From: Andrii Nakryiko <andrii@kernel.org>
To: <bpf@vger.kernel.org>, <ast@kernel.org>, <daniel@iogearbox.net>,
<patrick.mccarty@intel.com>, <msuchanek@suse.de>
Cc: <andrii@kernel.org>, <kernel-team@fb.com>
Subject: [PATCH bpf-next] libbpf: Fix build with latest gcc/binutils with LTO
Date: Tue, 7 Sep 2021 15:10:23 -0700 [thread overview]
Message-ID: <20210907221023.2660953-1-andrii@kernel.org> (raw)
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: Patrick McCarty <patrick.mccarty@intel.com>
Signed-off-by: Patrick McCarty <patrick.mccarty@intel.com>
Co-developed-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
tools/lib/bpf/libbpf_internal.h | 25 +++++++++++++++++++------
tools/lib/bpf/xsk.c | 4 ++--
2 files changed, 21 insertions(+), 8 deletions(-)
diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 533b0211f40a..4f6ff5c23695 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -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
-# define COMPAT_VERSION(internal_name, api_name, version) \
+#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) \
+#define DEFAULT_VERSION(internal_name, api_name, version) \
asm(".symver " #internal_name "," #api_name "@@" #version);
-#else
-# define COMPAT_VERSION(internal_name, api_name, version)
-# define DEFAULT_VERSION(internal_name, api_name, version) \
+
+#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,
diff --git a/tools/lib/bpf/xsk.c b/tools/lib/bpf/xsk.c
index e9b619aa0cdf..a2111696ba91 100644
--- a/tools/lib/bpf/xsk.c
+++ b/tools/lib/bpf/xsk.c
@@ -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)
{
--
2.30.2
reply other threads:[~2021-09-07 22:23 UTC|newest]
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