linux-kernel - [PATCH v2 5/9] perf tools: Add methods to test dso is 64-bit or 32-bit

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Date:	Tue, 10 May 2016 07:40:33 +0000
From:	He Kuang <hekuang@...wei.com>
To:	<peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
	<alexander.shishkin@...ux.intel.com>, <jolsa@...hat.com>,
	<wangnan0@...wei.com>, <hekuang@...wei.com>, <jpoimboe@...hat.com>,
	<ak@...ux.intel.com>, <eranian@...gle.com>, <namhyung@...nel.org>,
	<adrian.hunter@...el.com>, <sukadev@...ux.vnet.ibm.com>,
	<masami.hiramatsu.pt@...achi.com>, <tumanova@...ux.vnet.ibm.com>,
	<kan.liang@...el.com>, <penberg@...nel.org>, <dsahern@...il.com>
CC:	<linux-kernel@...r.kernel.org>
Subject: [PATCH v2 5/9] perf tools: Add methods to test dso is 64-bit or 32-bit

32-bit programs can be run on 64-bit machines, so we should choose
unwind methods according to 'thread->map' instead of the host
architecture.

This patch adds methods to test whether a dso is 64-bit or 32-bit by
the class info in elf.

Signed-off-by: He Kuang <hekuang@...wei.com>
---
 tools/perf/util/symbol-elf.c | 16 +++++++++++++++
 tools/perf/util/symbol.c     | 49 ++++++++++++++++++++++++++++++++++++++++++++
 tools/perf/util/symbol.h     |  2 ++
 3 files changed, 67 insertions(+)

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 3f9d679..9f290b9 100644
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -636,6 +636,22 @@ bool __weak elf__needs_adjust_symbols(GElf_Ehdr ehdr)
 	return ehdr.e_type == ET_EXEC || ehdr.e_type == ET_REL;
 }
 
+int elf_is_64_bit(char *name)
+{
+	Elf *elf;
+	int fd;
+
+	fd = open(name, O_RDONLY);
+	if (fd < 0)
+		return -1;
+
+	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
+	if (elf == NULL)
+		return -1;
+
+	return (gelf_getclass(elf) == ELFCLASS64);
+}
+
 int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
 		 enum dso_binary_type type)
 {
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 4630751..592bf8c 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1395,6 +1395,55 @@ static bool dso__is_compatible_symtab_type(struct dso *dso, bool kmod,
 	}
 }
 
+int dso_is_64_bit(struct dso *dso, struct map *map)
+{
+	char *name;
+	u_int i;
+	bool kmod;
+	char *root_dir = (char *) "";
+	struct machine *machine;
+
+	if (map->groups && map->groups->machine)
+		machine = map->groups->machine;
+	else
+		machine = NULL;
+
+	if (machine)
+		root_dir = machine->root_dir;
+
+	name = malloc(PATH_MAX);
+	if (!name)
+		return -1;
+
+	kmod = dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE ||
+		dso->symtab_type == DSO_BINARY_TYPE__SYSTEM_PATH_KMODULE_COMP ||
+		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE ||
+		dso->symtab_type == DSO_BINARY_TYPE__GUEST_KMODULE_COMP;
+
+	/*
+	 * Iterate over candidate debug images.
+	 * Keep track of "interesting" ones (those which have a symtab, dynsym,
+	 * and/or opd section) for processing.
+	 */
+	for (i = 0; i < DSO_BINARY_TYPE__SYMTAB_CNT; i++) {
+		enum dso_binary_type symtab_type = binary_type_symtab[i];
+
+		if (!dso__is_compatible_symtab_type(dso, kmod, symtab_type))
+			continue;
+
+		if (dso__read_binary_type_filename(dso, symtab_type,
+						   root_dir, name, PATH_MAX))
+			continue;
+
+		if (!is_regular_file(name))
+			continue;
+
+		return elf_is_64_bit(name);
+	}
+
+	return -1;
+}
+
 int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 {
 	char *name;
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 4e6910e..d33fbf4 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -308,6 +308,8 @@ int setup_list(struct strlist **list, const char *list_str,
 	       const char *list_name);
 int setup_intlist(struct intlist **list, const char *list_str,
 		  const char *list_name);
+int elf_is_64_bit(char *name);
+int dso_is_64_bit(struct dso *dso, struct map *map);
 
 #ifdef HAVE_LIBELF_SUPPORT
 bool elf__needs_adjust_symbols(GElf_Ehdr ehdr);
-- 
1.8.5.2