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SubjectRe: [PATCH] perf tools: add compatibility with libelf 0.8 and autodetect
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On Sat, Oct 24, 2009 at 12:02 AM, Ingo Molnar <mingo@elte.hu> wrote:
> Mind doing a small change:
>
> I think we want a small cleanup here: a perf_elf_begin() wrapper in a
> header file to hide this #ifdef. (That's how Git wraps environmental
> libraries as well.)

Ok, does this patch do what you had in mind? I wasn't quite sure how to
implement; changing the cmd behind someone's back might be considered
surprising.

Another take would be to #define our own ELF_C_READ_MMAP, but that would be
lying, too...

> Also, this would be an urgent fix for v2.6.32 too, to make perf build on
> Arch Linux, agreed?

Hopefully :)

Regards,
Marti


[PATCH] perf tools: add compatibility with libelf 0.8 and autodetect

The Makefile now automatically defines LIBELF_NO_MMAP when libelf 0.8 is
detected. libelf 0.8 is still maintained and some distributions such as
Arch Linux use it instead of elfutils.

Signed-off-by: Marti Raudsepp <marti@juffo.org>
---
tools/perf/Makefile | 6 +++++-
tools/perf/util/symbol.c | 9 +++++----
tools/perf/util/symbol.h | 11 +++++++++++
3 files changed, 21 insertions(+), 5 deletions(-)
diff --git a/tools/perf/Makefile b/tools/perf/Makefile
index 742a32e..46e877b 100644
--- a/tools/perf/Makefile
+++ b/tools/perf/Makefile
@@ -422,7 +422,11 @@ ifeq ($(uname_S),Darwin)
PTHREAD_LIBS =
endif

-ifneq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf * elf = elf_begin(0, ELF_C_READ_MMAP, 0); return (long)elf; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
+ifeq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf * elf = elf_begin(0, ELF_C_READ, 0); return (long)elf; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
+ ifneq ($(shell sh -c "(echo '\#include <libelf.h>'; echo 'int main(void) { Elf * elf = elf_begin(0, ELF_C_READ_MMAP, 0); return (long)elf; }') | $(CC) -x c - $(ALL_CFLAGS) -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64 -o /dev/null $(ALL_LDFLAGS) > /dev/null 2>&1 && echo y"), y)
+ BASIC_CFLAGS += -DLIBELF_NO_MMAP
+ endif
+else
msg := $(error No libelf.h/libelf found, please install libelf-dev/elfutils-libelf-devel and glibc-dev[el]);
endif

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 47ea060..ec69c42 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -5,7 +5,6 @@

#include "debug.h"

-#include <libelf.h>
#include <gelf.h>
#include <elf.h>

@@ -413,7 +412,8 @@ static int dso__synthesize_plt_symbols(struct dso *self, int v)
if (fd < 0)
goto out;

- elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ elf = perf_elf_begin(fd, ELF_C_READ, NULL);
+
if (elf == NULL)
goto out_close;

@@ -533,7 +533,8 @@ static int dso__load_sym(struct dso *self, int fd, const char *name,
Elf *elf;
int nr = 0, kernel = !strcmp("[kernel]", self->name);

- elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ elf = perf_elf_begin(fd, ELF_C_READ, NULL);
+
if (elf == NULL) {
if (v)
fprintf(stderr, "%s: cannot read %s ELF file.\n",
@@ -675,7 +676,7 @@ static char *dso__read_build_id(struct dso *self, int v)
if (fd < 0)
goto out;

- elf = elf_begin(fd, ELF_C_READ_MMAP, NULL);
+ elf = perf_elf_begin(fd, ELF_C_READ, NULL);
if (elf == NULL) {
if (v)
fprintf(stderr, "%s: cannot read %s ELF file.\n",
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 6e84907..50750e9 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -8,6 +8,8 @@
#include "module.h"
#include "event.h"

+#include <libelf.h>
+
#ifdef HAVE_CPLUS_DEMANGLE
extern char *cplus_demangle(const char *, int);

@@ -27,6 +29,15 @@ static inline char *bfd_demangle(void __used *v, const char __used *c,
#endif
#endif

+static inline Elf *perf_elf_begin(int fd, Elf_Cmd cmd, Elf *ref)
+{
+#ifndef LIBELF_NO_MMAP
+ if (cmd == ELF_C_READ)
+ cmd = ELF_C_READ_MMAP;
+#endif
+ return elf_begin(fd, cmd, ref);
+}
+
#ifndef DMGL_PARAMS
#define DMGL_PARAMS (1 << 0) /* Include function args */
#define DMGL_ANSI (1 << 1) /* Include const, volatile, etc */
--
1.6.5.1


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