perf tests: Add kcore to the object code reading test
authorAdrian Hunter <adrian.hunter@intel.com>
Wed, 7 Aug 2013 11:38:53 +0000 (14:38 +0300)
committerArnaldo Carvalho de Melo <acme@redhat.com>
Wed, 7 Aug 2013 20:35:34 +0000 (17:35 -0300)
Make the "object code reading" test attempt to read from kcore.

The test uses objdump which struggles with kcore. i.e.  doesn't always
work, sometimes takes a long time.  The test has been made to work
around those issues.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Namhyung Kim <namhyung@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1375875537-4509-10-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
tools/perf/tests/code-reading.c

index 0c7b052cead281406f49e5bd8dfe246249729631..8e0943b966d7858537d2675965e44cb2b87b7b67 100644 (file)
 #define BUFSZ  1024
 #define READLEN        128
 
+struct state {
+       u64 done[1024];
+       size_t done_cnt;
+};
+
 static unsigned int hex(char c)
 {
        if (c >= '0' && c <= '9')
@@ -107,6 +112,9 @@ static int read_via_objdump(const char *filename, u64 addr, void *buf,
 
        pr_debug("Objdump command is: %s\n", cmd);
 
+       /* Ignore objdump errors */
+       strcat(cmd, " 2>/dev/null");
+
        f = popen(cmd, "r");
        if (!f) {
                pr_debug("popen failed\n");
@@ -126,7 +134,8 @@ static int read_via_objdump(const char *filename, u64 addr, void *buf,
 }
 
 static int read_object_code(u64 addr, size_t len, u8 cpumode,
-                           struct thread *thread, struct machine *machine)
+                           struct thread *thread, struct machine *machine,
+                           struct state *state)
 {
        struct addr_location al;
        unsigned char buf1[BUFSZ];
@@ -146,7 +155,8 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 
        pr_debug("File is: %s\n", al.map->dso->long_name);
 
-       if (al.map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS) {
+       if (al.map->dso->symtab_type == DSO_BINARY_TYPE__KALLSYMS &&
+           !dso__is_kcore(al.map->dso)) {
                pr_debug("Unexpected kernel address - skipping\n");
                return 0;
        }
@@ -175,6 +185,24 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
        if (map__load(al.map, NULL))
                return -1;
 
+       /* objdump struggles with kcore - try each map only once */
+       if (dso__is_kcore(al.map->dso)) {
+               size_t d;
+
+               for (d = 0; d < state->done_cnt; d++) {
+                       if (state->done[d] == al.map->start) {
+                               pr_debug("kcore map tested already");
+                               pr_debug(" - skipping\n");
+                               return 0;
+                       }
+               }
+               if (state->done_cnt >= ARRAY_SIZE(state->done)) {
+                       pr_debug("Too many kcore maps - skipping\n");
+                       return 0;
+               }
+               state->done[state->done_cnt++] = al.map->start;
+       }
+
        /* Read the object code using objdump */
        objdump_addr = map__rip_2objdump(al.map, al.addr);
        ret = read_via_objdump(al.map->dso->long_name, objdump_addr, buf2, len);
@@ -186,10 +214,19 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
                if (cpumode == PERF_RECORD_MISC_KERNEL ||
                    cpumode == PERF_RECORD_MISC_GUEST_KERNEL) {
                        len -= ret;
-                       if (len)
+                       if (len) {
                                pr_debug("Reducing len to %zu\n", len);
-                       else
+                       } else if (dso__is_kcore(al.map->dso)) {
+                               /*
+                                * objdump cannot handle very large segments
+                                * that may be found in kcore.
+                                */
+                               pr_debug("objdump failed for kcore");
+                               pr_debug(" - skipping\n");
+                               return 0;
+                       } else {
                                return -1;
+                       }
                }
        }
        if (ret < 0) {
@@ -209,7 +246,7 @@ static int read_object_code(u64 addr, size_t len, u8 cpumode,
 
 static int process_sample_event(struct machine *machine,
                                struct perf_evlist *evlist,
-                               union perf_event *event)
+                               union perf_event *event, struct state *state)
 {
        struct perf_sample sample;
        struct thread *thread;
@@ -228,14 +265,15 @@ static int process_sample_event(struct machine *machine,
 
        cpumode = event->header.misc & PERF_RECORD_MISC_CPUMODE_MASK;
 
-       return read_object_code(sample.ip, READLEN, cpumode, thread, machine);
+       return read_object_code(sample.ip, READLEN, cpumode, thread, machine,
+                               state);
 }
 
 static int process_event(struct machine *machine, struct perf_evlist *evlist,
-                        union perf_event *event)
+                        union perf_event *event, struct state *state)
 {
        if (event->header.type == PERF_RECORD_SAMPLE)
-               return process_sample_event(machine, evlist, event);
+               return process_sample_event(machine, evlist, event, state);
 
        if (event->header.type < PERF_RECORD_MAX)
                return machine__process_event(machine, event);
@@ -243,14 +281,15 @@ static int process_event(struct machine *machine, struct perf_evlist *evlist,
        return 0;
 }
 
-static int process_events(struct machine *machine, struct perf_evlist *evlist)
+static int process_events(struct machine *machine, struct perf_evlist *evlist,
+                         struct state *state)
 {
        union perf_event *event;
        int i, ret;
 
        for (i = 0; i < evlist->nr_mmaps; i++) {
                while ((event = perf_evlist__mmap_read(evlist, i)) != NULL) {
-                       ret = process_event(machine, evlist, event);
+                       ret = process_event(machine, evlist, event, state);
                        if (ret < 0)
                                return ret;
                }
@@ -331,10 +370,12 @@ static void do_something(void)
 enum {
        TEST_CODE_READING_OK,
        TEST_CODE_READING_NO_VMLINUX,
+       TEST_CODE_READING_NO_KCORE,
        TEST_CODE_READING_NO_ACCESS,
+       TEST_CODE_READING_NO_KERNEL_OBJ,
 };
 
-static int do_test_code_reading(void)
+static int do_test_code_reading(bool try_kcore)
 {
        struct machines machines;
        struct machine *machine;
@@ -348,6 +389,9 @@ static int do_test_code_reading(void)
                        .uses_mmap   = true,
                },
        };
+       struct state state = {
+               .done_cnt = 0,
+       };
        struct thread_map *threads = NULL;
        struct cpu_map *cpus = NULL;
        struct perf_evlist *evlist = NULL;
@@ -355,7 +399,7 @@ static int do_test_code_reading(void)
        int err = -1, ret;
        pid_t pid;
        struct map *map;
-       bool have_vmlinux, excl_kernel = false;
+       bool have_vmlinux, have_kcore, excl_kernel = false;
 
        pid = getpid();
 
@@ -368,6 +412,10 @@ static int do_test_code_reading(void)
                goto out_err;
        }
 
+       /* Force the use of kallsyms instead of vmlinux to try kcore */
+       if (try_kcore)
+               symbol_conf.kallsyms_name = "/proc/kallsyms";
+
        /* Load kernel map */
        map = machine->vmlinux_maps[MAP__FUNCTION];
        ret = map__load(map, NULL);
@@ -375,9 +423,15 @@ static int do_test_code_reading(void)
                pr_debug("map__load failed\n");
                goto out_err;
        }
-       have_vmlinux = map->dso->symtab_type == DSO_BINARY_TYPE__VMLINUX;
-       /* No point getting kernel events if there is no vmlinux */
-       if (!have_vmlinux)
+       have_vmlinux = dso__is_vmlinux(map->dso);
+       have_kcore = dso__is_kcore(map->dso);
+
+       /* 2nd time through we just try kcore */
+       if (try_kcore && !have_kcore)
+               return TEST_CODE_READING_NO_KCORE;
+
+       /* No point getting kernel events if there is no kernel object */
+       if (!have_vmlinux && !have_kcore)
                excl_kernel = true;
 
        threads = thread_map__new_by_tid(pid);
@@ -461,11 +515,13 @@ static int do_test_code_reading(void)
 
        perf_evlist__disable(evlist);
 
-       ret = process_events(machine, evlist);
+       ret = process_events(machine, evlist, &state);
        if (ret < 0)
                goto out_err;
 
-       if (!have_vmlinux)
+       if (!have_vmlinux && !have_kcore && !try_kcore)
+               err = TEST_CODE_READING_NO_KERNEL_OBJ;
+       else if (!have_vmlinux && !try_kcore)
                err = TEST_CODE_READING_NO_VMLINUX;
        else if (excl_kernel)
                err = TEST_CODE_READING_NO_ACCESS;
@@ -492,7 +548,9 @@ int test__code_reading(void)
 {
        int ret;
 
-       ret = do_test_code_reading();
+       ret = do_test_code_reading(false);
+       if (!ret)
+               ret = do_test_code_reading(true);
 
        switch (ret) {
        case TEST_CODE_READING_OK:
@@ -500,9 +558,15 @@ int test__code_reading(void)
        case TEST_CODE_READING_NO_VMLINUX:
                fprintf(stderr, " (no vmlinux)");
                return 0;
+       case TEST_CODE_READING_NO_KCORE:
+               fprintf(stderr, " (no kcore)");
+               return 0;
        case TEST_CODE_READING_NO_ACCESS:
                fprintf(stderr, " (no access)");
                return 0;
+       case TEST_CODE_READING_NO_KERNEL_OBJ:
+               fprintf(stderr, " (no kernel obj)");
+               return 0;
        default:
                return -1;
        };