Commit a7fa19f5 authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo

perf intel-pt: Add intel_pt_fast_forward()

Intel PT decoding is done in time order. In order to support efficient time
interval filtering, add a facility to "fast forward" towards a particular
timestamp. That involves finding the right buffer, stepping to that buffer,
and then stepping forward PSBs. Because decoding must begin at a PSB,
"fast forward" stops at the last PSB that has a timestamp before the target
timestamp.
Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190604130017.31207-9-adrian.hunter@intel.comSigned-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 6c1f0b18
......@@ -126,6 +126,7 @@ struct intel_pt_decoder {
uint64_t timestamp;
uint64_t tsc_timestamp;
uint64_t ref_timestamp;
uint64_t buf_timestamp;
uint64_t sample_timestamp;
uint64_t ret_addr;
uint64_t ctc_timestamp;
......@@ -519,6 +520,7 @@ static int intel_pt_get_data(struct intel_pt_decoder *decoder, bool reposition)
intel_pt_log("No more data\n");
return -ENODATA;
}
decoder->buf_timestamp = buffer.ref_timestamp;
if (!buffer.consecutive || reposition) {
intel_pt_reposition(decoder);
decoder->ref_timestamp = buffer.ref_timestamp;
......@@ -2854,3 +2856,131 @@ unsigned char *intel_pt_find_overlap(unsigned char *buf_a, size_t len_a,
return buf_b; /* No overlap */
}
}
/**
* struct fast_forward_data - data used by intel_pt_ff_cb().
* @timestamp: timestamp to fast forward towards
* @buf_timestamp: buffer timestamp of last buffer with trace data earlier than
* the fast forward timestamp.
*/
struct fast_forward_data {
uint64_t timestamp;
uint64_t buf_timestamp;
};
/**
* intel_pt_ff_cb - fast forward lookahead callback.
* @buffer: Intel PT trace buffer
* @data: opaque pointer to fast forward data (struct fast_forward_data)
*
* Determine if @buffer trace is past the fast forward timestamp.
*
* Return: 1 (stop lookahead) if @buffer trace is past the fast forward
* timestamp, and 0 otherwise.
*/
static int intel_pt_ff_cb(struct intel_pt_buffer *buffer, void *data)
{
struct fast_forward_data *d = data;
unsigned char *buf;
uint64_t tsc;
size_t rem;
size_t len;
buf = (unsigned char *)buffer->buf;
len = buffer->len;
if (!intel_pt_next_psb(&buf, &len) ||
!intel_pt_next_tsc(buf, len, &tsc, &rem))
return 0;
tsc = intel_pt_8b_tsc(tsc, buffer->ref_timestamp);
intel_pt_log("Buffer 1st timestamp " x64_fmt " ref timestamp " x64_fmt "\n",
tsc, buffer->ref_timestamp);
/*
* If the buffer contains a timestamp earlier that the fast forward
* timestamp, then record it, else stop.
*/
if (tsc < d->timestamp)
d->buf_timestamp = buffer->ref_timestamp;
else
return 1;
return 0;
}
/**
* intel_pt_fast_forward - reposition decoder forwards.
* @decoder: Intel PT decoder
* @timestamp: timestamp to fast forward towards
*
* Reposition decoder at the last PSB with a timestamp earlier than @timestamp.
*
* Return: 0 on success or negative error code on failure.
*/
int intel_pt_fast_forward(struct intel_pt_decoder *decoder, uint64_t timestamp)
{
struct fast_forward_data d = { .timestamp = timestamp };
unsigned char *buf;
size_t len;
int err;
intel_pt_log("Fast forward towards timestamp " x64_fmt "\n", timestamp);
/* Find buffer timestamp of buffer to fast forward to */
err = decoder->lookahead(decoder->data, intel_pt_ff_cb, &d);
if (err < 0)
return err;
/* Walk to buffer with same buffer timestamp */
if (d.buf_timestamp) {
do {
decoder->pos += decoder->len;
decoder->len = 0;
err = intel_pt_get_next_data(decoder, true);
/* -ENOLINK means non-consecutive trace */
if (err && err != -ENOLINK)
return err;
} while (decoder->buf_timestamp != d.buf_timestamp);
}
if (!decoder->buf)
return 0;
buf = (unsigned char *)decoder->buf;
len = decoder->len;
if (!intel_pt_next_psb(&buf, &len))
return 0;
/*
* Walk PSBs while the PSB timestamp is less than the fast forward
* timestamp.
*/
do {
uint64_t tsc;
size_t rem;
if (!intel_pt_next_tsc(buf, len, &tsc, &rem))
break;
tsc = intel_pt_8b_tsc(tsc, decoder->buf_timestamp);
/*
* A TSC packet can slip past MTC packets but, after fast
* forward, decoding starts at the TSC timestamp. That means
* the timestamps may not be exactly the same as the timestamps
* that would have been decoded without fast forward.
*/
if (tsc < timestamp) {
intel_pt_log("Fast forward to next PSB timestamp " x64_fmt "\n", tsc);
decoder->pos += decoder->len - len;
decoder->buf = buf;
decoder->len = len;
intel_pt_reposition(decoder);
} else {
break;
}
} while (intel_pt_step_psb(&buf, &len));
return 0;
}
......@@ -130,6 +130,8 @@ void intel_pt_decoder_free(struct intel_pt_decoder *decoder);
const struct intel_pt_state *intel_pt_decode(struct intel_pt_decoder *decoder);
int intel_pt_fast_forward(struct intel_pt_decoder *decoder, uint64_t timestamp);
unsigned char *intel_pt_find_overlap(unsigned char *buf_a, size_t len_a,
unsigned char *buf_b, size_t len_b,
bool have_tsc, bool *consecutive);
......
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