From 34e271ae55382fbdb04f3e13e856457d8e0dee45 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Tue, 2 Dec 2025 15:57:18 -0800 Subject: [PATCH] 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 Reviewed-by: Ian Rogers Signed-off-by: Namhyung Kim --- 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 af67f8ef74b49..c2a67ce459417 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 9090e8238a447..bd6ffa8e45784 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 0000000000000..bbbc66957e5d0 --- /dev/null +++ b/tools/perf/tests/kallsyms-split.c @@ -0,0 +1,156 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#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 f5fba95b6f3ff..cb67ddbd03753 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 -- 2.47.3