[tip:perfcounters/core] perf_counter: Implement dso__load using libelf

tip-bot for Arnaldo Carvalho de Melo
2009-05-26T12:13:43Z

Commit-ID: 62eb93905b3b43cea407cfbc061cc7b40ae1c6e9
Gitweb: http://git.kernel.org/tip/62eb93905b3b43cea407cfbc061cc7b40ae1c6e9
Author: Arnaldo Carvalho de Melo <acme@redhat.com>
AuthorDate: Mon, 18 May 2009 14:28:47 -0300
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Tue, 26 May 2009 13:52:53 +0200

perf_counter: Implement dso__load using libelf

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
Documentation/perf_counter/Makefile | 2 +-
Documentation/perf_counter/builtin-report.c | 122 ++++++++++++++++++++++++++-
2 files changed, 121 insertions(+), 3 deletions(-)

diff --git a/Documentation/perf_counter/Makefile b/Documentation/perf_counter/Makefile
index 49c601e..6bffa86 100644
--- a/Documentation/perf_counter/Makefile
+++ b/Documentation/perf_counter/Makefile
@@ -160,7 +160,7 @@ uname_V := $(shell sh -c 'uname -v 2>/dev/null || echo not')
# CFLAGS and LDFLAGS are for the users to override from the command line.

CFLAGS = -g -O2 -Wall
-LDFLAGS = -lpthread -lrt
+LDFLAGS = -lpthread -lrt -lelf
ALL_CFLAGS = $(CFLAGS)
ALL_LDFLAGS = $(LDFLAGS)
STRIP ?= strip
diff --git a/Documentation/perf_counter/builtin-report.c b/Documentation/perf_counter/builtin-report.c
index 864f68f..ad2f327 100644
--- a/Documentation/perf_counter/builtin-report.c
+++ b/Documentation/perf_counter/builtin-report.c
@@ -8,6 +8,9 @@
#include <stdlib.h>
#include <string.h>
#include <limits.h>
+#include <gelf.h>
+#include <elf.h>
+#include <libelf.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
@@ -195,10 +198,123 @@ static struct symbol *dso__find_symbol(struct dso *self, uint64_t ip)
return NULL;
}

+/**
+ * elf_symtab__for_each_symbol - iterate thru all the symbols
+ *
+ * @self: struct elf_symtab instance to iterate
+ * @index: uint32_t index
+ * @sym: GElf_Sym iterator
+ */
+#define elf_symtab__for_each_symbol(syms, nr_syms, index, sym) \
+ for (index = 0, gelf_getsym(syms, index, &sym);\
+ index < nr_syms; \
+ index++, gelf_getsym(syms, index, &sym))
+
+static inline uint8_t elf_sym__type(const GElf_Sym *sym)
+{
+ return GELF_ST_TYPE(sym->st_info);
+}
+
+static inline bool elf_sym__is_function(const GElf_Sym *sym)
+{
+ return elf_sym__type(sym) == STT_FUNC &&
+ sym->st_name != 0 &&
+ sym->st_shndx != SHN_UNDEF;
+}
+
+static inline const char *elf_sym__name(const GElf_Sym *sym,
+ const Elf_Data *symstrs)
+{
+ return symstrs->d_buf + sym->st_name;
+}
+
+static Elf_Scn *elf_section_by_name(Elf *elf, GElf_Ehdr *ep,
+ GElf_Shdr *shp, const char *name,
+ size_t *index)
+{
+ Elf_Scn *sec = NULL;
+ size_t cnt = 1;
+
+ while ((sec = elf_nextscn(elf, sec)) != NULL) {
+ char *str;
+
+ gelf_getshdr(sec, shp);
+ str = elf_strptr(elf, ep->e_shstrndx, shp->sh_name);
+ if (!strcmp(name, str)) {
+ if (index)
+ *index = cnt;
+ break;
+ }
+ ++cnt;
+ }
+
+ return sec;
+}
+
static int dso__load(struct dso *self)
{
- /* FIXME */
- return 0;
+ int fd = open(self->name, O_RDONLY), err = -1;
+
+ if (fd == -1)
+ return -1;
+
+ Elf *elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ if (elf == NULL) {
+ fprintf(stderr, "%s: cannot read %s ELF file.\n",
+ __func__, self->name);
+ goto out_close;
+ }
+
+ GElf_Ehdr ehdr;
+ if (gelf_getehdr(elf, &ehdr) == NULL) {
+ fprintf(stderr, "%s: cannot get elf header.\n", __func__);
+ goto out_elf_end;
+ }
+
+ GElf_Shdr shdr;
+ Elf_Scn *sec = elf_section_by_name(elf, &ehdr, &shdr, ".symtab", NULL);
+ if (sec == NULL)
+ sec = elf_section_by_name(elf, &ehdr, &shdr, ".dynsym", NULL);
+
+ if (sec == NULL)
+ goto out_elf_end;
+
+ if (gelf_getshdr(sec, &shdr) == NULL)
+ goto out_elf_end;
+
+ Elf_Data *syms = elf_getdata(sec, NULL);
+ if (syms == NULL)
+ goto out_elf_end;
+
+ sec = elf_getscn(elf, shdr.sh_link);
+ if (sec == NULL)
+ goto out_elf_end;
+
+ Elf_Data *symstrs = elf_getdata(sec, NULL);
+ if (symstrs == NULL)
+ goto out_elf_end;
+
+ const uint32_t nr_syms = shdr.sh_size / shdr.sh_entsize;
+
+ GElf_Sym sym;
+ uint32_t index;
+ elf_symtab__for_each_symbol(syms, nr_syms, index, sym) {
+ if (!elf_sym__is_function(&sym))
+ continue;
+ struct symbol *f = symbol__new(sym.st_value, sym.st_size,
+ elf_sym__name(&sym, symstrs));
+ if (f == NULL)
+ goto out_elf_end;
+
+ dso__insert_symbol(self, f);
+ }
+
+ err = 0;
+out_elf_end:
+ elf_end(elf);
+out_close:
+ close(fd);
+ return err;
}

static size_t dso__fprintf(struct dso *self, FILE *fp)
@@ -614,6 +730,8 @@ int cmd_report(int argc, char **argv)
int ret, rc = EXIT_FAILURE;
unsigned long total = 0;

+ elf_version(EV_CURRENT);
+
page_size = getpagesize();

process_options(argc, argv);