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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: 1cad078842
("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>
This commit is contained in:
parent
a06d729646
commit
b7e3a28019
2 changed files with 29 additions and 3 deletions
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@ -23,6 +23,31 @@ do { \
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#define pr_info(fmt, ...) __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
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#define pr_debug(fmt, ...) __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
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/* Use these barrier functions instead of smp_[rw]mb() when they are
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* used in a libbpf header file. That way they can be built into the
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* application that uses libbpf.
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*/
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#if defined(__i386__) || defined(__x86_64__)
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# define libbpf_smp_rmb() asm volatile("" : : : "memory")
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# define libbpf_smp_wmb() asm volatile("" : : : "memory")
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# define libbpf_smp_mb() \
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asm volatile("lock; addl $0,-4(%%rsp)" : : : "memory", "cc")
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#elif defined(__aarch64__)
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# define libbpf_smp_rmb() asm volatile("dmb ishld" : : : "memory")
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# define libbpf_smp_wmb() asm volatile("dmb ishst" : : : "memory")
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# define libbpf_smp_mb() asm volatile("dmb ish" : : : "memory")
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#elif defined(__arm__)
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/* These are only valid for armv7 and above */
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# define libbpf_smp_rmb() asm volatile("dmb ish" : : : "memory")
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# define libbpf_smp_wmb() asm volatile("dmb ishst" : : : "memory")
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# define libbpf_smp_mb() asm volatile("dmb ish" : : : "memory")
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#else
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# warning Architecture missing native barrier functions in libbpf_util.h.
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# define libbpf_smp_rmb() __sync_synchronize()
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# define libbpf_smp_wmb() __sync_synchronize()
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# define libbpf_smp_mb() __sync_synchronize()
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#endif
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#ifdef __cplusplus
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} /* extern "C" */
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#endif
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@ -16,6 +16,7 @@
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#include <linux/if_xdp.h>
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#include "libbpf.h"
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#include "libbpf_util.h"
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#ifdef __cplusplus
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extern "C" {
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@ -123,7 +124,7 @@ static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, size_t nb)
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/* Make sure everything has been written to the ring before indicating
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* this to the kernel by writing the producer pointer.
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*/
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smp_wmb();
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libbpf_smp_wmb();
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*prod->producer += nb;
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}
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@ -137,7 +138,7 @@ static inline size_t xsk_ring_cons__peek(struct xsk_ring_cons *cons,
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/* Make sure we do not speculatively read the data before
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* we have received the packet buffers from the ring.
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*/
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smp_rmb();
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libbpf_smp_rmb();
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*idx = cons->cached_cons;
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cons->cached_cons += entries;
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@ -151,7 +152,7 @@ static inline void xsk_ring_cons__release(struct xsk_ring_cons *cons, size_t nb)
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/* Make sure data has been read before indicating we are done
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* with the entries by updating the consumer pointer.
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*/
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smp_mb();
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libbpf_smp_mb();
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*cons->consumer += nb;
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}
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