From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754091AbbFQWnA (ORCPT ); Wed, 17 Jun 2015 18:43:00 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:35833 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751962AbbFQWaf (ORCPT ); Wed, 17 Jun 2015 18:30:35 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Nicolas Schichan , "David S. Miller" , Kamal Mostafa Subject: [PATCH 3.13.y-ckt 079/122] ARM: net fix emit_udiv() for BPF_ALU | BPF_DIV | BPF_K intruction. Date: Wed, 17 Jun 2015 15:28:26 -0700 Message-Id: <1434580149-3095-80-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1434580149-3095-1-git-send-email-kamal@canonical.com> References: <1434580149-3095-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11-ckt22 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicolas Schichan commit 19fc99d0c6ba7d9b65456496b5bb2169d5f74cd0 upstream. In that case, emit_udiv() will be called with rn == ARM_R0 (r_scratch) and loading rm first into ARM_R0 will result in jit_udiv() function being called the same dividend and divisor. Fix that by loading rn first into ARM_R1 and then rm into ARM_R0. Signed-off-by: Nicolas Schichan Fixes: aee636c4809f (bpf: do not use reciprocal divide) Acked-by: Mircea Gherzan Signed-off-by: David S. Miller Signed-off-by: Kamal Mostafa --- arch/arm/net/bpf_jit_32.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index 271b5e9..6adf591 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -449,10 +449,21 @@ static inline void emit_udiv(u8 rd, u8 rm, u8 rn, struct jit_ctx *ctx) return; } #endif - if (rm != ARM_R0) - emit(ARM_MOV_R(ARM_R0, rm), ctx); + + /* + * For BPF_ALU | BPF_DIV | BPF_K instructions, rm is ARM_R4 + * (r_A) and rn is ARM_R0 (r_scratch) so load rn first into + * ARM_R1 to avoid accidentally overwriting ARM_R0 with rm + * before using it as a source for ARM_R1. + * + * For BPF_ALU | BPF_DIV | BPF_X rm is ARM_R4 (r_A) and rn is + * ARM_R5 (r_X) so there is no particular register overlap + * issues. + */ if (rn != ARM_R1) emit(ARM_MOV_R(ARM_R1, rn), ctx); + if (rm != ARM_R0) + emit(ARM_MOV_R(ARM_R0, rm), ctx); ctx->seen |= SEEN_CALL; emit_mov_i(ARM_R3, (u32)jit_udiv, ctx); -- 1.9.1