// SPDX-License-Identifier: GPL-2.0-only /* * Routines for doing kexec-based kdump * * Copyright (C) 2017 Linaro Limited * Author: AKASHI Takahiro <takahiro.akashi@linaro.org> */ #include <linux/crash_dump.h> #include <linux/errno.h> #include <linux/io.h> #include <linux/memblock.h> #include <linux/uaccess.h> #include <asm/memory.h> /** * copy_oldmem_page() - copy one page from old kernel memory * @pfn: page frame number to be copied * @buf: buffer where the copied page is placed * @csize: number of bytes to copy * @offset: offset in bytes into the page * @userbuf: if set, @buf is in a user address space * * This function copies one page from old kernel memory into buffer pointed by * @buf. If @buf is in userspace, set @userbuf to %1. Returns number of bytes * copied or negative error in case of failure. */ 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 = memremap(__pfn_to_phys(pfn), PAGE_SIZE, MEMREMAP_WB); if (!vaddr) return -ENOMEM; if (userbuf) { if (copy_to_user((char __user *)buf, vaddr + offset, csize)) { memunmap(vaddr); return -EFAULT; } } else { memcpy(buf, vaddr + offset, csize); } memunmap(vaddr); return csize; } /** * elfcorehdr_read - read from ELF core header * @buf: buffer where the data is placed * @count: number of bytes to read * @ppos: address in the memory * * This function reads @count bytes from elf core header which exists * on crash dump kernel's memory. */ ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos) { memcpy(buf, phys_to_virt((phys_addr_t)*ppos), count); return count; }