@@ -2582,7 +2582,6 @@ static int trace__fprintf_sample(struct trace *trace, struct evsel *evsel,
static void *syscall__augmented_args(struct syscall *sc, struct perf_sample *sample, int *augmented_args_size, int raw_augmented_args_size)
{
- void *augmented_args = NULL;
/*
* For now with BPF raw_augmented we hook into raw_syscalls:sys_enter
* and there we get all 6 syscall args plus the tracepoint common fields
@@ -2600,10 +2599,24 @@ static void *syscall__augmented_args(struct syscall *sc, struct perf_sample *sam
int args_size = raw_augmented_args_size ?: sc->args_size;
*augmented_args_size = sample->raw_size - args_size;
- if (*augmented_args_size > 0)
- augmented_args = sample->raw_data + args_size;
+ if (*augmented_args_size > 0) {
+ static uintptr_t argbuf[1024]; /* assuming single-threaded */
+
+ if ((size_t)(*augmented_args_size) > sizeof(argbuf))
+ return NULL;
+
+ /*
+ * The perf ring-buffer is 8-byte aligned but sample->raw_data
+ * is not because it's preceded by u32 size. Later, beautifier
+ * will use the augmented args with stricter alignments like in
+ * some struct. To make sure it's aligned, let's copy the args
+ * into a static buffer as it's single-threaded for now.
+ */
+ memcpy(argbuf, sample->raw_data + args_size, *augmented_args_size);
- return augmented_args;
+ return argbuf;
+ }
+ return NULL;
}
static void syscall__exit(struct syscall *sc)
Some version of compilers reported unaligned accesses in perf trace when undefined-behavior sanitizer is on. I found that it uses raw data in the sample directly and assuming it's properly aligned. Unlike other sample fields, the raw data is not 8-byte aligned because there's a size field (u32) before the actual data. So I added a static buffer in syscall__augmented_args() and return it instead. This is not ideal but should work well as perf trace is single-threaded. A better approach would be aligning the raw data by adding a 4-byte data before the augmented args but I'm afraid it'd break the backward compatibility. Closes: https://lore.kernel.org/r/Z2STgyD1p456Qqhg@google.com Cc: Howard Chu <howardchu95@gmail.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> --- tools/perf/builtin-trace.c | 21 +++++++++++++++++---- 1 file changed, 17 insertions(+), 4 deletions(-)