From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 30D29DDA6 for ; Tue, 20 Aug 2024 02:42:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.255 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724121735; cv=none; b=O+fG2qV68RHZEJTLROHrvWTsgDyfMPudxVL8dZXfW5EdvTMi8RreFdE7uJKschNWMkcq+o/ixhy2RRiog4bV9eMAh8EDaEDaWBzPYkpr21BJUttF73LP2u7C94gDShAfvnePhutExHw7B31xP3tsEOnEcV88uhWSuGLtsEysrjQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724121735; c=relaxed/simple; bh=lEG2Ze+wSXd5onXixxVibMXfauGoTixD//TQtTVyirA=; h=Message-ID:Date:MIME-Version:Subject:To:References:From: In-Reply-To:Content-Type; b=Co96wUcY0ZexQQAZDGcBDdgkRmFWZasYdYkAZuwBGpASZZGbMGngacXbhog0/t0v485MhfYZDoZ38KJ76pgnN8L+780fQfvQ4gkZzmpCIUGfi2QqTRBu93BQNVhOvI5lp3vtZpneWX7IEJ0BYsVWk5td65hdmjMR+b/HZz2hxBY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.255 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.105]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4WntyM3TpRz13cKH; Tue, 20 Aug 2024 10:41:31 +0800 (CST) Received: from kwepemh500013.china.huawei.com (unknown [7.202.181.146]) by mail.maildlp.com (Postfix) with ESMTPS id 6FF571402E0; Tue, 20 Aug 2024 10:42:05 +0800 (CST) Received: from [10.67.109.254] (10.67.109.254) by kwepemh500013.china.huawei.com (7.202.181.146) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 20 Aug 2024 10:42:04 +0800 Message-ID: <44c60279-82d8-3519-8f83-7e2c834a018d@huawei.com> Date: Tue, 20 Aug 2024 10:42:03 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.2.0 Subject: Re: [PATCH v2] RISC-V: Implement kgdb_roundup_cpus() to enable future NMI Roundup Content-Language: en-US To: , , , , , , , References: <20240727063438.886155-1-ruanjinjie@huawei.com> From: Jinjie Ruan In-Reply-To: <20240727063438.886155-1-ruanjinjie@huawei.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To kwepemh500013.china.huawei.com (7.202.181.146) Ping. On 2024/7/27 14:34, Jinjie Ruan wrote: > Until now, the generic weak kgdb_roundup_cpus() has been used for kgdb on > RISCV. A custom one allows to debug CPUs that are stuck with interrupts > disabled with NMI support in the future. And using an IPI is better than > the generic one since it avoids the potential situation described in the > generic kgdb_call_nmi_hook(). As Andrew pointed out, once there is NMI > support, we can easily extend this and the CPU backtrace support > to use NMIs. > > After this patch, the kgdb test show that: > # echo g > /proc/sysrq-trigger > [2]kdb> btc > btc: cpu status: Currently on cpu 2 > Available cpus: 0-1(-), 2, 3(-) > Stack traceback for pid 0 > 0xffffffff81c13a40 0 0 1 0 - 0xffffffff81c14510 swapper/0 > CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.10.0-g3120273055b6-dirty #51 > Hardware name: riscv-virtio,qemu (DT) > Call Trace: > [] dump_backtrace+0x28/0x30 > [] show_stack+0x38/0x44 > [] dump_stack_lvl+0x58/0x7a > [] dump_stack+0x18/0x20 > [] kgdb_cpu_enter+0x682/0x6b2 > [] kgdb_nmicallback+0xa0/0xac > [] handle_IPI+0x9c/0x120 > [] handle_percpu_devid_irq+0xa4/0x1e4 > [] generic_handle_domain_irq+0x28/0x36 > [] ipi_mux_process+0xe8/0x110 > [] imsic_handle_irq+0xf8/0x13a > [] generic_handle_domain_irq+0x28/0x36 > [] riscv_intc_aia_irq+0x2e/0x40 > [] handle_riscv_irq+0x54/0x86 > [] call_on_irq_stack+0x32/0x40 > > Rebased on Ryo Takakura's "RISC-V: Enable IPI CPU Backtrace" patch. > > Signed-off-by: Jinjie Ruan > Reviewed-by: Andrew Jones > --- > v2: > - Update the commit title and message. > - Add Reviewed-by. > --- > arch/riscv/kernel/smp.c | 27 +++++++++++++++++++++++++-- > 1 file changed, 25 insertions(+), 2 deletions(-) > > diff --git a/arch/riscv/kernel/smp.c b/arch/riscv/kernel/smp.c > index 9b047899791c..c180a647a30e 100644 > --- a/arch/riscv/kernel/smp.c > +++ b/arch/riscv/kernel/smp.c > @@ -13,6 +13,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -35,6 +36,7 @@ enum ipi_message_type { > IPI_IRQ_WORK, > IPI_TIMER, > IPI_CPU_BACKTRACE, > + IPI_KGDB_ROUNDUP, > IPI_MAX > }; > > @@ -115,6 +117,7 @@ void arch_irq_work_raise(void) > > static irqreturn_t handle_IPI(int irq, void *data) > { > + unsigned int cpu = smp_processor_id(); > int ipi = irq - ipi_virq_base; > > switch (ipi) { > @@ -128,7 +131,7 @@ static irqreturn_t handle_IPI(int irq, void *data) > ipi_stop(); > break; > case IPI_CPU_CRASH_STOP: > - ipi_cpu_crash_stop(smp_processor_id(), get_irq_regs()); > + ipi_cpu_crash_stop(cpu, get_irq_regs()); > break; > case IPI_IRQ_WORK: > irq_work_run(); > @@ -141,8 +144,11 @@ static irqreturn_t handle_IPI(int irq, void *data) > case IPI_CPU_BACKTRACE: > nmi_cpu_backtrace(get_irq_regs()); > break; > + case IPI_KGDB_ROUNDUP: > + kgdb_nmicallback(cpu, get_irq_regs()); > + break; > default: > - pr_warn("CPU%d: unhandled IPI%d\n", smp_processor_id(), ipi); > + pr_warn("CPU%d: unhandled IPI%d\n", cpu, ipi); > break; > } > > @@ -209,6 +215,7 @@ static const char * const ipi_names[] = { > [IPI_IRQ_WORK] = "IRQ work interrupts", > [IPI_TIMER] = "Timer broadcast interrupts", > [IPI_CPU_BACKTRACE] = "CPU backtrace interrupts", > + [IPI_KGDB_ROUNDUP] = "KGDB roundup interrupts", > }; > > void show_ipi_stats(struct seq_file *p, int prec) > @@ -339,3 +346,19 @@ void arch_trigger_cpumask_backtrace(const cpumask_t *mask, int exclude_cpu) > { > nmi_trigger_cpumask_backtrace(mask, exclude_cpu, riscv_backtrace_ipi); > } > + > +#ifdef CONFIG_KGDB > +void kgdb_roundup_cpus(void) > +{ > + int this_cpu = raw_smp_processor_id(); > + int cpu; > + > + for_each_online_cpu(cpu) { > + /* No need to roundup ourselves */ > + if (cpu == this_cpu) > + continue; > + > + send_ipi_single(cpu, IPI_KGDB_ROUNDUP); > + } > +} > +#endif