1 files changed, 84 insertions, 40 deletions

diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index bc4a5e9ebb7..6eb97b3a748 100644
--- a/arch/arm/mm/context.c
+++ b/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:
@@ -34,12 +35,12 @@
  * The ASID is used to tag entries in the CPU caches and TLBs.
  * The context ID is used by debuggers and trace logic, and
  * should be unique within all running processes.
+ *
+ * In big endian operation, the two 32 bit words are swapped if accessed
+ * by non-64-bit operations.
  */
 #define ASID_FIRST_VERSION	(1ULL << ASID_BITS)
-#define NUM_USER_ASIDS		(ASID_FIRST_VERSION - 1)
-
-#define ASID_TO_IDX(asid)	((asid & ~ASID_MASK) - 1)
-#define IDX_TO_ASID(idx)	((idx + 1) & ~ASID_MASK)
+#define NUM_USER_ASIDS		ASID_FIRST_VERSION
 
 static DEFINE_RAW_SPINLOCK(cpu_asid_lock);
 static atomic64_t asid_generation = ATOMIC64_INIT(ASID_FIRST_VERSION);
@@ -49,27 +50,49 @@ static DEFINE_PER_CPU(atomic64_t, active_asids);
 static DEFINE_PER_CPU(u64, reserved_asids);
 static cpumask_t tlb_flush_pending;
 
-#ifdef CONFIG_ARM_LPAE
-static void cpu_set_reserved_ttbr0(void)
+#ifdef CONFIG_ARM_ERRATA_798181
+void a15_erratum_get_cpumask(int this_cpu, struct mm_struct *mm,
+			     cpumask_t *mask)
 {
-	unsigned long ttbl = __pa(swapper_pg_dir);
-	unsigned long ttbh = 0;
+	int cpu;
+	unsigned long flags;
+	u64 context_id, asid;
 
-	/*
-	 * Set TTBR0 to swapper_pg_dir which contains only global entries. The
-	 * ASID is set to 0.
-	 */
-	asm volatile(
-	"	mcrr	p15, 0, %0, %1, c2		@ set TTBR0\n"
-	:
-	: "r" (ttbl), "r" (ttbh));
-	isb();
+	raw_spin_lock_irqsave(&cpu_asid_lock, flags);
+	context_id = mm->context.id.counter;
+	for_each_online_cpu(cpu) {
+		if (cpu == this_cpu)
+			continue;
+		/*
+		 * We only need to send an IPI if the other CPUs are
+		 * running the same ASID as the one being invalidated.
+		 */
+		asid = per_cpu(active_asids, cpu).counter;
+		if (asid == 0)
+			asid = per_cpu(reserved_asids, cpu);
+		if (context_id == asid)
+			cpumask_set_cpu(cpu, mask);
+	}
+	raw_spin_unlock_irqrestore(&cpu_asid_lock, flags);
 }
+#endif
+
+#ifdef CONFIG_ARM_LPAE
+/*
+ * With LPAE, the ASID and page tables are updated atomicly, so there is
+ * no need for a reserved set of tables (the active ASID tracking prevents
+ * any issues across a rollover).
+ */
+#define cpu_set_reserved_ttbr0()
 #else
 static void cpu_set_reserved_ttbr0(void)
 {
 	u32 ttb;
-	/* Copy TTBR1 into TTBR0 */
+	/*
+	 * Copy TTBR1 into TTBR0.
+	 * This points at swapper_pg_dir, which contains only global
+	 * entries so any speculative walks are perfectly safe.
+	 */
 	asm volatile(
 	"	mrc	p15, 0, %0, c2, c0, 1		@ read TTBR1\n"
 	"	mcr	p15, 0, %0, c2, c0, 0		@ set TTBR0\n"
@@ -125,16 +148,22 @@ static void flush_context(unsigned int cpu)
 			asid = 0;
 		} else {
 			asid = atomic64_xchg(&per_cpu(active_asids, i), 0);
-			__set_bit(ASID_TO_IDX(asid), asid_map);
+			/*
+			 * If this CPU has already been through a
+			 * rollover, but hasn't run another task in
+			 * the meantime, we must preserve its reserved
+			 * ASID, as this is the only trace we have of
+			 * the process it is still running.
+			 */
+			if (asid == 0)
+				asid = per_cpu(reserved_asids, i);
+			__set_bit(asid & ~ASID_MASK, asid_map);
 		}
 		per_cpu(reserved_asids, i) = asid;
 	}
 
 	/* Queue a TLB invalidate and flush the I-cache if necessary. */
-	if (!tlb_ops_need_broadcast())
-		cpumask_set_cpu(cpu, &tlb_flush_pending);
-	else
-		cpumask_setall(&tlb_flush_pending);
+	cpumask_setall(&tlb_flush_pending);
 
 	if (icache_is_vivt_asid_tagged())
 		__flush_icache_all();
@@ -149,9 +178,10 @@ static int is_reserved_asid(u64 asid)
 	return 0;
 }
 
-static void new_context(struct mm_struct *mm, unsigned int cpu)
+static u64 new_context(struct mm_struct *mm, unsigned int cpu)
 {
-	u64 asid = mm->context.id;
+	static u32 cur_idx = 1;
+	u64 asid = atomic64_read(&mm->context.id);
 	u64 generation = atomic64_read(&asid_generation);
 
 	if (asid != 0 && is_reserved_asid(asid)) {
@@ -164,51 +194,65 @@ static void new_context(struct mm_struct *mm, unsigned int cpu)
 		/*
 		 * Allocate a free ASID. If we can't find one, take a
 		 * note of the currently active ASIDs and mark the TLBs
-		 * as requiring flushes.
+		 * as requiring flushes. We always count from ASID #1,
+		 * as we reserve ASID #0 to switch via TTBR0 and to
+		 * avoid speculative page table walks from hitting in
+		 * any partial walk caches, which could be populated
+		 * from overlapping level-1 descriptors used to map both
+		 * the module area and the userspace stack.
 		 */
-		asid = find_first_zero_bit(asid_map, NUM_USER_ASIDS);
+		asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, cur_idx);
 		if (asid == NUM_USER_ASIDS) {
 			generation = atomic64_add_return(ASID_FIRST_VERSION,
 							 &asid_generation);
 			flush_context(cpu);
-			asid = find_first_zero_bit(asid_map, NUM_USER_ASIDS);
+			asid = find_next_zero_bit(asid_map, NUM_USER_ASIDS, 1);
 		}
 		__set_bit(asid, asid_map);
-		asid = generation | IDX_TO_ASID(asid);
+		cur_idx = asid;
+		asid |= generation;
 		cpumask_clear(mm_cpumask(mm));
 	}
 
-	mm->context.id = asid;
+	return asid;
 }
 
 void check_and_switch_context(struct mm_struct *mm, struct task_struct *tsk)
 {
 	unsigned long flags;
 	unsigned int cpu = smp_processor_id();
+	u64 asid;
 
 	if (unlikely(mm->context.vmalloc_seq != init_mm.context.vmalloc_seq))
 		__check_vmalloc_seq(mm);
 
 	/*
-	 * Required during context switch to avoid speculative page table
-	 * walking with the wrong TTBR.
+	 * We cannot update the pgd and the ASID atomicly with classic
+	 * MMU, so switch exclusively to global mappings to avoid
+	 * speculative page table walking with the wrong TTBR.
 	 */
 	cpu_set_reserved_ttbr0();
 
-	if (!((mm->context.id ^ atomic64_read(&asid_generation)) >> ASID_BITS)
-	    && atomic64_xchg(&per_cpu(active_asids, cpu), mm->context.id))
+	asid = atomic64_read(&mm->context.id);
+	if (!((asid ^ atomic64_read(&asid_generation)) >> ASID_BITS)
+	    && atomic64_xchg(&per_cpu(active_asids, cpu), asid))
 		goto switch_mm_fastpath;
 
 	raw_spin_lock_irqsave(&cpu_asid_lock, flags);
 	/* Check that our ASID belongs to the current generation. */
-	if ((mm->context.id ^ atomic64_read(&asid_generation)) >> ASID_BITS)
-		new_context(mm, cpu);
-
-	atomic64_set(&per_cpu(active_asids, cpu), mm->context.id);
-	cpumask_set_cpu(cpu, mm_cpumask(mm));
+	asid = atomic64_read(&mm->context.id);
+	if ((asid ^ atomic64_read(&asid_generation)) >> ASID_BITS) {
+		asid = new_context(mm, cpu);
+		atomic64_set(&mm->context.id, asid);
+	}
 
-	if (cpumask_test_and_clear_cpu(cpu, &tlb_flush_pending))
+	if (cpumask_test_and_clear_cpu(cpu, &tlb_flush_pending)) {
+		local_flush_bp_all();
 		local_flush_tlb_all();
+	}
+
+	atomic64_set(&per_cpu(active_asids, cpu), asid);
+	cpumask_set_cpu(cpu, mm_cpumask(mm));
 	raw_spin_unlock_irqrestore(&cpu_asid_lock, flags);
 
 switch_mm_fastpath: