[PATCH AUTOSEL 4.14 5/7] perf/x86/amd/ibs: Work around erratum #1197
From: Sasha Levin <sashal@kernel.org>
Date: 2021-08-30 12:01:42
Also in:
lkml, stable
Subsystem:
performance events subsystem, the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds, Thomas Gleixner, Borislav Petkov, Dave Hansen
From: Kim Phillips <redacted> [ 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 <redacted> 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 (local) 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 3fe68f7f9d5e..5043425ced6b 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;
@@ -674,6 +675,10 @@ 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; }
@@ -767,6 +772,9 @@ 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) {
--
2.30.2