ARM: LPAE: use 64-bit accessors for TTBR registers

This patch adds TTBR accessor macros, and modifies cpu_get_pgd() and
the LPAE version of cpu_set_reserved_ttbr0() to use these instead.

In the process, we also fix these functions to correctly handle cases
where the physical address lies beyond the 4G limit of 32-bit addressing.

Signed-off-by: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
Acked-by: Nicolas Pitre <nico@linaro.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Subash Patel <subash.rp@samsung.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm/include/asm/proc-fns.h

@@ -116,13 +116,25 @@ extern void cpu_resume(void);
 #define cpu_switch_mm(pgd,mm) cpu_do_switch_mm(virt_to_phys(pgd),mm)
 
 #ifdef CONFIG_ARM_LPAE
+
+#define cpu_get_ttbr(nr)					\
+	({							\
+		u64 ttbr;					\
+		__asm__("mrrc	p15, " #nr ", %Q0, %R0, c2"	\
+			: "=r" (ttbr));				\
+		ttbr;						\
+	})
+
+#define cpu_set_ttbr(nr, val)					\
+	do {							\
+		u64 ttbr = val;					\
+		__asm__("mcrr	p15, " #nr ", %Q0, %R0, c2"	\
+			: : "r" (ttbr));			\
+	} while (0)
+
 #define cpu_get_pgd()	\
 	({						\
-		unsigned long pg, pg2;			\
+		u64 pg = cpu_get_ttbr(0);		\
-		__asm__("mrrc	p15, 0, %0, %1, c2"	\
-			: "=r" (pg), "=r" (pg2)		\
-			:				\
-			: "cc");			\
 		pg &= ~(PTRS_PER_PGD*sizeof(pgd_t)-1);	\
 		(pgd_t *)phys_to_virt(pg);		\
 	})

arch/arm/mm/context.c

@@ -20,6 +20,7 @@
 #include <asm/smp_plat.h>
 #include <asm/thread_notify.h>
 #include <asm/tlbflush.h>
+#include <asm/proc-fns.h>
 
 /*
  * On ARMv6, we have the following structure in the Context ID:
@@ -55,17 +56,11 @@ static cpumask_t tlb_flush_pending;
 #ifdef CONFIG_ARM_LPAE
 static void cpu_set_reserved_ttbr0(void)
 {
-	unsigned long ttbl = __pa(swapper_pg_dir);
-	unsigned long ttbh = 0;
-
 	/*
 	 * Set TTBR0 to swapper_pg_dir which contains only global entries. The
 	 * ASID is set to 0.
 	 */
-	asm volatile(
+	cpu_set_ttbr(0, __pa(swapper_pg_dir));
-	"	mcrr	p15, 0, %0, %1, c2		@ set TTBR0\n"
-	:
-	: "r" (ttbl), "r" (ttbh));
 	isb();
 }
 #else