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authorKim Phillips <kim.phillips@amd.com>2021-08-17 17:10:42 -0500
committerIngo Molnar <mingo@kernel.org>2021-08-26 08:58:02 +0200
commit26db2e0c51fe83e1dd852c1321407835b481806e (patch)
tree30b289fd7faadcd661cbad57e2c0740023e77ad5
parent0b3a8738b76fe2087f7bc2bd59f4c78504c79180 (diff)
perf/x86/amd/ibs: Work around erratum #1197
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
-rw-r--r--arch/x86/events/amd/ibs.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c
index 40669eac9d6d..921f47b9bb24 100644
--- a/arch/x86/events/amd/ibs.c
+++ b/arch/x86/events/amd/ibs.c
@@ -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) {