From 4ae362be509306eafa6441603686d33fefe321c1 Mon Sep 17 00:00:00 2001 From: Vivek Goyal Date: Mon, 9 Jan 2006 20:51:50 -0800 Subject: [PATCH] kdump: read previous kernel's memory - Moving the crash_dump.c file to arch dependent part as kmap_atomic_pfn is specific to i386 and highmem may not exist in other archs. - Use ioremap for x86_64 to map the previous kernel memory. - In copy_oldmem_page(), we now directly copy to the user/kernel buffer and avoid the unneccesary copy to a kmalloc'd page. Signed-off-by: Rachita Kothiyal Signed-off-by: Vivek Goyal Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/crash_dump.c | 74 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 arch/i386/kernel/crash_dump.c (limited to 'arch/i386/kernel/crash_dump.c') diff --git a/arch/i386/kernel/crash_dump.c b/arch/i386/kernel/crash_dump.c new file mode 100644 index 00000000000..3f532df488b --- /dev/null +++ b/arch/i386/kernel/crash_dump.c @@ -0,0 +1,74 @@ +/* + * kernel/crash_dump.c - Memory preserving reboot related code. + * + * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) + * Copyright (C) IBM Corporation, 2004. All rights reserved + */ + +#include +#include +#include + +#include + +static void *kdump_buf_page; + +/** + * copy_oldmem_page - copy one page from "oldmem" + * @pfn: page frame number to be copied + * @buf: target memory address for the copy; this can be in kernel address + * space or user address space (see @userbuf) + * @csize: number of bytes to copy + * @offset: offset in bytes into the page (based on pfn) to begin the copy + * @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 + * in the current kernel. We stitch up a pte, similar to kmap_atomic. + * + * 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) +{ + void *vaddr; + + if (!csize) + return 0; + + vaddr = kmap_atomic_pfn(pfn, KM_PTE0); + + if (!userbuf) { + memcpy(buf, (vaddr + offset), csize); + kunmap_atomic(vaddr, KM_PTE0); + } else { + if (!kdump_buf_page) { + printk(KERN_WARNING "Kdump: Kdump buffer page not" + " allocated\n"); + return -EFAULT; + } + copy_page(kdump_buf_page, vaddr); + kunmap_atomic(vaddr, KM_PTE0); + if (copy_to_user(buf, (kdump_buf_page + offset), csize)) + return -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) { + printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer" + " page\n"); + ret = -ENOMEM; + } + + return ret; +} +arch_initcall(kdump_buf_page_init); -- cgit v1.2.3