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Commit 1f121b03 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

perf tools: Deal with kernel module names in '[]' correctly 



Before patch ba92732e ('perf kmaps: Check kmaps to make code more
robust'), 'perf report' and 'perf annotate' will segfault if trace data
contains kernel module information like this:

 # perf report -D -i ./perf.data
 ...
 0 0 0x188 [0x50]: PERF_RECORD_MMAP -1/0: [0xffffffbff1018000(0xf068000) @ 0]: x [test_module]
 ...

 # perf report -i ./perf.data --objdump=/path/to/objdump --kallsyms=/path/to/kallsyms

 perf: Segmentation fault
 -------- backtrace --------
 /path/to/perf[0x503478]
 /lib64/libc.so.6(+0x3545f)[0x7fb201f3745f]
 /path/to/perf[0x499b56]
 /path/to/perf(dso__load_kallsyms+0x13c)[0x49b56c]
 /path/to/perf(dso__load+0x72e)[0x49c21e]
 /path/to/perf(map__load+0x6e)[0x4ae9ee]
 /path/to/perf(thread__find_addr_map+0x24c)[0x47deec]
 /path/to/perf(perf_event__preprocess_sample+0x88)[0x47e238]
 /path/to/perf[0x43ad02]
 /path/to/perf[0x4b55bc]
 /path/to/perf(ordered_events__flush+0xca)[0x4b57ea]
 /path/to/perf[0x4b1a01]
 /path/to/perf(perf_session__process_events+0x3be)[0x4b428e]
 /path/to/perf(cmd_report+0xf11)[0x43bfc1]
 /path/to/perf[0x474702]
 /path/to/perf(main+0x5f5)[0x42de95]
 /lib64/libc.so.6(__libc_start_main+0xf4)[0x7fb201f23bd4]
 /path/to/perf[0x42dfc4]

This is because __kmod_path__parse treats '[' leading names as kernel
name instead of names of kernel module.

If perf.data contains build information and the buildid of such modules
can be found, the dso->kernel of it will be set to DSO_TYPE_KERNEL by
__event_process_build_id(), not kernel module.

It will then be passed to dso__load() -> dso__load_kernel_sym() ->
dso__load_kcore() if --kallsyms is provided.

The refered patch adds NULL pointer checker to avoid segfault. However,
such kernel modules are still processed incorrectly.

This patch fixes __kmod_path__parse, makes it treat names like
'[test_module]' as kernel modules.

kmod-path.c is also update to reflect the above changes.

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Link: http://lkml.kernel.org/r/1433321541-170245-1-git-send-email-wangnan0@huawei.com


[ Fixed the merged with 0443f36b ("perf machine: Fix the search
  for the kernel DSO on the unified list" ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 4fc62a89

tools/perf/tests/kmod-path.c

+72 −0
Original line number Diff line number Diff line
@@ -34,9 +34,21 @@ static int test(const char *path, bool alloc_name, bool alloc_ext, 
	return 0;

}



static int test_is_kernel_module(const char *path, int cpumode, bool expect)

{

	TEST_ASSERT_VAL("is_kernel_module",

			(!!is_kernel_module(path, cpumode)) == (!!expect));

	pr_debug("%s (cpumode: %d) - is_kernel_module: %s\n",

			path, cpumode, expect ? "true" : "false");

	return 0;

}



#define T(path, an, ae, k, c, n, e) \

	TEST_ASSERT_VAL("failed", !test(path, an, ae, k, c, n, e))



#define M(path, c, e) \

	TEST_ASSERT_VAL("failed", !test_is_kernel_module(path, c, e))



int test__kmod_path__parse(void)

{

	/* path                alloc_name  alloc_ext   kmod  comp   name     ext */
@@ -44,30 +56,90 @@ int test__kmod_path__parse(void) 
	T("/xxxx/xxxx/x-x.ko", false     , true      , true, false, NULL   , NULL);

	T("/xxxx/xxxx/x-x.ko", true      , false     , true, false, "[x_x]", NULL);

	T("/xxxx/xxxx/x-x.ko", false     , false     , true, false, NULL   , NULL);

	M("/xxxx/xxxx/x-x.ko", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);

	M("/xxxx/xxxx/x-x.ko", PERF_RECORD_MISC_KERNEL, true);

	M("/xxxx/xxxx/x-x.ko", PERF_RECORD_MISC_USER, false);



	/* path                alloc_name  alloc_ext   kmod  comp  name   ext */

	T("/xxxx/xxxx/x.ko.gz", true     , true      , true, true, "[x]", "gz");

	T("/xxxx/xxxx/x.ko.gz", false    , true      , true, true, NULL , "gz");

	T("/xxxx/xxxx/x.ko.gz", true     , false     , true, true, "[x]", NULL);

	T("/xxxx/xxxx/x.ko.gz", false    , false     , true, true, NULL , NULL);

	M("/xxxx/xxxx/x.ko.gz", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);

	M("/xxxx/xxxx/x.ko.gz", PERF_RECORD_MISC_KERNEL, true);

	M("/xxxx/xxxx/x.ko.gz", PERF_RECORD_MISC_USER, false);



	/* path              alloc_name  alloc_ext  kmod   comp  name    ext */

	T("/xxxx/xxxx/x.gz", true      , true     , false, true, "x.gz" ,"gz");

	T("/xxxx/xxxx/x.gz", false     , true     , false, true, NULL   ,"gz");

	T("/xxxx/xxxx/x.gz", true      , false    , false, true, "x.gz" , NULL);

	T("/xxxx/xxxx/x.gz", false     , false    , false, true, NULL   , NULL);

	M("/xxxx/xxxx/x.gz", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);

	M("/xxxx/xxxx/x.gz", PERF_RECORD_MISC_KERNEL, false);

	M("/xxxx/xxxx/x.gz", PERF_RECORD_MISC_USER, false);



	/* path   alloc_name  alloc_ext  kmod   comp  name     ext */

	T("x.gz", true      , true     , false, true, "x.gz", "gz");

	T("x.gz", false     , true     , false, true, NULL  , "gz");

	T("x.gz", true      , false    , false, true, "x.gz", NULL);

	T("x.gz", false     , false    , false, true, NULL  , NULL);

	M("x.gz", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);

	M("x.gz", PERF_RECORD_MISC_KERNEL, false);

	M("x.gz", PERF_RECORD_MISC_USER, false);



	/* path      alloc_name  alloc_ext  kmod  comp  name  ext */

	T("x.ko.gz", true      , true     , true, true, "[x]", "gz");

	T("x.ko.gz", false     , true     , true, true, NULL , "gz");

	T("x.ko.gz", true      , false    , true, true, "[x]", NULL);

	T("x.ko.gz", false     , false    , true, true, NULL , NULL);

	M("x.ko.gz", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);

	M("x.ko.gz", PERF_RECORD_MISC_KERNEL, true);

	M("x.ko.gz", PERF_RECORD_MISC_USER, false);



	/* path            alloc_name  alloc_ext  kmod  comp   name             ext */

	T("[test_module]", true      , true     , true, false, "[test_module]", NULL);

	T("[test_module]", false     , true     , true, false, NULL           , NULL);

	T("[test_module]", true      , false    , true, false, "[test_module]", NULL);

	T("[test_module]", false     , false    , true, false, NULL           , NULL);

	M("[test_module]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);

	M("[test_module]", PERF_RECORD_MISC_KERNEL, true);

	M("[test_module]", PERF_RECORD_MISC_USER, false);



	/* path            alloc_name  alloc_ext  kmod  comp   name             ext */

	T("[test.module]", true      , true     , true, false, "[test.module]", NULL);

	T("[test.module]", false     , true     , true, false, NULL           , NULL);

	T("[test.module]", true      , false    , true, false, "[test.module]", NULL);

	T("[test.module]", false     , false    , true, false, NULL           , NULL);

	M("[test.module]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, true);

	M("[test.module]", PERF_RECORD_MISC_KERNEL, true);

	M("[test.module]", PERF_RECORD_MISC_USER, false);



	/* path     alloc_name  alloc_ext  kmod   comp   name      ext */

	T("[vdso]", true      , true     , false, false, "[vdso]", NULL);

	T("[vdso]", false     , true     , false, false, NULL    , NULL);

	T("[vdso]", true      , false    , false, false, "[vdso]", NULL);

	T("[vdso]", false     , false    , false, false, NULL    , NULL);

	M("[vdso]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);

	M("[vdso]", PERF_RECORD_MISC_KERNEL, false);

	M("[vdso]", PERF_RECORD_MISC_USER, false);



	/* path         alloc_name  alloc_ext  kmod   comp   name          ext */

	T("[vsyscall]", true      , true     , false, false, "[vsyscall]", NULL);

	T("[vsyscall]", false     , true     , false, false, NULL        , NULL);

	T("[vsyscall]", true      , false    , false, false, "[vsyscall]", NULL);

	T("[vsyscall]", false     , false    , false, false, NULL        , NULL);

	M("[vsyscall]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);

	M("[vsyscall]", PERF_RECORD_MISC_KERNEL, false);

	M("[vsyscall]", PERF_RECORD_MISC_USER, false);



	/* path                alloc_name  alloc_ext  kmod   comp   name      ext */

	T("[kernel.kallsyms]", true      , true     , false, false, "[kernel.kallsyms]", NULL);

	T("[kernel.kallsyms]", false     , true     , false, false, NULL               , NULL);

	T("[kernel.kallsyms]", true      , false    , false, false, "[kernel.kallsyms]", NULL);

	T("[kernel.kallsyms]", false     , false    , false, false, NULL               , NULL);

	M("[kernel.kallsyms]", PERF_RECORD_MISC_CPUMODE_UNKNOWN, false);

	M("[kernel.kallsyms]", PERF_RECORD_MISC_KERNEL, false);

	M("[kernel.kallsyms]", PERF_RECORD_MISC_USER, false);



	return 0;

}

tools/perf/util/dso.c

+42 −5
Original line number Diff line number Diff line
@@ -166,12 +166,28 @@ bool is_supported_compression(const char *ext) 
	return false;

}



bool is_kernel_module(const char *pathname)

bool is_kernel_module(const char *pathname, int cpumode)

{

	struct kmod_path m;

	int mode = cpumode & PERF_RECORD_MISC_CPUMODE_MASK;



	if (kmod_path__parse(&m, pathname))

		return NULL;

	WARN_ONCE(mode != cpumode,

		  "Internal error: passing unmasked cpumode (%x) to is_kernel_module",

		  cpumode);



	switch (mode) {

	case PERF_RECORD_MISC_USER:

	case PERF_RECORD_MISC_HYPERVISOR:

	case PERF_RECORD_MISC_GUEST_USER:

		return false;

	/* Treat PERF_RECORD_MISC_CPUMODE_UNKNOWN as kernel */

	default:

		if (kmod_path__parse(&m, pathname)) {

			pr_err("Failed to check whether %s is a kernel module or not. Assume it is.",

					pathname);

			return true;

		}

	}



	return m.kmod;

}
@@ -215,12 +231,33 @@ int __kmod_path__parse(struct kmod_path *m, const char *path, 
{

	const char *name = strrchr(path, '/');

	const char *ext  = strrchr(path, '.');

	bool is_simple_name = false;



	memset(m, 0x0, sizeof(*m));

	name = name ? name + 1 : path;



	/*

	 * '.' is also a valid character for module name. For example:

	 * [aaa.bbb] is a valid module name. '[' should have higher

	 * priority than '.ko' suffix.

	 *

	 * The kernel names are from machine__mmap_name. Such

	 * name should belong to kernel itself, not kernel module.

	 */

	if (name[0] == '[') {

		is_simple_name = true;

		if ((strncmp(name, "[kernel.kallsyms]", 17) == 0) ||

		    (strncmp(name, "[guest.kernel.kallsyms", 22) == 0) ||

		    (strncmp(name, "[vdso]", 6) == 0) ||

		    (strncmp(name, "[vsyscall]", 10) == 0)) {

			m->kmod = false;



		} else

			m->kmod = true;

	}



	/* No extension, just return name. */

	if (ext == NULL) {

	if ((ext == NULL) || is_simple_name) {

		if (alloc_name) {

			m->name = strdup(name);

			return m->name ? 0 : -ENOMEM;

tools/perf/util/dso.h

+1 −1
Original line number Diff line number Diff line
@@ -220,7 +220,7 @@ char dso__symtab_origin(const struct dso *dso); 
int dso__read_binary_type_filename(const struct dso *dso, enum dso_binary_type type,

				   char *root_dir, char *filename, size_t size);

bool is_supported_compression(const char *ext);

bool is_kernel_module(const char *pathname);

bool is_kernel_module(const char *pathname, int cpumode);

bool decompress_to_file(const char *ext, const char *filename, int output_fd);

bool dso__needs_decompress(struct dso *dso);

tools/perf/util/header.c

+4 −4
Original line number Diff line number Diff line
@@ -1239,7 +1239,7 @@ static int __event_process_build_id(struct build_id_event *bev, 
{

	int err = -1;

	struct machine *machine;

	u16 misc;

	u16 cpumode;

	struct dso *dso;

	enum dso_kernel_type dso_type;
@@ -1247,9 +1247,9 @@ static int __event_process_build_id(struct build_id_event *bev, 
	if (!machine)

		goto out;



	misc = bev->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;

	cpumode = bev->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;



	switch (misc) {

	switch (cpumode) {

	case PERF_RECORD_MISC_KERNEL:

		dso_type = DSO_TYPE_KERNEL;

		break;
@@ -1270,7 +1270,7 @@ static int __event_process_build_id(struct build_id_event *bev, 


		dso__set_build_id(dso, &bev->build_id);



		if (!is_kernel_module(filename))

		if (!is_kernel_module(filename, cpumode))

			dso->kernel = dso_type;



		build_id__sprintf(dso->build_id, sizeof(dso->build_id),

tools/perf/util/machine.c

+21 −1
Original line number Diff line number Diff line
@@ -1149,9 +1149,29 @@ static int machine__process_kernel_mmap_event(struct machine *machine, 
		struct dso *dso;



		list_for_each_entry(dso, &machine->dsos.head, node) {

			if (!dso->kernel || is_kernel_module(dso->long_name))



			/*

			 * The cpumode passed to is_kernel_module is not the

			 * cpumode of *this* event. If we insist on passing

			 * correct cpumode to is_kernel_module, we should

			 * record the cpumode when we adding this dso to the

			 * linked list.

			 *

			 * However we don't really need passing correct

			 * cpumode.  We know the correct cpumode must be kernel

			 * mode (if not, we should not link it onto kernel_dsos

			 * list).

			 *

			 * Therefore, we pass PERF_RECORD_MISC_CPUMODE_UNKNOWN.

			 * is_kernel_module() treats it as a kernel cpumode.

			 */



			if (!dso->kernel ||

			    is_kernel_module(dso->long_name,

					     PERF_RECORD_MISC_CPUMODE_UNKNOWN))

				continue;





			kernel = dso;

			break;

		}