diff options
Diffstat (limited to 'arch/x86/include/asm/pgtable-3level.h')
| -rw-r--r-- | arch/x86/include/asm/pgtable-3level.h | 203 |
1 files changed, 60 insertions, 143 deletions
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h index e896ebef8c24..dabafba957ea 100644 --- a/arch/x86/include/asm/pgtable-3level.h +++ b/arch/x86/include/asm/pgtable-3level.h @@ -2,8 +2,6 @@ #ifndef _ASM_X86_PGTABLE_3LEVEL_H #define _ASM_X86_PGTABLE_3LEVEL_H -#include <asm/atomic64_32.h> - /* * Intel Physical Address Extension (PAE) Mode - three-level page * tables on PPro+ CPUs. @@ -21,7 +19,15 @@ pr_err("%s:%d: bad pgd %p(%016Lx)\n", \ __FILE__, __LINE__, &(e), pgd_val(e)) -/* Rules for using set_pte: the pte being assigned *must* be +#define pxx_xchg64(_pxx, _ptr, _val) ({ \ + _pxx##val_t *_p = (_pxx##val_t *)_ptr; \ + _pxx##val_t _o = *_p; \ + do { } while (!try_cmpxchg64(_p, &_o, (_val))); \ + native_make_##_pxx(_o); \ +}) + +/* + * Rules for using set_pte: the pte being assigned *must* be * either not present or in a state where the hardware will * not attempt to update the pte. In places where this is * not possible, use pte_get_and_clear to obtain the old pte @@ -29,83 +35,27 @@ */ static inline void native_set_pte(pte_t *ptep, pte_t pte) { - ptep->pte_high = pte.pte_high; + WRITE_ONCE(ptep->pte_high, pte.pte_high); smp_wmb(); - ptep->pte_low = pte.pte_low; -} - -#define pmd_read_atomic pmd_read_atomic -/* - * pte_offset_map_lock() on 32-bit PAE kernels was reading the pmd_t with - * a "*pmdp" dereference done by GCC. Problem is, in certain places - * where pte_offset_map_lock() is called, concurrent page faults are - * allowed, if the mmap_lock is hold for reading. An example is mincore - * vs page faults vs MADV_DONTNEED. On the page fault side - * pmd_populate() rightfully does a set_64bit(), but if we're reading the - * pmd_t with a "*pmdp" on the mincore side, a SMP race can happen - * because GCC will not read the 64-bit value of the pmd atomically. - * - * To fix this all places running pte_offset_map_lock() while holding the - * mmap_lock in read mode, shall read the pmdp pointer using this - * function to know if the pmd is null or not, and in turn to know if - * they can run pte_offset_map_lock() or pmd_trans_huge() or other pmd - * operations. - * - * Without THP if the mmap_lock is held for reading, the pmd can only - * transition from null to not null while pmd_read_atomic() runs. So - * we can always return atomic pmd values with this function. - * - * With THP if the mmap_lock is held for reading, the pmd can become - * trans_huge or none or point to a pte (and in turn become "stable") - * at any time under pmd_read_atomic(). We could read it truly - * atomically here with an atomic64_read() for the THP enabled case (and - * it would be a whole lot simpler), but to avoid using cmpxchg8b we - * only return an atomic pmdval if the low part of the pmdval is later - * found to be stable (i.e. pointing to a pte). We are also returning a - * 'none' (zero) pmdval if the low part of the pmd is zero. - * - * In some cases the high and low part of the pmdval returned may not be - * consistent if THP is enabled (the low part may point to previously - * mapped hugepage, while the high part may point to a more recently - * mapped hugepage), but pmd_none_or_trans_huge_or_clear_bad() only - * needs the low part of the pmd to be read atomically to decide if the - * pmd is unstable or not, with the only exception when the low part - * of the pmd is zero, in which case we return a 'none' pmd. - */ -static inline pmd_t pmd_read_atomic(pmd_t *pmdp) -{ - pmdval_t ret; - u32 *tmp = (u32 *)pmdp; - - ret = (pmdval_t) (*tmp); - if (ret) { - /* - * If the low part is null, we must not read the high part - * or we can end up with a partial pmd. - */ - smp_rmb(); - ret |= ((pmdval_t)*(tmp + 1)) << 32; - } - - return (pmd_t) { ret }; + WRITE_ONCE(ptep->pte_low, pte.pte_low); } static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte) { - set_64bit((unsigned long long *)(ptep), native_pte_val(pte)); + pxx_xchg64(pte, ptep, native_pte_val(pte)); } static inline void native_set_pmd(pmd_t *pmdp, pmd_t pmd) { - set_64bit((unsigned long long *)(pmdp), native_pmd_val(pmd)); + pxx_xchg64(pmd, pmdp, native_pmd_val(pmd)); } static inline void native_set_pud(pud_t *pudp, pud_t pud) { -#ifdef CONFIG_PAGE_TABLE_ISOLATION +#ifdef CONFIG_MITIGATION_PAGE_TABLE_ISOLATION pud.p4d.pgd = pti_set_user_pgtbl(&pudp->p4d.pgd, pud.p4d.pgd); #endif - set_64bit((unsigned long long *)(pudp), native_pud_val(pud)); + pxx_xchg64(pud, pudp, native_pud_val(pud)); } /* @@ -116,17 +66,16 @@ static inline void native_set_pud(pud_t *pudp, pud_t pud) static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { - ptep->pte_low = 0; + WRITE_ONCE(ptep->pte_low, 0); smp_wmb(); - ptep->pte_high = 0; + WRITE_ONCE(ptep->pte_high, 0); } -static inline void native_pmd_clear(pmd_t *pmd) +static inline void native_pmd_clear(pmd_t *pmdp) { - u32 *tmp = (u32 *)pmd; - *tmp = 0; + WRITE_ONCE(pmdp->pmd_low, 0); smp_wmb(); - *(tmp + 1) = 0; + WRITE_ONCE(pmdp->pmd_high, 0); } static inline void native_pud_clear(pud_t *pudp) @@ -149,41 +98,26 @@ static inline void pud_clear(pud_t *pudp) */ } + #ifdef CONFIG_SMP static inline pte_t native_ptep_get_and_clear(pte_t *ptep) { - pte_t res; - - res.pte = (pteval_t)arch_atomic64_xchg((atomic64_t *)ptep, 0); - - return res; + return pxx_xchg64(pte, ptep, 0ULL); } -#else -#define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp) -#endif -union split_pmd { - struct { - u32 pmd_low; - u32 pmd_high; - }; - pmd_t pmd; -}; - -#ifdef CONFIG_SMP static inline pmd_t native_pmdp_get_and_clear(pmd_t *pmdp) { - union split_pmd res, *orig = (union split_pmd *)pmdp; - - /* xchg acts as a barrier before setting of the high bits */ - res.pmd_low = xchg(&orig->pmd_low, 0); - res.pmd_high = orig->pmd_high; - orig->pmd_high = 0; + return pxx_xchg64(pmd, pmdp, 0ULL); +} - return res.pmd; +static inline pud_t native_pudp_get_and_clear(pud_t *pudp) +{ + return pxx_xchg64(pud, pudp, 0ULL); } #else +#define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp) #define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp) +#define native_pudp_get_and_clear(xp) native_local_pudp_get_and_clear(xp) #endif #ifndef pmdp_establish @@ -199,67 +133,47 @@ static inline pmd_t pmdp_establish(struct vm_area_struct *vma, * anybody. */ if (!(pmd_val(pmd) & _PAGE_PRESENT)) { - union split_pmd old, new, *ptr; - - ptr = (union split_pmd *)pmdp; - - new.pmd = pmd; - /* xchg acts as a barrier before setting of the high bits */ - old.pmd_low = xchg(&ptr->pmd_low, new.pmd_low); - old.pmd_high = ptr->pmd_high; - ptr->pmd_high = new.pmd_high; - return old.pmd; - } - - do { - old = *pmdp; - } while (cmpxchg64(&pmdp->pmd, old.pmd, pmd.pmd) != old.pmd); + old.pmd_low = xchg(&pmdp->pmd_low, pmd.pmd_low); + old.pmd_high = READ_ONCE(pmdp->pmd_high); + WRITE_ONCE(pmdp->pmd_high, pmd.pmd_high); - return old; -} -#endif - -#ifdef CONFIG_SMP -union split_pud { - struct { - u32 pud_low; - u32 pud_high; - }; - pud_t pud; -}; - -static inline pud_t native_pudp_get_and_clear(pud_t *pudp) -{ - union split_pud res, *orig = (union split_pud *)pudp; - -#ifdef CONFIG_PAGE_TABLE_ISOLATION - pti_set_user_pgtbl(&pudp->p4d.pgd, __pgd(0)); -#endif - - /* xchg acts as a barrier before setting of the high bits */ - res.pud_low = xchg(&orig->pud_low, 0); - res.pud_high = orig->pud_high; - orig->pud_high = 0; + return old; + } - return res.pud; + return pxx_xchg64(pmd, pmdp, pmd.pmd); } -#else -#define native_pudp_get_and_clear(xp) native_local_pudp_get_and_clear(xp) #endif -/* Encode and de-code a swap entry */ +/* + * Encode/decode swap entries and swap PTEs. Swap PTEs are all PTEs that + * are !pte_none() && !pte_present(). + * + * Format of swap PTEs: + * + * 6 6 6 6 5 5 5 5 5 5 5 5 5 5 4 4 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3 + * 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 + * < type -> <---------------------- offset ---------------------- + * + * 3 3 2 2 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 + * 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 9 8 7 6 5 4 3 2 1 0 + * --------------------------------------------> 0 E 0 0 0 0 0 0 0 + * + * E is the exclusive marker that is not stored in swap entries. + */ #define SWP_TYPE_BITS 5 +#define _SWP_TYPE_MASK ((1U << SWP_TYPE_BITS) - 1) #define SWP_OFFSET_FIRST_BIT (_PAGE_BIT_PROTNONE + 1) /* We always extract/encode the offset by shifting it all the way up, and then down again */ #define SWP_OFFSET_SHIFT (SWP_OFFSET_FIRST_BIT + SWP_TYPE_BITS) -#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > 5) -#define __swp_type(x) (((x).val) & 0x1f) -#define __swp_offset(x) ((x).val >> 5) -#define __swp_entry(type, offset) ((swp_entry_t){(type) | (offset) << 5}) +#define MAX_SWAPFILES_CHECK() BUILD_BUG_ON(MAX_SWAPFILES_SHIFT > SWP_TYPE_BITS) +#define __swp_type(x) (((x).val) & _SWP_TYPE_MASK) +#define __swp_offset(x) ((x).val >> SWP_TYPE_BITS) +#define __swp_entry(type, offset) ((swp_entry_t){((type) & _SWP_TYPE_MASK) \ + | (offset) << SWP_TYPE_BITS}) /* * Normally, __swp_entry() converts from arch-independent swp_entry_t to @@ -287,6 +201,9 @@ static inline pud_t native_pudp_get_and_clear(pud_t *pudp) #define __pte_to_swp_entry(pte) (__swp_entry(__pteval_swp_type(pte), \ __pteval_swp_offset(pte))) +/* We borrow bit 7 to store the exclusive marker in swap PTEs. */ +#define _PAGE_SWP_EXCLUSIVE _PAGE_PSE + #include <asm/pgtable-invert.h> #endif /* _ASM_X86_PGTABLE_3LEVEL_H */ |