提交 5ebe3a44 编写于 作者: J James Morse 提交者: Will Deacon

arm64: hibernate: Support DEBUG_PAGEALLOC

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 da24eb1f.
Reported-by: NWill Deacon <will.deacon@arm.com>
Signed-off-by: NJames Morse <james.morse@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>
上级 b6113038
......@@ -607,7 +607,6 @@ source kernel/Kconfig.preempt
source kernel/Kconfig.hz
config ARCH_SUPPORTS_DEBUG_PAGEALLOC
depends on !HIBERNATION
def_bool y
config ARCH_HAS_HOLES_MEMORYMODEL
......
......@@ -155,6 +155,16 @@ static inline pte_t pte_mknoncont(pte_t pte)
return clear_pte_bit(pte, __pgprot(PTE_CONT));
}
static inline pte_t pte_clear_rdonly(pte_t pte)
{
return clear_pte_bit(pte, __pgprot(PTE_RDONLY));
}
static inline pte_t pte_mkpresent(pte_t pte)
{
return set_pte_bit(pte, __pgprot(PTE_VALID));
}
static inline pmd_t pmd_mkcont(pmd_t pmd)
{
return __pmd(pmd_val(pmd) | PMD_SECT_CONT);
......
......@@ -235,6 +235,7 @@ static int create_safe_exec_page(void *src_start, size_t length,
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;
......
......@@ -139,4 +139,43 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
__pgprot(0),
__pgprot(PTE_VALID));
}
#endif
#ifdef CONFIG_HIBERNATION
/*
* When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
* is used to determine if a linear map page has been marked as not-valid by
* CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
* This is based on kern_addr_valid(), which almost does what we need.
*
* Because this is only called on the kernel linear map, p?d_sect() implies
* p?d_present(). When debug_pagealloc is enabled, sections mappings are
* disabled.
*/
bool kernel_page_present(struct page *page)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
unsigned long addr = (unsigned long)page_address(page);
pgd = pgd_offset_k(addr);
if (pgd_none(*pgd))
return false;
pud = pud_offset(pgd, addr);
if (pud_none(*pud))
return false;
if (pud_sect(*pud))
return true;
pmd = pmd_offset(pud, addr);
if (pmd_none(*pmd))
return false;
if (pmd_sect(*pmd))
return true;
pte = pte_offset_kernel(pmd, addr);
return pte_valid(*pte);
}
#endif /* CONFIG_HIBERNATION */
#endif /* CONFIG_DEBUG_PAGEALLOC */
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