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xtensa: get rid of __ARCH_USE_5LEVEL_HACK

PATCH In review Mike Rapoport 2 participants 5 messages Nov 5, 2019 – Nov 14, 2019

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Memory management Tensilica Xtensa port (xtensa) KASAN
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Mike Rapoport

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#0 lore raw

cover xtensa: get rid of __ARCH_USE_5LEVEL_HACK

From: Mike Rapoport <[email protected]>

Hi,

These patches update the xtensa page table folding/unfolding to take into account the 5th level.

Mike Rapoport (2):
xtensa: mm: fix PMD folding implementation
xtensa: get rid of __ARCH_USE_5LEVEL_HACK

 arch/xtensa/include/asm/pgtable.h |  4 ----
 arch/xtensa/mm/fault.c            | 16 ++++++++++++++--
 arch/xtensa/mm/kasan_init.c       |  8 ++++++--
 arch/xtensa/mm/mmu.c              |  4 +++-
 arch/xtensa/mm/tlb.c              |  9 ++++++++-
 5 files changed, 31 insertions(+), 10 deletions(-)
Signature · 1 line
2.7.4
author
#1 lore raw

PATCH 1/2 xtensa: mm: fix PMD folding implementation

From: Mike Rapoport <[email protected]>

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 <[email protected]>
---
 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(-)
arch/xtensa/include/asm/pgtable.h +0 -3
index 3f7fe5a..af72f02 100644
@@ -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) 					\
arch/xtensa/mm/fault.c +8 -2
index f81b147..68a0414 100644
@@ -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;
arch/xtensa/mm/kasan_init.c +4 -2
index af71525..ace98bd 100644
@@ -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)
arch/xtensa/mm/mmu.c +2 -1
index 03678c4..018dda2 100644
@@ -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;
arch/xtensa/mm/tlb.c +5 -1
index 59153d0..164a2ca 100644
@@ -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);
Signature · 1 line
2.7.4
author
#2 lore raw

PATCH 2/2 xtensa: get rid of __ARCH_USE_5LEVEL_HACK

In reply to Mike Rapoport

From: Mike Rapoport <[email protected]>

xtensa has 2-level page tables and already uses pgtable-nopmd for page table folding.

Add walks of p4d level where appropriate and drop usage of __ARCH_USE_5LEVEL_HACK.

Signed-off-by Mike Rapoport <[email protected]>
---
 arch/xtensa/include/asm/pgtable.h |  1 -
 arch/xtensa/mm/fault.c            | 10 ++++++++--
 arch/xtensa/mm/kasan_init.c       |  6 ++++--
 arch/xtensa/mm/mmu.c              |  3 ++-
 arch/xtensa/mm/tlb.c              |  5 ++++-
 5 files changed, 18 insertions(+), 7 deletions(-)
arch/xtensa/include/asm/pgtable.h +0 -1
index af72f02..27ac17c 100644
@@ -8,7 +8,6 @@
 #ifndef _XTENSA_PGTABLE_H
 #define _XTENSA_PGTABLE_H
 
-#define __ARCH_USE_5LEVEL_HACK
 #include <asm/page.h>
 #include <asm/kmem_layout.h>
 #include <asm-generic/pgtable-nopmd.h>
arch/xtensa/mm/fault.c +8 -2
index 68a0414..bee30a7 100644
@@ -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;
+		p4d_t *p4d, *p4d_k;
 		pud_t *pud, *pud_k;
 		pmd_t *pmd, *pmd_k;
 		pte_t *pte_k;

@@ -212,8 +213,13 @@ void do_page_fault(struct pt_regs *regs)
 
 		pgd_val(*pgd) = pgd_val(*pgd_k);
 
-		pud = pud_offset(pgd, address);
-		pud_k = pud_offset(pgd_k, address);
+		p4d = p4d_offset(pgd, address);
+		p4d_k = p4d_offset(pgd_k, address);
+		if (!p4d_present(*p4d) || !p4d_present(*p4d_k))
+			goto bad_page_fault;
+
+		pud = pud_offset(p4d, address);
+		pud_k = pud_offset(p4d_k, address);
 		if (!pud_present(*pud) || !pud_present(*pud_k))
 			goto bad_page_fault;
arch/xtensa/mm/kasan_init.c +4 -2
index ace98bd..9c95779 100644
@@ -20,7 +20,8 @@ void __init kasan_early_init(void)
 {
 	unsigned long vaddr = KASAN_SHADOW_START;
 	pgd_t *pgd = pgd_offset_k(vaddr);
-	pud_t *pud = pud_offset(pgd, vaddr);
+	p4d_t *p4d = p4d_offset(pgd, vaddr);
+	pud_t *pud = pud_offset(p4d, vaddr);
 	pmd_t *pmd = pmd_offset(pud, vaddr);
 	int i;
 

@@ -43,7 +44,8 @@ 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);
-	pud_t *pud = pud_offset(pgd, vaddr);
+	p4d_t *p4d = p4d_offset(pgd, vaddr);
+	pud_t *pud = pud_offset(p4d, vaddr);
 	pmd_t *pmd = pmd_offset(pud, vaddr);
 	pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE);
arch/xtensa/mm/mmu.c +2 -1
index 018dda2..37e478a 100644
@@ -22,7 +22,8 @@
 static void * __init init_pmd(unsigned long vaddr, unsigned long n_pages)
 {
 	pgd_t *pgd = pgd_offset_k(vaddr);
-	pud_t *pud = pud_offset(pgd, vaddr);
+	p4d_t *p4d = p4d_offset(pgd, vaddr);
+	pud_t *pud = pud_offset(p4d, vaddr);
 	pmd_t *pmd = pmd_offset(pud, vaddr);
 	pte_t *pte;
 	unsigned long i;
arch/xtensa/mm/tlb.c +4 -1
index 164a2ca..a460474 100644
@@ -178,7 +178,10 @@ static unsigned get_pte_for_vaddr(unsigned vaddr)
 	pgd = pgd_offset(mm, vaddr);
 	if (pgd_none_or_clear_bad(pgd))
 		return 0;
-	pud = pud_offset(pgd, vaddr);
+	p4d = p4d_offset(pgd, vaddr);
+	if (p4d_none_or_clear_bad(p4d))
+		return 0;
+	pud = pud_offset(p4d, vaddr);
 	if (pud_none_or_clear_bad(pud))
 		return 0;
 	pmd = pmd_offset(pud, vaddr);
Signature · 1 line
2.7.4
maintainer
#3 lore raw

Hi Mike,

Quoted 9 lines · Mike Rapoport

From: Mike Rapoport <[email protected]>

xtensa has 2-level page tables and already uses pgtable-nopmd for page table folding.

Add walks of p4d level where appropriate and drop usage of __ARCH_USE_5LEVEL_HACK.

Quoted 8 lines
Signed-off-by Mike Rapoport <[email protected]>
---
 arch/xtensa/include/asm/pgtable.h |  1 -
 arch/xtensa/mm/fault.c            | 10 ++++++++--
 arch/xtensa/mm/kasan_init.c       |  6 ++++--
 arch/xtensa/mm/mmu.c              |  3 ++-
 arch/xtensa/mm/tlb.c              |  5 ++++-
 5 files changed, 18 insertions(+), 7 deletions(-)

This change missed a spot in arch/xtensa/include/asm/fixmap.h. I've added the following hunk and queued both patches to the xtensa tree:

arch/xtensa/include/asm/fixmap.h +0 -0
index 7e25c1b50ac0..cfb8696917e9 100644
@@ -78,8 +78,10 @@ static inline unsigned long virt_to_fix(const

unsigned long vaddr)

 #define kmap_get_fixmap_pte(vaddr) \
        pte_offset_kernel( \

- pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
- (vaddr) \
- )
+ pmd_offset(pud_offset(p4d_offset(pgd_offset_k(vaddr), \
+ (vaddr)), \
+ (vaddr)), \
+ (vaddr)), \
+ (vaddr))

#endif

Signature · 2 lines
Thanks.
-- Max
author
#4 lore raw
Quoted 21 lines · Max Filippov

Hi Mike,

Quoted 9 lines · Mike Rapoport

From: Mike Rapoport <[email protected]>

xtensa has 2-level page tables and already uses pgtable-nopmd for page table folding.

Add walks of p4d level where appropriate and drop usage of __ARCH_USE_5LEVEL_HACK.

Quoted 8 lines
Signed-off-by Mike Rapoport <[email protected]>
---
 arch/xtensa/include/asm/pgtable.h |  1 -
 arch/xtensa/mm/fault.c            | 10 ++++++++--
 arch/xtensa/mm/kasan_init.c       |  6 ++++--
 arch/xtensa/mm/mmu.c              |  3 ++-
 arch/xtensa/mm/tlb.c              |  5 ++++-
 5 files changed, 18 insertions(+), 7 deletions(-)
Quoted 2 lines

This change missed a spot in arch/xtensa/include/asm/fixmap.h. I've added the following hunk and queued both patches to the xtensa tree:

Thanks!

Quoted 24 lines
arch/xtensa/include/asm/fixmap.h +5 -3
index 7e25c1b50ac0..cfb8696917e9 100644
@@ -78,8 +78,10 @@ static inline unsigned long virt_to_fix(const
 unsigned long vaddr)
 
 #define kmap_get_fixmap_pte(vaddr) \
        pte_offset_kernel( \
-               pmd_offset(pud_offset(pgd_offset_k(vaddr), (vaddr)), (vaddr)), \
-               (vaddr) \
-       )
+               pmd_offset(pud_offset(p4d_offset(pgd_offset_k(vaddr), \
+                                                (vaddr)), \
+                                     (vaddr)), \
+                          (vaddr)), \
+               (vaddr))

#endif

Signature · 2 lines
Thanks.
-- Max
Signature · 2 lines
Sincerely yours,
Mike.