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x86, kexec: x86_64: add identity map for pages at image->start

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Impact: Fix corner case that cannot yet occur

image->start may be outside of 0 ~ max_pfn, for example when jumping
back to original kernel from kexeced kenrel. This patch add identity
map for pages at image->start.

Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
Huang Ying 2009-03-10 10:57:04 +08:00 committed by H. Peter Anvin
parent fef3a7a174
commit 5359454701
1 changed files with 42 additions and 0 deletions
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42
arch/x86/kernel/machine_kexec_64.c
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@ -18,6 +18,41 @@
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
static int init_one_level2_page(struct kimage *image, pgd_t *pgd,
unsigned long addr)
{
pud_t *pud;
pmd_t *pmd;
struct page *page;
int result = -ENOMEM;
addr &= PMD_MASK;
pgd += pgd_index(addr);
if (!pgd_present(*pgd)) {
page = kimage_alloc_control_pages(image, 0);
if (!page)
goto out;
pud = (pud_t *)page_address(page);
memset(pud, 0, PAGE_SIZE);
set_pgd(pgd, __pgd(__pa(pud) | _KERNPG_TABLE));
}
pud = pud_offset(pgd, addr);
if (!pud_present(*pud)) {
page = kimage_alloc_control_pages(image, 0);
if (!page)
goto out;
pmd = (pmd_t *)page_address(page);
memset(pmd, 0, PAGE_SIZE);
set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
}
pmd = pmd_offset(pud, addr);
if (!pmd_present(*pmd))
set_pmd(pmd, __pmd(addr | __PAGE_KERNEL_LARGE_EXEC));
result = 0;
out:
return result;
}
static void init_level2_page(pmd_t *level2p, unsigned long addr)
{
unsigned long end_addr;
@ -153,6 +188,13 @@ static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
int result;
level4p = (pgd_t *)__va(start_pgtable);
result = init_level4_page(image, level4p, 0, max_pfn << PAGE_SHIFT);
if (result)
return result;
/*
* image->start may be outside 0 ~ max_pfn, for example when
* jump back to original kernel from kexeced kernel
*/
result = init_one_level2_page(image, level4p, image->start);
if (result)
return result;
return init_transition_pgtable(image, level4p);