diff options
Diffstat (limited to 'kernel/trace/ring_buffer.c')
-rw-r--r-- | kernel/trace/ring_buffer.c | 49 |
1 files changed, 44 insertions, 5 deletions
diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 655d6db3e3c3..3a0c7ed0e93f 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -29,6 +29,14 @@ #include <asm/local.h> +/* + * The "absolute" timestamp in the buffer is only 59 bits. + * If a clock has the 5 MSBs set, it needs to be saved and + * reinserted. + */ +#define TS_MSB (0xf8ULL << 56) +#define ABS_TS_MASK (~TS_MSB) + static void update_pages_handler(struct work_struct *work); /* @@ -783,6 +791,24 @@ static inline void verify_event(struct ring_buffer_per_cpu *cpu_buffer, } #endif +/* + * The absolute time stamp drops the 5 MSBs and some clocks may + * require them. The rb_fix_abs_ts() will take a previous full + * time stamp, and add the 5 MSB of that time stamp on to the + * saved absolute time stamp. Then they are compared in case of + * the unlikely event that the latest time stamp incremented + * the 5 MSB. + */ +static inline u64 rb_fix_abs_ts(u64 abs, u64 save_ts) +{ + if (save_ts & TS_MSB) { + abs |= save_ts & TS_MSB; + /* Check for overflow */ + if (unlikely(abs < save_ts)) + abs += 1ULL << 59; + } + return abs; +} static inline u64 rb_time_stamp(struct trace_buffer *buffer); @@ -811,8 +837,10 @@ u64 ring_buffer_event_time_stamp(struct trace_buffer *buffer, u64 ts; /* If the event includes an absolute time, then just use that */ - if (event->type_len == RINGBUF_TYPE_TIME_STAMP) - return rb_event_time_stamp(event); + if (event->type_len == RINGBUF_TYPE_TIME_STAMP) { + ts = rb_event_time_stamp(event); + return rb_fix_abs_ts(ts, cpu_buffer->tail_page->page->time_stamp); + } nest = local_read(&cpu_buffer->committing); verify_event(cpu_buffer, event); @@ -2754,8 +2782,15 @@ static void rb_add_timestamp(struct ring_buffer_per_cpu *cpu_buffer, (RB_ADD_STAMP_FORCE | RB_ADD_STAMP_ABSOLUTE); if (unlikely(info->delta > (1ULL << 59))) { + /* + * Some timers can use more than 59 bits, and when a timestamp + * is added to the buffer, it will lose those bits. + */ + if (abs && (info->ts & TS_MSB)) { + info->delta &= ABS_TS_MASK; + /* did the clock go backwards */ - if (info->before == info->after && info->before > info->ts) { + } else if (info->before == info->after && info->before > info->ts) { /* not interrupted */ static int once; @@ -3304,7 +3339,7 @@ static void dump_buffer_page(struct buffer_data_page *bpage, case RINGBUF_TYPE_TIME_STAMP: delta = rb_event_time_stamp(event); - ts = delta; + ts = rb_fix_abs_ts(delta, ts); pr_warn(" [%lld] absolute:%lld TIME STAMP\n", ts, delta); break; @@ -3380,7 +3415,7 @@ static void check_buffer(struct ring_buffer_per_cpu *cpu_buffer, case RINGBUF_TYPE_TIME_STAMP: delta = rb_event_time_stamp(event); - ts = delta; + ts = rb_fix_abs_ts(delta, ts); break; case RINGBUF_TYPE_PADDING: @@ -4367,6 +4402,7 @@ rb_update_read_stamp(struct ring_buffer_per_cpu *cpu_buffer, case RINGBUF_TYPE_TIME_STAMP: delta = rb_event_time_stamp(event); + delta = rb_fix_abs_ts(delta, cpu_buffer->read_stamp); cpu_buffer->read_stamp = delta; return; @@ -4397,6 +4433,7 @@ rb_update_iter_read_stamp(struct ring_buffer_iter *iter, case RINGBUF_TYPE_TIME_STAMP: delta = rb_event_time_stamp(event); + delta = rb_fix_abs_ts(delta, iter->read_stamp); iter->read_stamp = delta; return; @@ -4650,6 +4687,7 @@ rb_buffer_peek(struct ring_buffer_per_cpu *cpu_buffer, u64 *ts, case RINGBUF_TYPE_TIME_STAMP: if (ts) { *ts = rb_event_time_stamp(event); + *ts = rb_fix_abs_ts(*ts, reader->page->time_stamp); ring_buffer_normalize_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu, ts); } @@ -4741,6 +4779,7 @@ rb_iter_peek(struct ring_buffer_iter *iter, u64 *ts) case RINGBUF_TYPE_TIME_STAMP: if (ts) { *ts = rb_event_time_stamp(event); + *ts = rb_fix_abs_ts(*ts, iter->head_page->page->time_stamp); ring_buffer_normalize_time_stamp(cpu_buffer->buffer, cpu_buffer->cpu, ts); } |