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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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6
tools/lib/bpf/Makefile
View File

@@ -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
View File

@@ -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) {