1 files changed, 18 insertions, 31 deletions

diff --git a/tools/perf/util/auxtrace.h b/tools/perf/util/auxtrace.h
index cc1c1b9cec9c..5f383908ca6e 100644
--- a/tools/perf/util/auxtrace.h
+++ b/tools/perf/util/auxtrace.h
@@ -440,52 +440,39 @@ struct auxtrace_cache;
 
 #ifdef HAVE_AUXTRACE_SUPPORT
 
-/*
- * In snapshot mode the mmapped page is read-only which makes using
- * __sync_val_compare_and_swap() problematic.  However, snapshot mode expects
- * the buffer is not updated while the snapshot is made (e.g. Intel PT disables
- * the event) so there is not a race anyway.
- */
-static inline u64 auxtrace_mmap__read_snapshot_head(struct auxtrace_mmap *mm)
-{
-	struct perf_event_mmap_page *pc = mm->userpg;
-	u64 head = READ_ONCE(pc->aux_head);
-
-	/* Ensure all reads are done after we read the head */
-	smp_rmb();
-	return head;
-}
+u64 compat_auxtrace_mmap__read_head(struct auxtrace_mmap *mm);
+int compat_auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail);
 
-static inline u64 auxtrace_mmap__read_head(struct auxtrace_mmap *mm)
+static inline u64 auxtrace_mmap__read_head(struct auxtrace_mmap *mm,
+					   int kernel_is_64_bit __maybe_unused)
 {
 	struct perf_event_mmap_page *pc = mm->userpg;
-#if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
-	u64 head = READ_ONCE(pc->aux_head);
-#else
-	u64 head = __sync_val_compare_and_swap(&pc->aux_head, 0, 0);
+	u64 head;
+
+#if BITS_PER_LONG == 32
+	if (kernel_is_64_bit)
+		return compat_auxtrace_mmap__read_head(mm);
 #endif
+	head = READ_ONCE(pc->aux_head);
 
 	/* Ensure all reads are done after we read the head */
 	smp_rmb();
 	return head;
 }
 
-static inline void auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail)
+static inline int auxtrace_mmap__write_tail(struct auxtrace_mmap *mm, u64 tail,
+					    int kernel_is_64_bit __maybe_unused)
 {
 	struct perf_event_mmap_page *pc = mm->userpg;
-#if BITS_PER_LONG != 64 && defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
-	u64 old_tail;
-#endif
 
+#if BITS_PER_LONG == 32
+	if (kernel_is_64_bit)
+		return compat_auxtrace_mmap__write_tail(mm, tail);
+#endif
 	/* Ensure all reads are done before we write the tail out */
 	smp_mb();
-#if BITS_PER_LONG == 64 || !defined(HAVE_SYNC_COMPARE_AND_SWAP_SUPPORT)
-	pc->aux_tail = tail;
-#else
-	do {
-		old_tail = __sync_val_compare_and_swap(&pc->aux_tail, 0, 0);
-	} while (!__sync_bool_compare_and_swap(&pc->aux_tail, old_tail, tail));
-#endif
+	WRITE_ONCE(pc->aux_tail, tail);
+	return 0;
 }
 
 int auxtrace_mmap__mmap(struct auxtrace_mmap *mm,