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perf tools: Back [vdso] DSO with real data
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
|
--- 0x7fff3ace89af
Following output is new report of [vdso] sample dwarf backtrace:
# Overhead Command Shared Object Symbol
# ........ ....... ................. .............................
#
99.52% ex [vdso] [.] 0x00000000000009af
|
--- 0x7fff3ace89af
main
__libc_start_main
_start
Signed-off-by: Jiri Olsa <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
[ committer note: s/ALIGN/PERF_ALIGN/g to cope with the android build changes ]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>- Loading branch information
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,111 @@ | ||
|
|
||
| #include <unistd.h> | ||
| #include <stdio.h> | ||
| #include <string.h> | ||
| #include <sys/types.h> | ||
| #include <sys/stat.h> | ||
| #include <fcntl.h> | ||
| #include <stdlib.h> | ||
| #include <linux/kernel.h> | ||
|
|
||
| #include "vdso.h" | ||
| #include "util.h" | ||
| #include "symbol.h" | ||
| #include "linux/string.h" | ||
|
|
||
| static bool vdso_found; | ||
| static char vdso_file[] = "/tmp/perf-vdso.so-XXXXXX"; | ||
|
|
||
| static int find_vdso_map(void **start, void **end) | ||
| { | ||
| FILE *maps; | ||
| char line[128]; | ||
| int found = 0; | ||
|
|
||
| maps = fopen("/proc/self/maps", "r"); | ||
| if (!maps) { | ||
| pr_err("vdso: cannot open maps\n"); | ||
| return -1; | ||
| } | ||
|
|
||
| while (!found && fgets(line, sizeof(line), maps)) { | ||
| int m = -1; | ||
|
|
||
| /* We care only about private r-x mappings. */ | ||
| if (2 != sscanf(line, "%p-%p r-xp %*x %*x:%*x %*u %n", | ||
| start, end, &m)) | ||
| continue; | ||
| if (m < 0) | ||
| continue; | ||
|
|
||
| if (!strncmp(&line[m], VDSO__MAP_NAME, | ||
| sizeof(VDSO__MAP_NAME) - 1)) | ||
| found = 1; | ||
| } | ||
|
|
||
| fclose(maps); | ||
| return !found; | ||
| } | ||
|
|
||
| static char *get_file(void) | ||
| { | ||
| char *vdso = NULL; | ||
| char *buf = NULL; | ||
| void *start, *end; | ||
| size_t size; | ||
| int fd; | ||
|
|
||
| if (vdso_found) | ||
| return vdso_file; | ||
|
|
||
| if (find_vdso_map(&start, &end)) | ||
| return NULL; | ||
|
|
||
| size = end - start; | ||
|
|
||
| buf = memdup(start, size); | ||
| if (!buf) | ||
| return NULL; | ||
|
|
||
| fd = mkstemp(vdso_file); | ||
| if (fd < 0) | ||
| goto out; | ||
|
|
||
| if (size == (size_t) write(fd, buf, size)) | ||
| vdso = vdso_file; | ||
|
|
||
| close(fd); | ||
|
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| out: | ||
| free(buf); | ||
|
|
||
| vdso_found = (vdso != NULL); | ||
| return vdso; | ||
| } | ||
|
|
||
| void vdso__exit(void) | ||
| { | ||
| if (vdso_found) | ||
| unlink(vdso_file); | ||
| } | ||
|
|
||
| struct dso *vdso__dso_findnew(struct list_head *head) | ||
| { | ||
| struct dso *dso = dsos__find(head, VDSO__MAP_NAME); | ||
|
|
||
| if (!dso) { | ||
| char *file; | ||
|
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| file = get_file(); | ||
| if (!file) | ||
| return NULL; | ||
|
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||
| dso = dso__new(VDSO__MAP_NAME); | ||
| if (dso != NULL) { | ||
| dsos__add(head, dso); | ||
| dso__set_long_name(dso, file); | ||
| } | ||
| } | ||
|
|
||
| return dso; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,18 @@ | ||
| #ifndef __PERF_VDSO__ | ||
| #define __PERF_VDSO__ | ||
|
|
||
| #include <linux/types.h> | ||
| #include <string.h> | ||
| #include <stdbool.h> | ||
|
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| #define VDSO__MAP_NAME "[vdso]" | ||
|
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| static inline bool is_vdso_map(const char *filename) | ||
| { | ||
| return !strcmp(filename, VDSO__MAP_NAME); | ||
| } | ||
|
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| struct dso *vdso__dso_findnew(struct list_head *head); | ||
| void vdso__exit(void); | ||
|
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| #endif /* __PERF_VDSO__ */ |