um: add support for folded p4d page tables

The UML port uses 4 and 5 level fixups to support higher level page
table directories in the generic VM code.

Implement primitives necessary for the 4th level folding, add walks of
p4d level where appropriate and drop usage of __ARCH_USE_5LEVEL_HACK.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Mike Rapoport <[email protected]>
Cc: Anatoly Pugachev <[email protected]>
Cc: Anton Ivanov <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Greentime Hu <[email protected]>
Cc: Greg Ungerer <[email protected]>
Cc: Helge Deller <[email protected]>
Cc: "James E.J. Bottomley" <[email protected]>
Cc: Jeff Dike <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Mark Salter <[email protected]>
Cc: Matt Turner <[email protected]>
Cc: Michal Simek <[email protected]>
Cc: Peter Rosin <[email protected]>
Cc: Richard Weinberger <[email protected]>
Cc: Rolf Eike Beer <[email protected]>
Cc: Russell King <[email protected]>
Cc: Russell King <[email protected]>
Cc: Sam Creasey <[email protected]>
Cc: Vincent Chen <[email protected]>
Cc: Vineet Gupta <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: rppt

arch/um/include/asm/pgtable-2level.h

@@ -8,7 +8,6 @@
 #ifndef __UM_PGTABLE_2LEVEL_H
 #define __UM_PGTABLE_2LEVEL_H
 
-#define __ARCH_USE_5LEVEL_HACK
 #include <asm-generic/pgtable-nopmd.h>
 
 /* PGDIR_SHIFT determines what a third-level page table entry can map */

arch/um/include/asm/pgtable-3level.h

@@ -7,7 +7,6 @@
 #ifndef __UM_PGTABLE_3LEVEL_H
 #define __UM_PGTABLE_3LEVEL_H
 
-#define __ARCH_USE_5LEVEL_HACK
 #include <asm-generic/pgtable-nopud.h>
 
 /* PGDIR_SHIFT determines what a third-level page table entry can map */

arch/um/include/asm/pgtable.h

@@ -106,6 +106,9 @@ extern unsigned long end_iomem;
 #define pud_newpage(x)  (pud_val(x) & _PAGE_NEWPAGE)
 #define pud_mkuptodate(x) (pud_val(x) &= ~_PAGE_NEWPAGE)
 
+#define p4d_newpage(x)  (p4d_val(x) & _PAGE_NEWPAGE)
+#define p4d_mkuptodate(x) (p4d_val(x) &= ~_PAGE_NEWPAGE)
+
 #define pmd_page(pmd) phys_to_page(pmd_val(pmd) & PAGE_MASK)
 
 #define pte_page(x) pfn_to_page(pte_pfn(x))

arch/um/kernel/mem.c

@@ -96,6 +96,7 @@ static void __init fixrange_init(unsigned long start, unsigned long end,
 				 pgd_t *pgd_base)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	int i, j;
@@ -107,7 +108,8 @@ static void __init fixrange_init(unsigned long start, unsigned long end,
 	pgd = pgd_base + i;
 
 	for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
-		pud = pud_offset(pgd, vaddr);
+		p4d = p4d_offset(pgd, vaddr);
+		pud = pud_offset(p4d, vaddr);
 		if (pud_none(*pud))
 			one_md_table_init(pud);
 		pmd = pmd_offset(pud, vaddr);
@@ -124,6 +126,7 @@ static void __init fixaddr_user_init( void)
 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 	long size = FIXADDR_USER_END - FIXADDR_USER_START;
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -144,7 +147,8 @@ static void __init fixaddr_user_init( void)
 	for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 		      p += PAGE_SIZE) {
 		pgd = swapper_pg_dir + pgd_index(vaddr);
-		pud = pud_offset(pgd, vaddr);
+		p4d = p4d_offset(pgd, vaddr);
+		pud = pud_offset(p4d, vaddr);
 		pmd = pmd_offset(pud, vaddr);
 		pte = pte_offset_kernel(pmd, vaddr);
 		pte_set_val(*pte, p, PAGE_READONLY);

arch/um/kernel/skas/mmu.c

@@ -19,15 +19,21 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 			 unsigned long kernel)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
 
 	pgd = pgd_offset(mm, proc);
-	pud = pud_alloc(mm, pgd, proc);
-	if (!pud)
+
+	p4d = p4d_alloc(mm, pgd, proc);
+	if (!p4d)
 		goto out;
 
+	pud = pud_alloc(mm, p4d, proc);
+	if (!pud)
+		goto out_pud;
+
 	pmd = pmd_alloc(mm, pud, proc);
 	if (!pmd)
 		goto out_pmd;
@@ -44,6 +50,8 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 	pmd_free(mm, pmd);
  out_pmd:
 	pud_free(mm, pud);
+ out_pud:
+	p4d_free(mm, p4d);
  out:
 	return -ENOMEM;
 }

arch/um/kernel/skas/uaccess.c

@@ -17,6 +17,7 @@
 pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 
@@ -27,7 +28,11 @@ pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
 	if (!pgd_present(*pgd))
 		return NULL;
 
-	pud = pud_offset(pgd, addr);
+	p4d = p4d_offset(pgd, addr);
+	if (!p4d_present(*p4d))
+		return NULL;
+
+	pud = pud_offset(p4d, addr);
 	if (!pud_present(*pud))
 		return NULL;
 

arch/um/kernel/tlb.c

@@ -277,15 +277,15 @@ static inline int update_pmd_range(pud_t *pud, unsigned long addr,
 	return ret;
 }
 
-static inline int update_pud_range(pgd_t *pgd, unsigned long addr,
+static inline int update_pud_range(p4d_t *p4d, unsigned long addr,
 				   unsigned long end,
 				   struct host_vm_change *hvc)
 {
 	pud_t *pud;
 	unsigned long next;
 	int ret = 0;
 
-	pud = pud_offset(pgd, addr);
+	pud = pud_offset(p4d, addr);
 	do {
 		next = pud_addr_end(addr, end);
 		if (!pud_present(*pud)) {
@@ -299,6 +299,28 @@ static inline int update_pud_range(pgd_t *pgd, unsigned long addr,
 	return ret;
 }
 
+static inline int update_p4d_range(pgd_t *pgd, unsigned long addr,
+				   unsigned long end,
+				   struct host_vm_change *hvc)
+{
+	p4d_t *p4d;
+	unsigned long next;
+	int ret = 0;
+
+	p4d = p4d_offset(pgd, addr);
+	do {
+		next = p4d_addr_end(addr, end);
+		if (!p4d_present(*p4d)) {
+			if (hvc->force || p4d_newpage(*p4d)) {
+				ret = add_munmap(addr, next - addr, hvc);
+				p4d_mkuptodate(*p4d);
+			}
+		} else
+			ret = update_pud_range(p4d, addr, next, hvc);
+	} while (p4d++, addr = next, ((addr < end) && !ret));
+	return ret;
+}
+
 void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
 		      unsigned long end_addr, int force)
 {
@@ -316,8 +338,8 @@ void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
 				ret = add_munmap(addr, next - addr, &hvc);
 				pgd_mkuptodate(*pgd);
 			}
-		}
-		else ret = update_pud_range(pgd, addr, next, &hvc);
+		} else
+			ret = update_p4d_range(pgd, addr, next, &hvc);
 	} while (pgd++, addr = next, ((addr < end_addr) && !ret));
 
 	if (!ret)
@@ -338,6 +360,7 @@ static int flush_tlb_kernel_range_common(unsigned long start, unsigned long end)
 {
 	struct mm_struct *mm;
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -364,7 +387,23 @@ static int flush_tlb_kernel_range_common(unsigned long start, unsigned long end)
 			continue;
 		}
 
-		pud = pud_offset(pgd, addr);
+		p4d = p4d_offset(pgd, addr);
+		if (!p4d_present(*p4d)) {
+			last = ADD_ROUND(addr, P4D_SIZE);
+			if (last > end)
+				last = end;
+			if (p4d_newpage(*p4d)) {
+				updated = 1;
+				err = add_munmap(addr, last - addr, &hvc);
+				if (err < 0)
+					panic("munmap failed, errno = %d\n",
+					      -err);
+			}
+			addr = last;
+			continue;
+		}
+
+		pud = pud_offset(p4d, addr);
 		if (!pud_present(*pud)) {
 			last = ADD_ROUND(addr, PUD_SIZE);
 			if (last > end)
@@ -424,6 +463,7 @@ static int flush_tlb_kernel_range_common(unsigned long start, unsigned long end)
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -437,7 +477,11 @@ void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
 	if (!pgd_present(*pgd))
 		goto kill;
 
-	pud = pud_offset(pgd, address);
+	p4d = p4d_offset(pgd, address);
+	if (!p4d_present(*p4d))
+		goto kill;
+
+	pud = pud_offset(p4d, address);
 	if (!pud_present(*pud))
 		goto kill;
 

arch/um/kernel/trap.c

@@ -28,6 +28,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -104,7 +105,8 @@ int handle_page_fault(unsigned long address, unsigned long ip,
 		}
 
 		pgd = pgd_offset(mm, address);
-		pud = pud_offset(pgd, address);
+		p4d = p4d_offset(pgd, address);
+		pud = pud_offset(p4d, address);
 		pmd = pmd_offset(pud, address);
 		pte = pte_offset_kernel(pmd, address);
 	} while (!pte_present(*pte));