From: Rui Qi <qirui.001@bytedance.com>
Date: Fri, 22 May 2026 08:26:03 +0000 (+0800)
Subject: perf: Extract is_ignored_kernel_symbol() for kernel mapping symbol filtering
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e987110f09d2817d74a5d624c7bfb620d2bb0d40;p=thirdparty%2Flinux.git

perf: Extract is_ignored_kernel_symbol() for kernel mapping symbol filtering

Mapping symbol filtering is scattered across multiple files with
inconsistent checks.  The kernel's own is_mapping_symbol() covers x86
local symbols ('.L*' and 'L0*') on top of the '$' prefix used by
ARM/AArch64/RISC-V, but the perf tool only checks '$'.

Extract is_ignored_kernel_symbol() into symbol.h matching the kernel
definition, and convert the kallsyms and ksymbol event paths to use it.
Add ksymbol event name validation and early mapping symbol filtering
before any state mutation.

Signed-off-by: Rui Qi <qirui.001@bytedance.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---

diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index c2e0a99efe97d..e5d1e8b882a91 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -4,6 +4,7 @@
 #include <inttypes.h>
 #include <regex.h>
 #include <stdlib.h>
+#include <string.h>
 #include "callchain.h"
 #include "debug.h"
 #include "dso.h"
@@ -729,9 +730,15 @@ static int machine__process_ksymbol_register(struct machine *machine,
 {
 	struct symbol *sym;
 	struct dso *dso = NULL;
-	struct map *map = maps__find(machine__kernel_maps(machine), event->ksymbol.addr);
+	struct map *map;
 	int err = 0;
 
+	/* Ignore mapping symbols in ksymbol events - check early before any state mutation */
+	if (is_ignored_kernel_symbol(event->ksymbol.name))
+		return 0;
+
+	map = maps__find(machine__kernel_maps(machine), event->ksymbol.addr);
+
 	if (!map) {
 		dso = dso__new(event->ksymbol.name);
 
@@ -790,6 +797,10 @@ static int machine__process_ksymbol_unregister(struct machine *machine,
 	struct symbol *sym;
 	struct map *map;
 
+	/* Ignore mapping symbols in ksymbol events */
+	if (is_ignored_kernel_symbol(event->ksymbol.name))
+		return 0;
+
 	map = maps__find(machine__kernel_maps(machine), event->ksymbol.addr);
 	if (!map)
 		return 0;
@@ -814,6 +825,11 @@ int machine__process_ksymbol(struct machine *machine __maybe_unused,
 	if (dump_trace)
 		perf_event__fprintf_ksymbol(event, stdout);
 
+	if (event->header.size < offsetof(struct perf_record_ksymbol, name) + 2 ||
+	    !memchr(event->ksymbol.name, '\0',
+		    event->header.size - offsetof(struct perf_record_ksymbol, name)))
+		return -EINVAL;
+
 	/* no need to process non-JIT BPF as it cannot get samples */
 	if (event->ksymbol.len == 0)
 		return 0;
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index fcaeeddbbb6b9..714b6e6048fa2 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -770,8 +770,8 @@ static int map__process_kallsym_symbol(void *arg, const char *name,
 	if (!symbol_type__filter(type))
 		return 0;
 
-	/* Ignore local symbols for ARM modules */
-	if (name[0] == '$')
+	/* Ignore mapping symbols in kallsyms */
+	if (is_ignored_kernel_symbol(name))
 		return 0;
 
 	/*
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index bd6eb90c86683..95592779eb77c 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -28,6 +28,21 @@ struct maps;
 struct option;
 struct build_id;
 
+/*
+ * Ignore kernel mapping symbols, matching kernel is_mapping_symbol() logic.
+ * This checks for '$' prefix (used by ARM, AArch64, RISC-V) and
+ * x86 local symbol prefixes (.L* and L0*).
+ * Only use this for kernel symbols (kallsyms, ksymbol events, kernel ELF DSOs).
+ */
+static inline bool is_ignored_kernel_symbol(const char *str)
+{
+	if (str[0] == '.' && str[1] == 'L')
+		return true;
+	if (str[0] == 'L' && str[1] == '0')
+		return true;
+	return str[0] == '$';
+}
+
 /*
  * libelf 0.8.x and earlier do not support ELF_C_READ_MMAP;
  * for newer versions we can use mmap to reduce memory usage: