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=-9.8 required=3.0 tests=DATE_IN_FUTURE_06_12, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 D983AC47255 for ; Sat, 9 May 2020 13:49:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3B69218AC for ; Sat, 9 May 2020 13:49:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728073AbgEINt3 (ORCPT ); Sat, 9 May 2020 09:49:29 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:54368 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727834AbgEINt3 (ORCPT ); Sat, 9 May 2020 09:49:29 -0400 Received: from DGGEMS412-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 359F62E12B047D20BB97; Sat, 9 May 2020 21:49:14 +0800 (CST) Received: from euler.huawei.com (10.175.101.6) by DGGEMS412-HUB.china.huawei.com (10.3.19.212) with Microsoft SMTP Server id 14.3.487.0; Sat, 9 May 2020 21:49:09 +0800 From: Wei Li To: , , , , , , , , CC: , , Subject: [PATCH 3/4] arm64: kgdb: Fix single-stepping into the irq handler wrongly Date: Sun, 10 May 2020 05:41:58 +0800 Message-ID: <20200509214159.19680-4-liwei391@huawei.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200509214159.19680-1-liwei391@huawei.com> References: <20200509214159.19680-1-liwei391@huawei.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.101.6] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org After the single-step exception handling oops is fixed, when we execute single-step in kdb/kgdb, we may see it jumps to the irq_handler (where PSTATE.D is cleared) instead of the next instruction. Add the prepare and cleanup work for single-step when enabling and disabling to maintain the PSTATE.I and PSTATE.D carefully. Before this patch: * kdb: Entering kdb (current=0xffff8000119e2dc0, pid 0) on processor 0 due to Keyboard Entry [0]kdb> bp printk Instruction(i) BP #0 at 0xffff8000101486cc (printk) is enabled addr at ffff8000101486cc, hardtype=0 installed=0 [0]kdb> g / # echo h > /proc/sysrq-trigger Entering kdb (current=0xffff0000fada65c0, pid 267) on processor 0 due to Breakpoint @ 0xffff8000101486cc [0]kdb> ss Entering kdb (current=0xffff0000fada65c0, pid 267) on processor 0 due to SS trap @ 0xffff800010082ab8 [0]kdb> 0xffff800010082ab8 0xffff800010082ab8 = 0xffff800010082ab8 (el1_irq+0x78) [0]kdb> 0xffff800010082ab0 <+112>: nop 0xffff800010082ab4 <+116>: msr daifclr, #0xd 0xffff800010082ab8 <+120>: adrp x1, 0xffff8000113a7000 0xffff800010082abc <+124>: ldr x1, [x1, #1408] * kgdb: (gdb) target remote 127.1:23002 Remote debugging using 127.1:23002 arch_kgdb_breakpoint () at /home/liwei/main_code/linux/arch/arm64/include/asm/kgdb.h:21 21 asm ("brk %0" : : "I" (KGDB_COMPILED_DBG_BRK_IMM)); (gdb) b printk Breakpoint 1 at 0xffff8000101486cc: file /home/liwei/main_code/linux/kernel/printk/printk.c, line 2076. (gdb) c Continuing. [New Thread 287] [Switching to Thread 283] Thread 177 hit Breakpoint 1, printk (fmt=0xffff80001130c9d8 "\001\066sysrq: HELP : ") at /home/liwei/main_code/linux/kernel/printk/printk.c:2076 2076 { (gdb) stepi el1_irq () at /home/liwei/main_code/linux/arch/arm64/kernel/entry.S:608 608 irq_handler (gdb) After this patch: * kdb: Entering kdb (current=0xffff8000119d2dc0, pid 0) on processor 0 due to Keyboard Entry [0]kdb> bp printk Instruction(i) BP #0 at 0xffff80001014874c (printk) is enabled addr at ffff80001014874c, hardtype=0 installed=0 [0]kdb> g / # echo h > /proc/sysrq-trigger Entering kdb (current=0xffff0000fa6948c0, pid 265) on processor 0 due to Breakpoint @ 0xffff80001014874c [0]kdb> ss Entering kdb (current=0xffff0000fa6948c0, pid 265) on processor 0 due to SS trap @ 0xffff800010148750 [0]kdb> * kgdb: (gdb) target remote 127.1:23002 Remote debugging using 127.1:23002 arch_kgdb_breakpoint () at /home/liwei/main_code/linux/arch/arm64/include/asm/kgdb.h:21 21 asm ("brk %0" : : "I" (KGDB_COMPILED_DBG_BRK_IMM)); (gdb) b printk Breakpoint 1 at 0xffff80001014874c: file /home/liwei/main_code/linux/kernel/printk/printk.c, line 2076. (gdb) c Continuing. [New Thread 277] [Switching to Thread 276] Thread 171 hit Breakpoint 1, printk (fmt=0xffff8000112fc130 "\001\066sysrq: HELP : ") at /home/liwei/main_code/linux/kernel/printk/printk.c:2076 2076 { (gdb) stepi 0xffff800010148750 2076 { (gdb) Fixes: 44679a4f142b ("arm64: KGDB: Add step debugging support") Signed-off-by: Wei Li --- arch/arm64/kernel/kgdb.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/arch/arm64/kernel/kgdb.c b/arch/arm64/kernel/kgdb.c index 1a157ca33262..3910ac06c261 100644 --- a/arch/arm64/kernel/kgdb.c +++ b/arch/arm64/kernel/kgdb.c @@ -100,6 +100,8 @@ struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { { "fpcr", 4, -1 }, }; +static DEFINE_PER_CPU(unsigned long, kgdb_ss_flags); + char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) { if (regno >= DBG_MAX_REG_NUM || regno < 0) @@ -200,8 +202,11 @@ int kgdb_arch_handle_exception(int exception_vector, int signo, /* * Received continue command, disable single step */ - if (kernel_active_single_step()) + if (kernel_active_single_step()) { + kernel_cleanup_single_step(per_cpu(kgdb_ss_flags, + raw_smp_processor_id()), linux_regs); kernel_disable_single_step(); + } err = 0; break; @@ -221,8 +226,12 @@ int kgdb_arch_handle_exception(int exception_vector, int signo, /* * Enable single step handling */ - if (!kernel_active_single_step()) + if (!kernel_active_single_step()) { + kernel_prepare_single_step(&per_cpu(kgdb_ss_flags, + raw_smp_processor_id()), linux_regs); kernel_enable_single_step(linux_regs); + } + err = 0; break; default: -- 2.17.1