72ed7de74e
Non-PAE 32-bit dump kernels may wrap an address around 4G and poke unwanted space. ptes there are 32-bit long, and since pfn << PAGE_SIZE may exceed this limit, high pfn bits are cropped and wrong address mapped by kmap_atomic_pfn in copy_oldmem_page. Don't allow this behavior in non-PAE kdump kernels by checking pfns passed into copy_oldmem_page. In the case of failure, userspace process gets EFAULT. [v2] - fix comments - move ifdefs inside the function Signed-off-by: Jiri Slaby <jirislaby@gmail.com> Cc: Vivek Goyal <vgoyal@redhat.com> Cc: Eric W. Biederman <ebiederm@xmission.com> Cc: Simon Horman <horms@verge.net.au> Cc: Paul Mundt <lethal@linux-sh.org> LKML-Reference: <1256551903-30567-1-git-send-email-jirislaby@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
97 lines
2.6 KiB
C
97 lines
2.6 KiB
C
/*
|
|
* Memory preserving reboot related code.
|
|
*
|
|
* Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
|
|
* Copyright (C) IBM Corporation, 2004. All rights reserved
|
|
*/
|
|
|
|
#include <linux/errno.h>
|
|
#include <linux/highmem.h>
|
|
#include <linux/crash_dump.h>
|
|
|
|
#include <asm/uaccess.h>
|
|
|
|
static void *kdump_buf_page;
|
|
|
|
/* Stores the physical address of elf header of crash image. */
|
|
unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
|
|
|
|
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
|
|
}
|
|
|
|
/**
|
|
* 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().
|
|
*
|
|
* 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.
|
|
*
|
|
* 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.
|
|
*/
|
|
ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
|
|
size_t csize, unsigned long offset, int userbuf)
|
|
{
|
|
void *vaddr;
|
|
|
|
if (!csize)
|
|
return 0;
|
|
|
|
if (!is_crashed_pfn_valid(pfn))
|
|
return -EFAULT;
|
|
|
|
vaddr = kmap_atomic_pfn(pfn, KM_PTE0);
|
|
|
|
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\n");
|
|
kunmap_atomic(vaddr, KM_PTE0);
|
|
return -EFAULT;
|
|
}
|
|
copy_page(kdump_buf_page, vaddr);
|
|
kunmap_atomic(vaddr, KM_PTE0);
|
|
if (copy_to_user(buf, (kdump_buf_page + offset), csize))
|
|
return -EFAULT;
|
|
}
|
|
|
|
return csize;
|
|
}
|
|
|
|
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\n");
|
|
ret = -ENOMEM;
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
arch_initcall(kdump_buf_page_init);
|