[ARM] Control v6 'global' bit via Linux PTE entries

Unfortunately, we can't use the "user" bit in the page tables to
control whether a page table entry is "global" or "asid" specific,
since the vector page is mapped as "user" accessible but is not
process specific.

Therefore, give direct control of the ARMv6 "nG" (not global)
bit to the mm layers.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/mm-armv.c

@@ -383,6 +383,7 @@ static void __init build_mem_type_table(void)
 {
 	struct cachepolicy *cp;
 	unsigned int cr = get_cr();
+	unsigned int user_pgprot;
 	int cpu_arch = cpu_architecture();
 	int i;
 
@@ -408,6 +409,9 @@ static void __init build_mem_type_table(void)
 		}
 	}
 
+	cp = &cache_policies[cachepolicy];
+	user_pgprot = cp->pte;
+
 	/*
 	 * ARMv6 and above have extended page tables.
 	 */
@@ -426,11 +430,18 @@ static void __init build_mem_type_table(void)
 		mem_types[MT_MINICLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
 		mem_types[MT_CACHECLEAN].prot_sect |= PMD_SECT_APX|PMD_SECT_AP_WRITE;
 
+		/*
+		 * Mark the device area as "shared device"
+		 */
 		mem_types[MT_DEVICE].prot_pte |= L_PTE_BUFFERABLE;
 		mem_types[MT_DEVICE].prot_sect |= PMD_SECT_BUFFERED;
-	}
 
-	cp = &cache_policies[cachepolicy];
+		/*
+		 * User pages need to be mapped with the ASID
+		 * (iow, non-global)
+		 */
+		user_pgprot |= L_PTE_ASID;
+	}
 
 	if (cpu_arch >= CPU_ARCH_ARMv5) {
 		mem_types[MT_LOW_VECTORS].prot_pte |= cp->pte & PTE_CACHEABLE;
@@ -448,7 +459,7 @@ static void __init build_mem_type_table(void)
 
 	for (i = 0; i < 16; i++) {
 		unsigned long v = pgprot_val(protection_map[i]);
-		v &= (~(PTE_BUFFERABLE|PTE_CACHEABLE)) | cp->pte;
+		v &= (~(PTE_BUFFERABLE|PTE_CACHEABLE)) | user_pgprot;
 		protection_map[i] = __pgprot(v);
 	}
 

arch/arm/mm/proc-v6.S

@@ -133,7 +133,7 @@ ENTRY(cpu_v6_switch_mm)
 ENTRY(cpu_v6_set_pte)
 	str	r1, [r0], #-2048		@ linux version
 
-	bic	r2, r1, #0x00000ff0
+	bic	r2, r1, #0x000007f0
 	bic	r2, r2, #0x00000003
 	orr	r2, r2, #PTE_EXT_AP0 | 2
 
@@ -142,7 +142,7 @@ ENTRY(cpu_v6_set_pte)
 	orreq	r2, r2, #PTE_EXT_APX
 
 	tst	r1, #L_PTE_USER
-	orrne	r2, r2, #PTE_EXT_AP1 | PTE_EXT_NG
+	orrne	r2, r2, #PTE_EXT_AP1
 	tstne	r2, #PTE_EXT_APX
 	bicne	r2, r2, #PTE_EXT_APX | PTE_EXT_AP0
 

include/asm-arm/pgtable.h

@@ -230,6 +230,8 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
 #define L_PTE_WRITE		(1 << 5)
 #define L_PTE_EXEC		(1 << 6)
 #define L_PTE_DIRTY		(1 << 7)
+#define L_PTE_SHARED		(1 << 10)	/* shared between CPUs (v6) */
+#define L_PTE_ASID		(1 << 11)	/* non-global (use ASID, v6) */
 
 #ifndef __ASSEMBLY__