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arm64: hibernate: Support DEBUG_PAGEALLOC

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DEBUG_PAGEALLOC removes the valid bit of page table entries to prevent
any access to unallocated memory. Hibernate uses this as a hint that those
pages don't need to be saved/restored. This patch adds the
kernel_page_present() function it uses.

hibernate.c copies the resume kernel's linear map for use during restore.
Add _copy_pte() to fill-in the holes made by DEBUG_PAGEALLOC in the resume
kernel, so we can restore data the original kernel had at these addresses.

Finally, DEBUG_PAGEALLOC means the linear-map alias of KERNEL_START to
KERNEL_END may have holes in it, so we can't lazily clean this whole
area to the PoC. Only clean the new mmuoff region, and the kernel/kvm
idmaps.

This reverts commit da24eb1f3f.

Reported-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
This commit is contained in:
James Morse
2016-08-24 18:27:30 +01:00
committed by Will Deacon
parent b611303811
commit 5ebe3a44cc
4 changed files with 86 additions and 11 deletions
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45
arch/arm64/kernel/hibernate.c
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@@ -235,6 +235,7 @@ out:
return rc;
}
#define dcache_clean_range(start, end) __flush_dcache_area(start, (end - start))
int swsusp_arch_suspend(void)
{
@@ -252,8 +253,13 @@ int swsusp_arch_suspend(void)
if (__cpu_suspend_enter(&state)) {
ret = swsusp_save();
} else {
/* Clean kernel to PoC for secondary core startup */
__flush_dcache_area(LMADDR(KERNEL_START), KERNEL_END - KERNEL_START);
/* Clean kernel core startup/idle code to PoC*/
dcache_clean_range(__mmuoff_data_start, __mmuoff_data_end);
dcache_clean_range(__idmap_text_start, __idmap_text_end);
/* Clean kvm setup code to PoC? */
if (el2_reset_needed())
dcache_clean_range(__hyp_idmap_text_start, __hyp_idmap_text_end);
/*
* Tell the hibernation core that we've just restored
@@ -269,6 +275,33 @@ int swsusp_arch_suspend(void)
return ret;
}
static void _copy_pte(pte_t *dst_pte, pte_t *src_pte, unsigned long addr)
{
pte_t pte = *src_pte;
if (pte_valid(pte)) {
/*
* Resume will overwrite areas that may be marked
* read only (code, rodata). Clear the RDONLY bit from
* the temporary mappings we use during restore.
*/
set_pte(dst_pte, pte_clear_rdonly(pte));
} else if (debug_pagealloc_enabled() && !pte_none(pte)) {
/*
* debug_pagealloc will removed the PTE_VALID bit if
* the page isn't in use by the resume kernel. It may have
* been in use by the original kernel, in which case we need
* to put it back in our copy to do the restore.
*
* Before marking this entry valid, check the pfn should
* be mapped.
*/
BUG_ON(!pfn_valid(pte_pfn(pte)));
set_pte(dst_pte, pte_mkpresent(pte_clear_rdonly(pte)));
}
}
static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
unsigned long end)
{
@@ -284,13 +317,7 @@ static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
src_pte = pte_offset_kernel(src_pmd, start);
do {
if (!pte_none(*src_pte))
/*
* Resume will overwrite areas that may be marked
* read only (code, rodata). Clear the RDONLY bit from
* the temporary mappings we use during restore.
*/
set_pte(dst_pte, __pte(pte_val(*src_pte) & ~PTE_RDONLY));
_copy_pte(dst_pte, src_pte, addr);
} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
return 0;