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

Before patch ba92732e9808 ('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 0443f36b0de0 ("perf machine: Fix the search
  for the kernel DSO on the unified list" ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

5 files changed, 140 insertions, 11 deletions

diff --git a/tools/perf/tests/kmod-path.c b/tools/perf/tests/kmod-path.c
index e8d7cbb9320c..08c433b4bf4f 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 b335db3532a2..5ec9e892c89b 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -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;
 }
@@ -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;
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index 24a507a54147..ba2d90ed881f 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -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);
 
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 851143a7988d..ac5aaaeed7ff 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -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),
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index 4e29e80932e5..9e02c86f39f5 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -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;
                 }