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* [PATCH] libbpf: Fix build with latest gcc/binutils with LTO
@ 2021-08-27  7:28 Michal Suchanek
  2021-08-27 10:35 ` Michal Suchánek
  0 siblings, 1 reply; 4+ messages in thread
From: Michal Suchanek @ 2021-08-27  7:28 UTC (permalink / raw)
  To: bpf
  Cc: Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko,
	Martin KaFai Lau, Song Liu, Yonghong Song, John Fastabend,
	KP Singh, Björn Töpel, Magnus Karlsson, Jonathan Lemon,
	netdev, linux-kernel, Patrick McCarty, Michal Suchanek

From: Patrick McCarty <patrick.mccarty@intel.com>

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 the `COMPAT_VERSION` and
`DEFAULT_VERSION` macros, which expand to assembler directives.

Fixes: https://github.com/libbpf/libbpf/issues/338
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1863059
Fixes: https://bugzilla.opensuse.org/show_bug.cgi?id=1188749
Signed-off-by: Patrick McCarty <patrick.mccarty@intel.com>
Make the change conditional on GCC version
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
 tools/lib/bpf/libbpf_internal.h | 23 +++++++++++++++++------
 tools/lib/bpf/xsk.c             |  4 ++--
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 016ca7cb4f8a..af0f3fb102c0 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -86,20 +86,31 @@
 	(offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
 #endif
 
+#ifdef __GNUC__
+# if __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)))
+# endif
+#endif
+
+#if !defined(COMPAT_VERSION) || !defined(DEFAULT_VERSION)
 /* 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.
  */
-#ifdef SHARED
-# define COMPAT_VERSION(internal_name, api_name, version) \
+# ifdef 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
+#  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
 #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)
 {
-- 
2.31.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread
* [PATCH] libbpf: Fix build with latest gcc/binutils with LTO
@ 2021-08-27  7:25 Michal Suchanek
  2021-08-30 21:35 ` Andrii Nakryiko
  0 siblings, 1 reply; 4+ messages in thread
From: Michal Suchanek @ 2021-08-27  7:25 UTC (permalink / raw)
  To: bpf
  Cc: Patrick McCarty, Alexei Starovoitov, Daniel Borkmann,
	Andrii Nakryiko, Martin KaFai Lau, Song Liu, Yonghong Song,
	John Fastabend, KP Singh, Björn Töpel, Magnus Karlsson,
	Jonathan Lemon, netdev, linux-kernel, Michal Suchanek

From: Patrick McCarty <patrick.mccarty@intel.com>

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 the `COMPAT_VERSION` and
`DEFAULT_VERSION` macros, which expand to assembler directives.

Fixes: https://github.com/libbpf/libbpf/issues/338
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1863059
Fixes: https://bugzilla.opensuse.org/show_bug.cgi?id=1188749
Signed-off-by: Patrick McCarty <patrick.mccarty@intel.com>
Make the change conditional on GCC version
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
 tools/lib/bpf/libbpf_internal.h | 23 +++++++++++++++++------
 tools/lib/bpf/xsk.c             |  4 ++--
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 016ca7cb4f8a..af0f3fb102c0 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -86,20 +86,31 @@
 	(offsetof(TYPE, FIELD) + sizeof(((TYPE *)0)->FIELD))
 #endif
 
+#ifdef __GNUC__
+# if __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)))
+# endif
+#endif
+
+#if !defined(COMPAT_VERSION) || !defined(DEFAULT_VERSION)
 /* 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.
  */
-#ifdef SHARED
-# define COMPAT_VERSION(internal_name, api_name, version) \
+# ifdef 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
+#  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
 #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)
 {
-- 
2.31.1


^ permalink raw reply related	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2021-08-30 21:35 UTC | newest]

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2021-08-27  7:28 [PATCH] libbpf: Fix build with latest gcc/binutils with LTO Michal Suchanek
2021-08-27 10:35 ` Michal Suchánek
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2021-08-27  7:25 Michal Suchanek
2021-08-30 21:35 ` Andrii Nakryiko

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