From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F3CFAC43381 for ; Thu, 28 Feb 2019 10:57:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CE492218AE for ; Thu, 28 Feb 2019 10:57:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731705AbfB1K5h (ORCPT ); Thu, 28 Feb 2019 05:57:37 -0500 Received: from 59-120-53-16.HINET-IP.hinet.net ([59.120.53.16]:29645 "EHLO ATCSQR.andestech.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727810AbfB1K5e (ORCPT ); Thu, 28 Feb 2019 05:57:34 -0500 Received: from ATCSQR.andestech.com (localhost [127.0.0.2] (may be forged)) by ATCSQR.andestech.com with ESMTP id x1SAVb88086883 for ; Thu, 28 Feb 2019 18:31:37 +0800 (GMT-8) (envelope-from vincentc@andestech.com) Received: from mail.andestech.com (atcpcs16.andestech.com [10.0.1.222]) by ATCSQR.andestech.com with ESMTP id x1SAV3WW086808; Thu, 28 Feb 2019 18:31:03 +0800 (GMT-8) (envelope-from vincentc@andestech.com) Received: from atcsqa06.andestech.com (10.0.15.65) by ATCPCS16.andestech.com (10.0.1.222) with Microsoft SMTP Server id 14.3.123.3; Thu, 28 Feb 2019 18:31:37 +0800 From: Vincent Chen To: , , , , , , CC: , Subject: [PATCH 1/3] riscv: Add the support for c.ebreak check in is_valid_bugaddr() Date: Thu, 28 Feb 2019 18:31:29 +0800 Message-ID: <1551349891-22683-2-git-send-email-vincentc@andestech.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1551349891-22683-1-git-send-email-vincentc@andestech.com> References: <1551349891-22683-1-git-send-email-vincentc@andestech.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.0.15.65] X-DNSRBL: X-MAIL: ATCSQR.andestech.com x1SAV3WW086808 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The is_valid_bugaddr() function compares the instruction pointed to by $sepc with macro __BUG_INSN to check whether the current trap exception is caused by an "ebreak" instruction. Hence the macro __BUG_INSN is defined as "ebreak". However, this check flow is possibly erroneous because the expected trap instruction possibly be translated to "c.ebreak" by assembler if C extension is supported. Therefore, it requires a mechanism to distinguish the length of the instruction in $spec and compare it to the correct __BUG_INSN. By the way, I make the kernel go to die() like BUG() when the trap type is BUG_TRAP_TYPE_WARN because currently the WARN() does not trigger any trap exception. Signed-off-by: Vincent Chen --- arch/riscv/include/asm/bug.h | 7 ++++++- arch/riscv/kernel/traps.c | 8 +++++--- 2 files changed, 11 insertions(+), 4 deletions(-) diff --git a/arch/riscv/include/asm/bug.h b/arch/riscv/include/asm/bug.h index bfc7f09..1cab7f4 100644 --- a/arch/riscv/include/asm/bug.h +++ b/arch/riscv/include/asm/bug.h @@ -21,7 +21,12 @@ #include #ifdef CONFIG_GENERIC_BUG -#define __BUG_INSN _AC(0x00100073, UL) /* ebreak */ +#define __INSN_LENGTH_MASK _UL(0x3) +#define __INSN_LENGTH_32 _UL(0x3) +#define __COMPRESSED_INSN_MASK _UL(0xffff) + +#define __BUG_INSN_32 _UL(0x00100073) /* ebreak */ +#define __BUG_INSN_16 _UL(0x9002) /* c.ebreak */ #ifndef __ASSEMBLY__ typedef u32 bug_insn_t; diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index 24a9333..deae0e5 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -129,8 +129,7 @@ asmlinkage void do_trap_break(struct pt_regs *regs) case BUG_TRAP_TYPE_NONE: break; case BUG_TRAP_TYPE_WARN: - regs->sepc += sizeof(bug_insn_t); - return; + die(regs, "Kernel BUG. Kernel got an unexpected WARN trapped by ebreak"); case BUG_TRAP_TYPE_BUG: die(regs, "Kernel BUG"); } @@ -149,7 +148,10 @@ int is_valid_bugaddr(unsigned long pc) return 0; if (probe_kernel_address((bug_insn_t *)pc, insn)) return 0; - return (insn == __BUG_INSN); + if ((insn & __INSN_LENGTH_MASK) == __INSN_LENGTH_32) + return insn == __BUG_INSN_32; + else + return (insn & __COMPRESSED_INSN_MASK) == __BUG_INSN_16; } #endif /* CONFIG_GENERIC_BUG */ -- 1.7.1