| 1 | // SPDX-License-Identifier: GPL-2.0-only |
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| 2 | /* |
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| 3 | * Routines for doing kexec-based kdump |
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| 4 | * |
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| 5 | * Copyright (C) 2017 Linaro Limited |
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| 6 | * Author: AKASHI Takahiro <takahiro.akashi@linaro.org> |
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| 7 | */ |
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| 8 | |
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| 9 | #include <linux/crash_dump.h> |
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| 10 | #include <linux/errno.h> |
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| 11 | #include <linux/io.h> |
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| 12 | #include <linux/uio.h> |
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| 13 | #include <asm/memory.h> |
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| 14 | |
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| 15 | ssize_t copy_oldmem_page(struct iov_iter *iter, unsigned long pfn, |
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| 16 | size_t csize, unsigned long offset) |
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| 17 | { |
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| 18 | void *vaddr; |
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| 19 | |
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| 20 | if (!csize) |
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| 21 | return 0; |
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| 22 | |
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| 23 | vaddr = memremap(__pfn_to_phys(pfn), PAGE_SIZE, flags: MEMREMAP_WB); |
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| 24 | if (!vaddr) |
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| 25 | return -ENOMEM; |
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| 26 | |
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| 27 | csize = copy_to_iter(addr: vaddr + offset, bytes: csize, i: iter); |
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| 28 | |
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| 29 | memunmap(addr: vaddr); |
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| 30 | |
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| 31 | return csize; |
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| 32 | } |
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| 33 | |
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| 34 | /** |
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| 35 | * elfcorehdr_read - read from ELF core header |
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| 36 | * @buf: buffer where the data is placed |
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| 37 | * @count: number of bytes to read |
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| 38 | * @ppos: address in the memory |
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| 39 | * |
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| 40 | * This function reads @count bytes from elf core header which exists |
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| 41 | * on crash dump kernel's memory. |
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| 42 | */ |
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| 43 | ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) |
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| 44 | { |
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| 45 | memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count); |
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| 46 | *ppos += count; |
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| 47 | |
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| 48 | return count; |
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| 49 | } |
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| 50 | |
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