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| author |   Magnus Karlsson <magnus.karlsson@intel.com> | 2019-04-16 14:58:11 +0200 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2019-04-16 20:13:10 -0700 |
| commit | b7e3a28019c92ffe1f55de278c5641de33b6259a (patch) | |
| tree | 5182b3b6a640803c871995f07040247bd3d6f4b0 /tools/lib/bpf/libbpf_util.h | |
| parent | libbpf: remove likely/unlikely in xsk.h (diff) | |
| download | linux-dev-b7e3a28019c92ffe1f55de278c5641de33b6259a.tar.xz linux-dev-b7e3a28019c92ffe1f55de278c5641de33b6259a.zip | |
libbpf: remove dependency on barrier.h in xsk.h
The use of smp_rmb() and smp_wmb() creates a Linux header dependency
on barrier.h that is unnecessary in most parts. This patch implements
the two small defines that are needed from barrier.h. As a bonus, the
new implementations are faster than the default ones as they default
to sfence and lfence for x86, while we only need a compiler barrier in
our case. Just as it is when the same ring access code is compiled in
the kernel.
Fixes: 1cad07884239 ("libbpf: add support for using AF_XDP sockets")
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/lib/bpf/libbpf_util.h')
| -rw-r--r-- | tools/lib/bpf/libbpf_util.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/tools/lib/bpf/libbpf_util.h b/tools/lib/bpf/libbpf_util.h index 81ecda0cb9c9..71fbb2898b87 100644 --- a/tools/lib/bpf/libbpf_util.h +++ b/tools/lib/bpf/libbpf_util.h @@ -23,6 +23,31 @@ do { \ #define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__) #define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__) +/* Use these barrier functions instead of smp_[rw]mb() when they are + * used in a libbpf header file. That way they can be built into the + * application that uses libbpf. + */ +#if defined(__i386__) || defined(__x86_64__) +# define libbpf_smp_rmb() asm volatile("" : : : "memory") +# define libbpf_smp_wmb() asm volatile("" : : : "memory") +# define libbpf_smp_mb() \ + asm volatile("lock; addl $0,-4(%%rsp)" : : : "memory", "cc") +#elif defined(__aarch64__) +# define libbpf_smp_rmb() asm volatile("dmb ishld" : : : "memory") +# define libbpf_smp_wmb() asm volatile("dmb ishst" : : : "memory") +# define libbpf_smp_mb() asm volatile("dmb ish" : : : "memory") +#elif defined(__arm__) +/* These are only valid for armv7 and above */ +# define libbpf_smp_rmb() asm volatile("dmb ish" : : : "memory") +# define libbpf_smp_wmb() asm volatile("dmb ishst" : : : "memory") +# define libbpf_smp_mb() asm volatile("dmb ish" : : : "memory") +#else +# warning Architecture missing native barrier functions in libbpf_util.h. +# define libbpf_smp_rmb() __sync_synchronize() +# define libbpf_smp_wmb() __sync_synchronize() +# define libbpf_smp_mb() __sync_synchronize() +#endif + #ifdef __cplusplus } /* extern "C" */ #endif |