hardlockup_start(); cpus_read_unlock(); + mdelay(100); /* * Must be called outside the cpus locked section to prevent * recursive locking in the perf code. ... } void watchdog_hardlockup_disable(unsigned int cpu) { ... perf_event_disable(event); this_cpu_write(watchdog_ev, NULL); this_cpu_write(dead_event, event); + mdelay(100); cpumask_set_cpu(smp_processor_id(), &dead_events_mask); atomic_dec(&watchdog_cpus); ... } void hardlockup_detector_perf_cleanup(void) { ... perf_event_release_kernel(event); per_cpu(dead_event, cpu) = NULL; } + mdelay(100); cpumask_clear(&dead_events_mask); } Then, simultaneously performing CPU on/off and switching watchdog, it is almost certain to reproduce this leak. The problem here is that releasing perf_event is not within the CPU hotplug read-write lock. Commit: 941154bd6937 ("watchdog/hardlockup/perf: Prevent CPU hotplug deadlock") introduced deferred release to solve the deadlock caused by calling get_online_cpus() when releasing perf_event. Later, commit: efe951d3de91 ("perf/x86: Fix perf,x86,cpuhp deadlock") removed the get_online_cpus() call on the perf_event release path to solve another deadlock problem. Therefore, it is now possible to move the release of perf_event back into the CPU hotplug read-write lock, and release the event immediately after disabling it. Fixes: 941154bd6937 ("watchdog/hardlockup/perf: Prevent CPU hotplug deadlock") Signed-off-by: Li Huafei Signed-off-by: Ingo Molnar Cc: Thomas Gleixner Cc: Peter Zijlstra Link: https://lore.kernel.org/r/20241021193004.308303-1-lihuafei1@huawei.com --- include/linux/nmi.h | 4 ---- kernel/cpu.c | 5 ----- kernel/watchdog.c | 25 ------------------------- kernel/watchdog_perf.c | 28 +--------------------------- 4 files changed, 1 insertion(+), 61 deletions(-) (limited to 'include/linux') diff --git a/include/linux/nmi.h b/include/linux/nmi.h index a8dfb38c9bb6..e78fa535f61d 100644 --- a/include/linux/nmi.h +++ b/include/linux/nmi.h @@ -17,7 +17,6 @@ void lockup_detector_init(void); void lockup_detector_retry_init(void); void lockup_detector_soft_poweroff(void); -void lockup_detector_cleanup(void); extern int watchdog_user_enabled; extern int watchdog_thresh; @@ -37,7 +36,6 @@ extern int sysctl_hardlockup_all_cpu_backtrace; static inline void lockup_detector_init(void) { } static inline void lockup_detector_retry_init(void) { } static inline void lockup_detector_soft_poweroff(void) { } -static inline void lockup_detector_cleanup(void) { } #endif /* !CONFIG_LOCKUP_DETECTOR */ #ifdef CONFIG_SOFTLOCKUP_DETECTOR @@ -104,12 +102,10 @@ void watchdog_hardlockup_check(unsigned int cpu, struct pt_regs *regs); #if defined(CONFIG_HARDLOCKUP_DETECTOR_PERF) extern void hardlockup_detector_perf_stop(void); extern void hardlockup_detector_perf_restart(void); -extern void hardlockup_detector_perf_cleanup(void); extern void hardlockup_config_perf_event(const char *str); #else static inline void hardlockup_detector_perf_stop(void) { } static inline void hardlockup_detector_perf_restart(void) { } -static inline void hardlockup_detector_perf_cleanup(void) { } static inline void hardlockup_config_perf_event(const char *str) { } #endif diff --git a/kernel/cpu.c b/kernel/cpu.c index 07455d25329c..ad755db29efd 100644 --- a/kernel/cpu.c +++ b/kernel/cpu.c @@ -1453,11 +1453,6 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen, out: cpus_write_unlock(); - /* - * Do post unplug cleanup. This is still protected against - * concurrent CPU hotplug via cpu_add_remove_lock. - */ - lockup_detector_cleanup(); arch_smt_update(); return ret; } diff --git a/kernel/watchdog.c b/kernel/watchdog.c index b2da7de39d06..18156023e461 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -347,8 +347,6 @@ static int __init watchdog_thresh_setup(char *str) } __setup("watchdog_thresh=", watchdog_thresh_setup); -static void __lockup_detector_cleanup(void); - #ifdef CONFIG_SOFTLOCKUP_DETECTOR_INTR_STORM enum stats_per_group { STATS_SYSTEM, @@ -886,11 +884,6 @@ static void __lockup_detector_reconfigure(void) watchdog_hardlockup_start(); cpus_read_unlock(); - /* - * Must be called outside the cpus locked section to prevent - * recursive locking in the perf code. - */ - __lockup_detector_cleanup(); } void lockup_detector_reconfigure(void) @@ -940,24 +933,6 @@ static inline void lockup_detector_setup(void) } #endif /* !CONFIG_SOFTLOCKUP_DETECTOR */ -static void __lockup_detector_cleanup(void) -{ - lockdep_assert_held(&watchdog_mutex); - hardlockup_detector_perf_cleanup(); -} - -/** - * lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes - * - * Caller must not hold the cpu hotplug rwsem. - */ -void lockup_detector_cleanup(void) -{ - mutex_lock(&watchdog_mutex); - __lockup_detector_cleanup(); - mutex_unlock(&watchdog_mutex); -} - /** * lockup_detector_soft_poweroff - Interface to stop lockup detector(s) * diff --git a/kernel/watchdog_perf.c b/kernel/watchdog_perf.c index 59c1d86a73a2..2fdb96eaf493 100644 --- a/kernel/watchdog_perf.c +++ b/kernel/watchdog_perf.c @@ -21,8 +21,6 @@ #include static DEFINE_PER_CPU(struct perf_event *, watchdog_ev); -static DEFINE_PER_CPU(struct perf_event *, dead_event); -static struct cpumask dead_events_mask; static atomic_t watchdog_cpus = ATOMIC_INIT(0); @@ -181,36 +179,12 @@ void watchdog_hardlockup_disable(unsigned int cpu) if (event) { perf_event_disable(event); + perf_event_release_kernel(event); this_cpu_write(watchdog_ev, NULL); - this_cpu_write(dead_event, event); - cpumask_set_cpu(smp_processor_id(), &dead_events_mask); atomic_dec(&watchdog_cpus); } } -/** - * hardlockup_detector_perf_cleanup - Cleanup disabled events and destroy them - * - * Called from lockup_detector_cleanup(). Serialized by the caller. - */ -void hardlockup_detector_perf_cleanup(void) -{ - int cpu; - - for_each_cpu(cpu, &dead_events_mask) { - struct perf_event *event = per_cpu(dead_event, cpu); - - /* - * Required because for_each_cpu() reports unconditionally - * CPU0 as set on UP kernels. Sigh. - */ - if (event) - perf_event_release_kernel(event); - per_cpu(dead_event, cpu) = NULL; - } - cpumask_clear(&dead_events_mask); -} - /** * hardlockup_detector_perf_stop - Globally stop watchdog events * -- cgit v1.3 From fa6192adc32f4fdfe5b74edd5b210e12afd6ecc0 Mon Sep 17 00:00:00 2001 From: Jiri Olsa Date: Wed, 12 Feb 2025 23:04:33 +0100 Subject: uprobes/x86: Harden uretprobe syscall trampoline check Jann reported a possible issue when trampoline_check_ip returns address near the bottom of the address space that is allowed to call into the syscall if uretprobes are not set up: https://lore.kernel.org/bpf/202502081235.5A6F352985@keescook/T/#m9d416df341b8fbc11737dacbcd29f0054413cbbf Though the mmap minimum address restrictions will typically prevent creating mappings there, let's make sure uretprobe syscall checks for that. Fixes: ff474a78cef5 ("uprobe: Add uretprobe syscall to speed up return probe") Reported-by: Jann Horn Signed-off-by: Jiri Olsa Signed-off-by: Ingo Molnar Reviewed-by: Oleg Nesterov Reviewed-by: Kees Cook Acked-by: Andrii Nakryiko Acked-by: Masami Hiramatsu (Google) Acked-by: Alexei Starovoitov Cc: Andy Lutomirski Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20250212220433.3624297-1-jolsa@kernel.org --- arch/x86/kernel/uprobes.c | 14 +++++++++----- include/linux/uprobes.h | 2 ++ kernel/events/uprobes.c | 2 +- 3 files changed, 12 insertions(+), 6 deletions(-) (limited to 'include/linux') diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 5a952c5ea66b..9194695662b2 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -357,19 +357,23 @@ void *arch_uprobe_trampoline(unsigned long *psize) return &insn; } -static unsigned long trampoline_check_ip(void) +static unsigned long trampoline_check_ip(unsigned long tramp) { - unsigned long tramp = uprobe_get_trampoline_vaddr(); - return tramp + (uretprobe_syscall_check - uretprobe_trampoline_entry); } SYSCALL_DEFINE0(uretprobe) { struct pt_regs *regs = task_pt_regs(current); - unsigned long err, ip, sp, r11_cx_ax[3]; + unsigned long err, ip, sp, r11_cx_ax[3], tramp; + + /* If there's no trampoline, we are called from wrong place. */ + tramp = uprobe_get_trampoline_vaddr(); + if (unlikely(tramp == UPROBE_NO_TRAMPOLINE_VADDR)) + goto sigill; - if (regs->ip != trampoline_check_ip()) + /* Make sure the ip matches the only allowed sys_uretprobe caller. */ + if (unlikely(regs->ip != trampoline_check_ip(tramp))) goto sigill; err = copy_from_user(r11_cx_ax, (void __user *)regs->sp, sizeof(r11_cx_ax)); diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index a40efdda9052..2e46b69ff0a6 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -39,6 +39,8 @@ struct page; #define MAX_URETPROBE_DEPTH 64 +#define UPROBE_NO_TRAMPOLINE_VADDR (~0UL) + struct uprobe_consumer { /* * handler() can return UPROBE_HANDLER_REMOVE to signal the need to diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 921ad9162136..70c84b9d7be3 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -2169,8 +2169,8 @@ void uprobe_copy_process(struct task_struct *t, unsigned long flags) */ unsigned long uprobe_get_trampoline_vaddr(void) { + unsigned long trampoline_vaddr = UPROBE_NO_TRAMPOLINE_VADDR; struct xol_area *area; - unsigned long trampoline_vaddr = -1; /* Pairs with xol_add_vma() smp_store_release() */ area = READ_ONCE(current->mm->uprobes_state.xol_area); /* ^^^ */ -- cgit v1.3 From c53e14f1ea4a8f8ddd9b2cd850fcbc0d934b79f5 Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Mon, 10 Mar 2025 11:15:36 -0700 Subject: perf: Extend per event callchain limit to branch stack The commit 97c79a38cd45 ("perf core: Per event callchain limit") introduced a per-event term to allow finer tuning of the depth of callchains to save space. It should be applied to the branch stack as well. For example, autoFDO collections require maximum LBR entries. In the meantime, other system-wide LBR users may only be interested in the latest a few number of LBRs. A per-event LBR depth would save the perf output buffer. The patch simply drops the uninterested branches, but HW still collects the maximum branches. There may be a model-specific optimization that can reduce the HW depth for some cases to reduce the overhead further. But it isn't included in the patch set. Because it's not useful for all cases. For example, ARCH LBR can utilize the PEBS and XSAVE to collect LBRs. The depth should have less impact on the collecting overhead. The model-specific optimization may be implemented later separately. Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20250310181536.3645382-1-kan.liang@linux.intel.com --- include/linux/perf_event.h | 3 +++ include/uapi/linux/perf_event.h | 2 ++ 2 files changed, 5 insertions(+) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 76f4265efee9..3e270822b915 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1347,6 +1347,9 @@ static inline void perf_sample_save_brstack(struct perf_sample_data *data, if (branch_sample_hw_index(event)) size += sizeof(u64); + + brs->nr = min_t(u16, event->attr.sample_max_stack, brs->nr); + size += brs->nr * sizeof(struct perf_branch_entry); /* diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h index 0524d541d4e3..5fc753c23734 100644 --- a/include/uapi/linux/perf_event.h +++ b/include/uapi/linux/perf_event.h @@ -385,6 +385,8 @@ enum perf_event_read_format { * * @sample_max_stack: Max number of frame pointers in a callchain, * should be < /proc/sys/kernel/perf_event_max_stack + * Max number of entries of branch stack + * should be < hardware limit */ struct perf_event_attr { -- cgit v1.3 From cb4369129339060218baca718a578bb0b826e734 Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Fri, 14 Mar 2025 10:26:54 -0700 Subject: perf: Save PMU specific data in task_struct Some PMU specific data has to be saved/restored during context switch, e.g. LBR call stack data. Currently, the data is saved in event context structure, but only for per-process event. For system-wide event, because of missing the LBR call stack data after context switch, LBR callstacks are always shorter in comparison to per-process mode. For example, Per-process mode: $perf record --call-graph lbr -- taskset -c 0 ./tchain_edit - 99.90% 99.86% tchain_edit tchain_edit [.] f3 99.86% _start __libc_start_main generic_start_main main f1 - f2 f3 System-wide mode: $perf record --call-graph lbr -a -- taskset -c 0 ./tchain_edit - 99.88% 99.82% tchain_edit tchain_edit [.] f3 - 62.02% main f1 f2 f3 - 28.83% f1 - f2 f3 - 28.83% f1 - f2 f3 - 8.88% generic_start_main main f1 f2 f3 It isn't practical to simply allocate the data for system-wide event in CPU context structure for all tasks. We have no idea which CPU a task will be scheduled to. The duplicated LBR data has to be maintained on every CPU context structure. That's a huge waste. Otherwise, the LBR data still lost if the task is scheduled to another CPU. Save the pmu specific data in task_struct. The size of pmu specific data is 788 bytes for LBR call stack. Usually, the overall amount of threads doesn't exceed a few thousands. For 10K threads, keeping LBR data would consume additional ~8MB. The additional space will only be allocated during LBR call stack monitoring. It will be released when the monitoring is finished. Furthermore, moving task_ctx_data from perf_event_context to task_struct can reduce complexity and make things clearer. E.g. perf doesn't need to swap task_ctx_data on optimized context switch path. This patch set is just the first step. There could be other optimization/extension on top of this patch set. E.g. for cgroup profiling, perf just needs to save/store the LBR call stack information for tasks in specific cgroup. That could reduce the additional space. Also, the LBR call stack can be available for software events, or allow even debugging use cases, like LBRs on crash later. Because of the alignment requirement of Intel Arch LBR, the Kmem cache is used to allocate the PMU specific data. It's required when child task allocates the space. Save it in struct perf_ctx_data. The refcount in struct perf_ctx_data is used to track the users of pmu specific data. Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Alexey Budankov Link: https://lore.kernel.org/r/20250314172700.438923-1-kan.liang@linux.intel.com --- include/linux/perf_event.h | 35 +++++++++++++++++++++++++++++++++++ include/linux/sched.h | 2 ++ kernel/events/core.c | 1 + 3 files changed, 38 insertions(+) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 3e270822b915..75d9b1e93f39 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -1021,6 +1021,41 @@ struct perf_event_context { local_t nr_no_switch_fast; }; +/** + * struct perf_ctx_data - PMU specific data for a task + * @rcu_head: To avoid the race on free PMU specific data + * @refcount: To track users + * @global: To track system-wide users + * @ctx_cache: Kmem cache of PMU specific data + * @data: PMU specific data + * + * Currently, the struct is only used in Intel LBR call stack mode to + * save/restore the call stack of a task on context switches. + * + * The rcu_head is used to prevent the race on free the data. + * The data only be allocated when Intel LBR call stack mode is enabled. + * The data will be freed when the mode is disabled. + * The content of the data will only be accessed in context switch, which + * should be protected by rcu_read_lock(). + * + * Because of the alignment requirement of Intel Arch LBR, the Kmem cache + * is used to allocate the PMU specific data. The ctx_cache is to track + * the Kmem cache. + * + * Careful: Struct perf_ctx_data is added as a pointer in struct task_struct. + * When system-wide Intel LBR call stack mode is enabled, a buffer with + * constant size will be allocated for each task. + * Also, system memory consumption can further grow when the size of + * struct perf_ctx_data enlarges. + */ +struct perf_ctx_data { + struct rcu_head rcu_head; + refcount_t refcount; + int global; + struct kmem_cache *ctx_cache; + void *data; +}; + struct perf_cpu_pmu_context { struct perf_event_pmu_context epc; struct perf_event_pmu_context *task_epc; diff --git a/include/linux/sched.h b/include/linux/sched.h index 9632e3318e0d..7e183eeb50ec 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -65,6 +65,7 @@ struct mempolicy; struct nameidata; struct nsproxy; struct perf_event_context; +struct perf_ctx_data; struct pid_namespace; struct pipe_inode_info; struct rcu_node; @@ -1311,6 +1312,7 @@ struct task_struct { struct perf_event_context *perf_event_ctxp; struct mutex perf_event_mutex; struct list_head perf_event_list; + struct perf_ctx_data __rcu *perf_ctx_data; #endif #ifdef CONFIG_DEBUG_PREEMPT unsigned long preempt_disable_ip; diff --git a/kernel/events/core.c b/kernel/events/core.c index ace1bcc1e05f..20d28b7e30fb 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -14070,6 +14070,7 @@ int perf_event_init_task(struct task_struct *child, u64 clone_flags) child->perf_event_ctxp = NULL; mutex_init(&child->perf_event_mutex); INIT_LIST_HEAD(&child->perf_event_list); + child->perf_ctx_data = NULL; ret = perf_event_init_context(child, clone_flags); if (ret) { -- cgit v1.3 From fdfda868ee3b5da1fbdb7710b731e09d8dd3a615 Mon Sep 17 00:00:00 2001 From: "Peter Zijlstra (Intel)" Date: Fri, 14 Mar 2025 10:26:55 -0700 Subject: locking/percpu-rwsem: Add guard support To simplify the usage of the percpu rw semaphore. Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250314172700.438923-2-kan.liang@linux.intel.com --- include/linux/percpu-rwsem.h | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'include/linux') diff --git a/include/linux/percpu-rwsem.h b/include/linux/percpu-rwsem.h index c012df33a9f0..af7d75ede619 100644 --- a/include/linux/percpu-rwsem.h +++ b/include/linux/percpu-rwsem.h @@ -8,6 +8,7 @@ #include #include #include +#include struct percpu_rw_semaphore { struct rcu_sync rss; @@ -125,6 +126,13 @@ extern bool percpu_is_read_locked(struct percpu_rw_semaphore *); extern void percpu_down_write(struct percpu_rw_semaphore *); extern void percpu_up_write(struct percpu_rw_semaphore *); +DEFINE_GUARD(percpu_read, struct percpu_rw_semaphore *, + percpu_down_read(_T), percpu_up_read(_T)) +DEFINE_GUARD_COND(percpu_read, _try, percpu_down_read_trylock(_T)) + +DEFINE_GUARD(percpu_write, struct percpu_rw_semaphore *, + percpu_down_write(_T), percpu_up_write(_T)) + static inline bool percpu_is_write_locked(struct percpu_rw_semaphore *sem) { return atomic_read(&sem->block); -- cgit v1.3 From 506e64e710ff9573fd2b86686528762b7901b5e4 Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Fri, 14 Mar 2025 10:26:56 -0700 Subject: perf: attach/detach PMU specific data The LBR call stack data has to be saved/restored during context switch to fix the shorter LBRs call stacks issue in the system-wide mode. Allocate PMU specific data and attach them to the corresponding task_struct during LBR call stack monitoring. When a LBR call stack event is accounted, the perf_ctx_data for the related tasks will be allocated/attached by attach_perf_ctx_data(). When a LBR call stack event is unaccounted, the perf_ctx_data for related tasks will be detached/freed by detach_perf_ctx_data(). The LBR call stack event could be a per-task event or a system-wide event. - For a per-task event, perf only allocates the perf_ctx_data for the current task. If the allocation fails, perf will error out. - For a system-wide event, perf has to allocate the perf_ctx_data for both the existing tasks and the upcoming tasks. The allocation for the existing tasks is done in perf_event_alloc(). If any allocation fails, perf will error out. The allocation for the new tasks will be done in perf_event_fork(). A global reader/writer semaphore, global_ctx_data_rwsem, is added to address the global race. - The perf_ctx_data only be freed by the last LBR call stack event. The number of the per-task events is tracked by refcount of each task. Since the system-wide events impact all tasks, it's not practical to go through the whole task list to update the refcount for each system-wide event. The number of system-wide events is tracked by a global variable global_ctx_data_ref. Suggested-by: "Peter Zijlstra (Intel)" Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250314172700.438923-3-kan.liang@linux.intel.com --- include/linux/perf_event.h | 3 +- kernel/events/core.c | 289 +++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 291 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 75d9b1e93f39..2551170c0d18 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -676,11 +676,12 @@ struct swevent_hlist { #define PERF_ATTACH_GROUP 0x0002 #define PERF_ATTACH_TASK 0x0004 #define PERF_ATTACH_TASK_DATA 0x0008 -#define PERF_ATTACH_ITRACE 0x0010 +#define PERF_ATTACH_GLOBAL_DATA 0x0010 #define PERF_ATTACH_SCHED_CB 0x0020 #define PERF_ATTACH_CHILD 0x0040 #define PERF_ATTACH_EXCLUSIVE 0x0080 #define PERF_ATTACH_CALLCHAIN 0x0100 +#define PERF_ATTACH_ITRACE 0x0200 struct bpf_prog; struct perf_cgroup; diff --git a/kernel/events/core.c b/kernel/events/core.c index 20d28b7e30fb..e86d35e4f271 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -55,6 +55,7 @@ #include #include #include +#include #include "internal.h" @@ -5217,6 +5218,225 @@ static void unaccount_freq_event(void) atomic_dec(&nr_freq_events); } + +static struct perf_ctx_data * +alloc_perf_ctx_data(struct kmem_cache *ctx_cache, bool global) +{ + struct perf_ctx_data *cd; + + cd = kzalloc(sizeof(*cd), GFP_KERNEL); + if (!cd) + return NULL; + + cd->data = kmem_cache_zalloc(ctx_cache, GFP_KERNEL); + if (!cd->data) { + kfree(cd); + return NULL; + } + + cd->global = global; + cd->ctx_cache = ctx_cache; + refcount_set(&cd->refcount, 1); + + return cd; +} + +static void free_perf_ctx_data(struct perf_ctx_data *cd) +{ + kmem_cache_free(cd->ctx_cache, cd->data); + kfree(cd); +} + +static void __free_perf_ctx_data_rcu(struct rcu_head *rcu_head) +{ + struct perf_ctx_data *cd; + + cd = container_of(rcu_head, struct perf_ctx_data, rcu_head); + free_perf_ctx_data(cd); +} + +static inline void perf_free_ctx_data_rcu(struct perf_ctx_data *cd) +{ + call_rcu(&cd->rcu_head, __free_perf_ctx_data_rcu); +} + +static int +attach_task_ctx_data(struct task_struct *task, struct kmem_cache *ctx_cache, + bool global) +{ + struct perf_ctx_data *cd, *old = NULL; + + cd = alloc_perf_ctx_data(ctx_cache, global); + if (!cd) + return -ENOMEM; + + for (;;) { + if (try_cmpxchg((struct perf_ctx_data **)&task->perf_ctx_data, &old, cd)) { + if (old) + perf_free_ctx_data_rcu(old); + return 0; + } + + if (!old) { + /* + * After seeing a dead @old, we raced with + * removal and lost, try again to install @cd. + */ + continue; + } + + if (refcount_inc_not_zero(&old->refcount)) { + free_perf_ctx_data(cd); /* unused */ + return 0; + } + + /* + * @old is a dead object, refcount==0 is stable, try and + * replace it with @cd. + */ + } + return 0; +} + +static void __detach_global_ctx_data(void); +DEFINE_STATIC_PERCPU_RWSEM(global_ctx_data_rwsem); +static refcount_t global_ctx_data_ref; + +static int +attach_global_ctx_data(struct kmem_cache *ctx_cache) +{ + struct task_struct *g, *p; + struct perf_ctx_data *cd; + int ret; + + if (refcount_inc_not_zero(&global_ctx_data_ref)) + return 0; + + guard(percpu_write)(&global_ctx_data_rwsem); + if (refcount_inc_not_zero(&global_ctx_data_ref)) + return 0; +again: + /* Allocate everything */ + scoped_guard (rcu) { + for_each_process_thread(g, p) { + cd = rcu_dereference(p->perf_ctx_data); + if (cd && !cd->global) { + cd->global = 1; + if (!refcount_inc_not_zero(&cd->refcount)) + cd = NULL; + } + if (!cd) { + get_task_struct(p); + goto alloc; + } + } + } + + refcount_set(&global_ctx_data_ref, 1); + + return 0; +alloc: + ret = attach_task_ctx_data(p, ctx_cache, true); + put_task_struct(p); + if (ret) { + __detach_global_ctx_data(); + return ret; + } + goto again; +} + +static int +attach_perf_ctx_data(struct perf_event *event) +{ + struct task_struct *task = event->hw.target; + struct kmem_cache *ctx_cache = event->pmu->task_ctx_cache; + int ret; + + if (!ctx_cache) + return -ENOMEM; + + if (task) + return attach_task_ctx_data(task, ctx_cache, false); + + ret = attach_global_ctx_data(ctx_cache); + if (ret) + return ret; + + event->attach_state |= PERF_ATTACH_GLOBAL_DATA; + return 0; +} + +static void +detach_task_ctx_data(struct task_struct *p) +{ + struct perf_ctx_data *cd; + + scoped_guard (rcu) { + cd = rcu_dereference(p->perf_ctx_data); + if (!cd || !refcount_dec_and_test(&cd->refcount)) + return; + } + + /* + * The old ctx_data may be lost because of the race. + * Nothing is required to do for the case. + * See attach_task_ctx_data(). + */ + if (try_cmpxchg((struct perf_ctx_data **)&p->perf_ctx_data, &cd, NULL)) + perf_free_ctx_data_rcu(cd); +} + +static void __detach_global_ctx_data(void) +{ + struct task_struct *g, *p; + struct perf_ctx_data *cd; + +again: + scoped_guard (rcu) { + for_each_process_thread(g, p) { + cd = rcu_dereference(p->perf_ctx_data); + if (!cd || !cd->global) + continue; + cd->global = 0; + get_task_struct(p); + goto detach; + } + } + return; +detach: + detach_task_ctx_data(p); + put_task_struct(p); + goto again; +} + +static void detach_global_ctx_data(void) +{ + if (refcount_dec_not_one(&global_ctx_data_ref)) + return; + + guard(percpu_write)(&global_ctx_data_rwsem); + if (!refcount_dec_and_test(&global_ctx_data_ref)) + return; + + /* remove everything */ + __detach_global_ctx_data(); +} + +static void detach_perf_ctx_data(struct perf_event *event) +{ + struct task_struct *task = event->hw.target; + + event->attach_state &= ~PERF_ATTACH_TASK_DATA; + + if (task) + return detach_task_ctx_data(task); + + if (event->attach_state & PERF_ATTACH_GLOBAL_DATA) { + detach_global_ctx_data(); + event->attach_state &= ~PERF_ATTACH_GLOBAL_DATA; + } +} + static void unaccount_event(struct perf_event *event) { bool dec = false; @@ -5398,6 +5618,9 @@ static void __free_event(struct perf_event *event) if (is_cgroup_event(event)) perf_detach_cgroup(event); + if (event->attach_state & PERF_ATTACH_TASK_DATA) + detach_perf_ctx_data(event); + if (event->destroy) event->destroy(event); @@ -8607,10 +8830,58 @@ static void perf_event_task(struct task_struct *task, task_ctx); } +/* + * Allocate data for a new task when profiling system-wide + * events which require PMU specific data + */ +static void +perf_event_alloc_task_data(struct task_struct *child, + struct task_struct *parent) +{ + struct kmem_cache *ctx_cache = NULL; + struct perf_ctx_data *cd; + + if (!refcount_read(&global_ctx_data_ref)) + return; + + scoped_guard (rcu) { + cd = rcu_dereference(parent->perf_ctx_data); + if (cd) + ctx_cache = cd->ctx_cache; + } + + if (!ctx_cache) + return; + + guard(percpu_read)(&global_ctx_data_rwsem); + scoped_guard (rcu) { + cd = rcu_dereference(child->perf_ctx_data); + if (!cd) { + /* + * A system-wide event may be unaccount, + * when attaching the perf_ctx_data. + */ + if (!refcount_read(&global_ctx_data_ref)) + return; + goto attach; + } + + if (!cd->global) { + cd->global = 1; + refcount_inc(&cd->refcount); + } + } + + return; +attach: + attach_task_ctx_data(child, ctx_cache, true); +} + void perf_event_fork(struct task_struct *task) { perf_event_task(task, NULL, 1); perf_event_namespaces(task); + perf_event_alloc_task_data(task, current); } /* @@ -12490,6 +12761,18 @@ perf_event_alloc(struct perf_event_attr *attr, int cpu, if (IS_ERR(pmu)) return (void*)pmu; + /* + * The PERF_ATTACH_TASK_DATA is set in the event_init()->hw_config(). + * The attach should be right after the perf_init_event(). + * Otherwise, the __free_event() would mistakenly detach the non-exist + * perf_ctx_data because of the other errors between them. + */ + if (event->attach_state & PERF_ATTACH_TASK_DATA) { + err = attach_perf_ctx_data(event); + if (err) + return ERR_PTR(err); + } + /* * Disallow uncore-task events. Similarly, disallow uncore-cgroup * events (they don't make sense as the cgroup will be different @@ -13637,6 +13920,12 @@ void perf_event_exit_task(struct task_struct *child) * At this point we need to send EXIT events to cpu contexts. */ perf_event_task(child, NULL, 0); + + /* + * Detach the perf_ctx_data for the system-wide event. + */ + guard(percpu_read)(&global_ctx_data_rwsem); + detach_task_ctx_data(child); } static void perf_free_event(struct perf_event *event, -- cgit v1.3 From d57e94f5b891925e4f2796266eba31edd5a01903 Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Fri, 14 Mar 2025 10:26:57 -0700 Subject: perf: Supply task information to sched_task() To save/restore LBR call stack data in system-wide mode, the task_struct information is required. Extend the parameters of sched_task() to supply task_struct information. When schedule in, the LBR call stack data for new task will be restored. When schedule out, the LBR call stack data for old task will be saved. Only need to pass the required task_struct information. Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250314172700.438923-4-kan.liang@linux.intel.com --- arch/powerpc/perf/core-book3s.c | 8 ++++++-- arch/s390/kernel/perf_pai_crypto.c | 3 ++- arch/s390/kernel/perf_pai_ext.c | 3 ++- arch/x86/events/amd/brs.c | 3 ++- arch/x86/events/amd/lbr.c | 3 ++- arch/x86/events/core.c | 5 +++-- arch/x86/events/intel/core.c | 4 ++-- arch/x86/events/intel/lbr.c | 3 ++- arch/x86/events/perf_event.h | 14 +++++++++----- include/linux/perf_event.h | 2 +- kernel/events/core.c | 20 +++++++++++--------- 11 files changed, 42 insertions(+), 26 deletions(-) (limited to 'include/linux') diff --git a/arch/powerpc/perf/core-book3s.c b/arch/powerpc/perf/core-book3s.c index 2b79171ee185..f4e03aaabb4c 100644 --- a/arch/powerpc/perf/core-book3s.c +++ b/arch/powerpc/perf/core-book3s.c @@ -132,7 +132,10 @@ static unsigned long ebb_switch_in(bool ebb, struct cpu_hw_events *cpuhw) static inline void power_pmu_bhrb_enable(struct perf_event *event) {} static inline void power_pmu_bhrb_disable(struct perf_event *event) {} -static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) {} +static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) +{ +} static inline void power_pmu_bhrb_read(struct perf_event *event, struct cpu_hw_events *cpuhw) {} static void pmao_restore_workaround(bool ebb) { } #endif /* CONFIG_PPC32 */ @@ -444,7 +447,8 @@ static void power_pmu_bhrb_disable(struct perf_event *event) /* Called from ctxsw to prevent one process's branch entries to * mingle with the other process's entries during context switch. */ -static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +static void power_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) { if (!ppmu->bhrb_nr) return; diff --git a/arch/s390/kernel/perf_pai_crypto.c b/arch/s390/kernel/perf_pai_crypto.c index 10725f5a6f0f..63875270941b 100644 --- a/arch/s390/kernel/perf_pai_crypto.c +++ b/arch/s390/kernel/perf_pai_crypto.c @@ -518,7 +518,8 @@ static void paicrypt_have_samples(void) /* Called on schedule-in and schedule-out. No access to event structure, * but for sampling only event CRYPTO_ALL is allowed. */ -static void paicrypt_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +static void paicrypt_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) { /* We started with a clean page on event installation. So read out * results on schedule_out and if page was dirty, save old values. diff --git a/arch/s390/kernel/perf_pai_ext.c b/arch/s390/kernel/perf_pai_ext.c index a8f0bad99cf0..fd14d5ebccbc 100644 --- a/arch/s390/kernel/perf_pai_ext.c +++ b/arch/s390/kernel/perf_pai_ext.c @@ -542,7 +542,8 @@ static void paiext_have_samples(void) /* Called on schedule-in and schedule-out. No access to event structure, * but for sampling only event NNPA_ALL is allowed. */ -static void paiext_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +static void paiext_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) { /* We started with a clean page on event installation. So read out * results on schedule_out and if page was dirty, save old values. diff --git a/arch/x86/events/amd/brs.c b/arch/x86/events/amd/brs.c index 780acd3dff22..ec3427463382 100644 --- a/arch/x86/events/amd/brs.c +++ b/arch/x86/events/amd/brs.c @@ -381,7 +381,8 @@ static void amd_brs_poison_buffer(void) * On ctxswin, sched_in = true, called after the PMU has started * On ctxswout, sched_in = false, called before the PMU is stopped */ -void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); diff --git a/arch/x86/events/amd/lbr.c b/arch/x86/events/amd/lbr.c index 19c7b76e21bc..c06ccca96851 100644 --- a/arch/x86/events/amd/lbr.c +++ b/arch/x86/events/amd/lbr.c @@ -371,7 +371,8 @@ void amd_pmu_lbr_del(struct perf_event *event) perf_sched_cb_dec(event->pmu); } -void amd_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +void amd_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c index 20ad5cca6ad2..ae8c90adca0f 100644 --- a/arch/x86/events/core.c +++ b/arch/x86/events/core.c @@ -2638,9 +2638,10 @@ static const struct attribute_group *x86_pmu_attr_groups[] = { NULL, }; -static void x86_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +static void x86_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) { - static_call_cond(x86_pmu_sched_task)(pmu_ctx, sched_in); + static_call_cond(x86_pmu_sched_task)(pmu_ctx, task, sched_in); } static void x86_pmu_swap_task_ctx(struct perf_event_pmu_context *prev_epc, diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 5a8d6e1a9334..3efbb03fd77e 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -5294,10 +5294,10 @@ static void intel_pmu_cpu_dead(int cpu) } static void intel_pmu_sched_task(struct perf_event_pmu_context *pmu_ctx, - bool sched_in) + struct task_struct *task, bool sched_in) { intel_pmu_pebs_sched_task(pmu_ctx, sched_in); - intel_pmu_lbr_sched_task(pmu_ctx, sched_in); + intel_pmu_lbr_sched_task(pmu_ctx, task, sched_in); } static void intel_pmu_swap_task_ctx(struct perf_event_pmu_context *prev_epc, diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c index dc641b50814e..dafeee216f3b 100644 --- a/arch/x86/events/intel/lbr.c +++ b/arch/x86/events/intel/lbr.c @@ -539,7 +539,8 @@ void intel_pmu_lbr_swap_task_ctx(struct perf_event_pmu_context *prev_epc, task_context_opt(next_ctx_data)->lbr_callstack_users); } -void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); void *task_ctx; diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index a698e6484b3b..0d5019fb3ad2 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -875,7 +875,7 @@ struct x86_pmu { void (*check_microcode)(void); void (*sched_task)(struct perf_event_pmu_context *pmu_ctx, - bool sched_in); + struct task_struct *task, bool sched_in); /* * Intel Arch Perfmon v2+ @@ -1408,7 +1408,8 @@ void amd_pmu_lbr_reset(void); void amd_pmu_lbr_read(void); void amd_pmu_lbr_add(struct perf_event *event); void amd_pmu_lbr_del(struct perf_event *event); -void amd_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in); +void amd_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in); void amd_pmu_lbr_enable_all(void); void amd_pmu_lbr_disable_all(void); int amd_pmu_lbr_hw_config(struct perf_event *event); @@ -1462,7 +1463,8 @@ static inline void amd_pmu_brs_del(struct perf_event *event) perf_sched_cb_dec(event->pmu); } -void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in); +void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in); #else static inline int amd_brs_init(void) { @@ -1487,7 +1489,8 @@ static inline void amd_pmu_brs_del(struct perf_event *event) { } -static inline void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in) +static inline void amd_pmu_brs_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in) { } @@ -1670,7 +1673,8 @@ void intel_pmu_lbr_save_brstack(struct perf_sample_data *data, void intel_pmu_lbr_swap_task_ctx(struct perf_event_pmu_context *prev_epc, struct perf_event_pmu_context *next_epc); -void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, bool sched_in); +void intel_pmu_lbr_sched_task(struct perf_event_pmu_context *pmu_ctx, + struct task_struct *task, bool sched_in); u64 lbr_from_signext_quirk_wr(u64 val); diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 2551170c0d18..58f40c89d728 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -494,7 +494,7 @@ struct pmu { * context-switches callback */ void (*sched_task) (struct perf_event_pmu_context *pmu_ctx, - bool sched_in); + struct task_struct *task, bool sched_in); /* * Kmem cache of PMU specific data diff --git a/kernel/events/core.c b/kernel/events/core.c index e86d35e4f271..992829264577 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -3613,7 +3613,8 @@ static void perf_event_swap_task_ctx_data(struct perf_event_context *prev_ctx, } } -static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, bool sched_in) +static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, + struct task_struct *task, bool sched_in) { struct perf_event_pmu_context *pmu_ctx; struct perf_cpu_pmu_context *cpc; @@ -3622,7 +3623,7 @@ static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, bool sched_in cpc = this_cpc(pmu_ctx->pmu); if (cpc->sched_cb_usage && pmu_ctx->pmu->sched_task) - pmu_ctx->pmu->sched_task(pmu_ctx, sched_in); + pmu_ctx->pmu->sched_task(pmu_ctx, task, sched_in); } } @@ -3685,7 +3686,7 @@ perf_event_context_sched_out(struct task_struct *task, struct task_struct *next) WRITE_ONCE(ctx->task, next); WRITE_ONCE(next_ctx->task, task); - perf_ctx_sched_task_cb(ctx, false); + perf_ctx_sched_task_cb(ctx, task, false); perf_event_swap_task_ctx_data(ctx, next_ctx); perf_ctx_enable(ctx, false); @@ -3715,7 +3716,7 @@ unlock: perf_ctx_disable(ctx, false); inside_switch: - perf_ctx_sched_task_cb(ctx, false); + perf_ctx_sched_task_cb(ctx, task, false); task_ctx_sched_out(ctx, NULL, EVENT_ALL); perf_ctx_enable(ctx, false); @@ -3757,7 +3758,8 @@ void perf_sched_cb_inc(struct pmu *pmu) * PEBS requires this to provide PID/TID information. This requires we flush * all queued PEBS records before we context switch to a new task. */ -static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, bool sched_in) +static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, + struct task_struct *task, bool sched_in) { struct perf_cpu_context *cpuctx = this_cpu_ptr(&perf_cpu_context); struct pmu *pmu; @@ -3771,7 +3773,7 @@ static void __perf_pmu_sched_task(struct perf_cpu_pmu_context *cpc, bool sched_i perf_ctx_lock(cpuctx, cpuctx->task_ctx); perf_pmu_disable(pmu); - pmu->sched_task(cpc->task_epc, sched_in); + pmu->sched_task(cpc->task_epc, task, sched_in); perf_pmu_enable(pmu); perf_ctx_unlock(cpuctx, cpuctx->task_ctx); @@ -3789,7 +3791,7 @@ static void perf_pmu_sched_task(struct task_struct *prev, return; list_for_each_entry(cpc, this_cpu_ptr(&sched_cb_list), sched_cb_entry) - __perf_pmu_sched_task(cpc, sched_in); + __perf_pmu_sched_task(cpc, sched_in ? next : prev, sched_in); } static void perf_event_switch(struct task_struct *task, @@ -4088,7 +4090,7 @@ static void perf_event_context_sched_in(struct task_struct *task) perf_ctx_lock(cpuctx, ctx); perf_ctx_disable(ctx, false); - perf_ctx_sched_task_cb(ctx, true); + perf_ctx_sched_task_cb(ctx, task, true); perf_ctx_enable(ctx, false); perf_ctx_unlock(cpuctx, ctx); @@ -4119,7 +4121,7 @@ static void perf_event_context_sched_in(struct task_struct *task) perf_event_sched_in(cpuctx, ctx, NULL); - perf_ctx_sched_task_cb(cpuctx->task_ctx, true); + perf_ctx_sched_task_cb(cpuctx->task_ctx, task, true); if (!RB_EMPTY_ROOT(&ctx->pinned_groups.tree)) perf_ctx_enable(&cpuctx->ctx, false); -- cgit v1.3 From bd2da08d9363d191551d79e5b04121348e18af5a Mon Sep 17 00:00:00 2001 From: Kan Liang Date: Fri, 14 Mar 2025 10:27:00 -0700 Subject: perf: Clean up pmu specific data The pmu specific data is saved in task_struct now. Remove it from event context structure. Remove swap_task_ctx() as well. Signed-off-by: Kan Liang Signed-off-by: Peter Zijlstra (Intel) Link: https://lore.kernel.org/r/20250314172700.438923-7-kan.liang@linux.intel.com --- include/linux/perf_event.h | 12 -------- kernel/events/core.c | 76 ++-------------------------------------------- 2 files changed, 3 insertions(+), 85 deletions(-) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 58f40c89d728..5b8e3aabac02 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -501,16 +501,6 @@ struct pmu { */ struct kmem_cache *task_ctx_cache; - /* - * PMU specific parts of task perf event context (i.e. ctx->task_ctx_data) - * can be synchronized using this function. See Intel LBR callstack support - * implementation and Perf core context switch handling callbacks for usage - * examples. - */ - void (*swap_task_ctx) (struct perf_event_pmu_context *prev_epc, - struct perf_event_pmu_context *next_epc); - /* optional */ - /* * Set up pmu-private data structures for an AUX area */ @@ -933,7 +923,6 @@ struct perf_event_pmu_context { atomic_t refcount; /* event <-> epc */ struct rcu_head rcu_head; - void *task_ctx_data; /* pmu specific data */ /* * Set when one or more (plausibly active) event can't be scheduled * due to pmu overcommit or pmu constraints, except tolerant to @@ -981,7 +970,6 @@ struct perf_event_context { int nr_user; int is_active; - int nr_task_data; int nr_stat; int nr_freq; int rotate_disable; diff --git a/kernel/events/core.c b/kernel/events/core.c index 992829264577..4ce9795e5519 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -1254,20 +1254,6 @@ static void get_ctx(struct perf_event_context *ctx) refcount_inc(&ctx->refcount); } -static void *alloc_task_ctx_data(struct pmu *pmu) -{ - if (pmu->task_ctx_cache) - return kmem_cache_zalloc(pmu->task_ctx_cache, GFP_KERNEL); - - return NULL; -} - -static void free_task_ctx_data(struct pmu *pmu, void *task_ctx_data) -{ - if (pmu->task_ctx_cache && task_ctx_data) - kmem_cache_free(pmu->task_ctx_cache, task_ctx_data); -} - static void free_ctx(struct rcu_head *head) { struct perf_event_context *ctx; @@ -3577,42 +3563,6 @@ static void perf_event_sync_stat(struct perf_event_context *ctx, } } -#define double_list_for_each_entry(pos1, pos2, head1, head2, member) \ - for (pos1 = list_first_entry(head1, typeof(*pos1), member), \ - pos2 = list_first_entry(head2, typeof(*pos2), member); \ - !list_entry_is_head(pos1, head1, member) && \ - !list_entry_is_head(pos2, head2, member); \ - pos1 = list_next_entry(pos1, member), \ - pos2 = list_next_entry(pos2, member)) - -static void perf_event_swap_task_ctx_data(struct perf_event_context *prev_ctx, - struct perf_event_context *next_ctx) -{ - struct perf_event_pmu_context *prev_epc, *next_epc; - - if (!prev_ctx->nr_task_data) - return; - - double_list_for_each_entry(prev_epc, next_epc, - &prev_ctx->pmu_ctx_list, &next_ctx->pmu_ctx_list, - pmu_ctx_entry) { - - if (WARN_ON_ONCE(prev_epc->pmu != next_epc->pmu)) - continue; - - /* - * PMU specific parts of task perf context can require - * additional synchronization. As an example of such - * synchronization see implementation details of Intel - * LBR call stack data profiling; - */ - if (prev_epc->pmu->swap_task_ctx) - prev_epc->pmu->swap_task_ctx(prev_epc, next_epc); - else - swap(prev_epc->task_ctx_data, next_epc->task_ctx_data); - } -} - static void perf_ctx_sched_task_cb(struct perf_event_context *ctx, struct task_struct *task, bool sched_in) { @@ -3687,16 +3637,15 @@ perf_event_context_sched_out(struct task_struct *task, struct task_struct *next) WRITE_ONCE(next_ctx->task, task); perf_ctx_sched_task_cb(ctx, task, false); - perf_event_swap_task_ctx_data(ctx, next_ctx); perf_ctx_enable(ctx, false); /* * RCU_INIT_POINTER here is safe because we've not * modified the ctx and the above modification of - * ctx->task and ctx->task_ctx_data are immaterial - * since those values are always verified under - * ctx->lock which we're now holding. + * ctx->task is immaterial since this value is + * always verified under ctx->lock which we're now + * holding. */ RCU_INIT_POINTER(task->perf_event_ctxp, next_ctx); RCU_INIT_POINTER(next->perf_event_ctxp, ctx); @@ -5005,7 +4954,6 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx, struct perf_event *event) { struct perf_event_pmu_context *new = NULL, *pos = NULL, *epc; - void *task_ctx_data = NULL; if (!ctx->task) { /* @@ -5038,14 +4986,6 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx, if (!new) return ERR_PTR(-ENOMEM); - if (event->attach_state & PERF_ATTACH_TASK_DATA) { - task_ctx_data = alloc_task_ctx_data(pmu); - if (!task_ctx_data) { - kfree(new); - return ERR_PTR(-ENOMEM); - } - } - __perf_init_event_pmu_context(new, pmu); /* @@ -5080,14 +5020,7 @@ find_get_pmu_context(struct pmu *pmu, struct perf_event_context *ctx, epc->ctx = ctx; found_epc: - if (task_ctx_data && !epc->task_ctx_data) { - epc->task_ctx_data = task_ctx_data; - task_ctx_data = NULL; - ctx->nr_task_data++; - } raw_spin_unlock_irq(&ctx->lock); - - free_task_ctx_data(pmu, task_ctx_data); kfree(new); return epc; @@ -5103,7 +5036,6 @@ static void free_cpc_rcu(struct rcu_head *head) struct perf_cpu_pmu_context *cpc = container_of(head, typeof(*cpc), epc.rcu_head); - kfree(cpc->epc.task_ctx_data); kfree(cpc); } @@ -5111,7 +5043,6 @@ static void free_epc_rcu(struct rcu_head *head) { struct perf_event_pmu_context *epc = container_of(head, typeof(*epc), rcu_head); - kfree(epc->task_ctx_data); kfree(epc); } @@ -14103,7 +14034,6 @@ inherit_event(struct perf_event *parent_event, if (is_orphaned_event(parent_event) || !atomic_long_inc_not_zero(&parent_event->refcount)) { mutex_unlock(&parent_event->child_mutex); - /* task_ctx_data is freed with child_ctx */ free_event(child_event); return NULL; } -- cgit v1.3 From 12e766d16814808b6a581597cef6ce9fc029e917 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Mon, 17 Mar 2025 11:39:35 +0100 Subject: perf: Fix __percpu annotation With bcecd5a529c1 ("percpu: repurpose __percpu tag as a named address space qualifier") the normal compilers start caring about the __percpu annotation, as such f67d1ffd841f ("perf/core: Detach 'struct perf_cpu_pmu_context' and 'struct pmu' lifetimes") needs a fixup. Fixes: f67d1ffd841f ("perf/core: Detach 'struct perf_cpu_pmu_context' and 'struct pmu' lifetimes") Fixes: bcecd5a529c1 ("percpu: repurpose __percpu tag as a named address space qualifier") Reported-by: Stephen Rothwell Reported-by: jirislaby@kernel.org Signed-off-by: Peter Zijlstra (Intel) --- include/linux/perf_event.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h index 5b8e3aabac02..63dddb3b54f0 100644 --- a/include/linux/perf_event.h +++ b/include/linux/perf_event.h @@ -343,7 +343,7 @@ struct pmu { */ unsigned int scope; - struct perf_cpu_pmu_context __percpu **cpu_pmu_context; + struct perf_cpu_pmu_context * __percpu *cpu_pmu_context; atomic_t exclusive_cnt; /* < 0: cpu; > 0: tsk */ int task_ctx_nr; int hrtimer_interval_ms; -- cgit v1.3