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Commit ee11b90b authored by Kirill Smelkov's avatar Kirill Smelkov Committed by Ingo Molnar
Browse files

perf top: Fix annotate for userspace 



First, for programs and prelinked libraries, annotate code was
fooled by objdump output IPs (src->eip in the code) being
wrongly converted to absolute IPs. In such case there were no
conversion needed, but in

   src->eip = strtoull(src->line, NULL, 16);
   src->eip = map->unmap_ip(map, src->eip); // = eip + map->start - map->pgoff

we were reading absolute address from objdump (e.g. 8048604) and
then almost doubling it, because eip & map->start are
approximately close for small programs.

Needless to say, that later, in record_precise_ip() there was no
matching with real runtime IPs.

And second, like with `perf annotate` the problem with
non-prelinked *.so was that we were doing rip -> objdump address
conversion wrong.

Also, because unlike `perf annotate`, `perf top` code does
annotation based on absolute IPs for performance reasons(*), new
helper for mapping objdump addresse to IP is introduced.

(*) we get samples info in absolute IPs, and since we do lots of
    hit-testing on absolute IPs at runtime in record_precise_ip(), it's
    better to convert objdump addresses to IPs once and do no conversion
    at runtime.

I also had to fix how objdump output is parsed (with hardcoded
8/16 characters format, which was inappropriate for ET_DYN dsos
with small addresses like '4ac')

Also note, that not all objdump output lines has associtated
IPs, e.g. look at source lines here:

    000004ac <my_strlen>:
    extern "C"
    int my_strlen(const char *s)
     4ac:   55                      push   %ebp
     4ad:   89 e5                   mov    %esp,%ebp
     4af:   83 ec 10                sub    $0x10,%esp
    {
        int len = 0;
     4b2:   c7 45 fc 00 00 00 00    movl   $0x0,-0x4(%ebp)
     4b9:   eb 08                   jmp    4c3 <my_strlen+0x17>

        while (*s) {
            ++len;
     4bb:   83 45 fc 01             addl   $0x1,-0x4(%ebp)
            ++s;
     4bf:   83 45 08 01             addl   $0x1,0x8(%ebp)

So we mark them with eip=0, and ignore such lines in annotate
lookup code.

Signed-off-by: default avatarKirill Smelkov <kirr@landau.phys.spbu.ru>
[ Note: one hunk of this patch was applied by Mike in 57d81889 ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1265550376-12665-1-git-send-email-acme@infradead.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5ecaafdb

tools/perf/builtin-top.c

+9 −9
Original line number Diff line number Diff line
@@ -216,7 +216,7 @@ static void parse_source(struct sym_entry *syme) 
	while (!feof(file)) {

		struct source_line *src;

		size_t dummy = 0;

		char *c;

		char *c, *sep;



		src = malloc(sizeof(struct source_line));

		assert(src != NULL);
@@ -235,14 +235,11 @@ static void parse_source(struct sym_entry *syme) 
		*source->lines_tail = src;

		source->lines_tail = &src->next;



		if (strlen(src->line)>8 && src->line[8] == ':') {

			src->eip = strtoull(src->line, NULL, 16);

			src->eip = map->unmap_ip(map, src->eip);

		}

		if (strlen(src->line)>8 && src->line[16] == ':') {

			src->eip = strtoull(src->line, NULL, 16);

			src->eip = map->unmap_ip(map, src->eip);

		}

		src->eip = strtoull(src->line, &sep, 16);

		if (*sep == ':')

			src->eip = map__objdump_2ip(map, src->eip);

		else /* this line has no ip info (e.g. source line) */

			src->eip = 0;

	}

	pclose(file);

out_assign:
@@ -277,6 +274,9 @@ static void record_precise_ip(struct sym_entry *syme, int counter, u64 ip) 
		goto out_unlock;



	for (line = syme->src->lines; line; line = line->next) {

		/* skip lines without IP info */

		if (line->eip == 0)

			continue;

		if (line->eip == ip) {

			line->count[counter]++;

			break;

tools/perf/util/map.c

+8 −0
Original line number Diff line number Diff line
@@ -222,3 +222,11 @@ u64 map__rip_2objdump(struct map *map, u64 rip) 
			rip;

	return addr;

}



u64 map__objdump_2ip(struct map *map, u64 addr)

{

	u64 ip = map->dso->adjust_symbols ?

			addr :

			map->unmap_ip(map, addr);	/* RIP -> IP */

	return ip;

}

tools/perf/util/map.h

+2 −2
Original line number Diff line number Diff line
@@ -61,9 +61,9 @@ static inline u64 identity__map_ip(struct map *map __used, u64 ip) 
}





/* rip -> addr suitable for passing to `objdump --start-address=` */

/* rip/ip <-> addr suitable for passing to `objdump --start-address=` */

u64 map__rip_2objdump(struct map *map, u64 rip);



u64 map__objdump_2ip(struct map *map, u64 addr);



struct symbol;

struct mmap_event;