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tools: Remove feature-libelf-mmap feature detection

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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@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-5-andriin@fb.com
This commit is contained in:
Andrii Nakryiko 2020-08-18 18:36:07 -07:00 committed by Alexei Starovoitov
parent 85367030a6
commit 22dd1ac91a
8 changed files with 8 additions and 36 deletions
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1
tools/build/Makefile.feature
View File

@ -46,7 +46,6 @@ FEATURE_TESTS_BASIC := \
libelf-getphdrnum \
libelf-gelf_getnote \
libelf-getshdrstrndx \
libelf-mmap \
libnuma \
numa_num_possible_cpus \
libperl \

4
tools/build/feature/Makefile
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@ -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

4
tools/build/feature/test-all.c
View File

@ -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

9
tools/build/feature/test-libelf-mmap.c
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@ -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;
}

6
tools/lib/bpf/Makefile
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@ -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) -Wno-switch-enum
override CFLAGS += -Werror -Wall

14
tools/lib/bpf/libbpf.c
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@ -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;
@ -1064,6 +1058,11 @@ 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;
@ -1092,8 +1091,7 @@ 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) {

4
tools/perf/Makefile.config
View File

@ -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

2
tools/perf/util/symbol.h
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@ -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