From: Yang Shi <yang.shi@linaro.org>
Date: Thu, 12 Nov 2015 21:57:00 +0000 (-0800)
Subject: arm64: bpf: fix JIT frame pointer setup
X-Git-Tag: v4.4-rc2~28^2~39
X-Git-Url: http://git.cascardo.eti.br/?a=commitdiff_plain;h=0fcd593b943bfcc21ad84d3321422401de071d8a;p=cascardo%2Flinux.git

arm64: bpf: fix JIT frame pointer setup

BPF fp should point to the top of the BPF prog stack. The original
implementation made it point to the bottom incorrectly.
Move A64_SP to fp before reserve BPF prog stack space.

CC: Zi Shen Lim <zlim.lnx@gmail.com>
CC: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Reviewed-by: Zi Shen Lim <zlim.lnx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index a44e5293c6f5..ac8b548ce493 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -161,12 +161,12 @@ static void build_prologue(struct jit_ctx *ctx)
 	if (ctx->tmp_used)
 		emit(A64_PUSH(tmp1, tmp2, A64_SP), ctx);
 
-	/* Set up BPF stack */
-	emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
-
 	/* Set up frame pointer */
 	emit(A64_MOV(1, fp, A64_SP), ctx);
 
+	/* Set up BPF stack */
+	emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
+
 	/* Clear registers A and X */
 	emit_a64_mov_i64(ra, 0, ctx);
 	emit_a64_mov_i64(rx, 0, ctx);