Commit 3749e0bb authored by Adrian Hunter's avatar Adrian Hunter Committed by Arnaldo Carvalho de Melo
Browse files

perf thread-stack: Add thread_stack__br_sample_late() 



Add a thread stack function to create a branch stack for hardware events
where the sample records get created some time after the event occurred.

Signed-off-by: default avatarAdrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lore.kernel.org/lkml/20200429150751.12570-7-adrian.hunter@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 6cd2cbfc

tools/perf/util/thread-stack.c

+104 −0
Original line number Diff line number Diff line
@@ -645,6 +645,110 @@ void thread_stack__br_sample(struct thread *thread, int cpu, 
	}

}



/* Start of user space branch entries */

static bool us_start(struct branch_entry *be, u64 kernel_start, bool *start)

{

	if (!*start)

		*start = be->to && be->to < kernel_start;



	return *start;

}



/*

 * Start of branch entries after the ip fell in between 2 branches, or user

 * space branch entries.

 */

static bool ks_start(struct branch_entry *be, u64 sample_ip, u64 kernel_start,

		     bool *start, struct branch_entry *nb)

{

	if (!*start) {

		*start = (nb && sample_ip >= be->to && sample_ip <= nb->from) ||

			 be->from < kernel_start ||

			 (be->to && be->to < kernel_start);

	}



	return *start;

}



/*

 * Hardware sample records, created some time after the event occurred, need to

 * have subsequent addresses removed from the branch stack.

 */

void thread_stack__br_sample_late(struct thread *thread, int cpu,

				  struct branch_stack *dst, unsigned int sz,

				  u64 ip, u64 kernel_start)

{

	struct thread_stack *ts = thread__stack(thread, cpu);

	struct branch_entry *d, *s, *spos, *ssz;

	struct branch_stack *src;

	unsigned int nr = 0;

	bool start = false;



	dst->nr = 0;



	if (!ts)

		return;



	src = ts->br_stack_rb;

	if (!src->nr)

		return;



	spos = &src->entries[ts->br_stack_pos];

	ssz  = &src->entries[ts->br_stack_sz];



	d = &dst->entries[0];

	s = spos;



	if (ip < kernel_start) {

		/*

		 * User space sample: start copying branch entries when the

		 * branch is in user space.

		 */

		for (s = spos; s < ssz && nr < sz; s++) {

			if (us_start(s, kernel_start, &start)) {

				*d++ = *s;

				nr += 1;

			}

		}



		if (src->nr >= ts->br_stack_sz) {

			for (s = &src->entries[0]; s < spos && nr < sz; s++) {

				if (us_start(s, kernel_start, &start)) {

					*d++ = *s;

					nr += 1;

				}

			}

		}

	} else {

		struct branch_entry *nb = NULL;



		/*

		 * Kernel space sample: start copying branch entries when the ip

		 * falls in between 2 branches (or the branch is in user space

		 * because then the start must have been missed).

		 */

		for (s = spos; s < ssz && nr < sz; s++) {

			if (ks_start(s, ip, kernel_start, &start, nb)) {

				*d++ = *s;

				nr += 1;

			}

			nb = s;

		}



		if (src->nr >= ts->br_stack_sz) {

			for (s = &src->entries[0]; s < spos && nr < sz; s++) {

				if (ks_start(s, ip, kernel_start, &start, nb)) {

					*d++ = *s;

					nr += 1;

				}

				nb = s;

			}

		}

	}



	dst->nr = nr;

}



struct call_return_processor *

call_return_processor__new(int (*process)(struct call_return *cr, u64 *parent_db_id, void *data),

			   void *data)

tools/perf/util/thread-stack.h

+3 −0
Original line number Diff line number Diff line
@@ -91,6 +91,9 @@ void thread_stack__sample_late(struct thread *thread, int cpu, 
			       u64 kernel_start);

void thread_stack__br_sample(struct thread *thread, int cpu,

			     struct branch_stack *dst, unsigned int sz);

void thread_stack__br_sample_late(struct thread *thread, int cpu,

				  struct branch_stack *dst, unsigned int sz,

				  u64 sample_ip, u64 kernel_start);

int thread_stack__flush(struct thread *thread);

void thread_stack__free(struct thread *thread);

size_t thread_stack__depth(struct thread *thread, int cpu);