[PATCH v6 07/18] arm64/mm: Convert READ_ONCE(*ptep) to ptep_get(ptep)

Ryan Roberts
2024-02-15T10:33:51Z

There are a number of places in the arch code that read a pte by using
the READ_ONCE() macro. Refactor these call sites to instead use the
ptep_get() helper, which itself is a READ_ONCE(). Generated code should
be the same.

This will benefit us when we shortly introduce the transparent contpte
support. In this case, ptep_get() will become more complex so we now
have all the code abstracted through it.

Tested-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
arch/arm64/include/asm/pgtable.h | 12 +++++++++---
arch/arm64/kernel/efi.c | 2 +-
arch/arm64/mm/fault.c | 4 ++--
arch/arm64/mm/hugetlbpage.c | 6 +++---
arch/arm64/mm/kasan_init.c | 2 +-
arch/arm64/mm/mmu.c | 12 ++++++------
arch/arm64/mm/pageattr.c | 4 ++--
arch/arm64/mm/trans_pgd.c | 2 +-
8 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index b6d3e9e0a946..de034ca40bad 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -275,6 +275,12 @@ static inline void set_pte(pte_t *ptep, pte_t pte)
}
}

+#define ptep_get ptep_get
+static inline pte_t ptep_get(pte_t *ptep)
+{
+ return READ_ONCE(*ptep);
+}
+
extern void __sync_icache_dcache(pte_t pteval);
bool pgattr_change_is_safe(u64 old, u64 new);

@@ -302,7 +308,7 @@ static inline void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep,
if (!IS_ENABLED(CONFIG_DEBUG_VM))
return;

- old_pte = READ_ONCE(*ptep);
+ old_pte = ptep_get(ptep);

if (!pte_valid(old_pte) || !pte_valid(pte))
return;
@@ -904,7 +910,7 @@ static inline int __ptep_test_and_clear_young(pte_t *ptep)
{
pte_t old_pte, pte;

- pte = READ_ONCE(*ptep);
+ pte = ptep_get(ptep);
do {
old_pte = pte;
pte = pte_mkold(pte);
@@ -986,7 +992,7 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
{
pte_t old_pte, pte;

- pte = READ_ONCE(*ptep);
+ pte = ptep_get(ptep);
do {
old_pte = pte;
pte = pte_wrprotect(pte);
diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 0228001347be..d0e08e93b246 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -103,7 +103,7 @@ static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data)
{
struct set_perm_data *spd = data;
const efi_memory_desc_t *md = spd->md;
- pte_t pte = READ_ONCE(*ptep);
+ pte_t pte = ptep_get(ptep);

if (md->attribute & EFI_MEMORY_RO)
pte = set_pte_bit(pte, __pgprot(PTE_RDONLY));
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 55f6455a8284..a254761fa1bd 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -191,7 +191,7 @@ static void show_pte(unsigned long addr)
if (!ptep)
break;

- pte = READ_ONCE(*ptep);
+ pte = ptep_get(ptep);
pr_cont(", pte=%016llx", pte_val(pte));
pte_unmap(ptep);
} while(0);
@@ -214,7 +214,7 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
pte_t entry, int dirty)
{
pteval_t old_pteval, pteval;
- pte_t pte = READ_ONCE(*ptep);
+ pte_t pte = ptep_get(ptep);

if (pte_same(pte, entry))
return 0;
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 6720ec8d50e7..2892f925ed66 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -485,7 +485,7 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm,
size_t pgsize;
pte_t pte;

- if (!pte_cont(READ_ONCE(*ptep))) {
+ if (!pte_cont(ptep_get(ptep))) {
ptep_set_wrprotect(mm, addr, ptep);
return;
}
@@ -510,7 +510,7 @@ pte_t huge_ptep_clear_flush(struct vm_area_struct *vma,
size_t pgsize;
int ncontig;

- if (!pte_cont(READ_ONCE(*ptep)))
+ if (!pte_cont(ptep_get(ptep)))
return ptep_clear_flush(vma, addr, ptep);

ncontig = find_num_contig(mm, addr, ptep, &pgsize);
@@ -543,7 +543,7 @@ pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr
* when the permission changes from executable to non-executable
* in cases where cpu is affected with errata #2645198.
*/
- if (pte_user_exec(READ_ONCE(*ptep)))
+ if (pte_user_exec(ptep_get(ptep)))
return huge_ptep_clear_flush(vma, addr, ptep);
}
return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep);
diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c
index 4c7ad574b946..c2a9f4f6c7dd 100644
--- a/arch/arm64/mm/kasan_init.c
+++ b/arch/arm64/mm/kasan_init.c
@@ -113,7 +113,7 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE);
next = addr + PAGE_SIZE;
set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
- } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
+ } while (ptep++, addr = next, addr != end && pte_none(ptep_get(ptep)));
}

static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 3a27d887f7dd..343629a17042 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -173,7 +173,7 @@ static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,

ptep = pte_set_fixmap_offset(pmdp, addr);
do {
- pte_t old_pte = READ_ONCE(*ptep);
+ pte_t old_pte = ptep_get(ptep);

set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot));

@@ -182,7 +182,7 @@ static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end,
* only allow updates to the permission attributes.
*/
BUG_ON(!pgattr_change_is_safe(pte_val(old_pte),
- READ_ONCE(pte_val(*ptep))));
+ pte_val(ptep_get(ptep))));

phys += PAGE_SIZE;
} while (ptep++, addr += PAGE_SIZE, addr != end);
@@ -852,7 +852,7 @@ static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr,

do {
ptep = pte_offset_kernel(pmdp, addr);
- pte = READ_ONCE(*ptep);
+ pte = ptep_get(ptep);
if (pte_none(pte))
continue;

@@ -985,7 +985,7 @@ static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr,

do {
ptep = pte_offset_kernel(pmdp, addr);
- pte = READ_ONCE(*ptep);
+ pte = ptep_get(ptep);

/*
* This is just a sanity check here which verifies that
@@ -1004,7 +1004,7 @@ static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr,
*/
ptep = pte_offset_kernel(pmdp, 0UL);
for (i = 0; i < PTRS_PER_PTE; i++) {
- if (!pte_none(READ_ONCE(ptep[i])))
+ if (!pte_none(ptep_get(&ptep[i])))
return;
}

@@ -1473,7 +1473,7 @@ pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte
* when the permission changes from executable to non-executable
* in cases where cpu is affected with errata #2645198.
*/
- if (pte_user_exec(READ_ONCE(*ptep)))
+ if (pte_user_exec(ptep_get(ptep)))
return ptep_clear_flush(vma, addr, ptep);
}
return ptep_get_and_clear(vma->vm_mm, addr, ptep);
diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c
index 924843f1f661..73a5e8f82586 100644
--- a/arch/arm64/mm/pageattr.c
+++ b/arch/arm64/mm/pageattr.c
@@ -36,7 +36,7 @@ bool can_set_direct_map(void)
static int change_page_range(pte_t *ptep, unsigned long addr, void *data)
{
struct page_change_data *cdata = data;
- pte_t pte = READ_ONCE(*ptep);
+ pte_t pte = ptep_get(ptep);

pte = clear_pte_bit(pte, cdata->clear_mask);
pte = set_pte_bit(pte, cdata->set_mask);
@@ -245,5 +245,5 @@ bool kernel_page_present(struct page *page)
return true;

ptep = pte_offset_kernel(pmdp, addr);
- return pte_valid(READ_ONCE(*ptep));
+ return pte_valid(ptep_get(ptep));
}
diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c
index 7b14df3c6477..f71ab4704cce 100644
--- a/arch/arm64/mm/trans_pgd.c
+++ b/arch/arm64/mm/trans_pgd.c
@@ -33,7 +33,7 @@ static void *trans_alloc(struct trans_pgd_info *info)

static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr)
{
- pte_t pte = READ_ONCE(*src_ptep);
+ pte_t pte = ptep_get(src_ptep);

if (pte_valid(pte)) {
/*
--
2.25.1