Unverified Commit 1458eb2c authored by Alexandre Ghiti's avatar Alexandre Ghiti Committed by Palmer Dabbelt
Browse files

riscv: Fix set_huge_pte_at() for NAPOT mapping 



As stated by the privileged specification, we must clear a NAPOT
mapping and emit a sfence.vma before setting a new translation.

Fixes: 82a1a1f3 ("riscv: mm: support Svnapot in hugetlb page")
Signed-off-by: default avatarAlexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240117195741.1926459-2-alexghiti@rivosinc.com


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 6613476e

arch/riscv/mm/hugetlbpage.c

+40 −2
Original line number Diff line number Diff line
@@ -177,13 +177,36 @@ pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags) 
	return entry;

}



static void clear_flush(struct mm_struct *mm,

			unsigned long addr,

			pte_t *ptep,

			unsigned long pgsize,

			unsigned long ncontig)

{

	struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);

	unsigned long i, saddr = addr;



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

		ptep_get_and_clear(mm, addr, ptep);



	flush_tlb_range(&vma, saddr, addr);

}



/*

 * 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

 * PTEs invalid, then issue SFENCE.VMA instruction(s) covering all 4 KiB regions

 * within the range, [...] then update the PTE(s), as described in Section

 * 4.2.1.". That's the equivalent of the Break-Before-Make approach used by

 * arm64.

 */

void set_huge_pte_at(struct mm_struct *mm,

		     unsigned long addr,

		     pte_t *ptep,

		     pte_t pte,

		     unsigned long sz)

{

	unsigned long hugepage_shift;

	unsigned long hugepage_shift, pgsize;

	int i, pte_num;



	if (sz >= PGDIR_SIZE)
@@ -198,7 +221,22 @@ void set_huge_pte_at(struct mm_struct *mm, 
		hugepage_shift = PAGE_SHIFT;



	pte_num = sz >> hugepage_shift;

	for (i = 0; i < pte_num; i++, ptep++, addr += (1 << hugepage_shift))

	pgsize = 1 << hugepage_shift;



	if (!pte_present(pte)) {

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

			set_ptes(mm, addr, ptep, pte, 1);

		return;

	}



	if (!pte_napot(pte)) {

		set_ptes(mm, addr, ptep, pte, 1);

		return;

	}



	clear_flush(mm, addr, ptep, pgsize, pte_num);



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

		set_pte_at(mm, addr, ptep, pte);

}