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51 lines
1.5 KiB
51 lines
1.5 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* kernel/crash_dump.c - Memory preserving reboot related code. |
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* |
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* Created by: Simon Horman <[email protected]> |
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* Original code moved from kernel/crash.c |
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* Original code comment copied from the i386 version of this file |
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*/ |
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#include <linux/errno.h> |
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#include <linux/types.h> |
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#include <linux/crash_dump.h> |
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#include <asm/page.h> |
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#include <linux/uaccess.h> |
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/** |
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* copy_oldmem_page - copy one page from "oldmem" |
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* @pfn: page frame number to be copied |
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* @buf: target memory address for the copy; this can be in kernel address |
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* space or user address space (see @userbuf) |
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* @csize: number of bytes to copy |
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* @offset: offset in bytes into the page (based on pfn) to begin the copy |
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* @userbuf: if set, @buf is in user address space, use copy_to_user(), |
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* otherwise @buf is in kernel address space, use memcpy(). |
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* |
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* Copy a page from "oldmem". For this page, there is no pte mapped |
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* in the current kernel. We stitch up a pte, similar to kmap_atomic. |
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* |
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* Calling copy_to_user() in atomic context is not desirable. Hence first |
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* copying the data to a pre-allocated kernel page and then copying to user |
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* space in non-atomic context. |
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*/ |
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ssize_t |
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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) |
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return 0; |
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vaddr = __va(pfn<<PAGE_SHIFT); |
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if (userbuf) { |
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if (copy_to_user(buf, (vaddr + offset), csize)) { |
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return -EFAULT; |
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} |
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} else |
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memcpy(buf, (vaddr + offset), csize); |
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return csize; |
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} |
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