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Date: Fri, 7 Nov 2014 14:20:05 +0900
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Ingo Molnar <mingo@...nel.org>,
Paul Mackerras <paulus@...ba.org>,
Namhyung Kim <namhyung.kim@....com>,
Namhyung Kim <namhyung@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
Jiri Olsa <jolsa@...hat.com>,
Adrian Hunter <adrian.hunter@...el.com>,
David Ahern <dsahern@...il.com>
Subject: [PATCH 2/3] perf symbol: Implement a very simple ELF symbol parser
It'll be used to show (userspace) symbol names when libelf isn't (or
cannot be) linked.
# Overhead Command Shared Object Symbol
# ........ .......... ................. .........................
#
37.01% mem-memcpy libc-2.17.so [.] __memcpy_ssse3_back
24.25% perf ld-2.17.so [.] _dl_relocate_object
22.16% perf [kernel.kallsyms] [k] kmem_cache_alloc
14.29% mem-memset libc-2.17.so [.] __memset_sse2
2.21% perf [kernel.kallsyms] [k] flush_signal_handlers
0.07% perf [kernel.kallsyms] [k] intel_pmu_enable_all
Cc: Adrian Hunter <adrian.hunter@...el.com>
Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
tools/perf/util/symbol-minimal.c | 143 ++++++++++++++++++++++++++++++++++++---
tools/perf/util/symbol-minimal.h | 64 ++++++++++++++++++
tools/perf/util/symbol.h | 10 ++-
3 files changed, 208 insertions(+), 9 deletions(-)
create mode 100644 tools/perf/util/symbol-minimal.h
diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index 226cf41ed7e6..9da571d83a25 100644
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -1,11 +1,13 @@
#include "symbol.h"
#include "util.h"
+#include "debug.h"
#include <stdio.h>
#include <fcntl.h>
#include <string.h>
#include <byteswap.h>
#include <sys/stat.h>
+#include <sys/mman.h>
static bool check_need_swap(int file_endian)
@@ -242,22 +244,81 @@ int sysfs__read_build_id(const char *filename, void *build_id, size_t size)
return ret;
}
+static const char *symsrc__symname(struct symsrc *ss, Elf_Shdr *strsec, int idx)
+{
+ return ss->ptr + strsec->sh_offset + idx;
+}
+
int symsrc__init(struct symsrc *ss, struct dso *dso __maybe_unused,
const char *name,
enum dso_binary_type type)
{
- int fd = open(name, O_RDONLY);
+ int fd;
+ unsigned i;
+ Elf_Ehdr ehdr;
+ struct stat stbuf;
+ void *ptr;
+
+ fd = open(name, O_RDONLY);
if (fd < 0)
return -1;
ss->name = strdup(name);
- if (!ss->name)
- goto out_close;
+ if (!ss->name) {
+ close(fd);
+ return -1;
+ }
ss->fd = fd;
ss->type = type;
+ /* only consider native case (no swap) */
+ if (read(fd, &ehdr, sizeof(ehdr)) < 0)
+ goto out_close;
+
+ if (memcmp(ehdr.e_ident, ELFMAG, SELFMAG) ||
+ ehdr.e_ident[EI_VERSION] != EV_CURRENT)
+ goto out_close;
+
+ if (ehdr.e_ident[EI_CLASS] != ELFCLASS)
+ goto out_close;
+
+ if (check_need_swap(ehdr.e_ident[EI_DATA]))
+ goto out_close;
+
+ if (ehdr.e_shentsize != sizeof(Elf_Shdr))
+ goto out_close;
+
+ if (fstat(fd, &stbuf) < 0)
+ goto out_close;
+
+ ptr = mmap(NULL, stbuf.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
+ if (ptr == MAP_FAILED)
+ goto out_close;
+
+ ss->ptr = ptr;
+ ss->len = stbuf.st_size;
+ ss->sec = ptr + ehdr.e_shoff;
+
+ ss->symtab = NULL;
+ for (i = 0; i < ehdr.e_shnum; i++) {
+ Elf_Shdr *shdrp = &ss->sec[i];
+ const char *shname;
+
+ shname = symsrc__symname(ss, &ss->sec[ehdr.e_shstrndx],
+ shdrp->sh_name);
+
+ if (!strcmp(shname, ".text"))
+ ss->adjust_offset = shdrp->sh_addr - shdrp->sh_offset;
+
+ if (shdrp->sh_type == SHT_SYMTAB) {
+ ss->symtab = shdrp;
+ ss->strtab = &ss->sec[shdrp->sh_link];
+ }
+ }
+
return 0;
+
out_close:
close(fd);
return -1;
@@ -276,6 +337,7 @@ bool symsrc__has_symtab(struct symsrc *ss __maybe_unused)
void symsrc__destroy(struct symsrc *ss)
{
+ munmap(ss->ptr, ss->len);
zfree(&ss->name);
close(ss->fd);
}
@@ -332,7 +394,9 @@ int dso__load_sym(struct dso *dso, struct map *map __maybe_unused,
symbol_filter_t filter __maybe_unused,
int kmodule __maybe_unused)
{
- unsigned char *build_id[BUILD_ID_SIZE];
+ Elf_Ehdr *ehdr = ss->ptr;
+ Elf_Sym *symtab;
+ size_t i, nr_sym;
int ret;
if (dso->kernel)
@@ -342,11 +406,74 @@ int dso__load_sym(struct dso *dso, struct map *map __maybe_unused,
if (ret >= 0)
dso->is_64_bit = ret;
- if (filename__read_build_id(ss->name, build_id, BUILD_ID_SIZE) > 0) {
- dso__set_build_id(dso, build_id);
- return 1;
+ if (dso->has_build_id) {
+ u8 build_id[BUILD_ID_SIZE];
+
+ if (filename__read_build_id(ss->name, build_id, BUILD_ID_SIZE) < 0)
+ return -1;
+
+ if (!dso__build_id_equal(dso, build_id))
+ return -1;
}
- return 0;
+
+ if (map->type != MAP__FUNCTION)
+ return 0;
+
+ if (!ss->symtab)
+ return 0;
+
+ symtab = ss->ptr + ss->symtab->sh_offset;
+ nr_sym = ss->symtab->sh_size / ss->symtab->sh_entsize;
+
+ pr_debug4("loading symbols from %s\n", ss->name);
+ ret = 0;
+ for (i = 0; i < nr_sym; i++) {
+ struct symbol *s;
+ Elf_Sym *sym = &symtab[i];
+ const char *symname = symsrc__symname(ss, ss->strtab, sym->st_name);
+ unsigned long sym_addr = sym->st_value;
+
+ if (ELF_ST_TYPE(sym->st_info) != STT_FUNC)
+ continue;
+
+ if (sym->st_shndx == SHN_UNDEF)
+ continue;
+
+ if (ehdr->e_machine == EM_ARM) {
+ /* Reject ARM ELF "mapping symbols": these aren't unique
+ * and don't identify functions, so will confuse the
+ * profile output: */
+ if (!strcmp(symname, "$a") ||
+ !strcmp(symname, "$d") ||
+ !strcmp(symname, "$t"))
+ continue;
+
+ /* On ARM, symbols for thumb functions have 1 added to
+ * the symbol address as a flag - remove it */
+ if (sym->st_value & 1)
+ sym_addr--;
+ }
+ sym_addr -= ss->adjust_offset;
+
+ pr_debug4("sym: %s (%lx+%lu)\n", symname, sym_addr, sym->st_size);
+ s = symbol__new(sym_addr, sym->st_size,
+ ELF_ST_BIND(sym->st_info), symname);
+ if (!s)
+ break;
+
+ if (filter && filter(map, s))
+ symbol__delete(s);
+ else {
+ symbols__insert(&dso->symbols[map->type], s);
+ ret++;
+ }
+ }
+
+ if (ret > 0) {
+ symbols__fixup_duplicate(&dso->symbols[map->type]);
+ symbols__fixup_end(&dso->symbols[map->type]);
+ }
+ return ret;
}
int file__read_maps(int fd __maybe_unused, bool exe __maybe_unused,
diff --git a/tools/perf/util/symbol-minimal.h b/tools/perf/util/symbol-minimal.h
new file mode 100644
index 000000000000..7b8b38426359
--- /dev/null
+++ b/tools/perf/util/symbol-minimal.h
@@ -0,0 +1,64 @@
+#ifndef __PERF_SYMBOL_MINIMAL_H
+#define __PERF_SYMBOL_MINIMAL_H
+
+#include <elf.h>
+#include <linux/bitops.h>
+
+#if BITS_PER_LONG == 32
+
+# define ELFCLASS ELFCLASS32
+
+# define Elf_Half Elf32_Half
+# define Elf_Word Elf32_Word
+# define Elf_Sword Elf32_Sword
+# define Elf_Xword Elf32_Xword
+# define Elf_Sxword Elf32_Sxword
+# define Elf_Addr Elf32_Addr
+# define Elf_Off Elf32_Off
+# define Elf_Section Elf32_Section
+# define Elf_Versym Elf32_Versym
+
+# define Elf_Ehdr Elf32_Ehdr
+# define Elf_Phdr Elf32_Phdr
+# define Elf_Shdr Elf32_Shdr
+# define Elf_Nhdr Elf32_Nhdr
+# define Elf_Sym Elf32_Sym
+# define Elf_Syminfo Elf32_Syminfo
+# define Elf_Rel Elf32_Rel
+# define Elf_Rela Elf32_Rela
+# define Elf_Dyn Elf32_Dyn
+
+# define ELF_ST_BIND(val) ELF32_ST_BIND(val)
+# define ELF_ST_TYPE(val) ELF32_ST_TYPE(val)
+# define ELF_ST_INFO(bind, type) ELF32_ST_INFO(bind, type)
+
+#else /* BITS_PER_LONG == 64 */
+
+# define ELFCLASS ELFCLASS64
+
+# define Elf_Half Elf64_Half
+# define Elf_Word Elf64_Word
+# define Elf_Sword Elf64_Sword
+# define Elf_Xword Elf64_Xword
+# define Elf_Sxword Elf64_Sxword
+# define Elf_Addr Elf64_Addr
+# define Elf_Off Elf64_Off
+# define Elf_Section Elf64_Section
+# define Elf_Versym Elf64_Versym
+
+# define Elf_Ehdr Elf64_Ehdr
+# define Elf_Phdr Elf64_Phdr
+# define Elf_Shdr Elf64_Shdr
+# define Elf_Nhdr Elf64_Nhdr
+# define Elf_Sym Elf64_Sym
+# define Elf_Syminfo Elf64_Syminfo
+# define Elf_Rel Elf64_Rel
+# define Elf_Rela Elf64_Rela
+# define Elf_Dyn Elf64_Dyn
+
+# define ELF_ST_BIND(val) ELF64_ST_BIND(val)
+# define ELF_ST_TYPE(val) ELF64_ST_TYPE(val)
+# define ELF_ST_INFO(bind, type) ELF64_ST_INFO(bind, type)
+
+#endif /* BITS_PER_LONG == 64 */
+#endif /* __PERF_SYMBOL_MINIMAL_H */
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index ded3ca7266de..1c1dc5b9b3f8 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -18,8 +18,9 @@
#ifdef HAVE_LIBELF_SUPPORT
#include <libelf.h>
#include <gelf.h>
+#else
+#include "symbol-minimal.h"
#endif
-#include <elf.h>
#include "dso.h"
@@ -229,6 +230,13 @@ struct symsrc {
bool adjust_symbols;
bool is_64_bit;
+#else
+ void *ptr;
+ size_t len;
+ Elf_Shdr *sec;
+ Elf_Shdr *symtab;
+ Elf_Shdr *strtab;
+ long adjust_offset;
#endif
};
--
2.1.2
--
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