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Message-ID: <20200818215908.2746786-5-andriin@fb.com>
Date: Tue, 18 Aug 2020 14:59:08 -0700
From: Andrii Nakryiko <andriin@...com>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>, <ast@...com>,
<daniel@...earbox.net>
CC: <andrii.nakryiko@...il.com>, <kernel-team@...com>,
Andrii Nakryiko <andriin@...com>
Subject: [PATCH bpf-next 4/4] tools: remove feature-libelf-mmap feature detection
It's trivial to handle missing ELF_C_MMAP_READ support in libelf the way that
objtool has solved it in
("774bec3fddcc objtool: Add fallback from ELF_C_READ_MMAP to ELF_C_READ").
So instead of having an entire feature detector for that, just do what objtool
does for perf and libbpf. And keep their Makefiles a bit simpler.
Signed-off-by: Andrii Nakryiko <andriin@...com>
---
tools/build/Makefile.feature | 1 -
tools/build/feature/Makefile | 4 ----
tools/build/feature/test-all.c | 4 ----
tools/build/feature/test-libelf-mmap.c | 9 ---------
tools/lib/bpf/Makefile | 6 +-----
tools/lib/bpf/libbpf.c | 14 ++++++--------
tools/perf/Makefile.config | 4 ----
tools/perf/util/symbol.h | 2 +-
8 files changed, 8 insertions(+), 36 deletions(-)
delete mode 100644 tools/build/feature/test-libelf-mmap.c
diff --git a/tools/build/Makefile.feature b/tools/build/Makefile.feature
index c1daf4d57518..38415d251075 100644
--- a/tools/build/Makefile.feature
+++ b/tools/build/Makefile.feature
@@ -46,7 +46,6 @@ FEATURE_TESTS_BASIC := \
libelf-getphdrnum \
libelf-gelf_getnote \
libelf-getshdrstrndx \
- libelf-mmap \
libnuma \
numa_num_possible_cpus \
libperl \
diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile
index d220fe952747..b2a2347c67ed 100644
--- a/tools/build/feature/Makefile
+++ b/tools/build/feature/Makefile
@@ -25,7 +25,6 @@ FILES= \
test-libelf-getphdrnum.bin \
test-libelf-gelf_getnote.bin \
test-libelf-getshdrstrndx.bin \
- test-libelf-mmap.bin \
test-libdebuginfod.bin \
test-libnuma.bin \
test-numa_num_possible_cpus.bin \
@@ -146,9 +145,6 @@ $(OUTPUT)test-dwarf.bin:
$(OUTPUT)test-dwarf_getlocations.bin:
$(BUILD) $(DWARFLIBS)
-$(OUTPUT)test-libelf-mmap.bin:
- $(BUILD) -lelf
-
$(OUTPUT)test-libelf-getphdrnum.bin:
$(BUILD) -lelf
diff --git a/tools/build/feature/test-all.c b/tools/build/feature/test-all.c
index 5479e543b194..5284e6e9c756 100644
--- a/tools/build/feature/test-all.c
+++ b/tools/build/feature/test-all.c
@@ -30,10 +30,6 @@
# include "test-libelf.c"
#undef main
-#define main main_test_libelf_mmap
-# include "test-libelf-mmap.c"
-#undef main
-
#define main main_test_get_current_dir_name
# include "test-get_current_dir_name.c"
#undef main
diff --git a/tools/build/feature/test-libelf-mmap.c b/tools/build/feature/test-libelf-mmap.c
deleted file mode 100644
index 2c3ef81affe2..000000000000
--- a/tools/build/feature/test-libelf-mmap.c
+++ /dev/null
@@ -1,9 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0
-#include <libelf.h>
-
-int main(void)
-{
- Elf *elf = elf_begin(0, ELF_C_READ_MMAP, 0);
-
- return (long)elf;
-}
diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 99796cfc1b9b..eb193bdf43f9 100644
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -56,7 +56,7 @@ ifndef VERBOSE
endif
FEATURE_USER = .libbpf
-FEATURE_TESTS = libelf libelf-mmap zlib bpf
+FEATURE_TESTS = libelf zlib bpf
FEATURE_DISPLAY = libelf zlib bpf
INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi
@@ -98,10 +98,6 @@ else
CFLAGS := -g -Wall
endif
-ifeq ($(feature-libelf-mmap), 1)
- override CFLAGS += -DHAVE_LIBELF_MMAP_SUPPORT
-endif
-
# Append required CFLAGS
override CFLAGS += $(EXTRA_WARNINGS)
override CFLAGS += -Werror -Wall
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index f3f4963d6ba4..78d883c5a8f7 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -150,12 +150,6 @@ static void pr_perm_msg(int err)
___err; })
#endif
-#ifdef HAVE_LIBELF_MMAP_SUPPORT
-# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ_MMAP
-#else
-# define LIBBPF_ELF_C_READ_MMAP ELF_C_READ
-#endif
-
static inline __u64 ptr_to_u64(const void *ptr)
{
return (__u64) (unsigned long) ptr;
@@ -1062,6 +1056,11 @@ static void bpf_object__elf_finish(struct bpf_object *obj)
obj->efile.obj_buf_sz = 0;
}
+/* if libelf is old and doesn't support mmap(), fall back to read() */
+#ifndef ELF_C_READ_MMAP
+#define ELF_C_READ_MMAP ELF_C_READ
+#endif
+
static int bpf_object__elf_init(struct bpf_object *obj)
{
int err = 0;
@@ -1090,8 +1089,7 @@ static int bpf_object__elf_init(struct bpf_object *obj)
return err;
}
- obj->efile.elf = elf_begin(obj->efile.fd,
- LIBBPF_ELF_C_READ_MMAP, NULL);
+ obj->efile.elf = elf_begin(obj->efile.fd, ELF_C_READ_MMAP, NULL);
}
if (!obj->efile.elf) {
diff --git a/tools/perf/Makefile.config b/tools/perf/Makefile.config
index 190be4fa5c21..81bb099f6f06 100644
--- a/tools/perf/Makefile.config
+++ b/tools/perf/Makefile.config
@@ -483,10 +483,6 @@ ifndef NO_LIBELF
EXTLIBS += -lelf
$(call detected,CONFIG_LIBELF)
- ifeq ($(feature-libelf-mmap), 1)
- CFLAGS += -DHAVE_LIBELF_MMAP_SUPPORT
- endif
-
ifeq ($(feature-libelf-getphdrnum), 1)
CFLAGS += -DHAVE_ELF_GETPHDRNUM_SUPPORT
endif
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index ff4f4c47e148..03e264a27cd3 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -28,7 +28,7 @@ struct option;
* 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 HAVE_LIBELF_MMAP_SUPPORT
+#ifdef ELF_C_READ_MMAP
# define PERF_ELF_C_READ_MMAP ELF_C_READ_MMAP
#else
# define PERF_ELF_C_READ_MMAP ELF_C_READ
--
2.24.1
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