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>

diff --git a/Documentation/perf_counter/Makefile b/Documentation/perf_counter/Makefile
index 49c601e..6bffa86 100644 (file)
--- 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 (file)
--- 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);