2018-07-25 21:09:48

by Brian Brooks

Subject: [PATCH v2 bpf-next] samples/bpf: xdpsock: order memory on AArch64

Define u_smp_rmb() and u_smp_wmb() to respective barrier instructions.
This ensures the processor will order accesses to queue indices against
accesses to queue ring entries.

Signed-off-by: Brian Brooks <[email protected]>
---
samples/bpf/xdpsock_user.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
index 5904b1543831..1e82f7c617c3 100644
--- a/samples/bpf/xdpsock_user.c
+++ b/samples/bpf/xdpsock_user.c
@@ -145,8 +145,13 @@ static void dump_stats(void);
} while (0)

#define barrier() __asm__ __volatile__("": : :"memory")
+#ifdef __aarch64__
+#define u_smp_rmb() __asm__ __volatile__("dmb ishld": : :"memory")
+#define u_smp_wmb() __asm__ __volatile__("dmb ishst": : :"memory")
+#else
#define u_smp_rmb() barrier()
#define u_smp_wmb() barrier()
+#endif
#define likely(x) __builtin_expect(!!(x), 1)
#define unlikely(x) __builtin_expect(!!(x), 0)

--
2.18.0

2018-07-26 12:19:43

by Björn Töpel

Subject: Re: [PATCH v2 bpf-next] samples/bpf: xdpsock: order memory on AArch64

Den ons 25 juli 2018 kl 23:09 skrev Brian Brooks <[email protected]>:
>
> Define u_smp_rmb() and u_smp_wmb() to respective barrier instructions.
> This ensures the processor will order accesses to queue indices against
> accesses to queue ring entries.
>

Thanks Brian!

Acked-by: Björn Töpel <[email protected]>

> Signed-off-by: Brian Brooks <[email protected]>
> ---
> samples/bpf/xdpsock_user.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/samples/bpf/xdpsock_user.c b/samples/bpf/xdpsock_user.c
> index 5904b1543831..1e82f7c617c3 100644
> --- a/samples/bpf/xdpsock_user.c
> +++ b/samples/bpf/xdpsock_user.c
> @@ -145,8 +145,13 @@ static void dump_stats(void);
> } while (0)
>
> #define barrier() __asm__ __volatile__("": : :"memory")
> +#ifdef __aarch64__
> +#define u_smp_rmb() __asm__ __volatile__("dmb ishld": : :"memory")
> +#define u_smp_wmb() __asm__ __volatile__("dmb ishst": : :"memory")
> +#else
> #define u_smp_rmb() barrier()
> #define u_smp_wmb() barrier()
> +#endif
> #define likely(x) __builtin_expect(!!(x), 1)
> #define unlikely(x) __builtin_expect(!!(x), 0)
>
> --
> 2.18.0
>

2018-07-27 01:51:25

by Daniel Borkmann

Subject: Re: [PATCH v2 bpf-next] samples/bpf: xdpsock: order memory on AArch64

On 07/25/2018 11:08 PM, Brian Brooks wrote:
> Define u_smp_rmb() and u_smp_wmb() to respective barrier instructions.
> This ensures the processor will order accesses to queue indices against
> accesses to queue ring entries.
>
> Signed-off-by: Brian Brooks <[email protected]>

Applied to bpf-next, thanks Brian!