From 70c3856b2f1304e0abc65f1b96a8c60ddfc0fb9e Mon Sep 17 00:00:00 2001
From: Eric B Munson <ebmunson@us.ibm.com>
Date: Mon, 14 Jun 2010 14:56:33 +0100
Subject: perf symbols: Function descriptor symbol lookup
Currently symbol resolution does not work for 64-bit programs on architectures
that use function descriptors such as ppc64.
The problem is that a symbol doesn't point to a text address, it points to a
data area that contains (amongst other things) a pointer to the text address.
We look for a section called ".opd" which is the function descriptor area. To
create the full symbol table, when we see a symbol in the function descriptor
section we load the first pointer and use that as the text address.
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <1276523793-15422-1-git-send-email-ebmunson@us.ibm.com>
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Eric B Munson <ebmunson@us.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/symbol.c | 37 ++++++++++++++++++++++++++++++++++---
1 file changed, 34 insertions(+), 3 deletions(-)
(limited to 'tools')
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b63e5713849..971d0a05d6b 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -933,6 +933,25 @@ static bool elf_sec__is_a(GElf_Shdr *self, Elf_Data *secstrs, enum map_type type
}
}
+static size_t elf_addr_to_index(Elf *elf, GElf_Addr addr)
+{
+ Elf_Scn *sec = NULL;
+ GElf_Shdr shdr;
+ size_t cnt = 1;
+
+ while ((sec = elf_nextscn(elf, sec)) != NULL) {
+ gelf_getshdr(sec, &shdr);
+
+ if ((addr >= shdr.sh_addr) &&
+ (addr < (shdr.sh_addr + shdr.sh_size)))
+ return cnt;
+
+ ++cnt;
+ }
+
+ return -1;
+}
+
static int dso__load_sym(struct dso *self, struct map *map, const char *name,
int fd, symbol_filter_t filter, int kmodule)
{
@@ -944,12 +963,13 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
int err = -1;
uint32_t idx;
GElf_Ehdr ehdr;
- GElf_Shdr shdr;
- Elf_Data *syms;
+ GElf_Shdr shdr, opdshdr;
+ Elf_Data *syms, *opddata = NULL;
GElf_Sym sym;
- Elf_Scn *sec, *sec_strndx;
+ Elf_Scn *sec, *sec_strndx, *opdsec;
Elf *elf;
int nr = 0;
+ size_t opdidx = 0;
elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
if (elf == NULL) {
@@ -969,6 +989,10 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
goto out_elf_end;
}
+ opdsec = elf_section_by_name(elf, &ehdr, &opdshdr, ".opd", &opdidx);
+ if (opdsec)
+ opddata = elf_rawdata(opdsec, NULL);
+
syms = elf_getdata(sec, NULL);
if (syms == NULL)
goto out_elf_end;
@@ -1013,6 +1037,13 @@ static int dso__load_sym(struct dso *self, struct map *map, const char *name,
if (!is_label && !elf_sym__is_a(&sym, map->type))
continue;
+ if (opdsec && sym.st_shndx == opdidx) {
+ u32 offset = sym.st_value - opdshdr.sh_addr;
+ u64 *opd = opddata->d_buf + offset;
+ sym.st_value = *opd;
+ sym.st_shndx = elf_addr_to_index(elf, sym.st_value);
+ }
+
sec = elf_getscn(elf, sym.st_shndx);
if (!sec)
goto out_elf_end;
--
cgit v1.2.3-70-g09d2