diff options
Diffstat (limited to 'tools/perf/util/auxtrace.h')
-rw-r--r-- | tools/perf/util/auxtrace.h | 49 |
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, |