netdev - [PATCH bpf-next 4/6] bpf, arm32: save 4 bytes of unneeded stack space

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Date:   Mon, 14 May 2018 02:26:10 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     alexei.starovoitov@...il.com
Cc:     netdev@...r.kernel.org, Daniel Borkmann <daniel@...earbox.net>
Subject: [PATCH bpf-next 4/6] bpf, arm32: save 4 bytes of unneeded stack space

The extra skb_copy_bits() buffer is not used anymore, therefore
remove the extra 4 byte stack space requirement.

Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
---
 arch/arm/net/bpf_jit_32.c | 13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c
index 82689b9..d3ea645 100644
--- a/arch/arm/net/bpf_jit_32.c
+++ b/arch/arm/net/bpf_jit_32.c
@@ -234,18 +234,11 @@ static void jit_fill_hole(void *area, unsigned int size)
 #define SCRATCH_SIZE 80
 
 /* total stack size used in JITed code */
-#define _STACK_SIZE \
-	(ctx->prog->aux->stack_depth + \
-	 + SCRATCH_SIZE + \
-	 + 4 /* extra for skb_copy_bits buffer */)
-
-#define STACK_SIZE ALIGN(_STACK_SIZE, STACK_ALIGNMENT)
+#define _STACK_SIZE	(ctx->prog->aux->stack_depth + SCRATCH_SIZE)
+#define STACK_SIZE	ALIGN(_STACK_SIZE, STACK_ALIGNMENT)
 
 /* Get the offset of eBPF REGISTERs stored on scratch space. */
-#define STACK_VAR(off) (STACK_SIZE-off-4)
-
-/* Offset of skb_copy_bits buffer */
-#define SKB_BUFFER STACK_VAR(SCRATCH_SIZE)
+#define STACK_VAR(off) (STACK_SIZE - off)
 
 #if __LINUX_ARM_ARCH__ < 7
 
-- 
2.9.5