ARC: mm: PAE: use 40-bit physical page mask

32-bit PAGE_MASK can not be used as a mask for physical addresses
when PAE is enabled. PAGE_MASK_PHYS must be used for physical
addresses instead of PAGE_MASK.

Without this, init gets SIGSEGV if pte_modify was called:

| potentially unexpected fatal signal 11.
| Path: /bin/busybox
| CPU: 0 PID: 1 Comm: init Not tainted 5.12.0-rc5-00003-g1e43c377a79f-dirty
| Insn could not be fetched
|     @no matching VMA found
|  ECR: 0x00040000 EFA: 0x00000000 ERET: 0x00000000
| STAT: 0x80080082 [IE U     ]   BTA: 0x00000000
|  SP: 0x5f9ffe44  FP: 0x00000000 BLK: 0xaf3d4
| LPS: 0x000d093e LPE: 0x000d0950 LPC: 0x00000000
| r00: 0x00000002 r01: 0x5f9fff14 r02: 0x5f9fff20
| ...
| Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

Signed-off-by: Vladimir Isaev <[email protected]>
Reported-by: kernel test robot <[email protected]>
Cc: Vineet Gupta <[email protected]>
Cc: [email protected]
Signed-off-by: Vineet Gupta <[email protected]>

Author: Vladimir Isaev

arch/arc/include/asm/page.h

@@ -7,6 +7,18 @@
 
 #include <uapi/asm/page.h>
 
+#ifdef CONFIG_ARC_HAS_PAE40
+
+#define MAX_POSSIBLE_PHYSMEM_BITS	40
+#define PAGE_MASK_PHYS			(0xff00000000ull | PAGE_MASK)
+
+#else /* CONFIG_ARC_HAS_PAE40 */
+
+#define MAX_POSSIBLE_PHYSMEM_BITS	32
+#define PAGE_MASK_PHYS			PAGE_MASK
+
+#endif /* CONFIG_ARC_HAS_PAE40 */
+
 #ifndef __ASSEMBLY__
 
 #define clear_page(paddr)		memset((paddr), 0, PAGE_SIZE)

arch/arc/include/asm/pgtable.h

@@ -107,8 +107,8 @@
 #define ___DEF (_PAGE_PRESENT | _PAGE_CACHEABLE)
 
 /* Set of bits not changed in pte_modify */
-#define _PAGE_CHG_MASK	(PAGE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_SPECIAL)
-
+#define _PAGE_CHG_MASK	(PAGE_MASK_PHYS | _PAGE_ACCESSED | _PAGE_DIRTY | \
+							   _PAGE_SPECIAL)
 /* More Abbrevaited helpers */
 #define PAGE_U_NONE     __pgprot(___DEF)
 #define PAGE_U_R        __pgprot(___DEF | _PAGE_READ)
@@ -132,13 +132,7 @@
 #define PTE_BITS_IN_PD0		(_PAGE_GLOBAL | _PAGE_PRESENT | _PAGE_HW_SZ)
 #define PTE_BITS_RWX		(_PAGE_EXECUTE | _PAGE_WRITE | _PAGE_READ)
 
-#ifdef CONFIG_ARC_HAS_PAE40
-#define PTE_BITS_NON_RWX_IN_PD1	(0xff00000000 | PAGE_MASK | _PAGE_CACHEABLE)
-#define MAX_POSSIBLE_PHYSMEM_BITS 40
-#else
-#define PTE_BITS_NON_RWX_IN_PD1	(PAGE_MASK | _PAGE_CACHEABLE)
-#define MAX_POSSIBLE_PHYSMEM_BITS 32
-#endif
+#define PTE_BITS_NON_RWX_IN_PD1	(PAGE_MASK_PHYS | _PAGE_CACHEABLE)
 
 /**************************************************************************
  * Mapping of vm_flags (Generic VM) to PTE flags (arch specific)

arch/arc/include/uapi/asm/page.h

@@ -33,5 +33,4 @@
 
 #define PAGE_MASK	(~(PAGE_SIZE-1))
 
-
 #endif /* _UAPI__ASM_ARC_PAGE_H */

arch/arc/mm/ioremap.c

@@ -53,9 +53,10 @@ EXPORT_SYMBOL(ioremap);
 void __iomem *ioremap_prot(phys_addr_t paddr, unsigned long size,
 			   unsigned long flags)
 {
+	unsigned int off;
 	unsigned long vaddr;
 	struct vm_struct *area;
-	phys_addr_t off, end;
+	phys_addr_t end;
 	pgprot_t prot = __pgprot(flags);
 
 	/* Don't allow wraparound, zero size */
@@ -72,7 +73,7 @@ void __iomem *ioremap_prot(phys_addr_t paddr, unsigned long size,
 
 	/* Mappings have to be page-aligned */
 	off = paddr & ~PAGE_MASK;
-	paddr &= PAGE_MASK;
+	paddr &= PAGE_MASK_PHYS;
 	size = PAGE_ALIGN(end + 1) - paddr;
 
 	/*

arch/arc/mm/tlb.c

@@ -576,7 +576,7 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long vaddr_unaligned,
 		      pte_t *ptep)
 {
 	unsigned long vaddr = vaddr_unaligned & PAGE_MASK;
-	phys_addr_t paddr = pte_val(*ptep) & PAGE_MASK;
+	phys_addr_t paddr = pte_val(*ptep) & PAGE_MASK_PHYS;
 	struct page *page = pfn_to_page(pte_pfn(*ptep));
 
 	create_tlb(vma, vaddr, ptep);