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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D4F00EE801F for ; Mon, 11 Sep 2023 07:14:08 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=MjJH62QW; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4RkdHg010Kz3cH4 for ; Mon, 11 Sep 2023 17:14:07 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ellerman.id.au header.i=@ellerman.id.au header.a=rsa-sha256 header.s=201909 header.b=MjJH62QW; dkim-atps=neutral Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4RkdGf3Mffz2yDM for ; Mon, 11 Sep 2023 17:13:14 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ellerman.id.au; s=201909; t=1694416391; bh=x3DI2GOmDJf3VCeCLcNSuqidmRFWPmzeO7ZN5ro3wQk=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=MjJH62QWRh2VQSSbKneqoRlIRvXqFkvpJavlxEypjGnB2nzGPtho60W8xhSKnqmG4 Ts4Ba6UX+Vnn9kc3aMY7D2eJ6xx+5LqYwqNcB1adFOpBO8xwGyuPX8zGt3eE2bR1uc qiMMmr0z3GATVZbl+XH7RqFOrI+eq6Mc8uZD/mK9BV3lUjX3hXndpQGpKQZC2q3znN 8AdA7uSulHTaMIpElPecLEjyi0zlB59wOAZFKVXnAUGeGpkwTK53+gi/NlvOsQDBRd B2Tel2+x0yx3vsGdmZc09eMDVr5s/kSOji9saNoTcU8BhFlSyfr85ESMHUwpdRKDyM sKx7Yc6nd3ddA== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4RkdGb0fxzz4xFD; Mon, 11 Sep 2023 17:13:11 +1000 (AEST) From: Michael Ellerman To: Hari Bathini , lkml , linuxppc-dev , Kexec-ml Subject: Re: [PATCH v2 2/3] vmcore: allow fadump to export vmcore even if is_kdump_kernel() is false In-Reply-To: <20230905183604.568996-2-hbathini@linux.ibm.com> References: <20230905183604.568996-1-hbathini@linux.ibm.com> <20230905183604.568996-2-hbathini@linux.ibm.com> Date: Mon, 11 Sep 2023 17:13:08 +1000 Message-ID: <8734zltc6z.fsf@mail.lhotse> MIME-Version: 1.0 Content-Type: text/plain X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sourabh Jain , Dave Young , Mahesh J Salgaonkar , Baoquan He Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hari Bathini writes: > Currently, is_kdump_kernel() returns true when elfcorehdr_addr is set. > While elfcorehdr_addr is set for kexec based kernel dump mechanism, > alternate dump capturing methods like fadump [1] also set it to export > the vmcore. Since, is_kdump_kernel() is used to restrict resources in > crash dump capture kernel and such restrictions are not desirable for > fadump, allow is_kdump_kernel() to be defined differently for fadump > case. With that change, include is_fadump_active() check in functions > is_vmcore_usable() & vmcore_unusable() to be able to export vmcore for > fadump case too. ... > diff --git a/include/linux/crash_dump.h b/include/linux/crash_dump.h > index 0f3a656293b0..de8a9fabfb6f 100644 > --- a/include/linux/crash_dump.h > +++ b/include/linux/crash_dump.h > @@ -50,6 +50,7 @@ void vmcore_cleanup(void); > #define vmcore_elf64_check_arch(x) (elf_check_arch(x) || vmcore_elf_check_arch_cross(x)) > #endif > > +#ifndef is_kdump_kernel > /* > * is_kdump_kernel() checks whether this kernel is booting after a panic of > * previous kernel or not. This is determined by checking if previous kernel > @@ -64,6 +65,19 @@ static inline bool is_kdump_kernel(void) > { > return elfcorehdr_addr != ELFCORE_ADDR_MAX; > } > +#endif > + > +#ifndef is_fadump_active > +/* > + * If f/w assisted dump capturing mechanism (fadump), instead of kexec based > + * dump capturing mechanism (kdump) is exporting the vmcore, then this function > + * will be defined in arch specific code to return true, when appropriate. > + */ > +static inline bool is_fadump_active(void) > +{ > + return false; > +} > +#endif > > /* is_vmcore_usable() checks if the kernel is booting after a panic and > * the vmcore region is usable. > @@ -75,7 +89,8 @@ static inline bool is_kdump_kernel(void) > > static inline int is_vmcore_usable(void) > { > - return is_kdump_kernel() && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0; > + return (is_kdump_kernel() || is_fadump_active()) > + && elfcorehdr_addr != ELFCORE_ADDR_ERR ? 1 : 0; > } > > /* vmcore_unusable() marks the vmcore as unusable, > @@ -84,7 +99,7 @@ static inline int is_vmcore_usable(void) > > static inline void vmcore_unusable(void) > { > - if (is_kdump_kernel()) > + if (is_kdump_kernel() || is_fadump_active()) > elfcorehdr_addr = ELFCORE_ADDR_ERR; > } I think it would be cleaner to decouple is_vmcore_usable() and vmcore_usable() from is_kdump_kernel(). ie, make them operate solely based on the value of elforehdr_addr: static inline int is_vmcore_usable(void) { elfcorehdr_addr != ELFCORE_ADDR_ERR && \ elfcorehdr_addr != ELFCORE_ADDR_MAX; } static inline void vmcore_unusable(void) { elfcorehdr_addr = ELFCORE_ADDR_ERR; } Then all we need on powerpc is a way to override is_kdump_kernel(). cheers