From: Magnus Karlsson <magnus.karlsson@intel.com>
To: magnus.karlsson@intel.com, bjorn.topel@intel.com, ast@kernel.org,
daniel@iogearbox.net, netdev@vger.kernel.org
Cc: bpf@vger.kernel.org, bruce.richardson@intel.com,
ciara.loftus@intel.com, ilias.apalodimas@linaro.org,
xiaolong.ye@intel.com, ferruh.yigit@intel.com,
qi.z.zhang@intel.com, georgmueller@gmx.net
Subject: [PATCH bpf 2/2] libbpf: remove dependency on barrier.h in xsk.h
Date: Tue, 9 Apr 2019 08:44:13 +0200 [thread overview]
Message-ID: <1554792253-27081-3-git-send-email-magnus.karlsson@intel.com> (raw)
In-Reply-To: <1554792253-27081-1-git-send-email-magnus.karlsson@intel.com>
The use of smp_rmb() and smp_wmb() creates a Linux header dependency
on barrier.h that is uneccessary 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>
---
tools/lib/bpf/xsk.h | 19 +++++++++++++++++--
1 file changed, 17 insertions(+), 2 deletions(-)
diff --git a/tools/lib/bpf/xsk.h b/tools/lib/bpf/xsk.h
index 3638147..317b44f 100644
--- a/tools/lib/bpf/xsk.h
+++ b/tools/lib/bpf/xsk.h
@@ -39,6 +39,21 @@ DEFINE_XSK_RING(xsk_ring_cons);
struct xsk_umem;
struct xsk_socket;
+#if !defined bpf_smp_rmb && !defined bpf_smp_wmb
+# if defined(__i386__) || defined(__x86_64__)
+# define bpf_smp_rmb() asm volatile("" : : : "memory")
+# define bpf_smp_wmb() asm volatile("" : : : "memory")
+# elif defined(__aarch64__)
+# define bpf_smp_rmb() asm volatile("dmb ishld" : : : "memory")
+# define bpf_smp_wmb() asm volatile("dmb ishst" : : : "memory")
+# elif defined(__arm__)
+# define bpf_smp_rmb() asm volatile("dmb ish" : : : "memory")
+# define bpf_smp_wmb() asm volatile("dmb ishst" : : : "memory")
+# else
+# error Architecture not supported by the XDP socket code in libbpf.
+# endif
+#endif
+
static inline __u64 *xsk_ring_prod__fill_addr(struct xsk_ring_prod *fill,
__u32 idx)
{
@@ -119,7 +134,7 @@ static inline void xsk_ring_prod__submit(struct xsk_ring_prod *prod, size_t nb)
/* Make sure everything has been written to the ring before signalling
* this to the kernel.
*/
- smp_wmb();
+ bpf_smp_wmb();
*prod->producer += nb;
}
@@ -133,7 +148,7 @@ static inline size_t xsk_ring_cons__peek(struct xsk_ring_cons *cons,
/* Make sure we do not speculatively read the data before
* we have received the packet buffers from the ring.
*/
- smp_rmb();
+ bpf_smp_rmb();
*idx = cons->cached_cons;
cons->cached_cons += entries;
--
2.7.4
next prev parent reply other threads:[~2019-04-09 6:44 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-09 6:44 [PATCH bpf 0/2] libbpf: remove two dependencies on Linux kernel headers and improve performance as a bonus Magnus Karlsson
2019-04-09 6:44 ` [PATCH bpf 1/2] libbpf: remove likely/unlikely in xsk.h Magnus Karlsson
2019-04-09 6:44 ` Magnus Karlsson [this message]
2019-04-09 9:10 ` [PATCH bpf 2/2] libbpf: remove dependency on barrier.h " Daniel Borkmann
2019-04-09 11:29 ` Magnus Karlsson
2019-04-09 22:28 ` Georg Müller
2019-04-09 22:46 ` Daniel Borkmann
2019-09-04 5:32 ` Yauheni Kaliuta
2019-09-04 6:39 ` Magnus Karlsson
2019-09-04 6:56 ` Yauheni Kaliuta
2019-09-04 10:25 ` Magnus Karlsson
2019-09-04 12:19 ` Yauheni Kaliuta
2019-09-04 12:21 ` Magnus Karlsson
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