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a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1604399638; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: references:references; bh=K8tv6h9J8+1UjPWtbytb7n5SLceTF9zssV9oZox9W+U=; b=9UUmg4StD1+gf6xD44eY0tbCb4Wv9S+7TAD5110OmAjL1mF4moT3f8RAipzm2mr9CGQRvT 96qYqMQSY/G9MBCw== Date: Tue, 03 Nov 2020 10:27:40 +0100 From: Thomas Gleixner To: LKML Subject: [patch V3 28/37] mips/crashdump: Simplify copy_oldmem_page() References: <20201103092712.714480842@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-transfer-encoding: 8-bit X-Mailman-Approved-At: Tue, 03 Nov 2020 21:51:18 +1100 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: Juri Lelli , linux-aio@kvack.org, Peter Zijlstra , Sebastian Andrzej Siewior , Joonas Lahtinen , dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org, Ben Segall , Chris Mason , Huang Rui , Paul Mackerras , Gerd Hoffmann , Daniel Bristot de Oliveira , sparclinux@vger.kernel.org, Vincent Chen , Christoph Hellwig , Vincent Guittot , Paul McKenney , Max Filippov , x86@kernel.org, Russell King , linux-csky@vger.kernel.org, Ingo Molnar , David Airlie , VMware Graphics , Mel Gorman , nouveau@lists.freedesktop.org, Dave Airlie , linux-snps-arc@lists.infradead.org, Ben Skeggs , linux-xtensa@linux-xtensa.org, Arnd Bergmann , intel-gfx@lists.freedesktop.org, Roland Scheidegger , Josef Bacik , Steven Rostedt , Linus Torvalds , Alexander Viro , spice-devel@lists.freedesktop.org, David Sterba , Rodrigo Vivi , Dietmar Eggemann , linux-arm-kernel@lists.infradead.org, Jani Nikula , Chris Zankel , Michal Simek , Thomas Bogendoerfer , Nick Hu , linux-mm@kvack.org, Vineet Gupta , linux-mips@vger.kernel.org, Christian Koenig , Benjamin LaHaise , Daniel Vetter , linux-fsdevel@vger.kernel.org, Andrew Morton , linuxppc-dev@lists.ozlabs.org, "David S. Miller" , linux-btrfs@vger.kernel.org, Greentime Hu Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Replace kmap_atomic_pfn() with kmap_local_pfn() which is preemptible and can take page faults. Remove the indirection of the dump page and the related cruft which is not longer required. Signed-off-by: Thomas Gleixner Cc: Thomas Bogendoerfer Cc: linux-mips@vger.kernel.org --- V3: New patch --- arch/mips/kernel/crash_dump.c | 42 +++++++----------------------------------- 1 file changed, 7 insertions(+), 35 deletions(-) --- a/arch/mips/kernel/crash_dump.c +++ b/arch/mips/kernel/crash_dump.c @@ -5,8 +5,6 @@ #include #include -static void *kdump_buf_page; - /** * copy_oldmem_page - copy one page from "oldmem" * @pfn: page frame number to be copied @@ -17,51 +15,25 @@ static void *kdump_buf_page; * @userbuf: if set, @buf is in user address space, use copy_to_user(), * otherwise @buf is in kernel address space, use memcpy(). * - * Copy a page from "oldmem". For this page, there is no pte mapped + * Copy a page from "oldmem". For this page, there might be no pte mapped * in the current kernel. - * - * Calling copy_to_user() in atomic context is not desirable. Hence first - * copying the data to a pre-allocated kernel page and then copying to user - * space in non-atomic context. */ -ssize_t copy_oldmem_page(unsigned long pfn, char *buf, - size_t csize, unsigned long offset, int userbuf) +ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize, + unsigned long offset, int userbuf) { void *vaddr; if (!csize) return 0; - vaddr = kmap_atomic_pfn(pfn); + vaddr = kmap_local_pfn(pfn); if (!userbuf) { - memcpy(buf, (vaddr + offset), csize); - kunmap_atomic(vaddr); + memcpy(buf, vaddr + offset, csize); } else { - if (!kdump_buf_page) { - pr_warn("Kdump: Kdump buffer page not allocated\n"); - - return -EFAULT; - } - copy_page(kdump_buf_page, vaddr); - kunmap_atomic(vaddr); - if (copy_to_user(buf, (kdump_buf_page + offset), csize)) - return -EFAULT; + if (copy_to_user(buf, vaddr + offset, csize)) + csize = -EFAULT; } return csize; } - -static int __init kdump_buf_page_init(void) -{ - int ret = 0; - - kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL); - if (!kdump_buf_page) { - pr_warn("Kdump: Failed to allocate kdump buffer page\n"); - ret = -ENOMEM; - } - - return ret; -} -arch_initcall(kdump_buf_page_init);