Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754923AbbHFHJ7 (ORCPT ); Thu, 6 Aug 2015 03:09:59 -0400 Received: from mail-pa0-f48.google.com ([209.85.220.48]:34544 "EHLO mail-pa0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753178AbbHFHJ5 (ORCPT ); Thu, 6 Aug 2015 03:09:57 -0400 Message-ID: <55C3083D.1000306@linaro.org> Date: Thu, 06 Aug 2015 16:09:49 +0900 From: AKASHI Takahiro User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Marc Zyngier , Mark Rutland CC: Catalin Marinas , Will Deacon , "vgoyal@redhat.com" , "hbabus@us.ibm.com" , "linaro-kernel@lists.linaro.org" , "geoff@infradead.org" , "kexec@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "broonie@kernel.org" , "david.griego@linaro.org" , "linux-arm-kernel@lists.infradead.org" Subject: Re: [v2 2/5] arm64: kdump: implement machine_crash_shutdown() References: <1429861989-8417-1-git-send-email-takahiro.akashi@linaro.org> <1429861989-8417-3-git-send-email-takahiro.akashi@linaro.org> <20150424103900.GF29183@leverpostej> <553A1E62.9030400@arm.com> In-Reply-To: <553A1E62.9030400@arm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3330 Lines: 106 Marc, Mark Sorry for not revisiting your comment below for a while. On 04/24/2015 07:43 PM, Marc Zyngier wrote: > On 24/04/15 11:39, Mark Rutland wrote: >> On Fri, Apr 24, 2015 at 08:53:05AM +0100, AKASHI Takahiro wrote: >>> kdump calls machine_crash_shutdown() to shut down non-boot cpus and >>> save per-cpu general-purpose registers before restarting the crash dump >>> kernel. See kernel_kexec(). >>> ipi_cpu_stop() is used and a bit modified to support this behavior. >>> >>> Signed-off-by: AKASHI Takahiro >>> --- >>> arch/arm64/include/asm/kexec.h | 34 ++++++++++++++++++++++- >>> arch/arm64/kernel/machine_kexec.c | 55 ++++++++++++++++++++++++++++++++++++- >>> arch/arm64/kernel/smp.c | 12 ++++++-- >>> 3 files changed, 97 insertions(+), 4 deletions(-) >>> >>> diff --git a/arch/arm64/include/asm/kexec.h b/arch/arm64/include/asm/kexec.h >>> index 3530ff5..eaf3fcb 100644 >>> --- a/arch/arm64/include/asm/kexec.h >>> +++ b/arch/arm64/include/asm/kexec.h >>> @@ -30,6 +30,8 @@ >>> >>> #if !defined(__ASSEMBLY__) >>> >>> +extern bool in_crash_kexec; >>> + >>> /** >>> * crash_setup_regs() - save registers for the panic kernel >>> * >>> @@ -40,7 +42,37 @@ >>> static inline void crash_setup_regs(struct pt_regs *newregs, >>> struct pt_regs *oldregs) >>> { >>> - /* Empty routine needed to avoid build errors. */ >>> + if (oldregs) { >>> + memcpy(newregs, oldregs, sizeof(*newregs)); >>> + } else { >>> + __asm__ __volatile__ ( >>> + "stp x0, x1, [%3]\n\t" >> >> Why the tabs? >> >> Please use #16 * N as the offset for consistency with entry.S, with 0 >> for the first N. >> >> [...] >> >>> +static void machine_kexec_mask_interrupts(void) >>> +{ >>> + unsigned int i; >>> + struct irq_desc *desc; >>> + >>> + for_each_irq_desc(i, desc) { >>> + struct irq_chip *chip; >>> + >>> + chip = irq_desc_get_chip(desc); >>> + if (!chip) >>> + continue; >>> + >>> + if (chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data)) >>> + chip->irq_eoi(&desc->irq_data); >>> + >>> + if (chip->irq_mask) >>> + chip->irq_mask(&desc->irq_data); >>> + >>> + if (chip->irq_disable && !irqd_irq_disabled(&desc->irq_data)) >>> + chip->irq_disable(&desc->irq_data); >>> + } >>> +} >> >> I'm surprised that this isn't left to the irqchip driver init code in >> the crash kernel. For all we know this state could be corrupt anyway. > > Indeed, parsing the irqdesc list is a recipe for disaster. Who knows > which locks have been taken or simply corrupted, pointers nuked... > >> Is there any reason we can't get the GIC driver to nuke all of this at >> probe time? Is it just enough to remove kexec_mask_interrupts() and add gic_eoi_irq() at the beginning of gic_cpu_init() in irq-gic.c and irq-gic-v3.c? > This feels like the better option. I can cook a patch or two for that. If you do, that will be much better :) BTW, in arm-gic-v3.h, GICD_CTRL_ARE_NS is defined as (1U << 4) but should it be 5? (I'm referring to the page 8-415 in IHI0069A.) Thanks, -Takahiro AKASHI > Thanks, > > M. > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/