@@ -23,6 +23,7 @@
#include "../../../util/auxtrace.h"
#include "../../../util/record.h"
#include "../../../util/arm-spe.h"
+#include <tools/libc_compat.h> // reallocarray
#define KiB(x) ((x) * 1024)
#define MiB(x) ((x) * 1024 * 1024)
@@ -31,6 +32,8 @@ struct arm_spe_recording {
struct auxtrace_record itr;
struct perf_pmu *arm_spe_pmu;
struct evlist *evlist;
+ int wrapped_cnt;
+ bool *wrapped;
};
static void arm_spe_set_timestamp(struct auxtrace_record *itr,
@@ -299,6 +302,146 @@ static int arm_spe_snapshot_finish(struct auxtrace_record *itr)
return -EINVAL;
}
+static int arm_spe_alloc_wrapped_array(struct arm_spe_recording *ptr, int idx)
+{
+ bool *wrapped;
+ int cnt = ptr->wrapped_cnt, new_cnt, i;
+
+ /*
+ * No need to allocate, so return early.
+ */
+ if (idx < cnt)
+ return 0;
+
+ /*
+ * Make ptr->wrapped as big as idx.
+ */
+ new_cnt = idx + 1;
+
+ /*
+ * Free'ed in arm_spe_recording_free().
+ */
+ wrapped = reallocarray(ptr->wrapped, new_cnt, sizeof(bool));
+ if (!wrapped)
+ return -ENOMEM;
+
+ /*
+ * init new allocated values.
+ */
+ for (i = cnt; i < new_cnt; i++)
+ wrapped[i] = false;
+
+ ptr->wrapped_cnt = new_cnt;
+ ptr->wrapped = wrapped;
+
+ return 0;
+}
+
+static bool arm_spe_buffer_has_wrapped(unsigned char *buffer,
+ size_t buffer_size, u64 head)
+{
+ u64 i, watermark;
+ u64 *buf = (u64 *)buffer;
+ size_t buf_size = buffer_size;
+
+ /*
+ * Defensively handle the case where head might be continually increasing - if its value is
+ * equal or greater than the size of the ring buffer, then we can safely determine it has
+ * wrapped around. Otherwise, continue to detect if head might have wrapped.
+ */
+ if (head >= buffer_size)
+ return true;
+
+ /*
+ * We want to look the very last 512 byte (chosen arbitrarily) in the ring buffer.
+ */
+ watermark = buf_size - 512;
+
+ /*
+ * The value of head is somewhere within the size of the ring buffer. This can be that there
+ * hasn't been enough data to fill the ring buffer yet or the trace time was so long that
+ * head has numerically wrapped around. To find we need to check if we have data at the
+ * very end of the ring buffer. We can reliably do this because mmap'ed pages are zeroed
+ * out and there is a fresh mapping with every new session.
+ */
+
+ /*
+ * head is less than 512 byte from the end of the ring buffer.
+ */
+ if (head > watermark)
+ watermark = head;
+
+ /*
+ * Speed things up by using 64 bit transactions (see "u64 *buf" above)
+ */
+ watermark /= sizeof(u64);
+ buf_size /= sizeof(u64);
+
+ /*
+ * If we find trace data at the end of the ring buffer, head has been there and has
+ * numerically wrapped around at least once.
+ */
+ for (i = watermark; i < buf_size; i++)
+ if (buf[i])
+ return true;
+
+ return false;
+}
+
+static int arm_spe_find_snapshot(struct auxtrace_record *itr, int idx,
+ struct auxtrace_mmap *mm, unsigned char *data,
+ u64 *head, u64 *old)
+{
+ int err;
+ bool wrapped;
+ struct arm_spe_recording *ptr =
+ container_of(itr, struct arm_spe_recording, itr);
+
+ /*
+ * Allocate memory to keep track of wrapping if this is the first
+ * time we deal with this *mm.
+ */
+ if (idx >= ptr->wrapped_cnt) {
+ err = arm_spe_alloc_wrapped_array(ptr, idx);
+ if (err)
+ return err;
+ }
+
+ /*
+ * Check to see if *head has wrapped around. If it hasn't only the
+ * amount of data between *head and *old is snapshot'ed to avoid
+ * bloating the perf.data file with zeros. But as soon as *head has
+ * wrapped around the entire size of the AUX ring buffer it taken.
+ */
+ wrapped = ptr->wrapped[idx];
+ if (!wrapped && arm_spe_buffer_has_wrapped(data, mm->len, *head)) {
+ wrapped = true;
+ ptr->wrapped[idx] = true;
+ }
+
+ pr_debug3("%s: mmap index %d old head %zu new head %zu size %zu\n",
+ __func__, idx, (size_t)*old, (size_t)*head, mm->len);
+
+ /*
+ * No wrap has occurred, we can just use *head and *old.
+ */
+ if (!wrapped)
+ return 0;
+
+ /*
+ * *head has wrapped around - adjust *head and *old to pickup the
+ * entire content of the AUX buffer.
+ */
+ if (*head >= mm->len) {
+ *old = *head - mm->len;
+ } else {
+ *head += mm->len;
+ *old = *head - mm->len;
+ }
+
+ return 0;
+}
+
static u64 arm_spe_reference(struct auxtrace_record *itr __maybe_unused)
{
struct timespec ts;
@@ -313,6 +456,7 @@ static void arm_spe_recording_free(struct auxtrace_record *itr)
struct arm_spe_recording *sper =
container_of(itr, struct arm_spe_recording, itr);
+ free(sper->wrapped);
free(sper);
}
@@ -336,6 +480,7 @@ struct auxtrace_record *arm_spe_recording_init(int *err,
sper->itr.pmu = arm_spe_pmu;
sper->itr.snapshot_start = arm_spe_snapshot_start;
sper->itr.snapshot_finish = arm_spe_snapshot_finish;
+ sper->itr.find_snapshot = arm_spe_find_snapshot;
sper->itr.parse_snapshot_options = arm_spe_parse_snapshot_options;
sper->itr.recording_options = arm_spe_recording_options;
sper->itr.info_priv_size = arm_spe_info_priv_size;