From: Kim Phillips kim.phillips@amd.com
[ Upstream commit 26db2e0c51fe83e1dd852c1321407835b481806e ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/events/amd/ibs.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/arch/x86/events/amd/ibs.c b/arch/x86/events/amd/ibs.c index f6e57bebbc6b..5c6aad14cdd9 100644 --- a/arch/x86/events/amd/ibs.c +++ b/arch/x86/events/amd/ibs.c @@ -89,6 +89,7 @@ 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; @@ -673,6 +674,10 @@ static int perf_ibs_handle_irq(struct perf_ibs *perf_ibs, struct pt_regs *iregs) 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(®s, ibs_data.regs[1]); regs.flags |= PERF_EFLAGS_EXACT; } @@ -766,6 +771,9 @@ 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) {