korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-11 12:28:41 +08:00
Code Issues Packages Projects Releases Wiki Activity

perf tools: Fixup module symbol end address properly

Browse Source 
I got a strange error on ARM to fail on processing FINISHED_ROUND
record.  It turned out that it was failing in symbol__alloc_hist()
because the symbol size is too big.

When a sample is captured on a specific BPF program, it failed.  I've
added a debug code and found the end address of the symbol is from
the next module which is placed far way.

  ffff800008795778-ffff80000879d6d8: bpf_prog_1bac53b8aac4bc58_netcg_sock    [bpf]
  ffff80000879d6d8-ffff80000ad656b4: bpf_prog_76867454b5944e15_netcg_getsockopt      [bpf]
  ffff80000ad656b4-ffffd69b7af74048: bpf_prog_1d50286d2eb1be85_hn_egress     [bpf]   <---------- here
  ffffd69b7af74048-ffffd69b7af74048: $x.5    [sha3_generic]
  ffffd69b7af74048-ffffd69b7af740b8: crypto_sha3_init        [sha3_generic]
  ffffd69b7af740b8-ffffd69b7af741e0: crypto_sha3_update      [sha3_generic]

The logic in symbols__fixup_end() just uses curr->start to update the
prev->end.  But in this case, it won't work as it's too different.

I think ARM has a different kernel memory layout for modules and BPF
than on x86.  Actually there's a logic to handle kernel and module
boundary.  Let's do the same for symbols between different modules.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Reviewed-by: Leo Yan <leo.yan@linux.dev>
Cc: Will Deacon <will@kernel.org>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20240212233322.1855161-1-namhyung@kernel.org
This commit is contained in:
Namhyung Kim 2024-02-12 15:33:22 -08:00
parent 6f146b249b
commit bacefe0c7b
1 changed files with 19 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
tools/perf/util/symbol.c
View File

@ -248,14 +248,31 @@ void symbols__fixup_end(struct rb_root_cached *symbols, bool is_kallsyms)
* segment is very big. Therefore do not fill this gap and do
* not assign it to the kernel dso map (kallsyms).
*
* Also BPF code can be allocated separately from text segments
* and modules. So the last entry in a module should not fill
* the gap too.
*
* In kallsyms, it determines module symbols using '[' character
* like in:
* ffffffffc1937000 T hdmi_driver_init [snd_hda_codec_hdmi]
*/
if (prev->end == prev->start) {
const char *prev_mod;
const char *curr_mod;
if (!is_kallsyms) {
prev->end = curr->start;
continue;
}
prev_mod = strchr(prev->name, '[');
curr_mod = strchr(curr->name, '[');
/* Last kernel/module symbol mapped to end of page */
if (is_kallsyms && (!strchr(prev->name, '[') !=
!strchr(curr->name, '[')))
if (!prev_mod != !curr_mod)
prev->end = roundup(prev->end + 4096, 4096);
/* Last symbol in the previous module */
else if (prev_mod && strcmp(prev_mod, curr_mod))
prev->end = roundup(prev->end + 4096, 4096);
else
prev->end = curr->start;