x86/mm/pae: Make pmd_t similar to pte_t

Instead of mucking about with at least 2 different ways of fudging
it, do the same thing we do for pte_t.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20221022114424.580310787%40infradead.org

diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index 28421a8..28556d2 100644 (file)
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -87,7 +87,7 @@ static inline pmd_t pmd_read_atomic(pmd_t *pmdp)
                ret |= ((pmdval_t)*(tmp + 1)) << 32;
        }
 
-       return (pmd_t) { ret };
+       return (pmd_t) { .pmd = ret };
 }
 
 static inline void native_set_pte_atomic(pte_t *ptep, pte_t pte)
@@ -121,12 +121,11 @@ static inline void native_pte_clear(struct mm_struct *mm, unsigned long addr,
        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;
+       pmdp->pmd_low = 0;
        smp_wmb();
-       *(tmp + 1) = 0;
+       pmdp->pmd_high = 0;
 }
 
 static inline void native_pud_clear(pud_t *pudp)
@@ -162,25 +161,17 @@ static inline pte_t native_ptep_get_and_clear(pte_t *ptep)
 #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;
+       pmd_t res;
 
        /* 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;
+       res.pmd_low = xchg(&pmdp->pmd_low, 0);
+       res.pmd_high = READ_ONCE(pmdp->pmd_high);
+       WRITE_ONCE(pmdp->pmd_high, 0);
 
-       return res.pmd;
+       return res;
 }
 #else
 #define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
@@ -199,17 +190,12 @@ 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;
+               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;
        }
 
        do {

diff --git a/arch/x86/include/asm/pgtable-3level_types.h b/arch/x86/include/asm/pgtable-3level_types.h
index 56baf43..8091134 100644 (file)
--- a/arch/x86/include/asm/pgtable-3level_types.h
+++ b/arch/x86/include/asm/pgtable-3level_types.h
@@ -18,6 +18,13 @@ typedef union {
        };
        pteval_t pte;
 } pte_t;
+
+typedef union {
+       struct {
+               unsigned long pmd_low, pmd_high;
+       };
+       pmdval_t pmd;
+} pmd_t;
 #endif /* !__ASSEMBLY__ */
 
 #define SHARED_KERNEL_PMD      (!static_cpu_has(X86_FEATURE_PTI))

diff --git a/arch/x86/include/asm/pgtable_64_types.h b/arch/x86/include/asm/pgtable_64_types.h
index 04f3606..38bf837 100644 (file)
--- a/arch/x86/include/asm/pgtable_64_types.h
+++ b/arch/x86/include/asm/pgtable_64_types.h
@@ -19,6 +19,7 @@ typedef unsigned long pgdval_t;
 typedef unsigned long  pgprotval_t;
 
 typedef struct { pteval_t pte; } pte_t;
+typedef struct { pmdval_t pmd; } pmd_t;
 
 #ifdef CONFIG_X86_5LEVEL
 extern unsigned int __pgtable_l5_enabled;

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index aa174fe..447d4be 100644 (file)
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -361,11 +361,9 @@ static inline pudval_t native_pud_val(pud_t pud)
 #endif
 
 #if CONFIG_PGTABLE_LEVELS > 2
-typedef struct { pmdval_t pmd; } pmd_t;
-
 static inline pmd_t native_make_pmd(pmdval_t val)
 {
-       return (pmd_t) { val };
+       return (pmd_t) { .pmd = val };
 }
 
 static inline pmdval_t native_pmd_val(pmd_t pmd)