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| author | Sandipan Das <sandipan.das@amd.com> | 2022-08-11 17:59:53 +0530 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-08-27 00:05:43 +0200 |
| commit | 703fb765f48897214e3eb110f35dddec80682f60 (patch) | |
| tree | f23cd920b092433d819d3fa160d540cfd0129f18 /arch/x86/events/amd | |
| parent | 257449c6a50298bd21dcabd644f66a0296b78532 (diff) | |
| download | linux-703fb765f48897214e3eb110f35dddec80682f60.tar.gz linux-703fb765f48897214e3eb110f35dddec80682f60.tar.bz2 linux-703fb765f48897214e3eb110f35dddec80682f60.zip | |
perf/x86/amd/lbr: Detect LbrExtV2 support
AMD Last Branch Record Extension Version 2 (LbrExtV2) is driven by Core PMC
overflows. It records recently taken branches up to the moment when the PMC
overflow occurs.
Detect the feature during PMU initialization and set the branch stack depth
using CPUID leaf 0x80000022 EBX.
Signed-off-by: Sandipan Das <sandipan.das@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/fc6e45378ada258f1bab79b0de6e05c393a8f1dd.1660211399.git.sandipan.das@amd.com
Diffstat (limited to 'arch/x86/events/amd')
| -rw-r--r-- | arch/x86/events/amd/Makefile | 2 | ||||
| -rw-r--r-- | arch/x86/events/amd/core.c | 9 | ||||
| -rw-r--r-- | arch/x86/events/amd/lbr.c | 21 |
3 files changed, 27 insertions, 5 deletions
diff --git a/arch/x86/events/amd/Makefile b/arch/x86/events/amd/Makefile index b9f5d4610256..527d947eb76b 100644 --- a/arch/x86/events/amd/Makefile +++ b/arch/x86/events/amd/Makefile @@ -1,5 +1,5 @@ # SPDX-License-Identifier: GPL-2.0 -obj-$(CONFIG_CPU_SUP_AMD) += core.o +obj-$(CONFIG_CPU_SUP_AMD) += core.o lbr.o obj-$(CONFIG_PERF_EVENTS_AMD_BRS) += brs.o obj-$(CONFIG_PERF_EVENTS_AMD_POWER) += power.o obj-$(CONFIG_X86_LOCAL_APIC) += ibs.o diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c index ef3520731a20..a3aa67b4fd50 100644 --- a/arch/x86/events/amd/core.c +++ b/arch/x86/events/amd/core.c @@ -1374,10 +1374,11 @@ static int __init amd_core_pmu_init(void) x86_pmu.flags |= PMU_FL_PAIR; } - /* - * BRS requires special event constraints and flushing on ctxsw. - */ - if (boot_cpu_data.x86 >= 0x19 && !amd_brs_init()) { + /* LBR and BRS are mutually exclusive features */ + if (amd_pmu_lbr_init() && !amd_brs_init()) { + /* + * BRS requires special event constraints and flushing on ctxsw. + */ x86_pmu.get_event_constraints = amd_get_event_constraints_f19h; x86_pmu.sched_task = amd_pmu_brs_sched_task; x86_pmu.limit_period = amd_pmu_limit_period; diff --git a/arch/x86/events/amd/lbr.c b/arch/x86/events/amd/lbr.c new file mode 100644 index 000000000000..4e5b5d35f35a --- /dev/null +++ b/arch/x86/events/amd/lbr.c @@ -0,0 +1,21 @@ +// SPDX-License-Identifier: GPL-2.0 +#include <linux/perf_event.h> +#include <asm/perf_event.h> + +#include "../perf_event.h" + +__init int amd_pmu_lbr_init(void) +{ + union cpuid_0x80000022_ebx ebx; + + if (x86_pmu.version < 2 || !boot_cpu_has(X86_FEATURE_AMD_LBR_V2)) + return -EOPNOTSUPP; + + /* Set number of entries */ + ebx.full = cpuid_ebx(EXT_PERFMON_DEBUG_FEATURES); + x86_pmu.lbr_nr = ebx.split.lbr_v2_stack_sz; + + pr_cont("%d-deep LBR, ", x86_pmu.lbr_nr); + + return 0; +} |