From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.loongson.cn (mail.loongson.cn [114.242.206.163]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 107BF2E3383 for ; Mon, 24 Mar 2025 04:31:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=114.242.206.163 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742790710; cv=none; b=Hl7I/1E9cdUwvt00xJYNO2mAu9WB5uKl9sjqL1fFbZHicKdTViTGAbJLqKWqGRnJ4SejFEptfqPLSeEfd+YOPu01vS8sE84h14/5bNDQGHoBQdM6zen8SqJ7AXYvSyzanDTTsuuiiszlCGLlE8Y4lTu3SGw+R7j6mXFYV1hF6m8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742790710; c=relaxed/simple; bh=hxQg9HlwvzfhGni7ezD0U429mcZreD+ANTevvZDApzE=; h=Subject:To:Cc:References:From:Message-ID:Date:MIME-Version: In-Reply-To:Content-Type; b=QmGIU5dc4vF9pXsJG2s0llmbrcmAXk814p7BeLIvaIjfuNp0KDUhw0v+8L9YjKEOTbHzcyOHKDbwa7if+SCWkMgSi787lX4X9Ha/9Mqq58qROGoXov5Xjv9ZLYulSRPAh0LQTDFtX0t4u9FMaS1FZiskvrxen4UpsVqCTrkQeYA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn; spf=pass smtp.mailfrom=loongson.cn; arc=none smtp.client-ip=114.242.206.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=loongson.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=loongson.cn Received: from loongson.cn (unknown [111.9.175.10]) by gateway (Coremail) with SMTP id _____8DxjXIw4OBn4rijAA--.12796S3; Mon, 24 Mar 2025 12:31:44 +0800 (CST) Received: from [10.136.12.26] (unknown [111.9.175.10]) by front1 (Coremail) with SMTP id qMiowMCx_cYs4OBn0ShdAA--.15158S3; Mon, 24 Mar 2025 12:31:42 +0800 (CST) Subject: Re: [PATCH v2] LoongArch: KGDB: Rework arch_kgdb_breakpoint() implementation To: Huacai Chen Cc: WangYuli , kernel@xen0n.name, guanwentao@uniontech.com, wentao@uniontech.com, loongarch@lists.linux.dev, linux-kernel@vger.kernel.org, zhoubinbin@loongson.cn, lihui@loongson.cn, rdunlap@infradead.org, chenhuacai@loongson.cn, zhanjun@uniontech.com, niecheng1@uniontech.com, Tiezhu Yang References: <943E06D656E4E707+20250321141001.109916-1-wangyuli@uniontech.com> <545ed081-bec3-395c-e0dd-a45146e00cd1@loongson.cn> From: Jinyang He Message-ID: <30b25aa7-106f-7ebf-296d-0e05d7da75eb@loongson.cn> Date: Mon, 24 Mar 2025 12:31:40 +0800 User-Agent: Mozilla/5.0 (X11; Linux loongarch64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US X-CM-TRANSID:qMiowMCx_cYs4OBn0ShdAA--.15158S3 X-CM-SenderInfo: pkhmx0p1dqwqxorr0wxvrqhubq/ X-Coremail-Antispam: 1Uk129KBj93XoWxWry7ur13XrW7tw1UXFWfCrX_yoW5KF45pF W8C3WqyF48Jry8CwnxtrWYvr1ayws7Ww1xXan8K34xCa4qq3W3Jr12yFnrua42gr1xKw10 vFyYga4Iq3WUA3XCm3ZEXasCq-sJn29KB7ZKAUJUUUUr529EdanIXcx71UUUUU7KY7ZEXa sCq-sGcSsGvfJ3Ic02F40EFcxC0VAKzVAqx4xG6I80ebIjqfuFe4nvWSU5nxnvy29KBjDU 0xBIdaVrnRJUUUPab4IE77IF4wAFF20E14v26r1j6r4UM7CY07I20VC2zVCF04k26cxKx2 IYs7xG6rWj6s0DM7CIcVAFz4kK6r1Y6r17M28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48v e4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_JFI_Gr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI 0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVCY1x0267AK xVW8Jr0_Cr1UM2kKe7AKxVWUXVWUAwAS0I0E0xvYzxvE52x082IY62kv0487Mc804VCY07 AIYIkI8VC2zVCFFI0UMc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7IYx2IY67AKxVWU XVWUAwAv7VC2z280aVAFwI0_Gr0_Cr1lOx8S6xCaFVCjc4AY6r1j6r4UM4x0Y48IcVAKI4 8JMxk0xIA0c2IEe2xFo4CEbIxvr21lc7CjxVAaw2AFwI0_JF0_Jw1l42xK82IYc2Ij64vI r41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1l4IxYO2xFxVAFwI0_JF0_Jw1lx2IqxVAqx4xG67 AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIY rxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I0E14 v26r1j6r4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWUJVW8 JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxUxUGYDU UUU On 2025-03-24 12:09, Huacai Chen wrote: > Hi, Jinyang, > > On Mon, Mar 24, 2025 at 9:42 AM Jinyang He wrote: >> On 2025-03-22 20:51, Huacai Chen wrote: >> >>> Hi, Tiezhu & Jinyang, >>> >>> On Fri, Mar 21, 2025 at 10:11 PM WangYuli wrote: >>>> The arch_kgdb_breakpoint() function defines the kgdb_breakinst >>>> symbol using inline assembly. >>>> >>>> There's a potential issue where the compiler might inline >>>> arch_kgdb_breakpoint(), which would then define the kgdb_breakinst >>>> symbol multiple times, leading to a linker error. >>>> >>>> To prevent this, declare arch_kgdb_breakpoint() as noline. >>>> >>>> Fix follow error with LLVM-19 *only* when LTO_CLANG_FULL: >>>> LD vmlinux.o >>>> ld.lld-19: error: ld-temp.o :3:1: symbol 'kgdb_breakinst' is already defined >>>> kgdb_breakinst: break 2 >>>> ^ >>>> >>>> Additionally, remove "nop" here because it's meaningless for LoongArch >>>> here. >>>> >>>> Fixes: e14dd076964e ("LoongArch: Add basic KGDB & KDB support") >>>> Co-developed-by: Winston Wen >>>> Signed-off-by: Winston Wen >>>> Co-developed-by: Wentao Guan >>>> Signed-off-by: Wentao Guan >>>> Co-developed-by: Huacai Chen >>>> Signed-off-by: Huacai Chen >>>> Tested-by: Yuli Wang >>>> Tested-by: Binbin Zhou >>>> Signed-off-by: Yuli Wang >>>> --- >>>> Changelog: >>>> *v1->v2: >>>> 1. Drop the nop which is no effect for LoongArch here. >>>> 2. Add "STACK_FRAME_NON_STANDARD" for arch_kgdb_breakpoint() to >>>> avoid the objtool warning. >>>> --- >>>> arch/loongarch/kernel/kgdb.c | 4 ++-- >>>> 1 file changed, 2 insertions(+), 2 deletions(-) >>>> >>>> diff --git a/arch/loongarch/kernel/kgdb.c b/arch/loongarch/kernel/kgdb.c >>>> index 445c452d72a7..38bd0561d7d5 100644 >>>> --- a/arch/loongarch/kernel/kgdb.c >>>> +++ b/arch/loongarch/kernel/kgdb.c >>>> @@ -224,13 +224,13 @@ void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) >>>> regs->csr_era = pc; >>>> } >>>> >>>> -void arch_kgdb_breakpoint(void) >>>> +noinline void arch_kgdb_breakpoint(void) >>>> { >>>> __asm__ __volatile__ ( \ >>>> ".globl kgdb_breakinst\n\t" \ >>>> - "nop\n" \ >>>> "kgdb_breakinst:\tbreak 2\n\t"); /* BRK_KDB = 2 */ >>>> } >>>> +STACK_FRAME_NON_STANDARD(arch_kgdb_breakpoint); >>> Is there a better solution than STACK_FRAME_NON_STANDARD()? In the >>> past we can use annotate_reachable() in arch_kgdb_breakpoint(), but >>> annotate_reachable() is no longer exist. >> Maybe we can parse the imm-code of `break` and set diffrent insn_type in >> objtool. >> The BRK_KDB imply the PC will go head, while the BRK_BUG imply PC stop. >> (arch/loongarch/include/uapi/asm/break.h) >> >> Tiezhu, how do you think? > Touching objtool may be a little complicated, is ANNOTATE_REACHABLE() > the successor of annotate_reachable()? I tried > ANNOTATE_REACHABLE(kgdb_breakinst) but there was still a warning. Should it annotate to the next insn of `break`? Like,     kgdb_breakinst:     break 2     another_label: ANNOTATE_REACHABLE(another_label) Jinyang > > Huacai > >> >>> Huacai >>> >>>> /* >>>> * Calls linux_debug_hook before the kernel dies. If KGDB is enabled, >>>> -- >>>> 2.49.0 >>>>