[PATCH bpf-next] samples/bpf: add BPF_ATOMIC_OP macro for BPF samples

From: Björn Töpel <redacted>

Brendan Jackman added extend atomic operations to the BPF instruction
set in commit 7064a7341a0d ("Merge branch 'Atomics for eBPF'"), which
introduces the BPF_ATOMIC_OP macro. However, that macro was missing
for the BPF samples. Fix that by adding it into bpf_insn.h.

Signed-off-by: Björn Töpel <redacted>
---
 samples/bpf/bpf_insn.h | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/samples/bpf/bpf_insn.h b/samples/bpf/bpf_insn.h
index db67a2847395..aee04534483a 100644
--- a/samples/bpf/bpf_insn.h
+++ b/samples/bpf/bpf_insn.h

@@ -134,15 +134,31 @@ struct bpf_insn;
 		.off   = OFF,					\
 		.imm   = 0 })
 
-/* Atomic memory add, *(uint *)(dst_reg + off16) += src_reg */
-
-#define BPF_STX_XADD(SIZE, DST, SRC, OFF)			\
+/*
+ * Atomic operations:
+ *
+ *   BPF_ADD                  *(uint *) (dst_reg + off16) += src_reg
+ *   BPF_AND                  *(uint *) (dst_reg + off16) &= src_reg
+ *   BPF_OR                   *(uint *) (dst_reg + off16) |= src_reg
+ *   BPF_XOR                  *(uint *) (dst_reg + off16) ^= src_reg
+ *   BPF_ADD | BPF_FETCH      src_reg = atomic_fetch_add(dst_reg + off16, src_reg);
+ *   BPF_AND | BPF_FETCH      src_reg = atomic_fetch_and(dst_reg + off16, src_reg);
+ *   BPF_OR | BPF_FETCH       src_reg = atomic_fetch_or(dst_reg + off16, src_reg);
+ *   BPF_XOR | BPF_FETCH      src_reg = atomic_fetch_xor(dst_reg + off16, src_reg);
+ *   BPF_XCHG                 src_reg = atomic_xchg(dst_reg + off16, src_reg)
+ *   BPF_CMPXCHG              r0 = atomic_cmpxchg(dst_reg + off16, r0, src_reg)
+ */
+
+#define BPF_ATOMIC_OP(SIZE, OP, DST, SRC, OFF)			\
 	((struct bpf_insn) {					\
 		.code  = BPF_STX | BPF_SIZE(SIZE) | BPF_ATOMIC,	\
 		.dst_reg = DST,					\
 		.src_reg = SRC,					\
 		.off   = OFF,					\
-		.imm   = BPF_ADD })
+		.imm   = OP })
+
+/* Legacy alias */
+#define BPF_STX_XADD(SIZE, DST, SRC, OFF) BPF_ATOMIC_OP(SIZE, BPF_ADD, DST, SRC, OFF)
 
 /* Memory store, *(uint *) (dst_reg + off16) = imm32 */
 

base-commit: 232164e041e925a920bfd28e63d5233cfad90b73
-- 
2.27.0

I actually deliberately skipped this file, thinking that people were
unlikely to want to add assembly-based atomics code under samples/

I guess it's nice for people to be able to e.g. move/copy code from
the selftests.

On Mon, 18 Jan 2021 at 10:18, Björn Töpel [off-list ref] wrote:

From: Björn Töpel <redacted>

Brendan Jackman added extend atomic operations to the BPF instruction
set in commit 7064a7341a0d ("Merge branch 'Atomics for eBPF'"), which
introduces the BPF_ATOMIC_OP macro. However, that macro was missing
for the BPF samples. Fix that by adding it into bpf_insn.h.

Signed-off-by: Björn Töpel <redacted>

Reviewed-by: Brendan Jackman <redacted>

On 2021-01-18 11:57, Brendan Jackman wrote:

I actually deliberately skipped this file, thinking that people were
unlikely to want to add assembly-based atomics code under samples/

I guess it's nice for people to be able to e.g. move/copy code from
the selftests.

Yes, that, and the fact that one sample broke w/o the BPF_ATOMIC_OP.

On Mon, 18 Jan 2021 at 10:18, Björn Töpel [off-list ref] wrote:

quoted

From: Björn Töpel <redacted>

Brendan Jackman added extend atomic operations to the BPF instruction
set in commit 7064a7341a0d ("Merge branch 'Atomics for eBPF'"), which
introduces the BPF_ATOMIC_OP macro. However, that macro was missing
for the BPF samples. Fix that by adding it into bpf_insn.h.

Signed-off-by: Björn Töpel <redacted>

Reviewed-by: Brendan Jackman <redacted>

Thanks!
Björn

Hello:

This patch was applied to bpf/bpf-next.git (refs/heads/master):

On Mon, 18 Jan 2021 10:17:53 +0100 you wrote:

From: Björn Töpel <redacted>

Brendan Jackman added extend atomic operations to the BPF instruction
set in commit 7064a7341a0d ("Merge branch 'Atomics for eBPF'"), which
introduces the BPF_ATOMIC_OP macro. However, that macro was missing
for the BPF samples. Fix that by adding it into bpf_insn.h.

[...]

Here is the summary with links:
  - [bpf-next] samples/bpf: add BPF_ATOMIC_OP macro for BPF samples
    https://git.kernel.org/bpf/bpf-next/c/af6953b633b3

You are awesome, thank you!
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