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mm: Introduce pudp/p4dp/pgdp_get() functions

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commit eba2591d99 upstream.

Instead of directly dereferencing page tables entries, which can cause
issues (see commit 20a004e7b0 ("arm64: mm: Use READ_ONCE/WRITE_ONCE when
accessing page tables"), let's introduce new functions to get the
pud/p4d/pgd entries (the pte and pmd versions already exist).

Note that arm pgd_t is actually an array so pgdp_get() is defined as a
macro to avoid a build error.

Those new functions will be used in subsequent commits by the riscv
architecture.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20231213203001.179237-3-alexghiti@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: WangYuli <wangyuli@uniontech.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alexandre Ghiti 2023-12-13 21:29:59 +01:00 committed by Greg Kroah-Hartman
parent 193b1fc1cb
commit 1a8b2391e0
2 changed files with 23 additions and 0 deletions
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2
arch/arm/include/asm/pgtable.h
View File

@ -151,6 +151,8 @@ extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
extern pgd_t swapper_pg_dir[PTRS_PER_PGD];
#define pgdp_get(pgpd) READ_ONCE(*pgdp)
#define pud_page(pud) pmd_page(__pmd(pud_val(pud)))
#define pud_write(pud) pmd_write(__pmd(pud_val(pud)))

21
include/linux/pgtable.h
View File

@ -292,6 +292,27 @@ static inline pmd_t pmdp_get(pmd_t *pmdp)
}
#endif
#ifndef pudp_get
static inline pud_t pudp_get(pud_t *pudp)
{
return READ_ONCE(*pudp);
}
#endif
#ifndef p4dp_get
static inline p4d_t p4dp_get(p4d_t *p4dp)
{
return READ_ONCE(*p4dp);
}
#endif
#ifndef pgdp_get
static inline pgd_t pgdp_get(pgd_t *pgdp)
{
return READ_ONCE(*pgdp);
}
#endif
#ifndef __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG
static inline int ptep_test_and_clear_young(struct vm_area_struct *vma,
unsigned long address,