[tip: perf/urgent] perf/x86/intel: Correct pt_regs->flags update for PEBS path

[tip-bot2 for Dapeng Mi]

The following commit has been merged into the perf/urgent branch of tip:

Commit-ID:     88aa1223bfffb1a0a98c639e9e1f71058f0d9178
Gitweb:        https://git.kernel.org/tip/88aa1223bfffb1a0a98c639e9e1f71058f0d9178
Author:        Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
AuthorDate:    Tue, 08 Sep 2026 15:51:01 +08:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Thu, 10 Sep 2026 10:22:50 +02:00

perf/x86/intel: Correct pt_regs->flags update for PEBS path

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 <dapeng1.mi@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20260908075102.540715-1-dapeng1.mi@xxxxxxxxxxxxxxx
---
 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 8940f02..d0bb767 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))