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libbpf-tools/offcputime: Add dso info and symbol offset to backtrace …
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…for -v option

Add additional information and change format of backtrace
- add symbol base offset, dso name, dso base offset
- symbol and dso info is included if it's available in target binary
- changed format:
INDEX ADDR [SYMBOL+OFFSET] (MODULE+OFFSET)

Print backtrace of ip if it failed to get syms.

Before:
  # offcputime -v
    psiginfo
    vscanf
    __snprintf_chk
    [unknown]
    [unknown]
    [unknown]
    [unknown]
    [unknown]
    sd_event_exit
    sd_event_dispatch
    sd_event_run
    [unknown]
    __libc_start_main
    [unknown]
    -                systemd-journal (204)
        1

    xas_load
    xas_find
    filemap_map_pages
    __handle_mm_fault
    handle_mm_fault
    do_page_fault
    do_translation_fault
    do_mem_abort
    do_el0_ia_bp_hardening
    el0_ia
    xas_load
    --
failed to get syms
      -                PmLogCtl (138757)
        1

After:
  # offcputime -v
    #0  0xffffffc01018b7e8 __arm64_sys_clock_nanosleep+0x0
    pixie-io#1  0xffffffc01009a93c el0_svc_handler+0x34
    pixie-io#2  0xffffffc010084a08 el0_svc+0x8
    pixie-io#3  0xffffffc01018b7e8 __arm64_sys_clock_nanosleep+0x0
    --
    pixie-io#4  0x0000007fa0bffd14 clock_nanosleep+0x94 (/usr/lib/libc-2.31.so+0x9ed14)
    pixie-io#5  0x0000007fa0c0530c nanosleep+0x1c (/usr/lib/libc-2.31.so+0xa430c)
    pixie-io#6  0x0000007fa0c051e4 sleep+0x34 (/usr/lib/libc-2.31.so+0xa41e4)
    pixie-io#7  0x000000558a5a9608 flb_loop+0x28 (/usr/bin/fluent-bit+0x52608)
    pixie-io#8  0x000000558a59f1c4 flb_main+0xa84 (/usr/bin/fluent-bit+0x481c4)
    pixie-io#9  0x0000007fa0b85124 __libc_start_main+0xe4 (/usr/lib/libc-2.31.so+0x24124)
    iovisor#10 0x000000558a59d828 _start+0x34 (/usr/bin/fluent-bit+0x46828)
    -                fluent-bit (1238)
        1

    #0  0xffffffc01027daa4 generic_copy_file_checks+0x334
    pixie-io#1  0xffffffc0102ba634 __handle_mm_fault+0x8dc
    pixie-io#2  0xffffffc0102baa20 handle_mm_fault+0x168
    pixie-io#3  0xffffffc010ad23c0 do_page_fault+0x148
    pixie-io#4  0xffffffc010ad27c0 do_translation_fault+0xb0
    pixie-io#5  0xffffffc0100816b0 do_mem_abort+0x50
    pixie-io#6  0xffffffc0100843b0 el0_da+0x1c
    pixie-io#7  0xffffffc01027daa4 generic_copy_file_checks+0x334
    --
    pixie-io#8  0x0000007f8dc12648 [unknown]
    pixie-io#9  0x0000007f8dc0aef8 [unknown]
    iovisor#10 0x0000007f8dc1c990 [unknown]
    iovisor#11 0x0000007f8dc08b0c [unknown]
    iovisor#12 0x0000007f8dc08e48 [unknown]
    iovisor#13 0x0000007f8dc081c8 [unknown]
    -                PmLogCtl (2412)
        1

Fixed: iovisor#3884
Signed-off-by: Eunseon Lee <[email protected]>
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@ekyooo @yonghong-song
ekyooo authored and yonghong-song committed Oct 27, 2022
1 parent 1ad8f4b commit 6a5c573
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Showing 3 changed files with 58 additions and 8 deletions.
42 changes: 35 additions & 7 deletions libbpf-tools/offcputime.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -197,6 +197,9 @@ static void print_map(struct ksyms *ksyms, struct syms_cache *syms_cache,
int err, i, ifd, sfd;
unsigned long *ip;
struct val_t val;
char *dso_name;
unsigned long dso_offset;
int idx;

ip = calloc(env.perf_max_stack_depth, sizeof(*ip));
if (!ip) {
Expand All @@ -207,6 +210,8 @@ static void print_map(struct ksyms *ksyms, struct syms_cache *syms_cache,
ifd = bpf_map__fd(obj->maps.info);
sfd = bpf_map__fd(obj->maps.stackmap);
while (!bpf_map_get_next_key(ifd, &lookup_key, &next_key)) {
idx = 0;

err = bpf_map_lookup_elem(ifd, &next_key, &val);
if (err < 0) {
fprintf(stderr, "failed to lookup info: %d\n", err);
Expand All @@ -219,9 +224,17 @@ static void print_map(struct ksyms *ksyms, struct syms_cache *syms_cache,
fprintf(stderr, " [Missed Kernel Stack]\n");
goto print_ustack;
}

for (i = 0; i < env.perf_max_stack_depth && ip[i]; i++) {
ksym = ksyms__map_addr(ksyms, ip[i]);
printf(" %s\n", ksym ? ksym->name : "Unknown");
if (!env.verbose) {
printf(" %s\n", ksym ? ksym->name : "unknown");
} else {
if (ksym)
printf(" #%-2d 0x%lx %s+0x%lx\n", idx++, ip[i], ksym->name, ip[i] - ksym->addr);
else
printf(" #%-2d 0x%lx [unknown]\n", idx++, ip[i]);
}
}

print_ustack:
Expand All @@ -235,15 +248,30 @@ static void print_map(struct ksyms *ksyms, struct syms_cache *syms_cache,

syms = syms_cache__get_syms(syms_cache, next_key.tgid);
if (!syms) {
fprintf(stderr, "failed to get syms\n");
if (!env.verbose) {
fprintf(stderr, "failed to get syms\n");
} else {
for (i = 0; i < env.perf_max_stack_depth && ip[i]; i++)
printf(" #%-2d 0x%016lx [unknown]\n", idx++, ip[i]);
}
goto skip_ustack;
}
for (i = 0; i < env.perf_max_stack_depth && ip[i]; i++) {
sym = syms__map_addr(syms, ip[i]);
if (sym)
printf(" %s\n", sym->name);
else
printf(" [unknown]\n");
if (!env.verbose) {
sym = syms__map_addr(syms, ip[i]);
if (sym)
printf(" %s\n", sym->name);
else
printf(" [unknown]\n");
} else {
sym = syms__map_addr_dso(syms, ip[i], &dso_name, &dso_offset);
printf(" #%-2d 0x%016lx", idx++, ip[i]);
if (sym)
printf(" %s+0x%lx", sym->name, sym->offset);
if (dso_name)
printf(" (%s+0x%lx)", dso_name, dso_offset);
printf("\n");
}
}

skip_ustack:
Expand Down
21 changes: 20 additions & 1 deletion libbpf-tools/trace_helpers.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -423,6 +423,7 @@ static int dso__add_sym(struct dso *dso, const char *name, uint64_t start,
sym->name = (void*)(unsigned long)off;
sym->start = start;
sym->size = size;
sym->offset = 0;

return 0;
}
Expand Down Expand Up @@ -635,8 +636,10 @@ static struct sym *dso__find_sym(struct dso *dso, uint64_t offset)
end = mid - 1;
}

if (start == end && dso->syms[start].start <= offset)
if (start == end && dso->syms[start].start <= offset) {
(dso->syms[start]).offset = offset - dso->syms[start].start;
return &dso->syms[start];
}
return NULL;
}

Expand Down Expand Up @@ -721,6 +724,22 @@ const struct sym *syms__map_addr(const struct syms *syms, unsigned long addr)
return dso__find_sym(dso, offset);
}

const struct sym *syms__map_addr_dso(const struct syms *syms, unsigned long addr,
char **dso_name, unsigned long *dso_offset)
{
struct dso *dso;
uint64_t offset;

dso = syms__find_dso(syms, addr, &offset);
if (!dso)
return NULL;

*dso_name = dso->name;
*dso_offset = offset;

return dso__find_sym(dso, offset);
}

struct syms_cache {
struct {
struct syms *syms;
Expand Down
3 changes: 3 additions & 0 deletions libbpf-tools/trace_helpers.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -24,6 +24,7 @@ struct sym {
const char *name;
unsigned long start;
unsigned long size;
unsigned long offset;
};

struct syms;
Expand All @@ -32,6 +33,8 @@ struct syms *syms__load_pid(int tgid);
struct syms *syms__load_file(const char *fname);
void syms__free(struct syms *syms);
const struct sym *syms__map_addr(const struct syms *syms, unsigned long addr);
const struct sym *syms__map_addr_dso(const struct syms *syms, unsigned long addr,
char **dso_name, unsigned long *dso_offset);

struct syms_cache;

Expand Down

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