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path: root/arch/loongarch/kernel/proc.c
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2026-02-10LoongArch: Replace seq_printf() with seq_puts() for simple stringsGeorge Guo
Fix warnings like: "Prefer seq_puts to seq_printf" by checkpatch.pl. Replace seq_printf() calls with seq_puts() in show_cpuinfo() when outputting simple constant strings without format specifiers. This improves performance slightly as seq_puts() avoids parsing the format string. Signed-off-by: George Guo <guodongtai@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2026-02-10LoongArch: Add detection for SC.Q supportGeorge Guo
Check the CPUCFG2_SCQ bit to determine if the current CPU supports the SC.Q instruction. Reviewed-by: Hengqi Chen <hengqi.chen@gmail.com> Tested-by: Hengqi Chen <hengqi.chen@gmail.com> Co-developed-by: Yangyang Lian <lianyangyang@kylinos.cn> Signed-off-by: Yangyang Lian <lianyangyang@kylinos.cn> Signed-off-by: George Guo <guodongtai@kylinos.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2025-12-08LoongArch: Adjust time routines for 32BIT/64BITHuacai Chen
Adjust time routines for both 32BIT and 64BIT, including: rdtime_h() / rdtime_l() definitions for 32BIT and rdtime_d() definition for 64BIT, get_cycles() and get_cycles64() definitions for 32BIT/64BIT, show time frequency info ("CPU MHz" and "BogoMIPS") in /proc/cpuinfo, etc. Use do_div() for division which works on both 32BIT and 64BIT platforms. Reviewed-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2025-11-20LoongArch: Consolidate CPU names in /proc/cpuinfoHuacai Chen
Some processors have no IOCSR.VENDOR and IOCSR.CPUNAME, some processors have these registers but there is no valid information. Consolidate CPU names in /proc/cpuinfo: 1. Add "PRID" to display the PRID & Core-Name; 2. Let "Model Name" display "Unknown" if no valid name. Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2025-02-13LoongArch: Remove the deprecated notifier hook mechanismYuli Wang
The notifier hook mechanism in proc and cpuinfo is actually unnecessary for LoongArch because it's not used anywhere. It was originally added to the MIPS code in commit d6d3c9afaab4 ("MIPS: MT: proc: Add support for printing VPE and TC ids"), and LoongArch then inherited it. But as the kernel code stands now, this notifier hook mechanism doesn't really make sense for either LoongArch or MIPS. In addition, the seq_file forward declaration needs to be moved to its proper place, as only the show_ipi_list() function in smp.c requires it. Co-developed-by: Wentao Guan <guanwentao@uniontech.com> Signed-off-by: Wentao Guan <guanwentao@uniontech.com> Signed-off-by: Yuli Wang <wangyuli@uniontech.com> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2025-02-13LoongArch: Use str_yes_no() helper function for /proc/cpuinfoYuli Wang
Remove hard-coded strings by using the str_yes_no() helper function. Similar to commit c4a0a4a45a45 ("MIPS: kernel: proc: Use str_yes_no() helper function"). Co-developed-by: Wentao Guan <guanwentao@uniontech.com> Signed-off-by: Wentao Guan <guanwentao@uniontech.com> Signed-off-by: Yuli Wang <wangyuli@uniontech.com> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2024-09-24LoongArch: Rework CPU feature probe from CPUCFG/IOCSRJiaxun Yang
Probe ISA level, TLB, IOCSR information from CPUCFG to improve kernel resilience to different core implementations. BTW, IOCSR register definition appears to be a platform-specific spec instead of an architecture spec, even for the Loongson CPUs there is no guarantee that IOCSR will always present. Thus it's dangerous to perform IOCSR probing without checking CPU type and instruction availability. Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2023-06-29LoongArch: Introduce hardware page table walkerHuacai Chen
Loongson-3A6000 and newer processors have hardware page table walker (PTW) support. PTW can handle all fastpaths of TLBI/TLBL/TLBS/TLBM exceptions by hardware, software only need to handle slowpaths (page faults). BTW, PTW doesn't append _PAGE_MODIFIED for page table entries, so we change pmd_dirty() and pte_dirty() to also check _PAGE_DIRTY for the "dirty" attribute. Signed-off-by: Liang Gao <gaoliang@loongson.cn> Signed-off-by: Jun Yi <yijun@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2023-06-29LoongArch: Add SMT (Simultaneous Multi-Threading) supportHuacai Chen
Loongson-3A6000 has SMT (Simultaneous Multi-Threading) support, each physical core has two logical cores (threads). This patch add SMT probe and scheduler support via ACPI PPTT. If SCHED_SMT enabled, Loongson-3A6000 is treated as 4 cores, 8 threads; If SCHED_SMT disabled, Loongson-3A6000 is treated as 8 cores, 8 threads. Remove smp_num_siblings to support HMP (Heterogeneous Multi-Processing). Signed-off-by: Liupu Wang <wangliupu@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2023-04-18LoongArch: Fix probing of the CRC32 featureHuacai Chen
Not all LoongArch processors support CRC32 instructions. This feature is indicated by CPUCFG1.CRC32 (Bit25) but it is wrongly defined in the previous versions of the ISA manual (and so does in loongarch.h). The CRC32 feature is set unconditionally now, so fix it. BTW, expose the CRC32 feature in /proc/cpuinfo. Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2022-08-12LoongArch: cpuinfo: Fix a warning for CONFIG_CPUMASK_OFFSTACKHuacai Chen
When CONFIG_CPUMASK_OFFSTACK and CONFIG_DEBUG_PER_CPU_MAPS is selected, cpu_max_bits_warn() generates a runtime warning similar as below while we show /proc/cpuinfo. Fix this by using nr_cpu_ids (the runtime limit) instead of NR_CPUS to iterate CPUs. [ 3.052463] ------------[ cut here ]------------ [ 3.059679] WARNING: CPU: 3 PID: 1 at include/linux/cpumask.h:108 show_cpuinfo+0x5e8/0x5f0 [ 3.070072] Modules linked in: efivarfs autofs4 [ 3.076257] CPU: 0 PID: 1 Comm: systemd Not tainted 5.19-rc5+ #1052 [ 3.084034] Hardware name: Loongson Loongson-3A5000-7A1000-1w-V0.1-CRB/Loongson-LS3A5000-7A1000-1w-EVB-V1.21, BIOS Loongson-UDK2018-V2.0.04082-beta7 04/27 [ 3.099465] Stack : 9000000100157b08 9000000000f18530 9000000000cf846c 9000000100154000 [ 3.109127] 9000000100157a50 0000000000000000 9000000100157a58 9000000000ef7430 [ 3.118774] 90000001001578e8 0000000000000040 0000000000000020 ffffffffffffffff [ 3.128412] 0000000000aaaaaa 1ab25f00eec96a37 900000010021de80 900000000101c890 [ 3.138056] 0000000000000000 0000000000000000 0000000000000000 0000000000aaaaaa [ 3.147711] ffff8000339dc220 0000000000000001 0000000006ab4000 0000000000000000 [ 3.157364] 900000000101c998 0000000000000004 9000000000ef7430 0000000000000000 [ 3.167012] 0000000000000009 000000000000006c 0000000000000000 0000000000000000 [ 3.176641] 9000000000d3de08 9000000001639390 90000000002086d8 00007ffff0080286 [ 3.186260] 00000000000000b0 0000000000000004 0000000000000000 0000000000071c1c [ 3.195868] ... [ 3.199917] Call Trace: [ 3.203941] [<90000000002086d8>] show_stack+0x38/0x14c [ 3.210666] [<9000000000cf846c>] dump_stack_lvl+0x60/0x88 [ 3.217625] [<900000000023d268>] __warn+0xd0/0x100 [ 3.223958] [<9000000000cf3c90>] warn_slowpath_fmt+0x7c/0xcc [ 3.231150] [<9000000000210220>] show_cpuinfo+0x5e8/0x5f0 [ 3.238080] [<90000000004f578c>] seq_read_iter+0x354/0x4b4 [ 3.245098] [<90000000004c2e90>] new_sync_read+0x17c/0x1c4 [ 3.252114] [<90000000004c5174>] vfs_read+0x138/0x1d0 [ 3.258694] [<90000000004c55f8>] ksys_read+0x70/0x100 [ 3.265265] [<9000000000cfde9c>] do_syscall+0x7c/0x94 [ 3.271820] [<9000000000202fe4>] handle_syscall+0xc4/0x160 [ 3.281824] ---[ end trace 8b484262b4b8c24c ]--- Cc: stable@vger.kernel.org Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2022-06-03LoongArch: Add multi-processor (SMP) supportHuacai Chen
LoongArch-based procesors have 4, 8 or 16 cores per package. This patch adds multi-processor (SMP) support for LoongArch. Reviewed-by: WANG Xuerui <git@xen0n.name> Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2022-06-03LoongArch: Add misc common routinesHuacai Chen
Add some misc common routines for LoongArch, including: asm-offsets routines, futex functions, i/o memory access functions, frame-buffer functions, procfs information display, etc. Reviewed-by: WANG Xuerui <git@xen0n.name> Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>