[PATCH 1/5] perf jitdump: Byte-swap debug entries via unaligned-safe accessors
From: Arnaldo Carvalho de Melo <acme@kernel.org>
Date: 2026-09-04 14:41:12
Also in:
lkml
Subsystem:
performance events subsystem, the rest · Maintainers:
Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo, Namhyung Kim, Linus Torvalds
From: Arnaldo Carvalho de Melo <redacted> debug_entry records are packed with a variable-length name[] field, so entries after the first may start at addresses that are not naturally aligned for their u64 addr and int lineno/discrim fields. On strict alignment architectures the byte-swap loop in jit_get_next_entry() performed misaligned 64-bit loads and stores through struct member access, which is undefined behavior. Use get_unaligned()/put_unaligned() for the byte-swap of each field. Reported-by: sashiko-bot <sashiko-bot@kernel.org> Cc: Stephane Eranian <redacted> Assisted-by: LLM Signed-off-by: Arnaldo Carvalho de Melo <redacted> --- tools/perf/util/jitdump.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/jitdump.c b/tools/perf/util/jitdump.c
index d25a9fe9b020ce87..e0d5cc9a828189a2 100644
--- a/tools/perf/util/jitdump.c
+++ b/tools/perf/util/jitdump.c@@ -14,6 +14,8 @@ #include <sys/stat.h> #include <sys/mman.h> #include <linux/stringify.h> +#include <linux/kernel.h> +#include <linux/unaligned.h> #include "event.h" #include "debug.h"
@@ -343,9 +345,14 @@ jit_get_next_entry(struct jit_buf_desc *jd) /* name must be NUL-terminated within the record */ if (!memchr(ent->name, '\0', (char *)end - ent->name)) break; - ent->addr = bswap_64(ent->addr); - ent->lineno = bswap_32(ent->lineno); - ent->discrim = bswap_32(ent->discrim); + /* + * debug entries are packed with a variable-length + * name[], so entries after the first may be + * unaligned: byte-swap via unaligned-safe accessors. + */ + put_unaligned(bswap_64(get_unaligned(&ent->addr)), &ent->addr); + put_unaligned(bswap_32(get_unaligned(&ent->lineno)), &ent->lineno); + put_unaligned(bswap_32(get_unaligned(&ent->discrim)), &ent->discrim); ent = debug_entry_next(ent); } /* clamp so downstream consumers don't overrun */
--
2.55.0