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Message-ID: <20240806070706.128005-1-chenhuacai@loongson.cn>
Date: Tue, 6 Aug 2024 15:07:06 +0800
From: Huacai Chen <chenhuacai@...ngson.cn>
To: Arnd Bergmann <arnd@...db.de>,
Huacai Chen <chenhuacai@...nel.org>
Cc: loongarch@...ts.linux.dev,
linux-arch@...r.kernel.org,
Xuefeng Li <lixuefeng@...ngson.cn>,
Guo Ren <guoren@...nel.org>,
Xuerui Wang <kernel@...0n.name>,
Jiaxun Yang <jiaxun.yang@...goat.com>,
linux-kernel@...r.kernel.org,
loongson-kernel@...ts.loongnix.cn,
Huacai Chen <chenhuacai@...ngson.cn>
Subject: [PATCH] LoongArch: Use accessors to page table entries instead of direct dereference
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@...ngson.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 92636e82957c..da9e93024626 100644
--- a/arch/loongarch/include/asm/kfence.h
+++ b/arch/loongarch/include/asm/kfence.h
@@ -53,13 +53,13 @@ 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 3fbf1f37c58e..85431f20a14d 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));
@@ -603,7 +613,7 @@ 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 2634a9e8d82c..28681dfb4b85 100644
--- a/arch/loongarch/kvm/mmu.c
+++ b/arch/loongarch/kvm/mmu.c
@@ -714,19 +714,19 @@ 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 12222c56cb59..e4068906143b 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 bf789d114c2d..8a87a482c8f4 100644
--- a/arch/loongarch/mm/init.c
+++ b/arch/loongarch/mm/init.c
@@ -141,7 +141,7 @@ 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);
@@ -173,7 +173,7 @@ 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__);
@@ -184,7 +184,7 @@ 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__);
@@ -195,7 +195,7 @@ 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);
@@ -216,7 +216,7 @@ 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 bda018150000..eb6a29b491a7 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();
}
--
2.43.5
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