From b847415ce96efef819534b230d84695b1bc6d36b Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Fri, 11 Sep 2015 18:22:00 +0100 Subject: arm64: Fix the pte_hw_dirty() check when AF/DBM is enabled Commit 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits") introduced support for handling hardware updates of the access flag and dirty status. The PTE is automatically dirtied in hardware (if supported) by clearing the PTE_RDONLY bit when the PTE_DBM/PTE_WRITE bit is set. The pte_hw_dirty() macro was added to detect a hardware dirtied pte. The pte_dirty() macro checks for both software PTE_DIRTY and pte_hw_dirty(). Functions like pte_modify() clear the PTE_RDONLY bit since it is meant to be set in set_pte_at() when written to memory. In such cases, pte_hw_dirty() would return true even though such pte is clean. This patch changes pte_hw_dirty() to test the PTE_DBM/PTE_WRITE bit together with PTE_RDONLY. Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits") Reported-by: Julien Grall Tested-by: Julien Grall Tested-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Will Deacon --- arch/arm64/include/asm/pgtable.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/arm64/include/asm/pgtable.h') diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 6900b2d95371..69207f016891 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -146,7 +146,7 @@ extern struct page *empty_zero_page; #define pte_exec(pte) (!(pte_val(pte) & PTE_UXN)) #ifdef CONFIG_ARM64_HW_AFDBM -#define pte_hw_dirty(pte) (!(pte_val(pte) & PTE_RDONLY)) +#define pte_hw_dirty(pte) (pte_write(pte) && !(pte_val(pte) & PTE_RDONLY)) #else #define pte_hw_dirty(pte) (0) #endif @@ -238,7 +238,7 @@ extern void __sync_icache_dcache(pte_t pteval, unsigned long addr); * When hardware DBM is not present, the sofware PTE_DIRTY bit is updated via * the page fault mechanism. Checking the dirty status of a pte becomes: * - * PTE_DIRTY || !PTE_RDONLY + * PTE_DIRTY || (PTE_WRITE && !PTE_RDONLY) */ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte) -- cgit From 62d96c71d248834af2891293dc23cc344ae2ec36 Mon Sep 17 00:00:00 2001 From: Catalin Marinas Date: Fri, 11 Sep 2015 18:22:01 +0100 Subject: arm64: Fix pte_modify() to preserve the hardware dirty information The pte_modify() function with hardware AF/DBM enabled must transfer the hardware dirty information to the software PTE_DIRTY bit. However, it was setting this bit in newprot and the mask does not cover such bit. This patch sets PTE_DIRTY on the original pte which will be preserved in the returned value. Fixes: 2f4b829c625e ("arm64: Add support for hardware updates of the access and dirty pte bits") Cc: Julien Grall Tested-by: Julien Grall Tested-by: Will Deacon Signed-off-by: Catalin Marinas Signed-off-by: Will Deacon --- arch/arm64/include/asm/pgtable.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/arm64/include/asm/pgtable.h') diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 69207f016891..31df98adf005 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -503,7 +503,7 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) PTE_PROT_NONE | PTE_WRITE | PTE_TYPE_MASK; /* preserve the hardware dirty information */ if (pte_hw_dirty(pte)) - newprot |= PTE_DIRTY; + pte = pte_mkdirty(pte); pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask); return pte; } -- cgit From bf950040a53da35522e38066d9eb6ab7a1c9d136 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 11 Sep 2015 18:22:02 +0100 Subject: arm64: pgtable: use a single bit for PTE_WRITE regardless of DBM Depending on CONFIG_ARM64_HW_AFDBM, we use either bit 57 or 51 of the pte to represent PTE_WRITE. Given that bit 51 is reserved prior to ARMv8.1, we can just use that bit regardless of the config option. That also matches what happens if a kernel configured with ARM64_HW_AFDBM=y is run on a CPU without the DBM functionality. Cc: Julien Grall Tested-by: Julien Grall Signed-off-by: Will Deacon --- arch/arm64/include/asm/pgtable.h | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) (limited to 'arch/arm64/include/asm/pgtable.h') diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 31df98adf005..b0329be95cb1 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -26,13 +26,9 @@ * Software defined PTE bits definition. */ #define PTE_VALID (_AT(pteval_t, 1) << 0) +#define PTE_WRITE (PTE_DBM) /* same as DBM (51) */ #define PTE_DIRTY (_AT(pteval_t, 1) << 55) #define PTE_SPECIAL (_AT(pteval_t, 1) << 56) -#ifdef CONFIG_ARM64_HW_AFDBM -#define PTE_WRITE (PTE_DBM) /* same as DBM */ -#else -#define PTE_WRITE (_AT(pteval_t, 1) << 57) -#endif #define PTE_PROT_NONE (_AT(pteval_t, 1) << 58) /* only when !PTE_VALID */ /* -- cgit