[PATCH 1/2] perf/x86/intel: Correct pt_regs->flags update for PEBS path
From: Dapeng Mi <hidden>
Date: 2026-09-08 07:57:50
Also in:
lkml
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
pt_regs->flags holds the saved CPU FLAGS register. In the PEBS path,
it was incorrectly set to PERF_EFLAGS_EXACT instead of being populated
from the PEBS flags snapshot.
Update pt_regs->flags from PEBS GPR flags if GPRs group is present.
Fixes: c22497f5838c ("perf/x86/intel: Support adaptive PEBS v4")
Signed-off-by: Dapeng Mi <redacted>
---
arch/x86/events/intel/ds.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 8940f0292229..d0bb767a0fef 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c@@ -2432,7 +2432,7 @@ static inline void __setup_pebs_basic_group(struct perf_event *event, { /* The ip in basic is EventingIP */ set_linear_ip(regs, ip); - regs->flags = PERF_EFLAGS_EXACT; + regs->flags |= PERF_EFLAGS_EXACT; setup_pebs_time(event, data, tsc); if (sample_type & PERF_SAMPLE_WEIGHT_STRUCT)
@@ -2444,9 +2444,17 @@ static inline void __setup_pebs_gpr_group(struct perf_event *event, struct pebs_gprs *gprs, u64 sample_type) { + /* + * Update flags with PEBS data. PERF_EFLAGS_EXACT must be set + * in previous basic group handling. + */ + regs->flags = gprs->flags | PERF_EFLAGS_EXACT; + if (event->attr.precise_ip < 2) { set_linear_ip(regs, gprs->ip); regs->flags &= ~PERF_EFLAGS_EXACT; + } else if (regs->flags & X86_VM_MASK) { + regs->flags ^= (PERF_EFLAGS_VM | X86_VM_MASK); } if (sample_type & (PERF_SAMPLE_REGS_INTR | PERF_SAMPLE_REGS_USER))
base-commit: 609d28fba41e977425eff9848e553740bbf155ad -- 2.34.1