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SubjectRe: [PATCH v5 2/2] perf: report/annotate: fix segfault problem.
Ping again?
On 2015/4/15 9:27, Wang Nan wrote:
> Ping?
>
> On 2015/4/10 11:53, Wang Nan wrote:
>> perf report and perf annotate are easy to trigger segfault if trace data
>> contain 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 regard '[' leading name as kernel
>> instead of kernel module. If perf.data contain build information and
>> the buildid of such modules can be found, the DSO of it will be treated
>> as kernel, not kernel module. It will then be passed to
>> dso__load_kernel_sym() then dso__load_kcore() because of --kallsyms
>> argument. The segfault is triggered because the kmap structure is not
>> initialized.
>>
>> Although in --vmlinux case such segfault can be avoided, the symbols in
>> the kernel module are unable to be retrived since the attribute of DSO
>> is incorrect.
>>
>> This patch fixes __kmod_path__parse, make it to 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>
>> ---
>>
>> Different from v4: checks cpumode in is_kernel_module(), makes code simpler.
>> Appends tests of is_kernel_module().
>> ---
>> tools/perf/tests/kmod-path.c | 72 ++++++++++++++++++++++++++++++++++++++++++++
>> tools/perf/util/dso.c | 42 +++++++++++++++++++++++---
>> tools/perf/util/dso.h | 2 +-
>> tools/perf/util/header.c | 8 ++---
>> tools/perf/util/machine.c | 16 +++++++++-
>> 5 files changed, 130 insertions(+), 10 deletions(-)
>>
>> diff --git a/tools/perf/tests/kmod-path.c b/tools/perf/tests/kmod-path.c
>> index e8d7cbb..08c433b 100644
>> --- a/tools/perf/tests/kmod-path.c
>> +++ b/tools/perf/tests/kmod-path.c
>> @@ -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;
>> }
>> diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
>> index fc0ddd5..e9d4ae4 100644
>> --- a/tools/perf/util/dso.c
>> +++ b/tools/perf/util/dso.c
>> @@ -165,13 +165,25 @@ 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;
>> + /* caller should pass a masked cpumode. Mask again for safety. */
>> + switch (cpumode & PERF_RECORD_MISC_CPUMODE_MASK) {
>> + case PERF_RECORD_MISC_USER:
>> + case PERF_RECORD_MISC_HYPERVISOR:
>> + case PERF_RECORD_MISC_GUEST_USER:
>> + return false;
>> + /* Regard 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;
>> }
>>
>> @@ -214,12 +226,34 @@ 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;
>> diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
>> index e0901b4..cc3797c 100644
>> --- a/tools/perf/util/dso.h
>> +++ b/tools/perf/util/dso.h
>> @@ -216,7 +216,7 @@ 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);
>>
>> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
>> index fb43215..8c76a23 100644
>> --- a/tools/perf/util/header.c
>> +++ b/tools/perf/util/header.c
>> @@ -1232,7 +1232,7 @@ static int __event_process_build_id(struct build_id_event *bev,
>> int err = -1;
>> struct dsos *dsos;
>> struct machine *machine;
>> - u16 misc;
>> + u16 cpumode;
>> struct dso *dso;
>> enum dso_kernel_type dso_type;
>>
>> @@ -1240,9 +1240,9 @@ 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;
>> dsos = &machine->kernel_dsos;
>> @@ -1266,7 +1266,7 @@ 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),
>> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
>> index e335330..3769009 100644
>> --- a/tools/perf/util/machine.c
>> +++ b/tools/perf/util/machine.c
>> @@ -1109,7 +1109,21 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
>> struct dso *dso;
>>
>> list_for_each_entry(dso, &machine->kernel_dsos.head, node) {
>> - if (is_kernel_module(dso->long_name))
>> + /*
>> + * 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() treat it as a kernel cpumode.
>> + */
>> + if (is_kernel_module(dso->long_name,
>> + PERF_RECORD_MISC_CPUMODE_UNKNOWN))
>> continue;
>>
>> kernel = dso;
>>
>
>
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