diff options
| -rw-r--r-- | arch/arm64/Kconfig | 17 | ||||
| -rw-r--r-- | arch/arm64/include/asm/pgtable-hwdef.h | 3 | ||||
| -rw-r--r-- | arch/arm64/include/asm/pgtable.h | 147 | ||||
| -rw-r--r-- | arch/arm64/mm/proc.S | 13 |
4 files changed, 178 insertions, 2 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 318175f62c24..40f717f8820a 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -469,6 +469,23 @@ config ARM64_VA_BITS default 42 if ARM64_VA_BITS_42 default 48 if ARM64_VA_BITS_48 +config ARM64_HW_AFDBM + bool "Support for hardware updates of the Access and Dirty page flags" + default y + help + The ARMv8.1 architecture extensions introduce support for + hardware updates of the access and dirty information in page + table entries. When enabled in TCR_EL1 (HA and HD bits) on + capable processors, accesses to pages with PTE_AF cleared will + set this bit instead of raising an access flag fault. + Similarly, writes to read-only pages with the DBM bit set will + clear the read-only bit (AP[2]) instead of raising a + permission fault. + + Kernels built with this configuration option enabled continue + to work on pre-ARMv8.1 hardware and the performance impact is + minimal. If unsure, say Y. + config CPU_BIG_ENDIAN bool "Build big-endian kernel" help diff --git a/arch/arm64/include/asm/pgtable-hwdef.h b/arch/arm64/include/asm/pgtable-hwdef.h index 59bfae75dc98..24154b055835 100644 --- a/arch/arm64/include/asm/pgtable-hwdef.h +++ b/arch/arm64/include/asm/pgtable-hwdef.h @@ -104,6 +104,7 @@ #define PTE_SHARED (_AT(pteval_t, 3) << 8) /* SH[1:0], inner shareable */ #define PTE_AF (_AT(pteval_t, 1) << 10) /* Access Flag */ #define PTE_NG (_AT(pteval_t, 1) << 11) /* nG */ +#define PTE_DBM (_AT(pteval_t, 1) << 51) /* Dirty Bit Management */ #define PTE_PXN (_AT(pteval_t, 1) << 53) /* Privileged XN */ #define PTE_UXN (_AT(pteval_t, 1) << 54) /* User XN */ @@ -168,5 +169,7 @@ #define TCR_TG1_64K (UL(3) << 30) #define TCR_ASID16 (UL(1) << 36) #define TCR_TBI0 (UL(1) << 37) +#define TCR_HA (UL(1) << 39) +#define TCR_HD (UL(1) << 40) #endif diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 4d5c812847e9..8212e6aa0fb1 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -16,6 +16,7 @@ #ifndef __ASM_PGTABLE_H #define __ASM_PGTABLE_H +#include <asm/bug.h> #include <asm/proc-fns.h> #include <asm/memory.h> @@ -27,7 +28,11 @@ #define PTE_VALID (_AT(pteval_t, 1) << 0) #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 */ /* @@ -48,6 +53,9 @@ #define FIRST_USER_ADDRESS 0UL #ifndef __ASSEMBLY__ + +#include <linux/mmdebug.h> + extern void __pte_error(const char *file, int line, unsigned long val); extern void __pmd_error(const char *file, int line, unsigned long val); extern void __pud_error(const char *file, int line, unsigned long val); @@ -137,12 +145,20 @@ extern struct page *empty_zero_page; * The following only work if pte_present(). Undefined behaviour otherwise. */ #define pte_present(pte) (!!(pte_val(pte) & (PTE_VALID | PTE_PROT_NONE))) -#define pte_dirty(pte) (!!(pte_val(pte) & PTE_DIRTY)) #define pte_young(pte) (!!(pte_val(pte) & PTE_AF)) #define pte_special(pte) (!!(pte_val(pte) & PTE_SPECIAL)) #define pte_write(pte) (!!(pte_val(pte) & PTE_WRITE)) #define pte_exec(pte) (!(pte_val(pte) & PTE_UXN)) +#ifdef CONFIG_ARM64_HW_AFDBM +#define pte_hw_dirty(pte) (!(pte_val(pte) & PTE_RDONLY)) +#else +#define pte_hw_dirty(pte) (0) +#endif +#define pte_sw_dirty(pte) (!!(pte_val(pte) & PTE_DIRTY)) +#define pte_dirty(pte) (pte_sw_dirty(pte) || pte_hw_dirty(pte)) + +#define pte_valid(pte) (!!(pte_val(pte) && PTE_VALID)) #define pte_valid_user(pte) \ ((pte_val(pte) & (PTE_VALID | PTE_USER)) == (PTE_VALID | PTE_USER)) #define pte_valid_not_user(pte) \ @@ -209,20 +225,49 @@ static inline void set_pte(pte_t *ptep, pte_t pte) } } +struct mm_struct; +struct vm_area_struct; + extern void __sync_icache_dcache(pte_t pteval, unsigned long addr); +/* + * PTE bits configuration in the presence of hardware Dirty Bit Management + * (PTE_WRITE == PTE_DBM): + * + * Dirty Writable | PTE_RDONLY PTE_WRITE PTE_DIRTY (sw) + * 0 0 | 1 0 0 + * 0 1 | 1 1 0 + * 1 0 | 1 0 1 + * 1 1 | 0 1 x + * + * 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 + */ static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte) { if (pte_valid_user(pte)) { if (!pte_special(pte) && pte_exec(pte)) __sync_icache_dcache(pte, addr); - if (pte_dirty(pte) && pte_write(pte)) + if (pte_sw_dirty(pte) && pte_write(pte)) pte_val(pte) &= ~PTE_RDONLY; else pte_val(pte) |= PTE_RDONLY; } + /* + * If the existing pte is valid, check for potential race with + * hardware updates of the pte (ptep_set_access_flags safely changes + * valid ptes without going through an invalid entry). + */ + if (IS_ENABLED(CONFIG_DEBUG_VM) && IS_ENABLED(CONFIG_ARM64_HW_AFDBM) && + pte_valid(*ptep)) { + BUG_ON(!pte_young(pte)); + BUG_ON(pte_write(*ptep) && !pte_dirty(pte)); + } + set_pte(ptep, pte); } @@ -461,6 +506,9 @@ static inline pte_t pte_modify(pte_t pte, pgprot_t newprot) { const pteval_t mask = PTE_USER | PTE_PXN | PTE_UXN | PTE_RDONLY | PTE_PROT_NONE | PTE_WRITE | PTE_TYPE_MASK; + /* preserve the hardware dirty information */ + if (pte_hw_dirty(pte)) + newprot |= PTE_DIRTY; pte_val(pte) = (pte_val(pte) & ~mask) | (pgprot_val(newprot) & mask); return pte; } @@ -470,6 +518,101 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t newprot) return pte_pmd(pte_modify(pmd_pte(pmd), newprot)); } +#ifdef CONFIG_ARM64_HW_AFDBM +/* + * Atomic pte/pmd modifications. + */ +#define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG +static inline int ptep_test_and_clear_young(struct vm_area_struct *vma, + unsigned long address, + pte_t *ptep) +{ + pteval_t pteval; + unsigned int tmp, res; + + asm volatile("// ptep_test_and_clear_young\n" + " prfm pstl1strm, %2\n" + "1: ldxr %0, %2\n" + " ubfx %w3, %w0, %5, #1 // extract PTE_AF (young)\n" + " and %0, %0, %4 // clear PTE_AF\n" + " stxr %w1, %0, %2\n" + " cbnz %w1, 1b\n" + : "=&r" (pteval), "=&r" (tmp), "+Q" (pte_val(*ptep)), "=&r" (res) + : "L" (~PTE_AF), "I" (ilog2(PTE_AF))); + + return res; +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#define __HAVE_ARCH_PMDP_TEST_AND_CLEAR_YOUNG +static inline int pmdp_test_and_clear_young(struct vm_area_struct *vma, + unsigned long address, + pmd_t *pmdp) +{ + return ptep_test_and_clear_young(vma, address, (pte_t *)pmdp); +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +#define __HAVE_ARCH_PTEP_GET_AND_CLEAR +static inline pte_t ptep_get_and_clear(struct mm_struct *mm, + unsigned long address, pte_t *ptep) +{ + pteval_t old_pteval; + unsigned int tmp; + + asm volatile("// ptep_get_and_clear\n" + " prfm pstl1strm, %2\n" + "1: ldxr %0, %2\n" + " stxr %w1, xzr, %2\n" + " cbnz %w1, 1b\n" + : "=&r" (old_pteval), "=&r" (tmp), "+Q" (pte_val(*ptep))); + + return __pte(old_pteval); +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#define __HAVE_ARCH_PMDP_GET_AND_CLEAR +static inline pmd_t pmdp_get_and_clear(struct mm_struct *mm, + unsigned long address, pmd_t *pmdp) +{ + return pte_pmd(ptep_get_and_clear(mm, address, (pte_t *)pmdp)); +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +/* + * ptep_set_wrprotect - mark read-only while trasferring potential hardware + * dirty status (PTE_DBM && !PTE_RDONLY) to the software PTE_DIRTY bit. + */ +#define __HAVE_ARCH_PTEP_SET_WRPROTECT +static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long address, pte_t *ptep) +{ + pteval_t pteval; + unsigned long tmp; + + asm volatile("// ptep_set_wrprotect\n" + " prfm pstl1strm, %2\n" + "1: ldxr %0, %2\n" + " tst %0, %4 // check for hw dirty (!PTE_RDONLY)\n" + " csel %1, %3, xzr, eq // set PTE_DIRTY|PTE_RDONLY if dirty\n" + " orr %0, %0, %1 // if !dirty, PTE_RDONLY is already set\n" + " and %0, %0, %5 // clear PTE_WRITE/PTE_DBM\n" + " stxr %w1, %0, %2\n" + " cbnz %w1, 1b\n" + : "=&r" (pteval), "=&r" (tmp), "+Q" (pte_val(*ptep)) + : "r" (PTE_DIRTY|PTE_RDONLY), "L" (PTE_RDONLY), "L" (~PTE_WRITE) + : "cc"); +} + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +#define __HAVE_ARCH_PMDP_SET_WRPROTECT +static inline void pmdp_set_wrprotect(struct mm_struct *mm, + unsigned long address, pmd_t *pmdp) +{ + ptep_set_wrprotect(mm, address, (pte_t *)pmdp); +} +#endif +#endif /* CONFIG_ARM64_HW_AFDBM */ + extern pgd_t swapper_pg_dir[PTRS_PER_PGD]; extern pgd_t idmap_pg_dir[PTRS_PER_PGD]; diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 39139a3aa16d..a8be513dff6f 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -196,6 +196,19 @@ ENTRY(__cpu_setup) */ mrs x9, ID_AA64MMFR0_EL1 bfi x10, x9, #32, #3 +#ifdef CONFIG_ARM64_HW_AFDBM + /* + * Hardware update of the Access and Dirty bits. + */ + mrs x9, ID_AA64MMFR1_EL1 + and x9, x9, #0xf + cbz x9, 2f + cmp x9, #2 + b.lt 1f + orr x10, x10, #TCR_HD // hardware Dirty flag update +1: orr x10, x10, #TCR_HA // hardware Access flag update +2: +#endif /* CONFIG_ARM64_HW_AFDBM */ msr tcr_el1, x10 ret // return to head.S ENDPROC(__cpu_setup) |