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MIPS: kdump: Add support

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[ralf@linux-mips.org: Original patch by Maxim Uvarov <muvarov@gmail.com>
with plenty of further shining, polishing, debugging and testing by me.]

Signed-off-by: Maxim Uvarov <muvarov@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: kexec@lists.infradead.org
Cc: horms@verge.net.au
Patchwork: https://patchwork.linux-mips.org/patch/1025/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Ralf Baechle 2012-10-11 18:14:58 +02:00
parent 98cdee0eae
commit 7aa1c8f47e
11 changed files with 396 additions and 9 deletions
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77
arch/mips/kernel/crash_dump.c Normal file
View file

@ -0,0 +1,77 @@
#include <linux/highmem.h>
#include <linux/bootmem.h>
#include <linux/crash_dump.h>
#include <asm/uaccess.h>
unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
static int __init parse_savemaxmem(char *p)
{
if (p)
saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
return 1;
}
__setup("savemaxmem=", parse_savemaxmem);
static void *kdump_buf_page;
/**
* 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.
*
* 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;
vaddr = kmap_atomic_pfn(pfn);
if (!userbuf) {
memcpy(buf, (vaddr + offset), csize);
kunmap_atomic(vaddr);
} else {
if (!kdump_buf_page) {
pr_warning("Kdump: Kdump buffer page not allocated\n");
return -EFAULT;
}
copy_page(kdump_buf_page, vaddr);
kunmap_atomic(vaddr);
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) {
pr_warning("Kdump: Failed to allocate kdump buffer page\n");
ret = -ENOMEM;
}
return ret;
}
arch_initcall(kdump_buf_page_init);