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perf/x86/amd/ibs: Work around erratum #1197

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Erratum #1197 "IBS (Instruction Based Sampling) Register State May be
Incorrect After Restore From CC6" is published in a document:

  "Revision Guide for AMD Family 19h Models 00h-0Fh Processors" 56683 Rev. 1.04 July 2021

  https://bugzilla.kernel.org/show_bug.cgi?id=206537

Implement the erratum's suggested workaround and ignore IBS samples if
MSRC001_1031 == 0.

Signed-off-by: Kim Phillips <kim.phillips@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210817221048.88063-3-kim.phillips@amd.com
This commit is contained in:
Kim Phillips 2021-08-17 17:10:42 -05:00 committed by Ingo Molnar
parent 0b3a8738b7
commit 26db2e0c51
1 changed files with 8 additions and 0 deletions
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8
arch/x86/events/amd/ibs.c
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@ -90,6 +90,7 @@ struct perf_ibs {
unsigned long offset_mask[1];
int offset_max;
unsigned int fetch_count_reset_broken : 1;
unsigned int fetch_ignore_if_zero_rip : 1;
struct cpu_perf_ibs __percpu *pcpu;
struct attribute **format_attrs;
@ -672,6 +673,10 @@ fail:
if (check_rip && (ibs_data.regs[2] & IBS_RIP_INVALID)) {
regs.flags &= ~PERF_EFLAGS_EXACT;
} else {
/* Workaround for erratum #1197 */
if (perf_ibs->fetch_ignore_if_zero_rip && !(ibs_data.regs[1]))
goto out;
set_linear_ip(&regs, ibs_data.regs[1]);
regs.flags |= PERF_EFLAGS_EXACT;
}
@ -769,6 +774,9 @@ static __init void perf_event_ibs_init(void)
if (boot_cpu_data.x86 >= 0x16 && boot_cpu_data.x86 <= 0x18)
perf_ibs_fetch.fetch_count_reset_broken = 1;
if (boot_cpu_data.x86 == 0x19 && boot_cpu_data.x86_model < 0x10)
perf_ibs_fetch.fetch_ignore_if_zero_rip = 1;
perf_ibs_pmu_init(&perf_ibs_fetch, "ibs_fetch");
if (ibs_caps & IBS_CAPS_OPCNT) {