From: Huacai Chen chenhuacai@loongson.cn

commit 4574815abf43e2bf05643e1b3f7a2e5d6df894f0 upstream

As very well explained in commit 20a004e7b017cce282 ("arm64: mm: Use READ_ONCE/WRITE_ONCE when accessing page tables"), an architecture whose page table walker can modify the PTE in parallel must use READ_ONCE()/ WRITE_ONCE() macro to avoid any compiler transformation.

So apply that to LoongArch which is such an architecture, in order to avoid potential problems.

Similar to commit edf955647269422e ("riscv: Use accessors to page table entries instead of direct dereference").

Signed-off-by: Huacai Chen chenhuacai@loongson.cn --- arch/loongarch/include/asm/hugetlb.h | 4 +-- arch/loongarch/include/asm/kfence.h | 6 ++-- arch/loongarch/include/asm/pgtable.h | 48 +++++++++++++++++----------- arch/loongarch/kvm/mmu.c | 8 ++--- arch/loongarch/mm/hugetlbpage.c | 6 ++-- arch/loongarch/mm/init.c | 10 +++--- arch/loongarch/mm/kasan_init.c | 10 +++--- arch/loongarch/mm/pgtable.c | 2 +- 8 files changed, 52 insertions(+), 42 deletions(-)

diff --git a/arch/loongarch/include/asm/hugetlb.h b/arch/loongarch/include/asm/hugetlb.h index aa44b3fe43dd..5da32c00d483 100644 --- a/arch/loongarch/include/asm/hugetlb.h +++ b/arch/loongarch/include/asm/hugetlb.h @@ -34,7 +34,7 @@ static inline pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { pte_t clear; - pte_t pte = *ptep; + pte_t pte = ptep_get(ptep);

pte_val(clear) = (unsigned long)invalid_pte_table; set_pte_at(mm, addr, ptep, clear); @@ -65,7 +65,7 @@ static inline int huge_ptep_set_access_flags(struct vm_area_struct *vma, pte_t *ptep, pte_t pte, int dirty) { - int changed = !pte_same(*ptep, pte); + int changed = !pte_same(ptep_get(ptep), pte);

if (changed) { set_pte_at(vma->vm_mm, addr, ptep, pte); diff --git a/arch/loongarch/include/asm/kfence.h b/arch/loongarch/include/asm/kfence.h index 6c82aea1c993..2835b41d2a84 100644 --- a/arch/loongarch/include/asm/kfence.h +++ b/arch/loongarch/include/asm/kfence.h @@ -43,13 +43,13 @@ static inline bool kfence_protect_page(unsigned long addr, bool protect) { pte_t *pte = virt_to_kpte(addr);

- if (WARN_ON(!pte) || pte_none(*pte)) + if (WARN_ON(!pte) || pte_none(ptep_get(pte))) return false;

if (protect) - set_pte(pte, __pte(pte_val(*pte) & ~(_PAGE_VALID | _PAGE_PRESENT))); + set_pte(pte, __pte(pte_val(ptep_get(pte)) & ~(_PAGE_VALID | _PAGE_PRESENT))); else - set_pte(pte, __pte(pte_val(*pte) | (_PAGE_VALID | _PAGE_PRESENT))); + set_pte(pte, __pte(pte_val(ptep_get(pte)) | (_PAGE_VALID | _PAGE_PRESENT)));

preempt_disable(); local_flush_tlb_one(addr); diff --git a/arch/loongarch/include/asm/pgtable.h b/arch/loongarch/include/asm/pgtable.h index 29d9b12298bc..2df497d2f864 100644 --- a/arch/loongarch/include/asm/pgtable.h +++ b/arch/loongarch/include/asm/pgtable.h @@ -106,6 +106,9 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; #define KFENCE_AREA_START (VMEMMAP_END + 1) #define KFENCE_AREA_END (KFENCE_AREA_START + KFENCE_AREA_SIZE - 1)

+#define ptep_get(ptep) READ_ONCE(*(ptep)) +#define pmdp_get(pmdp) READ_ONCE(*(pmdp)) + #define pte_ERROR(e) \ pr_err("%s:%d: bad pte %016lx.\n", __FILE__, __LINE__, pte_val(e)) #ifndef __PAGETABLE_PMD_FOLDED @@ -147,11 +150,6 @@ static inline int p4d_present(p4d_t p4d) return p4d_val(p4d) != (unsigned long)invalid_pud_table; }

-static inline void p4d_clear(p4d_t *p4dp) -{ - p4d_val(*p4dp) = (unsigned long)invalid_pud_table; -} - static inline pud_t *p4d_pgtable(p4d_t p4d) { return (pud_t *)p4d_val(p4d); @@ -159,7 +157,12 @@ static inline pud_t *p4d_pgtable(p4d_t p4d)

static inline void set_p4d(p4d_t *p4d, p4d_t p4dval) { - *p4d = p4dval; + WRITE_ONCE(*p4d, p4dval); +} + +static inline void p4d_clear(p4d_t *p4dp) +{ + set_p4d(p4dp, __p4d((unsigned long)invalid_pud_table)); }

#define p4d_phys(p4d) PHYSADDR(p4d_val(p4d)) @@ -193,17 +196,20 @@ static inline int pud_present(pud_t pud) return pud_val(pud) != (unsigned long)invalid_pmd_table; }

-static inline void pud_clear(pud_t *pudp) +static inline pmd_t *pud_pgtable(pud_t pud) { - pud_val(*pudp) = ((unsigned long)invalid_pmd_table); + return (pmd_t *)pud_val(pud); }

-static inline pmd_t *pud_pgtable(pud_t pud) +static inline void set_pud(pud_t *pud, pud_t pudval) { - return (pmd_t *)pud_val(pud); + WRITE_ONCE(*pud, pudval); }

-#define set_pud(pudptr, pudval) do { *(pudptr) = (pudval); } while (0) +static inline void pud_clear(pud_t *pudp) +{ + set_pud(pudp, __pud((unsigned long)invalid_pmd_table)); +}

#define pud_phys(pud) PHYSADDR(pud_val(pud)) #define pud_page(pud) (pfn_to_page(pud_phys(pud) >> PAGE_SHIFT)) @@ -231,12 +237,15 @@ static inline int pmd_present(pmd_t pmd) return pmd_val(pmd) != (unsigned long)invalid_pte_table; }

-static inline void pmd_clear(pmd_t *pmdp) +static inline void set_pmd(pmd_t *pmd, pmd_t pmdval) { - pmd_val(*pmdp) = ((unsigned long)invalid_pte_table); + WRITE_ONCE(*pmd, pmdval); }

-#define set_pmd(pmdptr, pmdval) do { *(pmdptr) = (pmdval); } while (0) +static inline void pmd_clear(pmd_t *pmdp) +{ + set_pmd(pmdp, __pmd((unsigned long)invalid_pte_table)); +}

#define pmd_phys(pmd) PHYSADDR(pmd_val(pmd))

@@ -314,7 +323,8 @@ extern void paging_init(void);

static inline void set_pte(pte_t *ptep, pte_t pteval) { - *ptep = pteval; + WRITE_ONCE(*ptep, pteval); + if (pte_val(pteval) & _PAGE_GLOBAL) { pte_t *buddy = ptep_buddy(ptep); /* @@ -341,8 +351,8 @@ static inline void set_pte(pte_t *ptep, pte_t pteval) : [buddy] "+m" (buddy->pte), [tmp] "=&r" (tmp) : [global] "r" (page_global)); #else /* !CONFIG_SMP */ - if (pte_none(*buddy)) - pte_val(*buddy) = pte_val(*buddy) | _PAGE_GLOBAL; + if (pte_none(ptep_get(buddy))) + WRITE_ONCE(*buddy, __pte(pte_val(ptep_get(buddy)) | _PAGE_GLOBAL)); #endif /* CONFIG_SMP */ } } @@ -350,7 +360,7 @@ static inline void set_pte(pte_t *ptep, pte_t pteval) static inline void pte_clear(struct mm_struct *mm, unsigned long addr, pte_t *ptep) { /* Preserve global status for the pair */ - if (pte_val(*ptep_buddy(ptep)) & _PAGE_GLOBAL) + if (pte_val(ptep_get(ptep_buddy(ptep))) & _PAGE_GLOBAL) set_pte(ptep, __pte(_PAGE_GLOBAL)); else set_pte(ptep, __pte(0)); @@ -591,7 +601,7 @@ static inline pmd_t pmd_mkinvalid(pmd_t pmd) static inline pmd_t pmdp_huge_get_and_clear(struct mm_struct *mm, unsigned long address, pmd_t *pmdp) { - pmd_t old = *pmdp; + pmd_t old = pmdp_get(pmdp);

pmd_clear(pmdp);

diff --git a/arch/loongarch/kvm/mmu.c b/arch/loongarch/kvm/mmu.c index 80480df5f550..545a824e38b1 100644 --- a/arch/loongarch/kvm/mmu.c +++ b/arch/loongarch/kvm/mmu.c @@ -679,19 +679,19 @@ static int host_pfn_mapping_level(struct kvm *kvm, gfn_t gfn, * value) and then p*d_offset() walks into the target huge page instead * of the old page table (sees the new value). */ - pgd = READ_ONCE(*pgd_offset(kvm->mm, hva)); + pgd = pgdp_get(pgd_offset(kvm->mm, hva)); if (pgd_none(pgd)) goto out;

- p4d = READ_ONCE(*p4d_offset(&pgd, hva)); + p4d = p4dp_get(p4d_offset(&pgd, hva)); if (p4d_none(p4d) || !p4d_present(p4d)) goto out;

- pud = READ_ONCE(*pud_offset(&p4d, hva)); + pud = pudp_get(pud_offset(&p4d, hva)); if (pud_none(pud) || !pud_present(pud)) goto out;

- pmd = READ_ONCE(*pmd_offset(&pud, hva)); + pmd = pmdp_get(pmd_offset(&pud, hva)); if (pmd_none(pmd) || !pmd_present(pmd)) goto out;

diff --git a/arch/loongarch/mm/hugetlbpage.c b/arch/loongarch/mm/hugetlbpage.c index 1e76fcb83093..62ddcea0aa14 100644 --- a/arch/loongarch/mm/hugetlbpage.c +++ b/arch/loongarch/mm/hugetlbpage.c @@ -39,11 +39,11 @@ pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, pmd_t *pmd = NULL;

pgd = pgd_offset(mm, addr); - if (pgd_present(*pgd)) { + if (pgd_present(pgdp_get(pgd))) { p4d = p4d_offset(pgd, addr); - if (p4d_present(*p4d)) { + if (p4d_present(p4dp_get(p4d))) { pud = pud_offset(p4d, addr); - if (pud_present(*pud)) + if (pud_present(pudp_get(pud))) pmd = pmd_offset(pud, addr); } } diff --git a/arch/loongarch/mm/init.c b/arch/loongarch/mm/init.c index 4dd53427f657..71fa4b773eb3 100644 --- a/arch/loongarch/mm/init.c +++ b/arch/loongarch/mm/init.c @@ -140,7 +140,7 @@ void __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node, int __meminit vmemmap_check_pmd(pmd_t *pmd, int node, unsigned long addr, unsigned long next) { - int huge = pmd_val(*pmd) & _PAGE_HUGE; + int huge = pmd_val(pmdp_get(pmd)) & _PAGE_HUGE;

if (huge) vmemmap_verify((pte_t *)pmd, node, addr, next); @@ -172,7 +172,7 @@ pte_t * __init populate_kernel_pte(unsigned long addr) pud_t *pud; pmd_t *pmd;

- if (p4d_none(*p4d)) { + if (p4d_none(p4dp_get(p4d))) { pud = memblock_alloc(PAGE_SIZE, PAGE_SIZE); if (!pud) panic("%s: Failed to allocate memory\n", __func__); @@ -183,7 +183,7 @@ pte_t * __init populate_kernel_pte(unsigned long addr) }

pud = pud_offset(p4d, addr); - if (pud_none(*pud)) { + if (pud_none(pudp_get(pud))) { pmd = memblock_alloc(PAGE_SIZE, PAGE_SIZE); if (!pmd) panic("%s: Failed to allocate memory\n", __func__); @@ -194,7 +194,7 @@ pte_t * __init populate_kernel_pte(unsigned long addr) }

pmd = pmd_offset(pud, addr); - if (!pmd_present(*pmd)) { + if (!pmd_present(pmdp_get(pmd))) { pte_t *pte;

pte = memblock_alloc(PAGE_SIZE, PAGE_SIZE); @@ -215,7 +215,7 @@ void __init __set_fixmap(enum fixed_addresses idx, BUG_ON(idx <= FIX_HOLE || idx >= __end_of_fixed_addresses);

ptep = populate_kernel_pte(addr); - if (!pte_none(*ptep)) { + if (!pte_none(ptep_get(ptep))) { pte_ERROR(*ptep); return; } diff --git a/arch/loongarch/mm/kasan_init.c b/arch/loongarch/mm/kasan_init.c index c608adc99845..427d6b1aec09 100644 --- a/arch/loongarch/mm/kasan_init.c +++ b/arch/loongarch/mm/kasan_init.c @@ -105,7 +105,7 @@ static phys_addr_t __init kasan_alloc_zeroed_page(int node)

static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node, bool early) { - if (__pmd_none(early, READ_ONCE(*pmdp))) { + if (__pmd_none(early, pmdp_get(pmdp))) { phys_addr_t pte_phys = early ? __pa_symbol(kasan_early_shadow_pte) : kasan_alloc_zeroed_page(node); if (!early) @@ -118,7 +118,7 @@ static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,

static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node, bool early) { - if (__pud_none(early, READ_ONCE(*pudp))) { + if (__pud_none(early, pudp_get(pudp))) { phys_addr_t pmd_phys = early ? __pa_symbol(kasan_early_shadow_pmd) : kasan_alloc_zeroed_page(node); if (!early) @@ -131,7 +131,7 @@ static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,

static pud_t *__init kasan_pud_offset(p4d_t *p4dp, unsigned long addr, int node, bool early) { - if (__p4d_none(early, READ_ONCE(*p4dp))) { + if (__p4d_none(early, p4dp_get(p4dp))) { phys_addr_t pud_phys = early ? __pa_symbol(kasan_early_shadow_pud) : kasan_alloc_zeroed_page(node); if (!early) @@ -154,7 +154,7 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, : kasan_alloc_zeroed_page(node); next = addr + PAGE_SIZE; set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); - } while (ptep++, addr = next, addr != end && __pte_none(early, READ_ONCE(*ptep))); + } while (ptep++, addr = next, addr != end && __pte_none(early, ptep_get(ptep))); }

static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, @@ -166,7 +166,7 @@ static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, do { next = pmd_addr_end(addr, end); kasan_pte_populate(pmdp, addr, next, node, early); - } while (pmdp++, addr = next, addr != end && __pmd_none(early, READ_ONCE(*pmdp))); + } while (pmdp++, addr = next, addr != end && __pmd_none(early, pmdp_get(pmdp))); }

static void __init kasan_pud_populate(p4d_t *p4dp, unsigned long addr, diff --git a/arch/loongarch/mm/pgtable.c b/arch/loongarch/mm/pgtable.c index 2aae72e63871..6a038a27373a 100644 --- a/arch/loongarch/mm/pgtable.c +++ b/arch/loongarch/mm/pgtable.c @@ -128,7 +128,7 @@ pmd_t mk_pmd(struct page *page, pgprot_t prot) void set_pmd_at(struct mm_struct *mm, unsigned long addr, pmd_t *pmdp, pmd_t pmd) { - *pmdp = pmd; + WRITE_ONCE(*pmdp, pmd); flush_tlb_all(); }