From 5ebe3a44cc744d11cb60d8438106a9322b7c04dc Mon Sep 17 00:00:00 2001 From: James Morse Date: Wed, 24 Aug 2016 18:27:30 +0100 Subject: [PATCH] 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 da24eb1f3f9e2c7b75c5f8c40d8e48e2c4789596. Reported-by: Will Deacon Signed-off-by: James Morse Cc: Catalin Marinas Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon --- arch/arm64/Kconfig | 1 - arch/arm64/include/asm/pgtable.h | 10 +++++++ arch/arm64/kernel/hibernate.c | 45 +++++++++++++++++++++++++------- arch/arm64/mm/pageattr.c | 41 ++++++++++++++++++++++++++++- 4 files changed, 86 insertions(+), 11 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index bc3f00f586f1..9be0c164df4e 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -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 diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 7ba1cebb64d9..ffbb9a520563 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -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); diff --git a/arch/arm64/kernel/hibernate.c b/arch/arm64/kernel/hibernate.c index b4082017c4cb..71d82cfb62f5 100644 --- a/arch/arm64/kernel/hibernate.c +++ b/arch/arm64/kernel/hibernate.c @@ -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; diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index ca6d268e3313..8def55e7249b 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -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 */ -- 2.20.1