mirror of
https://github.com/crash-utility/crash
synced 2024-12-12 20:24:34 +00:00
1cfd513ea9
Instead of using positional initialization, use the more modern designated initializer style, as already used for 'crash_fops'. This makes the member initialization not only less ambiguous but also allows structure layout randomization of the underlying type (as done in grsecurity). Signed-off-by: Mathias Krause <minipli@grsecurity.net>
360 lines
7.7 KiB
C
360 lines
7.7 KiB
C
/*
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* linux/drivers/char/crash.c
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*
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* Copyright (C) 2004, 2011, 2016 Dave Anderson <anderson@redhat.com>
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* Copyright (C) 2004, 2011, 2016 Red Hat, Inc.
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* Copyright (C) 2019 Serapheim Dimitropoulos <serapheim delphix com>
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*/
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/******************************************************************************
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*
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*****************************************************************************/
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#include <linux/module.h>
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#include <linux/version.h>
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#include <linux/types.h>
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#include <linux/miscdevice.h>
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#include <linux/init.h>
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#include <asm/io.h>
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#include <asm/uaccess.h>
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#include <asm/types.h>
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#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/mmzone.h>
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extern int page_is_ram(unsigned long);
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#if LINUX_VERSION_CODE < KERNEL_VERSION(5, 8, 0)
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#define CAN_WRITE_KERNEL 1
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static inline long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
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{
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return probe_kernel_read(dst, src, size);
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}
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static inline long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
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{
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return probe_kernel_write(dst, src, size);
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}
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#endif
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#ifdef CONFIG_S390
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/*
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* For swapped prefix pages get bounce buffer using xlate_dev_mem_ptr()
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*/
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static inline void *map_virtual(u64 offset, struct page **pp)
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{
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struct page *page;
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unsigned long pfn;
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void *vaddr;
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vaddr = xlate_dev_mem_ptr(offset);
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pfn = ((unsigned long) vaddr) >> PAGE_SHIFT;
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if ((unsigned long) vaddr != offset)
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page = pfn_to_page(pfn);
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else
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page = NULL;
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if (!page_is_ram(pfn)) {
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printk(KERN_INFO
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"crash memory driver: !page_is_ram(pfn: %lx)\n", pfn);
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return NULL;
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}
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if (!pfn_valid(pfn)) {
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printk(KERN_INFO
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"crash memory driver: invalid pfn: %lx )\n", pfn);
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return NULL;
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}
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*pp = page;
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return vaddr;
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}
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/*
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* Free bounce buffer if necessary
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*/
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static inline void unmap_virtual(struct page *page)
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{
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void *vaddr;
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if (page) {
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/*
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* Because for bounce buffers vaddr will never be 0
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* unxlate_dev_mem_ptr() will always free the bounce buffer.
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*/
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vaddr = (void *)(page_to_pfn(page) << PAGE_SHIFT);
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unxlate_dev_mem_ptr(0, vaddr);
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}
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}
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#else /* all architectures except s390x */
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static inline void *
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map_virtual(u64 offset, struct page **pp)
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{
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struct page *page;
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unsigned long pfn;
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void *vaddr;
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pfn = (unsigned long)(offset >> PAGE_SHIFT);
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#ifdef NOTDEF
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/*
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* page_is_ram() is typically not exported, but there may
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* be another architecture, kernel version, or distribution
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* specific mechanism that can be plugged in here if desired.
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*/
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if (!page_is_ram(pfn)) {
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printk(KERN_INFO
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"crash memory driver: !page_is_ram(pfn: %lx)\n", pfn);
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return NULL;
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}
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#endif
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if (!pfn_valid(pfn)) {
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printk(KERN_INFO
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"crash memory driver: invalid pfn: %lx\n", pfn);
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return NULL;
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}
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page = pfn_to_page(pfn);
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vaddr = kmap(page);
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if (!vaddr) {
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printk(KERN_INFO
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"crash memory driver: pfn: %lx kmap(page: %lx) failed\n",
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pfn, (unsigned long)page);
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return NULL;
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}
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*pp = page;
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return (vaddr + (offset & (PAGE_SIZE-1)));
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}
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static inline void unmap_virtual(struct page *page)
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{
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kunmap(page);
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}
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#endif
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#define CRASH_VERSION "1.5"
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/*
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* These are the file operation functions that allow crash utility
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* access to physical memory.
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*/
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static loff_t
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crash_llseek(struct file * file, loff_t offset, int orig)
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{
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switch (orig) {
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case 0:
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file->f_pos = offset;
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return file->f_pos;
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case 1:
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file->f_pos += offset;
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return file->f_pos;
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default:
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return -EINVAL;
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}
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}
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#ifdef CAN_WRITE_KERNEL
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static ssize_t
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crash_write(struct file *file, const char *buf, size_t count, loff_t *poff)
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{
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void *vaddr;
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struct page *page;
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u64 offset;
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ssize_t written;
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char *buffer = file->private_data;
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offset = *poff;
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if (offset >> PAGE_SHIFT != (offset+count-1) >> PAGE_SHIFT)
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return -EINVAL;
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vaddr = map_virtual(offset, &page);
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if (!vaddr)
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return -EFAULT;
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/*
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* Use bounce buffer to bypass the CONFIG_HARDENED_USERCOPY
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* kernel text restriction.
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*/
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if (copy_from_user(buffer, buf, count)) {
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unmap_virtual(page);
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return -EFAULT;
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}
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if (copy_to_kernel_nofault(vaddr, buffer, count)) {
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unmap_virtual(page);
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return -EFAULT;
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}
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unmap_virtual(page);
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written = count;
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*poff += written;
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return written;
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}
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#endif
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/*
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* Determine the page address for an address offset value,
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* get a virtual address for it, and copy it out.
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* Accesses must fit within a page.
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*/
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static ssize_t
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crash_read(struct file *file, char *buf, size_t count, loff_t *poff)
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{
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void *vaddr;
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struct page *page;
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u64 offset;
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ssize_t read;
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char *buffer = file->private_data;
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offset = *poff;
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if (offset >> PAGE_SHIFT != (offset+count-1) >> PAGE_SHIFT)
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return -EINVAL;
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vaddr = map_virtual(offset, &page);
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if (!vaddr)
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return -EFAULT;
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/*
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* Use bounce buffer to bypass the CONFIG_HARDENED_USERCOPY
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* kernel text restriction.
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*/
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if (copy_from_kernel_nofault(buffer, vaddr, count)) {
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unmap_virtual(page);
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return -EFAULT;
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}
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if (copy_to_user(buf, buffer, count)) {
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unmap_virtual(page);
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return -EFAULT;
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}
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unmap_virtual(page);
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read = count;
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*poff += read;
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return read;
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}
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static int
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crash_open(struct inode * inode, struct file * filp)
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{
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if (!capable(CAP_SYS_RAWIO))
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return -EPERM;
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filp->private_data = (void *)__get_free_page(GFP_KERNEL);
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if (!filp->private_data)
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return -ENOMEM;
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return 0;
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}
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static int
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crash_release(struct inode *inode, struct file *filp)
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{
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free_pages((unsigned long)filp->private_data, 0);
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return 0;
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}
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/*
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* Note: This function is required for Linux 4.6 and later ARM64 kernels.
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* For earler kernel versions, remove this CONFIG_ARM64 section.
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*/
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#ifdef CONFIG_ARM64
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#define DEV_CRASH_ARCH_DATA _IOR('c', 1, long)
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static long
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crash_arch_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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extern u64 kimage_voffset;
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switch (cmd)
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{
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case DEV_CRASH_ARCH_DATA:
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return put_user(kimage_voffset, (unsigned long __user *)arg);
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default:
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return -EINVAL;
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}
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}
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#endif
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static long
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crash_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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{
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#ifdef DEV_CRASH_ARCH_DATA
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return crash_arch_ioctl(file, cmd, arg);
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#else
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return -EINVAL;
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#endif
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}
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static struct file_operations crash_fops = {
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.owner = THIS_MODULE,
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.llseek = crash_llseek,
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.read = crash_read,
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#ifdef CAN_WRITE_KERNEL
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.write = crash_write,
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#endif
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.unlocked_ioctl = crash_ioctl,
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.open = crash_open,
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.release = crash_release,
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};
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static struct miscdevice crash_dev = {
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.minor = MISC_DYNAMIC_MINOR,
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.name = "crash",
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.fops = &crash_fops
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};
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static int __init
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crash_init(void)
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{
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int ret;
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ret = misc_register(&crash_dev);
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if (ret) {
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printk(KERN_ERR
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"crash memory driver: cannot misc_register (MISC_DYNAMIC_MINOR)\n");
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goto out;
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}
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ret = 0;
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printk(KERN_INFO "crash memory driver: version %s\n", CRASH_VERSION);
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out:
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return ret;
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}
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static void __exit
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crash_cleanup_module(void)
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{
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misc_deregister(&crash_dev);
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}
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module_init(crash_init);
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module_exit(crash_cleanup_module);
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MODULE_LICENSE("GPL");
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