Unverified Commit 83d78ac6 authored by Alexandre Ghiti's avatar Alexandre Ghiti
Browse files

riscv: Fix hugetlb retrieval of number of ptes in case of !present pte 

Ryan sent a fix [1] for arm64 that applies to riscv too: in some hugetlb
functions, we must not use the pte value to get the size of a mapping
because the pte may not be present.

So use the already present size parameter for huge_pte_clear() and the
newly introduced size parameter for huge_ptep_get_and_clear(). And make
sure to gather A/D bits only on present ptes.

Fixes: 82a1a1f3 ("riscv: mm: support Svnapot in hugetlb page")
Link: https://lore.kernel.org/all/20250217140419.1702389-1-ryan.roberts@arm.com/ [1]
Link: https://lore.kernel.org/r/20250317072551.572169-1-alexghiti@rivosinc.com


Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
parent a3313375

arch/riscv/mm/hugetlbpage.c

+45 −31
Original line number Diff line number Diff line
@@ -148,22 +148,25 @@ unsigned long hugetlb_mask_last_page(struct hstate *h) 
static pte_t get_clear_contig(struct mm_struct *mm,

			      unsigned long addr,

			      pte_t *ptep,

			      unsigned long pte_num)

			      unsigned long ncontig)

{

	pte_t orig_pte = ptep_get(ptep);

	unsigned long i;



	for (i = 0; i < pte_num; i++, addr += PAGE_SIZE, ptep++) {

		pte_t pte = ptep_get_and_clear(mm, addr, ptep);



		if (pte_dirty(pte))

			orig_pte = pte_mkdirty(orig_pte);



		if (pte_young(pte))

			orig_pte = pte_mkyoung(orig_pte);

	pte_t pte, tmp_pte;

	bool present;



	pte = ptep_get_and_clear(mm, addr, ptep);

	present = pte_present(pte);

	while (--ncontig) {

		ptep++;

		addr += PAGE_SIZE;

		tmp_pte = ptep_get_and_clear(mm, addr, ptep);

		if (present) {

			if (pte_dirty(tmp_pte))

				pte = pte_mkdirty(pte);

			if (pte_young(tmp_pte))

				pte = pte_mkyoung(pte);

		}



	return orig_pte;

	}

	return pte;

}



static pte_t get_clear_contig_flush(struct mm_struct *mm,
@@ -212,6 +215,26 @@ static void clear_flush(struct mm_struct *mm, 
	flush_tlb_range(&vma, saddr, addr);

}



static int num_contig_ptes_from_size(unsigned long sz, size_t *pgsize)

{

	unsigned long hugepage_shift;



	if (sz >= PGDIR_SIZE)

		hugepage_shift = PGDIR_SHIFT;

	else if (sz >= P4D_SIZE)

		hugepage_shift = P4D_SHIFT;

	else if (sz >= PUD_SIZE)

		hugepage_shift = PUD_SHIFT;

	else if (sz >= PMD_SIZE)

		hugepage_shift = PMD_SHIFT;

	else

		hugepage_shift = PAGE_SHIFT;



	*pgsize = 1 << hugepage_shift;



	return sz >> hugepage_shift;

}



/*

 * When dealing with NAPOT mappings, the privileged specification indicates that

 * "if an update needs to be made, the OS generally should first mark all of the
@@ -226,22 +249,10 @@ void set_huge_pte_at(struct mm_struct *mm, 
		     pte_t pte,

		     unsigned long sz)

{

	unsigned long hugepage_shift, pgsize;

	size_t pgsize;

	int i, pte_num;



	if (sz >= PGDIR_SIZE)

		hugepage_shift = PGDIR_SHIFT;

	else if (sz >= P4D_SIZE)

		hugepage_shift = P4D_SHIFT;

	else if (sz >= PUD_SIZE)

		hugepage_shift = PUD_SHIFT;

	else if (sz >= PMD_SIZE)

		hugepage_shift = PMD_SHIFT;

	else

		hugepage_shift = PAGE_SHIFT;



	pte_num = sz >> hugepage_shift;

	pgsize = 1 << hugepage_shift;

	pte_num = num_contig_ptes_from_size(sz, &pgsize);



	if (!pte_present(pte)) {

		for (i = 0; i < pte_num; i++, ptep++, addr += pgsize)
@@ -295,13 +306,14 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, 
			      unsigned long addr,

			      pte_t *ptep, unsigned long sz)

{

	size_t pgsize;

	pte_t orig_pte = ptep_get(ptep);

	int pte_num;



	if (!pte_napot(orig_pte))

		return ptep_get_and_clear(mm, addr, ptep);



	pte_num = napot_pte_num(napot_cont_order(orig_pte));

	pte_num = num_contig_ptes_from_size(sz, &pgsize);



	return get_clear_contig(mm, addr, ptep, pte_num);

}
@@ -351,6 +363,7 @@ void huge_pte_clear(struct mm_struct *mm, 
		    pte_t *ptep,

		    unsigned long sz)

{

	size_t pgsize;

	pte_t pte = ptep_get(ptep);

	int i, pte_num;
@@ -359,8 +372,9 @@ void huge_pte_clear(struct mm_struct *mm, 
		return;

	}



	pte_num = napot_pte_num(napot_cont_order(pte));

	for (i = 0; i < pte_num; i++, addr += PAGE_SIZE, ptep++)

	pte_num = num_contig_ptes_from_size(sz, &pgsize);



	for (i = 0; i < pte_num; i++, addr += pgsize, ptep++)

		pte_clear(mm, addr, ptep);

}