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-rw-r--r--arch/x86/events/intel/ds.c35
1 files changed, 23 insertions, 12 deletions
diff --git a/arch/x86/events/intel/ds.c b/arch/x86/events/intel/ds.c
index 0319311dbdbb..be202390bbd3 100644
--- a/arch/x86/events/intel/ds.c
+++ b/arch/x86/events/intel/ds.c
@@ -1108,20 +1108,20 @@ static void setup_pebs_sample_data(struct perf_event *event,
}
/*
- * We use the interrupt regs as a base because the PEBS record
- * does not contain a full regs set, specifically it seems to
- * lack segment descriptors, which get used by things like
- * user_mode().
+ * We use the interrupt regs as a base because the PEBS record does not
+ * contain a full regs set, specifically it seems to lack segment
+ * descriptors, which get used by things like user_mode().
*
- * In the simple case fix up only the IP and BP,SP regs, for
- * PERF_SAMPLE_IP and PERF_SAMPLE_CALLCHAIN to function properly.
- * A possible PERF_SAMPLE_REGS will have to transfer all regs.
+ * In the simple case fix up only the IP for PERF_SAMPLE_IP.
+ *
+ * We must however always use BP,SP from iregs for the unwinder to stay
+ * sane; the record BP,SP can point into thin air when the record is
+ * from a previous PMI context or an (I)RET happend between the record
+ * and PMI.
*/
*regs = *iregs;
regs->flags = pebs->flags;
set_linear_ip(regs, pebs->ip);
- regs->bp = pebs->bp;
- regs->sp = pebs->sp;
if (sample_type & PERF_SAMPLE_REGS_INTR) {
regs->ax = pebs->ax;
@@ -1130,10 +1130,21 @@ static void setup_pebs_sample_data(struct perf_event *event,
regs->dx = pebs->dx;
regs->si = pebs->si;
regs->di = pebs->di;
- regs->bp = pebs->bp;
- regs->sp = pebs->sp;
- regs->flags = pebs->flags;
+ /*
+ * Per the above; only set BP,SP if we don't need callchains.
+ *
+ * XXX: does this make sense?
+ */
+ if (!(sample_type & PERF_SAMPLE_CALLCHAIN)) {
+ regs->bp = pebs->bp;
+ regs->sp = pebs->sp;
+ }
+
+ /*
+ * Preserve PERF_EFLAGS_VM from set_linear_ip().
+ */
+ regs->flags = pebs->flags | (regs->flags & PERF_EFLAGS_VM);
#ifndef CONFIG_X86_32
regs->r8 = pebs->r8;
regs->r9 = pebs->r9;