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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7dbf4dcfe2
Storing data for VDSO shared object, because we need it for the post
unwind processing.
The VDSO shared object is same for all process on a running system, so
it makes no difference when we store it inside the tracer - perf.
When [vdso] map memory is hit, we retrieve [vdso] DSO image and store it
into temporary file.
During the build-id processing phase, the [vdso] DSO image is stored in
build-id db, and build-id reference is made inside perf.data. The
build-id vdso file object is called '[vdso]'. We don't use temporary
file name which gets removed when record is finished.
During report phase the vdso build-id object is treated as any other
build-id DSO object.
Adding following API for vdso object:
bool is_vdso_map(const char *filename)
- returns true if the filename matches vdso map name
struct dso *vdso__dso_findnew(struct list_head *head)
- find/create proper vdso DSO object
vdso__exit(void)
- removes temporary VDSO image if there's any
This change makes backtrace dwarf post unwind possible from [vdso] maps.
Following output is current report of [vdso] sample dwarf backtrace:
# Overhead Command Shared Object Symbol
# ........ ....... ................. .............................
#
99.52% ex [vdso] [.] 0x00007fff3ace89af
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--- 0x7fff3ace89af
Following output is new report of [vdso] sample dwarf backtrace:
# Overhead Command Shared Object Symbol
# ........ ....... ................. .............................
#
99.52% ex [vdso] [.] 0x00000000000009af
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--- 0x7fff3ace89af
main
__libc_start_main
_start
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347295819-23177-5-git-send-email-jolsa@redhat.com
[ committer note: s/ALIGN/PERF_ALIGN/g to cope with the android build changes ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
112 lines
1.7 KiB
C
112 lines
1.7 KiB
C
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#include <unistd.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <linux/kernel.h>
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#include "vdso.h"
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#include "util.h"
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#include "symbol.h"
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#include "linux/string.h"
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static bool vdso_found;
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static char vdso_file[] = "/tmp/perf-vdso.so-XXXXXX";
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static int find_vdso_map(void **start, void **end)
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{
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FILE *maps;
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char line[128];
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int found = 0;
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maps = fopen("/proc/self/maps", "r");
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if (!maps) {
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pr_err("vdso: cannot open maps\n");
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return -1;
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}
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while (!found && fgets(line, sizeof(line), maps)) {
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int m = -1;
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/* We care only about private r-x mappings. */
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if (2 != sscanf(line, "%p-%p r-xp %*x %*x:%*x %*u %n",
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start, end, &m))
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continue;
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if (m < 0)
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continue;
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if (!strncmp(&line[m], VDSO__MAP_NAME,
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sizeof(VDSO__MAP_NAME) - 1))
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found = 1;
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}
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fclose(maps);
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return !found;
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}
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static char *get_file(void)
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{
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char *vdso = NULL;
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char *buf = NULL;
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void *start, *end;
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size_t size;
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int fd;
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if (vdso_found)
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return vdso_file;
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if (find_vdso_map(&start, &end))
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return NULL;
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size = end - start;
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buf = memdup(start, size);
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if (!buf)
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return NULL;
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fd = mkstemp(vdso_file);
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if (fd < 0)
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goto out;
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if (size == (size_t) write(fd, buf, size))
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vdso = vdso_file;
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close(fd);
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out:
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free(buf);
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vdso_found = (vdso != NULL);
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return vdso;
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}
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void vdso__exit(void)
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{
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if (vdso_found)
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unlink(vdso_file);
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}
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struct dso *vdso__dso_findnew(struct list_head *head)
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{
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struct dso *dso = dsos__find(head, VDSO__MAP_NAME);
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if (!dso) {
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char *file;
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file = get_file();
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if (!file)
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return NULL;
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dso = dso__new(VDSO__MAP_NAME);
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if (dso != NULL) {
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dsos__add(head, dso);
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dso__set_long_name(dso, file);
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}
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}
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return dso;
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}
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