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 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:
parent
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@ -607,7 +607,6 @@ source kernel/Kconfig.preempt
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source kernel/Kconfig.hz
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config ARCH_SUPPORTS_DEBUG_PAGEALLOC
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depends on !HIBERNATION
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def_bool y
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config ARCH_HAS_HOLES_MEMORYMODEL
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@ -155,6 +155,16 @@ static inline pte_t pte_mknoncont(pte_t pte)
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return clear_pte_bit(pte, __pgprot(PTE_CONT));
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}
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static inline pte_t pte_clear_rdonly(pte_t pte)
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{
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return clear_pte_bit(pte, __pgprot(PTE_RDONLY));
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}
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static inline pte_t pte_mkpresent(pte_t pte)
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{
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return set_pte_bit(pte, __pgprot(PTE_VALID));
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}
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static inline pmd_t pmd_mkcont(pmd_t pmd)
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{
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return __pmd(pmd_val(pmd) | PMD_SECT_CONT);
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@ -235,6 +235,7 @@ out:
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return rc;
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}
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#define dcache_clean_range(start, end) __flush_dcache_area(start, (end - start))
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int swsusp_arch_suspend(void)
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{
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@ -252,8 +253,13 @@ int swsusp_arch_suspend(void)
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if (__cpu_suspend_enter(&state)) {
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ret = swsusp_save();
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} else {
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/* Clean kernel to PoC for secondary core startup */
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__flush_dcache_area(LMADDR(KERNEL_START), KERNEL_END - KERNEL_START);
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/* Clean kernel core startup/idle code to PoC*/
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dcache_clean_range(__mmuoff_data_start, __mmuoff_data_end);
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dcache_clean_range(__idmap_text_start, __idmap_text_end);
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/* Clean kvm setup code to PoC? */
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if (el2_reset_needed())
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dcache_clean_range(__hyp_idmap_text_start, __hyp_idmap_text_end);
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/*
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* Tell the hibernation core that we've just restored
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@ -269,6 +275,33 @@ int swsusp_arch_suspend(void)
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return ret;
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}
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static void _copy_pte(pte_t *dst_pte, pte_t *src_pte, unsigned long addr)
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{
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pte_t pte = *src_pte;
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if (pte_valid(pte)) {
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/*
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* Resume will overwrite areas that may be marked
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* read only (code, rodata). Clear the RDONLY bit from
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* the temporary mappings we use during restore.
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*/
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set_pte(dst_pte, pte_clear_rdonly(pte));
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} else if (debug_pagealloc_enabled() && !pte_none(pte)) {
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/*
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* debug_pagealloc will removed the PTE_VALID bit if
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* the page isn't in use by the resume kernel. It may have
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* been in use by the original kernel, in which case we need
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* to put it back in our copy to do the restore.
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*
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* Before marking this entry valid, check the pfn should
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* be mapped.
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*/
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BUG_ON(!pfn_valid(pte_pfn(pte)));
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set_pte(dst_pte, pte_mkpresent(pte_clear_rdonly(pte)));
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}
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}
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static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
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unsigned long end)
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{
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@ -284,13 +317,7 @@ static int copy_pte(pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long start,
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src_pte = pte_offset_kernel(src_pmd, start);
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do {
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if (!pte_none(*src_pte))
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/*
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* Resume will overwrite areas that may be marked
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* read only (code, rodata). Clear the RDONLY bit from
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* the temporary mappings we use during restore.
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*/
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set_pte(dst_pte, __pte(pte_val(*src_pte) & ~PTE_RDONLY));
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_copy_pte(dst_pte, src_pte, addr);
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} while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
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return 0;
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@ -139,4 +139,43 @@ void __kernel_map_pages(struct page *page, int numpages, int enable)
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__pgprot(0),
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__pgprot(PTE_VALID));
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}
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#endif
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#ifdef CONFIG_HIBERNATION
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/*
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* When built with CONFIG_DEBUG_PAGEALLOC and CONFIG_HIBERNATION, this function
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* is used to determine if a linear map page has been marked as not-valid by
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* CONFIG_DEBUG_PAGEALLOC. Walk the page table and check the PTE_VALID bit.
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* This is based on kern_addr_valid(), which almost does what we need.
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*
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* Because this is only called on the kernel linear map, p?d_sect() implies
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* p?d_present(). When debug_pagealloc is enabled, sections mappings are
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* disabled.
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*/
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bool kernel_page_present(struct page *page)
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{
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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unsigned long addr = (unsigned long)page_address(page);
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pgd = pgd_offset_k(addr);
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if (pgd_none(*pgd))
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return false;
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pud = pud_offset(pgd, addr);
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if (pud_none(*pud))
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return false;
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if (pud_sect(*pud))
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return true;
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pmd = pmd_offset(pud, addr);
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if (pmd_none(*pmd))
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return false;
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if (pmd_sect(*pmd))
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return true;
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pte = pte_offset_kernel(pmd, addr);
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return pte_valid(*pte);
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}
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#endif /* CONFIG_HIBERNATION */
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#endif /* CONFIG_DEBUG_PAGEALLOC */
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