From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:50902 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752587AbeA2UHc (ORCPT ); Mon, 29 Jan 2018 15:07:32 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Russell King Subject: [PATCH 4.14 14/71] ARM: net: bpf: avoid bx instruction on non-Thumb capable CPUs Date: Mon, 29 Jan 2018 13:56:42 +0100 Message-Id: <20180129123828.240787243@linuxfoundation.org> In-Reply-To: <20180129123827.271171825@linuxfoundation.org> References: <20180129123827.271171825@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Russell King commit e9062481824384f00299971f923fecf6b3668001 upstream. Avoid the 'bx' instruction on CPUs that have no support for Thumb and thus do not implement this instruction by moving the generation of this opcode to a separate function that selects between: bx reg and mov pc, reg according to the capabilities of the CPU. Fixes: 39c13c204bb1 ("arm: eBPF JIT compiler") Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- arch/arm/net/bpf_jit_32.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -285,16 +285,20 @@ static inline void emit_mov_i(const u8 r emit_mov_i_no8m(rd, val, ctx); } -static inline void emit_blx_r(u8 tgt_reg, struct jit_ctx *ctx) +static void emit_bx_r(u8 tgt_reg, struct jit_ctx *ctx) { - ctx->seen |= SEEN_CALL; -#if __LINUX_ARM_ARCH__ < 5 - emit(ARM_MOV_R(ARM_LR, ARM_PC), ctx); - if (elf_hwcap & HWCAP_THUMB) emit(ARM_BX(tgt_reg), ctx); else emit(ARM_MOV_R(ARM_PC, tgt_reg), ctx); +} + +static inline void emit_blx_r(u8 tgt_reg, struct jit_ctx *ctx) +{ + ctx->seen |= SEEN_CALL; +#if __LINUX_ARM_ARCH__ < 5 + emit(ARM_MOV_R(ARM_LR, ARM_PC), ctx); + emit_bx_r(tgt_reg, ctx); #else emit(ARM_BLX_R(tgt_reg), ctx); #endif @@ -997,7 +1001,7 @@ static int emit_bpf_tail_call(struct jit emit_a32_mov_i(tmp2[1], off, false, ctx); emit(ARM_LDR_R(tmp[1], tmp[1], tmp2[1]), ctx); emit(ARM_ADD_I(tmp[1], tmp[1], ctx->prologue_bytes), ctx); - emit(ARM_BX(tmp[1]), ctx); + emit_bx_r(tmp[1], ctx); /* out: */ if (out_offset == -1) @@ -1166,7 +1170,7 @@ static void build_epilogue(struct jit_ct emit(ARM_POP(reg_set), ctx); /* Return back to the callee function */ if (!(ctx->seen & SEEN_CALL)) - emit(ARM_BX(ARM_LR), ctx); + emit_bx_r(ARM_LR, ctx); #endif }