Commit 006a5099 authored by Andrii Nakryiko's avatar Andrii Nakryiko Committed by Alexei Starovoitov
Browse files

libbpf: Fix build with latest gcc/binutils with LTO 

After updating to binutils 2.35, the build began to fail with an
assembler error. A bug was opened on the Red Hat Bugzilla a few days
later for the same issue.

Work around the problem by using the new `symver` attribute (introduced
in GCC 10) as needed instead of assembler directives.

This addresses Red Hat ([0]) and OpenSUSE ([1]) bug reports, as well as libbpf
issue ([2]).

  [0]: https://bugzilla.redhat.com/show_bug.cgi?id=1863059
  [1]: https://bugzilla.opensuse.org/show_bug.cgi?id=1188749
  [2]: Closes: https://github.com/libbpf/libbpf/issues/338



Co-developed-by: default avatarPatrick McCarty <patrick.mccarty@intel.com>
Co-developed-by: default avatarMichal Suchanek <msuchanek@suse.de>
Signed-off-by: default avatarPatrick McCarty <patrick.mccarty@intel.com>
Signed-off-by: default avatarMichal Suchanek <msuchanek@suse.de>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210907221023.2660953-1-andrii@kernel.org
parent d6be5947

tools/lib/bpf/libbpf_internal.h

+19 −6
Original line number Diff line number Diff line
@@ -90,17 +90,30 @@ 
/* Symbol versioning is different between static and shared library.

 * Properly versioned symbols are needed for shared library, but

 * only the symbol of the new version is needed for static library.

 * Starting with GNU C 10, use symver attribute instead of .symver assembler

 * directive, which works better with GCC LTO builds.

 */

#ifdef SHARED

#if defined(SHARED) && defined(__GNUC__) && __GNUC__ >= 10



#define DEFAULT_VERSION(internal_name, api_name, version) \

	__attribute__((symver(#api_name "@@" #version)))

#define COMPAT_VERSION(internal_name, api_name, version) \

	__attribute__((symver(#api_name "@" #version)))



#elif defined(SHARED)



#define COMPAT_VERSION(internal_name, api_name, version) \

	asm(".symver " #internal_name "," #api_name "@" #version);

#define DEFAULT_VERSION(internal_name, api_name, version) \

	asm(".symver " #internal_name "," #api_name "@@" #version);

#else



#else /* !SHARED */



#define COMPAT_VERSION(internal_name, api_name, version)

#define DEFAULT_VERSION(internal_name, api_name, version) \

	extern typeof(internal_name) api_name \

	__attribute__((alias(#internal_name)));



#endif



extern void libbpf_print(enum libbpf_print_level level,

tools/lib/bpf/xsk.c

+2 −2
Original line number Diff line number Diff line
@@ -281,6 +281,7 @@ static int xsk_create_umem_rings(struct xsk_umem *umem, int fd, 
	return err;

}



DEFAULT_VERSION(xsk_umem__create_v0_0_4, xsk_umem__create, LIBBPF_0.0.4)

int xsk_umem__create_v0_0_4(struct xsk_umem **umem_ptr, void *umem_area,

			    __u64 size, struct xsk_ring_prod *fill,

			    struct xsk_ring_cons *comp,
@@ -345,6 +346,7 @@ struct xsk_umem_config_v1 { 
	__u32 frame_headroom;

};



COMPAT_VERSION(xsk_umem__create_v0_0_2, xsk_umem__create, LIBBPF_0.0.2)

int xsk_umem__create_v0_0_2(struct xsk_umem **umem_ptr, void *umem_area,

			    __u64 size, struct xsk_ring_prod *fill,

			    struct xsk_ring_cons *comp,
@@ -358,8 +360,6 @@ int xsk_umem__create_v0_0_2(struct xsk_umem **umem_ptr, void *umem_area, 
	return xsk_umem__create_v0_0_4(umem_ptr, umem_area, size, fill, comp,

					&config);

}

COMPAT_VERSION(xsk_umem__create_v0_0_2, xsk_umem__create, LIBBPF_0.0.2)

DEFAULT_VERSION(xsk_umem__create_v0_0_4, xsk_umem__create, LIBBPF_0.0.4)



static enum xsk_prog get_xsk_prog(void)

{