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Message-ID: <20251202235718.1018752-6-namhyung@kernel.org>
Date: Tue, 2 Dec 2025 15:57:18 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
Ian Rogers <irogers@...gle.com>,
James Clark <james.clark@...aro.org>
Cc: Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org
Subject: [PATCH v2 5/5] perf test: Add kallsyms split test
Create a fake root directory for /proc/{version,modules,kallsyms} in
/tmp for testing. The kallsyms has a bad symbol in the module and it
causes the main map splitted. The test ensures it only has two maps -
kernel and the module and it finds the initial map after the module
without creating the split maps like [kernel].0 and so on.
$ perf test -vv "split kallsyms"
69: split kallsyms:
--- start ---
test child forked, pid 1016196
try to create fake root directory
create kernel maps from the fake root directory
maps__set_modules_path_dir: cannot open /tmp/perf-test.Zrv6Sy/lib/modules/X.Y.Z dir
Problems setting modules path maps, continuing anyway...
Failed to open /tmp/perf-test.Zrv6Sy/proc/kcore. Note /proc/kcore requires CAP_SYS_RAWIO capability to access.
Using /tmp/perf-test.Zrv6Sy/proc/kallsyms for symbols
kernel map loaded - check symbol and map
---- end(0) ----
69: split kallsyms : Ok
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
tools/perf/tests/Build | 1 +
tools/perf/tests/builtin-test.c | 1 +
tools/perf/tests/kallsyms-split.c | 156 ++++++++++++++++++++++++++++++
tools/perf/tests/tests.h | 1 +
4 files changed, 159 insertions(+)
create mode 100644 tools/perf/tests/kallsyms-split.c
diff --git a/tools/perf/tests/Build b/tools/perf/tests/Build
index af67f8ef74b49c58..c2a67ce459417e0f 100644
--- a/tools/perf/tests/Build
+++ b/tools/perf/tests/Build
@@ -69,6 +69,7 @@ perf-test-y += util.o
perf-test-y += hwmon_pmu.o
perf-test-y += tool_pmu.o
perf-test-y += subcmd-help.o
+perf-test-y += kallsyms-split.o
ifeq ($(SRCARCH),$(filter $(SRCARCH),x86 arm arm64 powerpc))
perf-test-$(CONFIG_DWARF_UNWIND) += dwarf-unwind.o
diff --git a/tools/perf/tests/builtin-test.c b/tools/perf/tests/builtin-test.c
index 9090e8238a447826..bd6ffa8e4578431a 100644
--- a/tools/perf/tests/builtin-test.c
+++ b/tools/perf/tests/builtin-test.c
@@ -140,6 +140,7 @@ static struct test_suite *generic_tests[] = {
&suite__symbols,
&suite__util,
&suite__subcmd_help,
+ &suite__kallsyms_split,
NULL,
};
diff --git a/tools/perf/tests/kallsyms-split.c b/tools/perf/tests/kallsyms-split.c
new file mode 100644
index 0000000000000000..bbbc66957e5d0453
--- /dev/null
+++ b/tools/perf/tests/kallsyms-split.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/compiler.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include "util/dso.h"
+#include "util/map.h"
+#include "util/symbol.h"
+#include "util/debug.h"
+#include "util/machine.h"
+#include "tests.h"
+
+/*
+ * This test is to check whether a bad symbol in a module won't split kallsyms maps.
+ * The main_symbol[1-3] should belong to the main [kernel.kallsyms] map even if the
+ * bad_symbol from the module is found in the middle.
+ */
+static char root_template[] = "/tmp/perf-test.XXXXXX";
+static char *root_dir;
+
+static const char proc_version[] = "Linux version X.Y.Z (just for perf test)\n";
+static const char proc_modules[] = "module 4096 1 - Live 0xffffffffcd000000\n";
+static const char proc_kallsyms[] =
+ "ffffffffab200000 T _stext\n"
+ "ffffffffab200010 T good_symbol\n"
+ "ffffffffab200020 t bad_symbol\n"
+ "ffffffffab200030 t main_symbol1\n"
+ "ffffffffab200040 t main_symbol2\n"
+ "ffffffffab200050 t main_symbol3\n"
+ "ffffffffab200060 T _etext\n"
+ "ffffffffcd000000 T start_module\t[module]\n"
+ "ffffffffab200020 u bad_symbol\t[module]\n"
+ "ffffffffcd000040 T end_module\t[module]\n";
+
+static struct {
+ const char *name;
+ const char *contents;
+ long len;
+} proc_files[] = {
+ { "version", proc_version, sizeof(proc_version) - 1 },
+ { "modules", proc_modules, sizeof(proc_modules) - 1 },
+ { "kallsyms", proc_kallsyms, sizeof(proc_kallsyms) - 1 },
+};
+
+static void remove_proc_dir(int sig __maybe_unused)
+{
+ char buf[128];
+
+ if (root_dir == NULL)
+ return;
+
+ for (unsigned i = 0; i < ARRAY_SIZE(proc_files); i++) {
+ scnprintf(buf, sizeof(buf), "%s/proc/%s", root_dir, proc_files[i].name);
+ remove(buf);
+ }
+
+ scnprintf(buf, sizeof(buf), "%s/proc", root_dir);
+ rmdir(buf);
+
+ rmdir(root_dir);
+ root_dir = NULL;
+}
+
+static int create_proc_dir(void)
+{
+ char buf[128];
+
+ root_dir = mkdtemp(root_template);
+ if (root_dir == NULL)
+ return -1;
+
+ scnprintf(buf, sizeof(buf), "%s/proc", root_dir);
+ if (mkdir(buf, 0700) < 0)
+ goto err;
+
+ for (unsigned i = 0; i < ARRAY_SIZE(proc_files); i++) {
+ int fd, len;
+
+ scnprintf(buf, sizeof(buf), "%s/proc/%s", root_dir, proc_files[i].name);
+ fd = open(buf, O_RDWR | O_CREAT, 0600);
+ if (fd < 0)
+ goto err;
+
+ len = write(fd, proc_files[i].contents, proc_files[i].len);
+ close(fd);
+ if (len != proc_files[i].len)
+ goto err;
+ }
+ return 0;
+
+err:
+ remove_proc_dir(0);
+ return -1;
+}
+
+static int test__kallsyms_split(struct test_suite *test __maybe_unused,
+ int subtest __maybe_unused)
+{
+ struct machine m;
+ struct map *map = NULL;
+ int ret = TEST_FAIL;
+
+ pr_debug("try to create fake root directory\n");
+ if (create_proc_dir() < 0) {
+ pr_debug("SKIP: cannot create a fake root directory\n");
+ return TEST_SKIP;
+ }
+
+ signal(SIGINT, remove_proc_dir);
+ signal(SIGPIPE, remove_proc_dir);
+ signal(SIGSEGV, remove_proc_dir);
+ signal(SIGTERM, remove_proc_dir);
+
+ pr_debug("create kernel maps from the fake root directory\n");
+ machine__init(&m, root_dir, HOST_KERNEL_ID);
+ if (machine__create_kernel_maps(&m) < 0) {
+ pr_debug("FAIL: failed to create kernel maps\n");
+ goto out;
+ }
+
+ /* force to use /proc/kallsyms */
+ symbol_conf.ignore_vmlinux = true;
+ symbol_conf.ignore_vmlinux_buildid = true;
+ symbol_conf.allow_aliases = true;
+
+ if (map__load(machine__kernel_map(&m)) < 0) {
+ pr_debug("FAIL: failed to load kallsyms\n");
+ goto out;
+ }
+
+ pr_debug("kernel map loaded - check symbol and map\n");
+ if (maps__nr_maps(machine__kernel_maps(&m)) != 2) {
+ pr_debug("FAIL: it should have the kernel and a module, but has %u maps\n",
+ maps__nr_maps(machine__kernel_maps(&m)));
+ goto out;
+ }
+
+ if (machine__find_kernel_symbol_by_name(&m, "main_symbol3", &map) == NULL) {
+ pr_debug("FAIL: failed to find a symbol\n");
+ goto out;
+ }
+
+ if (!RC_CHK_EQUAL(map, machine__kernel_map(&m))) {
+ pr_debug("FAIL: the symbol is not in the kernel map\n");
+ goto out;
+ }
+ ret = TEST_OK;
+
+out:
+ remove_proc_dir(0);
+ machine__exit(&m);
+ return ret;
+}
+
+DEFINE_SUITE("split kallsyms", kallsyms_split);
diff --git a/tools/perf/tests/tests.h b/tools/perf/tests/tests.h
index f5fba95b6f3ffbd3..cb67ddbd03753531 100644
--- a/tools/perf/tests/tests.h
+++ b/tools/perf/tests/tests.h
@@ -178,6 +178,7 @@ DECLARE_SUITE(event_groups);
DECLARE_SUITE(symbols);
DECLARE_SUITE(util);
DECLARE_SUITE(subcmd_help);
+DECLARE_SUITE(kallsyms_split);
/*
* PowerPC and S390 do not support creation of instruction breakpoints using the
--
2.52.0.158.g65b55ccf14-goog
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