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LoongArch: Refine the init_hw_perf_events() function

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(1) Use the existing CPUCFG6_PMNUM_SHIFT macro definition instead of
the magic value 4 to get the PMU number.

(2) Detect the value of PMU bits via CPUCFG instruction according to
the ISA manual instead of hard-coded as 64, because the value may be
different for various micro-architectures.

Link: https://loongson.github.io/LoongArch-Documentation/LoongArch-Vol1-EN.html#_cpucfg
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
This commit is contained in:
Tiezhu Yang 2025-11-09 16:02:01 +08:00 committed by Huacai Chen
parent 17f838512a
commit 4c8a7c9827
2 changed files with 5 additions and 3 deletions
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1
arch/loongarch/include/asm/loongarch.h
View File

@ -128,6 +128,7 @@
#define CPUCFG6_PMNUM GENMASK(7, 4)
#define CPUCFG6_PMNUM_SHIFT 4
#define CPUCFG6_PMBITS GENMASK(13, 8)
#define CPUCFG6_PMBITS_SHIFT 8
#define CPUCFG6_UPM BIT(14)
#define LOONGARCH_CPUCFG16 0x10

7
arch/loongarch/kernel/perf_event.c
View File

@ -845,13 +845,14 @@ static const struct loongarch_perf_event *loongarch_pmu_map_raw_event(u64 config
static int __init init_hw_perf_events(void)
{
int counters;
int bits, counters;
if (!cpu_has_pmp)
return -ENODEV;
pr_info("Performance counters: ");
counters = ((read_cpucfg(LOONGARCH_CPUCFG6) & CPUCFG6_PMNUM) >> 4) + 1;
bits = ((read_cpucfg(LOONGARCH_CPUCFG6) & CPUCFG6_PMBITS) >> CPUCFG6_PMBITS_SHIFT) + 1;
counters = ((read_cpucfg(LOONGARCH_CPUCFG6) & CPUCFG6_PMNUM) >> CPUCFG6_PMNUM_SHIFT) + 1;
loongarch_pmu.num_counters = counters;
loongarch_pmu.max_period = (1ULL << 63) - 1;
@ -867,7 +868,7 @@ static int __init init_hw_perf_events(void)
on_each_cpu(reset_counters, NULL, 1);
pr_cont("%s PMU enabled, %d %d-bit counters available to each CPU.\n",
loongarch_pmu.name, counters, 64);
loongarch_pmu.name, counters, bits);
perf_pmu_register(&pmu, "cpu", PERF_TYPE_RAW);