ARM: LPAE: Add context switching support

With LPAE, TTBRx registers are 64-bit. The ASID is stored in TTBR0
rather than a separate Context ID register. This patch makes the
necessary changes to handle context switching on LPAE.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 17 insertions, 2 deletions

diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index 93aac068da94..ee9bb363d606 100644
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -22,6 +22,21 @@ unsigned int cpu_last_asid = ASID_FIRST_VERSION;
 DEFINE_PER_CPU(struct mm_struct *, current_mm);
 #endif
 
+#ifdef CONFIG_ARM_LPAE
+#define cpu_set_asid(asid) {                                            \
+        unsigned long ttbl, ttbh;                                       \
+        asm volatile(                                                   \
+        "       mrrc    p15, 0, %0, %1, c2              @ read TTBR0\n" \
+        "       mov     %1, %2, lsl #(48 - 32)          @ set ASID\n"   \
+        "       mcrr    p15, 0, %0, %1, c2              @ set TTBR0\n"  \
+        : "=&r" (ttbl), "=&r" (ttbh)                                    \
+        : "r" (asid & ~ASID_MASK));                                     \
+}
+#else
+#define cpu_set_asid(asid) \
+        asm("   mcr     p15, 0, %0, c13, c0, 1\n" : : "r" (asid))
+#endif
+
 /*
  * We fork()ed a process, and we need a new context for the child
  * to run in.  We reserve version 0 for initial tasks so we will
@@ -37,7 +52,7 @@ void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 static void flush_context(void)
 {
         /* set the reserved ASID before flushing the TLB */
-        asm("mcr        p15, 0, %0, c13, c0, 1\n" : : "r" (0));
+        cpu_set_asid(0);
         isb();
         local_flush_tlb_all();
         if (icache_is_vivt_asid_tagged()) {
@@ -99,7 +114,7 @@ static void reset_context(void *info)
         set_mm_context(mm, asid);
 
         /* set the new ASID */
-        asm("mcr        p15, 0, %0, c13, c0, 1\n" : : "r" (mm->context.id));
+        cpu_set_asid(mm->context.id);
         isb();
 }