perf tools: Fix compatibility with libelf 0.8 and autodetect

The Makefile now automatically defines LIBELF_NO_MMAP when
libelf 0.8.x 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>
Cc: Lucas De Marchi <lucas.de.marchi@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <1256400636.3007.16.camel@newn>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

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
 

tools/perf/util/symbol.c

@@ -413,7 +413,7 @@ 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 = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 	if (elf == NULL)
 		goto out_close;
 
@@ -533,7 +533,7 @@ 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 = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 	if (elf == NULL) {
 		if (v)
 			fprintf(stderr, "%s: cannot read %s ELF file.\n",
@@ -675,7 +675,7 @@ 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 = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);
 	if (elf == NULL) {
 		if (v)
 			fprintf(stderr, "%s: cannot read %s ELF file.\n",

tools/perf/util/symbol.h

@@ -27,6 +27,16 @@ static inline char *bfd_demangle(void __used *v, const char __used *c,
 #endif
 #endif
 
+/*
+ * libelf 0.8.x and earlier do not support ELF_C_READ_MMAP;
+ * for newer versions we can use mmap to reduce memory usage:
+ */
+#ifdef LIBELF_NO_MMAP
+# define PERF_ELF_C_READ_MMAP ELF_C_READ
+#else
+# define PERF_ELF_C_READ_MMAP ELF_C_READ_MMAP
+#endif
+
 #ifndef DMGL_PARAMS
 #define DMGL_PARAMS      (1 << 0)       /* Include function args */
 #define DMGL_ANSI        (1 << 1)       /* Include const, volatile, etc */