linux-kernel - [PATCH] perf lookup of ppc64 symbols

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Date:	Mon, 14 Jun 2010 14:56:33 +0100
From:	Eric B Munson <ebmunson@...ibm.com>
To:	mingo@...e.hu
Cc:	a.p.zijlstra@...llo.nl, paulus@...ba.org, acme@...hat.com,
	linux-kernel@...r.kernel.org, Eric B Munson <ebmunson@...ibm.com>,
	Anton Blanchard <anton@...ba.org>
Subject: [PATCH] perf lookup of ppc64 symbols

Currently symbol resolution does not work for 64-bit programs
using perf.  For this to work perf needs to lookup symbol names in
the OPD.  This patch adds this functionality.  The OPD data is
used to find symbol names when available.

Signed-off-by: Anton Blanchard <anton@...ba.org>
Signed-off-by: Eric B Munson <ebmunson@...ibm.com>
---
 tools/perf/util/symbol.c |   37 ++++++++++++++++++++++++++++++++++---
 1 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b63e571..971d0a0 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;
-- 
1.7.0.4

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