Commit 546e42c8 authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Paul Walmsley
Browse files

riscv: Use an atomic xchg in pudp_huge_get_and_clear() 



Make sure we return the right pud value and not a value that could
have been overwritten in between by a different core.

Fixes: c3cc2a4a ("riscv: Add support for PUD THP")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250814-dev-alex-thp_pud_xchg-v1-1-b4704dfae206@rivosinc.com


[pjw@kernel.org: use xchg rather than atomic_long_xchg; avoid atomic op for !CONFIG_SMP like x86]
Signed-off-by: default avatarPaul Walmsley <pjw@kernel.org>
parent a03ee11b

arch/riscv/include/asm/pgtable.h

+17 −0
Original line number Diff line number Diff line
@@ -942,6 +942,23 @@ static inline int pudp_test_and_clear_young(struct vm_area_struct *vma, 
	return ptep_test_and_clear_young(vma, address, (pte_t *)pudp);

}



#define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR

static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm,

					    unsigned long address,  pud_t *pudp)

{

#ifdef CONFIG_SMP

	pud_t pud = __pud(xchg(&pudp->pud, 0));

#else

	pud_t pud = *pudp;



	pud_clear(pudp);

#endif



	page_table_check_pud_clear(mm, pud);



	return pud;

}



static inline int pud_young(pud_t pud)

{

	return pte_young(pud_pte(pud));