From: Daniel Borkmann <daniel@iogearbox.net>
Date: Mon, 14 May 2018 21:22:31 +0000 (+0200)
Subject: bpf, arm64: save 4 bytes of unneeded stack space
X-Git-Tag: v5.15~8692^2~223^2~9^2~3
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=09ece3d0f2ee524b8d1d3c775d9eeb50c40558d8;p=mirror_ubuntu-kernels.git

bpf, arm64: save 4 bytes of unneeded stack space

Follow-up to 816d9ef32a8b ("bpf, arm64: remove ld_abs/ld_ind") in
that the extra 4 byte JIT scratchpad is not needed anymore since it
was in ld_abs/ld_ind as stack buffer for bpf_load_pointer().

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index 0b40c8fb0706..85113cab2046 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -21,7 +21,6 @@
 #include <linux/bpf.h>
 #include <linux/filter.h>
 #include <linux/printk.h>
-#include <linux/skbuff.h>
 #include <linux/slab.h>
 
 #include <asm/byteorder.h>
@@ -188,7 +187,7 @@ static int build_prologue(struct jit_ctx *ctx)
 	 *                        | ... | BPF prog stack
 	 *                        |     |
 	 *                        +-----+ <= (BPF_FP - prog->aux->stack_depth)
-	 *                        |RSVD | JIT scratchpad
+	 *                        |RSVD | padding
 	 * current A64_SP =>      +-----+ <= (BPF_FP - ctx->stack_size)
 	 *                        |     |
 	 *                        | ... | Function call stack
@@ -220,9 +219,7 @@ static int build_prologue(struct jit_ctx *ctx)
 		return -1;
 	}
 
-	/* 4 byte extra for skb_copy_bits buffer */
-	ctx->stack_size = prog->aux->stack_depth + 4;
-	ctx->stack_size = STACK_ALIGN(ctx->stack_size);
+	ctx->stack_size = STACK_ALIGN(prog->aux->stack_depth);
 
 	/* Set up function call stack */
 	emit(A64_SUB_I(1, A64_SP, A64_SP, ctx->stack_size), ctx);