scripts/decode_stacktrace.sh: fix build ID and PC source parsing

Support for parsing PC source info in stacktraces (e.g.  '(P)') was added
in commit 2bff77c665ed ("scripts/decode_stacktrace.sh: fix decoding of
lines with an additional info").  However, this logic was placed after the
build ID processing.  This incorrect order fails to parse lines containing
both elements, e.g.:

  drm_gem_mmap_obj+0x114/0x200 [drm 03d0564e0529947d67bb2008c3548be77279fd27] (P)

This patch fixes the problem by extracting the PC source info first and
then processing the module build ID.  With this change, the line above is
now properly parsed as such:

  drm_gem_mmap_obj (./include/linux/mmap_lock.h:212 ./include/linux/mm.h:811 drivers/gpu/drm/drm_gem.c:1177) drm (P)

While here, also add a brief explanation the build ID section.

Link: https://lkml.kernel.org/r/20251030010347.2731925-1-cmllamas@google.com
Fixes: 2bff77c665ed ("scripts/decode_stacktrace.sh: fix decoding of lines with an additional info")
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Reviewed-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: Breno Leitao <leitao@debian.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matthieu Baerts <matttbe@kernel.org>
Cc: Miroslav Benes <mbenes@suse.cz>
Cc: Puranjay Mohan <puranjay@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/scripts/decode_stacktrace.sh b/scripts/decode_stacktrace.sh
index c73cb802a0a3fc6559c5f53ff844e5cc6e433615..8d01b741de624c2e50d8657d45d8393af448aca7 100755 (executable)
--- a/scripts/decode_stacktrace.sh
+++ b/scripts/decode_stacktrace.sh
@@ -277,12 +277,6 @@ handle_line() {
                fi
        done
 
-       if [[ ${words[$last]} =~ ^[0-9a-f]+\] ]]; then
-               words[$last-1]="${words[$last-1]} ${words[$last]}"
-               unset words[$last] spaces[$last]
-               last=$(( $last - 1 ))
-       fi
-
        # Extract info after the symbol if present. E.g.:
        # func_name+0x54/0x80 (P)
        #                     ^^^
@@ -295,6 +289,14 @@ handle_line() {
                last=$(( $last - 1 ))
        fi
 
+       # Join module name with its build id if present, as these were
+       # split during tokenization (e.g. "[module" and "modbuildid]").
+       if [[ ${words[$last]} =~ ^[0-9a-f]+\] ]]; then
+               words[$last-1]="${words[$last-1]} ${words[$last]}"
+               unset words[$last] spaces[$last]
+               last=$(( $last - 1 ))
+       fi
+
        if [[ ${words[$last]} =~ \[([^]]+)\] ]]; then
                module=${words[$last]}
                # some traces format is "(%pS)", which like "(foo+0x0/0x1 [bar])"