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Subject[tip:perf/core] perf symbols: Add support for reading from /proc/ kcore
Commit-ID:  8e0cf965f95edd41df11cca50b92b4cb6ea8d80a
Gitweb: http://git.kernel.org/tip/8e0cf965f95edd41df11cca50b92b4cb6ea8d80a
Author: Adrian Hunter <adrian.hunter@intel.com>
AuthorDate: Wed, 7 Aug 2013 14:38:51 +0300
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Wed, 7 Aug 2013 17:35:33 -0300

perf symbols: Add support for reading from /proc/kcore

In the absence of vmlinux, perf tools uses kallsyms for symbols. If the
user has access, now also map to /proc/kcore.

The dso data_type is now set to either DSO_BINARY_TYPE__KCORE or
DSO_BINARY_TYPE__GUEST_KCORE as approprite.

This patch breaks the "vmlinux symtab matches kallsyms" test. That is
fixed in a following patch.

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/1375875537-4509-8-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/dso.c | 5 +
tools/perf/util/dso.h | 8 ++
tools/perf/util/machine.c | 16 +++
tools/perf/util/map.c | 18 ++++
tools/perf/util/map.h | 13 +++
tools/perf/util/symbol-elf.c | 51 +++++++++
tools/perf/util/symbol-minimal.c | 7 ++
tools/perf/util/symbol.c | 227 ++++++++++++++++++++++++++++++++++++++-
tools/perf/util/symbol.h | 5 +
9 files changed, 347 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index 1955804..e3c1ff8 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -95,6 +95,11 @@ int dso__binary_type_file(struct dso *dso, enum dso_binary_type type,
dso->long_name);
break;

+ case DSO_BINARY_TYPE__KCORE:
+ case DSO_BINARY_TYPE__GUEST_KCORE:
+ snprintf(file, size, "%s", dso->long_name);
+ break;
+
default:
case DSO_BINARY_TYPE__KALLSYMS:
case DSO_BINARY_TYPE__GUEST_KALLSYMS:
diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index 735a837..b793053 100644
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -21,6 +21,8 @@ enum dso_binary_type {
DSO_BINARY_TYPE__SYSTEM_PATH_DSO,
DSO_BINARY_TYPE__GUEST_KMODULE,
DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE,
+ DSO_BINARY_TYPE__KCORE,
+ DSO_BINARY_TYPE__GUEST_KCORE,
DSO_BINARY_TYPE__NOT_FOUND,
};

@@ -155,4 +157,10 @@ static inline bool dso__is_vmlinux(struct dso *dso)
dso->data_type == DSO_BINARY_TYPE__GUEST_VMLINUX;
}

+static inline bool dso__is_kcore(struct dso *dso)
+{
+ return dso->data_type == DSO_BINARY_TYPE__KCORE ||
+ dso->data_type == DSO_BINARY_TYPE__GUEST_KCORE;
+}
+
#endif /* __PERF_DSO */
diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
index dc35dcf..ef3b49c 100644
--- a/tools/perf/util/machine.c
+++ b/tools/perf/util/machine.c
@@ -856,6 +856,18 @@ static void machine__set_kernel_mmap_len(struct machine *machine,
}
}

+static bool machine__uses_kcore(struct machine *machine)
+{
+ struct dso *dso;
+
+ list_for_each_entry(dso, &machine->kernel_dsos, node) {
+ if (dso__is_kcore(dso))
+ return true;
+ }
+
+ return false;
+}
+
static int machine__process_kernel_mmap_event(struct machine *machine,
union perf_event *event)
{
@@ -864,6 +876,10 @@ static int machine__process_kernel_mmap_event(struct machine *machine,
enum dso_kernel_type kernel_type;
bool is_kernel_mmap;

+ /* If we have maps from kcore then we do not need or want any others */
+ if (machine__uses_kcore(machine))
+ return 0;
+
machine__mmap_name(machine, kmmap_prefix, sizeof(kmmap_prefix));
if (machine__is_host(machine))
kernel_type = DSO_TYPE_KERNEL;
diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index 4d599fe..9e8304c 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -555,3 +555,21 @@ struct map *maps__find(struct rb_root *maps, u64 ip)

return NULL;
}
+
+struct map *maps__first(struct rb_root *maps)
+{
+ struct rb_node *first = rb_first(maps);
+
+ if (first)
+ return rb_entry(first, struct map, rb_node);
+ return NULL;
+}
+
+struct map *maps__next(struct map *map)
+{
+ struct rb_node *next = rb_next(&map->rb_node);
+
+ if (next)
+ return rb_entry(next, struct map, rb_node);
+ return NULL;
+}
diff --git a/tools/perf/util/map.h b/tools/perf/util/map.h
index a887f2c..2cc93cb 100644
--- a/tools/perf/util/map.h
+++ b/tools/perf/util/map.h
@@ -112,6 +112,8 @@ size_t __map_groups__fprintf_maps(struct map_groups *mg,
void maps__insert(struct rb_root *maps, struct map *map);
void maps__remove(struct rb_root *maps, struct map *map);
struct map *maps__find(struct rb_root *maps, u64 addr);
+struct map *maps__first(struct rb_root *maps);
+struct map *maps__next(struct map *map);
void map_groups__init(struct map_groups *mg);
void map_groups__exit(struct map_groups *mg);
int map_groups__clone(struct map_groups *mg,
@@ -139,6 +141,17 @@ static inline struct map *map_groups__find(struct map_groups *mg,
return maps__find(&mg->maps[type], addr);
}

+static inline struct map *map_groups__first(struct map_groups *mg,
+ enum map_type type)
+{
+ return maps__first(&mg->maps[type]);
+}
+
+static inline struct map *map_groups__next(struct map *map)
+{
+ return maps__next(map);
+}
+
struct symbol *map_groups__find_symbol(struct map_groups *mg,
enum map_type type, u64 addr,
struct map **mapp,
diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 3eaa7b4..a7b9ab5 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -951,6 +951,57 @@ out_elf_end:
return err;
}

+static int elf_read_maps(Elf *elf, bool exe, mapfn_t mapfn, void *data)
+{
+ GElf_Phdr phdr;
+ size_t i, phdrnum;
+ int err;
+ u64 sz;
+
+ if (elf_getphdrnum(elf, &phdrnum))
+ return -1;
+
+ for (i = 0; i < phdrnum; i++) {
+ if (gelf_getphdr(elf, i, &phdr) == NULL)
+ return -1;
+ if (phdr.p_type != PT_LOAD)
+ continue;
+ if (exe) {
+ if (!(phdr.p_flags & PF_X))
+ continue;
+ } else {
+ if (!(phdr.p_flags & PF_R))
+ continue;
+ }
+ sz = min(phdr.p_memsz, phdr.p_filesz);
+ if (!sz)
+ continue;
+ err = mapfn(phdr.p_vaddr, sz, phdr.p_offset, data);
+ if (err)
+ return err;
+ }
+ return 0;
+}
+
+int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
+ bool *is_64_bit)
+{
+ int err;
+ Elf *elf;
+
+ elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+ if (elf == NULL)
+ return -1;
+
+ if (is_64_bit)
+ *is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
+
+ err = elf_read_maps(elf, exe, mapfn, data);
+
+ elf_end(elf);
+ return err;
+}
+
void symbol__elf_init(void)
{
elf_version(EV_CURRENT);
diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index a7390cd..3a802c3 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -301,6 +301,13 @@ int dso__load_sym(struct dso *dso, struct map *map __maybe_unused,
return 0;
}

+int file__read_maps(int fd __maybe_unused, bool exe __maybe_unused,
+ mapfn_t mapfn __maybe_unused, void *data __maybe_unused,
+ bool *is_64_bit __maybe_unused)
+{
+ return -1;
+}
+
void symbol__elf_init(void)
{
}
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b9056a8..77f3b95 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -327,6 +327,16 @@ static struct symbol *symbols__find(struct rb_root *symbols, u64 ip)
return NULL;
}

+static struct symbol *symbols__first(struct rb_root *symbols)
+{
+ struct rb_node *n = rb_first(symbols);
+
+ if (n)
+ return rb_entry(n, struct symbol, rb_node);
+
+ return NULL;
+}
+
struct symbol_name_rb_node {
struct rb_node rb_node;
struct symbol sym;
@@ -397,6 +407,11 @@ struct symbol *dso__find_symbol(struct dso *dso,
return symbols__find(&dso->symbols[type], addr);
}

+struct symbol *dso__first_symbol(struct dso *dso, enum map_type type)
+{
+ return symbols__first(&dso->symbols[type]);
+}
+
struct symbol *dso__find_symbol_by_name(struct dso *dso, enum map_type type,
const char *name)
{
@@ -533,6 +548,53 @@ static int dso__load_all_kallsyms(struct dso *dso, const char *filename,
return kallsyms__parse(filename, &args, map__process_kallsym_symbol);
}

+static int dso__split_kallsyms_for_kcore(struct dso *dso, struct map *map,
+ symbol_filter_t filter)
+{
+ struct map_groups *kmaps = map__kmap(map)->kmaps;
+ struct map *curr_map;
+ struct symbol *pos;
+ int count = 0, moved = 0;
+ struct rb_root *root = &dso->symbols[map->type];
+ struct rb_node *next = rb_first(root);
+
+ while (next) {
+ char *module;
+
+ pos = rb_entry(next, struct symbol, rb_node);
+ next = rb_next(&pos->rb_node);
+
+ module = strchr(pos->name, '\t');
+ if (module)
+ *module = '\0';
+
+ curr_map = map_groups__find(kmaps, map->type, pos->start);
+
+ if (!curr_map || (filter && filter(curr_map, pos))) {
+ rb_erase(&pos->rb_node, root);
+ symbol__delete(pos);
+ } else {
+ pos->start -= curr_map->start - curr_map->pgoff;
+ if (pos->end)
+ pos->end -= curr_map->start - curr_map->pgoff;
+ if (curr_map != map) {
+ rb_erase(&pos->rb_node, root);
+ symbols__insert(
+ &curr_map->dso->symbols[curr_map->type],
+ pos);
+ ++moved;
+ } else {
+ ++count;
+ }
+ }
+ }
+
+ /* Symbols have been adjusted */
+ dso->adjust_symbols = 1;
+
+ return count + moved;
+}
+
/*
* Split the symbols into maps, making sure there are no overlaps, i.e. the
* kernel range is broken in several maps, named [kernel].N, as we don't have
@@ -674,6 +736,161 @@ bool symbol__restricted_filename(const char *filename,
return restricted;
}

+struct kcore_mapfn_data {
+ struct dso *dso;
+ enum map_type type;
+ struct list_head maps;
+};
+
+static int kcore_mapfn(u64 start, u64 len, u64 pgoff, void *data)
+{
+ struct kcore_mapfn_data *md = data;
+ struct map *map;
+
+ map = map__new2(start, md->dso, md->type);
+ if (map == NULL)
+ return -ENOMEM;
+
+ map->end = map->start + len;
+ map->pgoff = pgoff;
+
+ list_add(&map->node, &md->maps);
+
+ return 0;
+}
+
+/*
+ * If kallsyms is referenced by name then we look for kcore in the same
+ * directory.
+ */
+static bool kcore_filename_from_kallsyms_filename(char *kcore_filename,
+ const char *kallsyms_filename)
+{
+ char *name;
+
+ strcpy(kcore_filename, kallsyms_filename);
+ name = strrchr(kcore_filename, '/');
+ if (!name)
+ return false;
+
+ if (!strcmp(name, "/kallsyms")) {
+ strcpy(name, "/kcore");
+ return true;
+ }
+
+ return false;
+}
+
+static int dso__load_kcore(struct dso *dso, struct map *map,
+ const char *kallsyms_filename)
+{
+ struct map_groups *kmaps = map__kmap(map)->kmaps;
+ struct machine *machine = kmaps->machine;
+ struct kcore_mapfn_data md;
+ struct map *old_map, *new_map, *replacement_map = NULL;
+ bool is_64_bit;
+ int err, fd;
+ char kcore_filename[PATH_MAX];
+ struct symbol *sym;
+
+ /* This function requires that the map is the kernel map */
+ if (map != machine->vmlinux_maps[map->type])
+ return -EINVAL;
+
+ if (!kcore_filename_from_kallsyms_filename(kcore_filename,
+ kallsyms_filename))
+ return -EINVAL;
+
+ md.dso = dso;
+ md.type = map->type;
+ INIT_LIST_HEAD(&md.maps);
+
+ fd = open(kcore_filename, O_RDONLY);
+ if (fd < 0)
+ return -EINVAL;
+
+ /* Read new maps into temporary lists */
+ err = file__read_maps(fd, md.type == MAP__FUNCTION, kcore_mapfn, &md,
+ &is_64_bit);
+ if (err)
+ goto out_err;
+
+ if (list_empty(&md.maps)) {
+ err = -EINVAL;
+ goto out_err;
+ }
+
+ /* Remove old maps */
+ old_map = map_groups__first(kmaps, map->type);
+ while (old_map) {
+ struct map *next = map_groups__next(old_map);
+
+ if (old_map != map)
+ map_groups__remove(kmaps, old_map);
+ old_map = next;
+ }
+
+ /* Find the kernel map using the first symbol */
+ sym = dso__first_symbol(dso, map->type);
+ list_for_each_entry(new_map, &md.maps, node) {
+ if (sym && sym->start >= new_map->start &&
+ sym->start < new_map->end) {
+ replacement_map = new_map;
+ break;
+ }
+ }
+
+ if (!replacement_map)
+ replacement_map = list_entry(md.maps.next, struct map, node);
+
+ /* Add new maps */
+ while (!list_empty(&md.maps)) {
+ new_map = list_entry(md.maps.next, struct map, node);
+ list_del(&new_map->node);
+ if (new_map == replacement_map) {
+ map->start = new_map->start;
+ map->end = new_map->end;
+ map->pgoff = new_map->pgoff;
+ map->map_ip = new_map->map_ip;
+ map->unmap_ip = new_map->unmap_ip;
+ map__delete(new_map);
+ /* Ensure maps are correctly ordered */
+ map_groups__remove(kmaps, map);
+ map_groups__insert(kmaps, map);
+ } else {
+ map_groups__insert(kmaps, new_map);
+ }
+ }
+
+ /*
+ * Set the data type and long name so that kcore can be read via
+ * dso__data_read_addr().
+ */
+ if (dso->kernel == DSO_TYPE_GUEST_KERNEL)
+ dso->data_type = DSO_BINARY_TYPE__GUEST_KCORE;
+ else
+ dso->data_type = DSO_BINARY_TYPE__KCORE;
+ dso__set_long_name(dso, strdup(kcore_filename));
+
+ close(fd);
+
+ if (map->type == MAP__FUNCTION)
+ pr_debug("Using %s for kernel object code\n", kcore_filename);
+ else
+ pr_debug("Using %s for kernel data\n", kcore_filename);
+
+ return 0;
+
+out_err:
+ while (!list_empty(&md.maps)) {
+ map = list_entry(md.maps.next, struct map, node);
+ list_del(&map->node);
+ map__delete(map);
+ }
+ close(fd);
+ return -EINVAL;
+}
+
int dso__load_kallsyms(struct dso *dso, const char *filename,
struct map *map, symbol_filter_t filter)
{
@@ -691,7 +908,10 @@ int dso__load_kallsyms(struct dso *dso, const char *filename,
else
dso->symtab_type = DSO_BINARY_TYPE__KALLSYMS;

- return dso__split_kallsyms(dso, map, filter);
+ if (!dso__load_kcore(dso, map, filename))
+ return dso__split_kallsyms_for_kcore(dso, map, filter);
+ else
+ return dso__split_kallsyms(dso, map, filter);
}

static int dso__load_perf_map(struct dso *dso, struct map *map,
@@ -1065,7 +1285,7 @@ do_kallsyms:
pr_debug("Using %s for symbols\n", kallsyms_filename);
free(kallsyms_allocated_filename);

- if (err > 0) {
+ if (err > 0 && !dso__is_kcore(dso)) {
dso__set_long_name(dso, strdup("[kernel.kallsyms]"));
map__fixup_start(map);
map__fixup_end(map);
@@ -1109,8 +1329,9 @@ static int dso__load_guest_kernel_sym(struct dso *dso, struct map *map,
}

err = dso__load_kallsyms(dso, kallsyms_filename, map, filter);
- if (err > 0) {
+ if (err > 0)
pr_debug("Using %s for symbols\n", kallsyms_filename);
+ if (err > 0 && !dso__is_kcore(dso)) {
machine__mmap_name(machine, path, sizeof(path));
dso__set_long_name(dso, strdup(path));
map__fixup_start(map);
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 5f720dc..fd5b70e 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -215,6 +215,7 @@ struct symbol *dso__find_symbol(struct dso *dso, enum map_type type,
u64 addr);
struct symbol *dso__find_symbol_by_name(struct dso *dso, enum map_type type,
const char *name);
+struct symbol *dso__first_symbol(struct dso *dso, enum map_type type);

int filename__read_build_id(const char *filename, void *bf, size_t size);
int sysfs__read_build_id(const char *filename, void *bf, size_t size);
@@ -247,4 +248,8 @@ void symbols__fixup_duplicate(struct rb_root *symbols);
void symbols__fixup_end(struct rb_root *symbols);
void __map_groups__fixup_end(struct map_groups *mg, enum map_type type);

+typedef int (*mapfn_t)(u64 start, u64 len, u64 pgoff, void *data);
+int file__read_maps(int fd, bool exe, mapfn_t mapfn, void *data,
+ bool *is_64_bit);
+
#endif /* __PERF_SYMBOL */

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