linux-kernel - [PATCH 1/2] xtensa: mm: fix PMD folding implementation

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Message-Id: <1572964400-16542-2-git-send-email-rppt@kernel.org>
Date:   Tue,  5 Nov 2019 16:33:19 +0200
From:   Mike Rapoport <rppt@...nel.org>
To:     Chris Zankel <chris@...kel.net>, Max Filippov <jcmvbkbc@...il.com>
Cc:     linux-xtensa@...ux-xtensa.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Mike Rapoport <rppt@...nel.org>,
        Mike Rapoport <rppt@...ux.ibm.com>
Subject: [PATCH 1/2] xtensa: mm: fix PMD folding implementation

From: Mike Rapoport <rppt@...ux.ibm.com>

There was a definition of pmd_offset() in arch/xtensa/include/asm/pgtable.h
that shadowed the generic implementation defined in
include/asm-generic/pgtable-nopmd.h.

As the result, xtensa had shortcuts in page table traversal in several
places instead of doing level unfolding.

Remove local override for pmd_offset() and add page table unfolding where
necessary.

Signed-off-by: Mike Rapoport <rppt@...ux.ibm.com>
---
 arch/xtensa/include/asm/pgtable.h |  3 ---
 arch/xtensa/mm/fault.c            | 10 ++++++++--
 arch/xtensa/mm/kasan_init.c       |  6 ++++--
 arch/xtensa/mm/mmu.c              |  3 ++-
 arch/xtensa/mm/tlb.c              |  6 +++++-
 5 files changed, 19 insertions(+), 9 deletions(-)

diff --git a/arch/xtensa/include/asm/pgtable.h b/arch/xtensa/include/asm/pgtable.h
index 3f7fe5a..af72f02 100644
--- a/arch/xtensa/include/asm/pgtable.h
+++ b/arch/xtensa/include/asm/pgtable.h
@@ -371,9 +371,6 @@ ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr, pte_t *ptep)
 
 #define pgd_index(address)	((address) >> PGDIR_SHIFT)
 
-/* Find an entry in the second-level page table.. */
-#define pmd_offset(dir,address) ((pmd_t*)(dir))
-
 /* Find an entry in the third-level page table.. */
 #define pte_index(address)	(((address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1))
 #define pte_offset_kernel(dir,addr) 					\
diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index f81b147..68a0414 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c
@@ -197,6 +197,7 @@ void do_page_fault(struct pt_regs *regs)
 		struct mm_struct *act_mm = current->active_mm;
 		int index = pgd_index(address);
 		pgd_t *pgd, *pgd_k;
+		pud_t *pud, *pud_k;
 		pmd_t *pmd, *pmd_k;
 		pte_t *pte_k;
 
@@ -211,8 +212,13 @@ void do_page_fault(struct pt_regs *regs)
 
 		pgd_val(*pgd) = pgd_val(*pgd_k);
 
-		pmd = pmd_offset(pgd, address);
-		pmd_k = pmd_offset(pgd_k, address);
+		pud = pud_offset(pgd, address);
+		pud_k = pud_offset(pgd_k, address);
+		if (!pud_present(*pud) || !pud_present(*pud_k))
+			goto bad_page_fault;
+
+		pmd = pmd_offset(pud, address);
+		pmd_k = pmd_offset(pud_k, address);
 		if (!pmd_present(*pmd) || !pmd_present(*pmd_k))
 			goto bad_page_fault;
 
diff --git a/arch/xtensa/mm/kasan_init.c b/arch/xtensa/mm/kasan_init.c
index af71525..ace98bd 100644
--- a/arch/xtensa/mm/kasan_init.c
+++ b/arch/xtensa/mm/kasan_init.c
@@ -20,7 +20,8 @@ void __init kasan_early_init(void)
 {
 	unsigned long vaddr = KASAN_SHADOW_START;
 	pgd_t *pgd = pgd_offset_k(vaddr);
-	pmd_t *pmd = pmd_offset(pgd, vaddr);
+	pud_t *pud = pud_offset(pgd, vaddr);
+	pmd_t *pmd = pmd_offset(pud, vaddr);
 	int i;
 
 	for (i = 0; i < PTRS_PER_PTE; ++i)
@@ -42,7 +43,8 @@ static void __init populate(void *start, void *end)
 	unsigned long i, j;
 	unsigned long vaddr = (unsigned long)start;
 	pgd_t *pgd = pgd_offset_k(vaddr);
-	pmd_t *pmd = pmd_offset(pgd, vaddr);
+	pud_t *pud = pud_offset(pgd, vaddr);
+	pmd_t *pmd = pmd_offset(pud, vaddr);
 	pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
 
 	if (!pte)
diff --git a/arch/xtensa/mm/mmu.c b/arch/xtensa/mm/mmu.c
index 03678c4..018dda2 100644
--- a/arch/xtensa/mm/mmu.c
+++ b/arch/xtensa/mm/mmu.c
@@ -22,7 +22,8 @@
 static void * __init init_pmd(unsigned long vaddr, unsigned long n_pages)
 {
 	pgd_t *pgd = pgd_offset_k(vaddr);
-	pmd_t *pmd = pmd_offset(pgd, vaddr);
+	pud_t *pud = pud_offset(pgd, vaddr);
+	pmd_t *pmd = pmd_offset(pud, vaddr);
 	pte_t *pte;
 	unsigned long i;
 
diff --git a/arch/xtensa/mm/tlb.c b/arch/xtensa/mm/tlb.c
index 59153d0..164a2ca 100644
--- a/arch/xtensa/mm/tlb.c
+++ b/arch/xtensa/mm/tlb.c
@@ -169,6 +169,7 @@ static unsigned get_pte_for_vaddr(unsigned vaddr)
 	struct task_struct *task = get_current();
 	struct mm_struct *mm = task->mm;
 	pgd_t *pgd;
+	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
 
@@ -177,7 +178,10 @@ static unsigned get_pte_for_vaddr(unsigned vaddr)
 	pgd = pgd_offset(mm, vaddr);
 	if (pgd_none_or_clear_bad(pgd))
 		return 0;
-	pmd = pmd_offset(pgd, vaddr);
+	pud = pud_offset(pgd, vaddr);
+	if (pud_none_or_clear_bad(pud))
+		return 0;
+	pmd = pmd_offset(pud, vaddr);
 	if (pmd_none_or_clear_bad(pmd))
 		return 0;
 	pte = pte_offset_map(pmd, vaddr);
-- 
2.7.4