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arch/x86/kernel/crash_dump_32.c
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/* |
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* Memory preserving reboot related code. |
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* * Created by: Hariprasad Nellitheertha (hari@in.ibm.com) * Copyright (C) IBM Corporation, 2004. All rights reserved */ |
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#include <linux/slab.h> |
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#include <linux/errno.h> |
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#include <linux/highmem.h> #include <linux/crash_dump.h> |
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#include <asm/uaccess.h> |
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static void *kdump_buf_page; |
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static inline bool is_crashed_pfn_valid(unsigned long pfn) { #ifndef CONFIG_X86_PAE /* * non-PAE kdump kernel executed from a PAE one will crop high pte * bits and poke unwanted space counting again from address 0, we * don't want that. pte must fit into unsigned long. In fact the * test checks high 12 bits for being zero (pfn will be shifted left * by PAGE_SHIFT). */ return pte_pfn(pfn_pte(pfn, __pgprot(0))) == pfn; #else return true; #endif } |
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/** * 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(). * |
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* 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. |
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* * 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. |
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*/ ssize_t copy_oldmem_page(unsigned long pfn, char *buf, |
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size_t csize, unsigned long offset, int userbuf) |
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{ |
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void *vaddr; |
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if (!csize) return 0; |
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if (!is_crashed_pfn_valid(pfn)) return -EFAULT; |
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vaddr = kmap_atomic_pfn(pfn); |
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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 "); |
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kunmap_atomic(vaddr, KM_PTE0); |
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return -EFAULT; } |
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copy_page(kdump_buf_page, vaddr); kunmap_atomic(vaddr, KM_PTE0); if (copy_to_user(buf, (kdump_buf_page + offset), csize)) return -EFAULT; |
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} |
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return csize; } |
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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 "); ret = -ENOMEM; } return ret; } arch_initcall(kdump_buf_page_init); |