From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:44434 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754628AbeA2UQm (ORCPT ); Mon, 29 Jan 2018 15:16:42 -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 18/71] ARM: net: bpf: correct stack layout documentation Date: Mon, 29 Jan 2018 13:56:46 +0100 Message-Id: <20180129123828.532416909@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 0005e55a79cfda88199e41a406a829c88d708c67 upstream. The stack layout documentation incorrectly suggests that the BPF JIT scratch space starts immediately below BPF_FP. This is not correct, so let's fix the documentation to reflect reality. Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- arch/arm/net/bpf_jit_32.c | 35 +++++++++++++++++++++++++++-------- 1 file changed, 27 insertions(+), 8 deletions(-) --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -28,24 +28,43 @@ int bpf_jit_enable __read_mostly; /* - * eBPF prog stack layout + * eBPF prog stack layout: * * high - * original ARM_SP => +-----+ eBPF prologue - * |FP/LR| - * current ARM_FP => +-----+ - * | ... | callee saved registers - * eBPF fp register => +-----+ <= (BPF_FP) + * original ARM_SP => +-----+ + * | | callee saved registers + * +-----+ <= (BPF_FP + SCRATCH_SIZE) * | ... | eBPF JIT scratch space - * | | eBPF prog stack + * eBPF fp register => +-----+ + * (BPF_FP) | ... | eBPF prog stack * +-----+ * |RSVD | JIT scratchpad - * current ARM_SP => +-----+ <= (BPF_FP - STACK_SIZE) + * current ARM_SP => +-----+ <= (BPF_FP - STACK_SIZE + SCRATCH_SIZE) * | | * | ... | Function call stack * | | * +-----+ * low + * + * The callee saved registers depends on whether frame pointers are enabled. + * With frame pointers (to be compliant with the ABI): + * + * high + * original ARM_SP => +------------------+ \ + * | pc | | + * current ARM_FP => +------------------+ } callee saved registers + * |r4-r8,r10,fp,ip,lr| | + * +------------------+ / + * low + * + * Without frame pointers: + * + * high + * original ARM_SP => +------------------+ + * | lr | (optional) + * | r4-r8,r10 | callee saved registers + * +------------------+ + * low */ #define STACK_OFFSET(k) (k)