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perf tools: Deal with kernel module names in '[]' correctly
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Before patch ba92732 ('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: Wang Nan <wangnan0@huawei.com>
Acked-by: Jiri 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 0443f36 ("perf machine: Fix the search
  for the kernel DSO on the unified list" ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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Wang Nan authored and Arnaldo Carvalho de Melo committed Jun 3, 2015
1 parent 4fc62a8 commit 1f121b0
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Showing 5 changed files with 140 additions and 11 deletions.
72 changes: 72 additions & 0 deletions tools/perf/tests/kmod-path.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -34,40 +34,112 @@ 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 */
T("/xxxx/xxxx/x-x.ko", true , true , true, false, "[x_x]", NULL);
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;
}
47 changes: 42 additions & 5 deletions tools/perf/util/dso.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;

if (kmod_path__parse(&m, pathname))
return NULL;
int mode = cpumode & PERF_RECORD_MISC_CPUMODE_MASK;

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;
}
Expand Down Expand Up @@ -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;
Expand Down
2 changes: 1 addition & 1 deletion tools/perf/util/dso.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);

Expand Down
8 changes: 4 additions & 4 deletions tools/perf/util/header.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1239,17 +1239,17 @@ 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;

machine = perf_session__findnew_machine(session, bev->pid);
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;
Expand All @@ -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),
Expand Down
22 changes: 21 additions & 1 deletion tools/perf/util/machine.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
}
Expand Down

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