zte's code,first commit
Change-Id: I9a04da59e459a9bc0d67f101f700d9d7dc8d681b
diff --git a/ap/os/linux/linux-3.4.x/arch/arm/mm/context.c b/ap/os/linux/linux-3.4.x/arch/arm/mm/context.c
new file mode 100644
index 0000000..806cc4f
--- /dev/null
+++ b/ap/os/linux/linux-3.4.x/arch/arm/mm/context.c
@@ -0,0 +1,171 @@
+/*
+ * linux/arch/arm/mm/context.c
+ *
+ * Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/percpu.h>
+
+#include <asm/mmu_context.h>
+#include <asm/tlbflush.h>
+
+static DEFINE_RAW_SPINLOCK(cpu_asid_lock);
+unsigned int cpu_last_asid = ASID_FIRST_VERSION;
+
+#ifdef CONFIG_ARM_LPAE
+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(
+ " mcrr p15, 0, %0, %1, c2 @ set TTBR0\n"
+ :
+ : "r" (ttbl), "r" (ttbh));
+ isb();
+}
+#else
+void cpu_set_reserved_ttbr0(void)
+{
+ u32 ttb;
+ /* Copy TTBR1 into TTBR0 */
+ asm volatile(
+ " mrc p15, 0, %0, c2, c0, 1 @ read TTBR1\n"
+ " mcr p15, 0, %0, c2, c0, 0 @ set TTBR0\n"
+ : "=r" (ttb));
+ isb();
+}
+#endif
+
+/*
+ * We fork()ed a process, and we need a new context for the child
+ * to run in.
+ */
+void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+{
+ mm->context.id = 0;
+ raw_spin_lock_init(&mm->context.id_lock);
+}
+
+static void flush_context(void)
+{
+ cpu_set_reserved_ttbr0();
+ local_flush_tlb_all();
+ if (icache_is_vivt_asid_tagged()) {
+ __flush_icache_all();
+ dsb();
+ }
+}
+
+#ifdef CONFIG_SMP
+
+static void set_mm_context(struct mm_struct *mm, unsigned int asid)
+{
+ unsigned long flags;
+
+ /*
+ * Locking needed for multi-threaded applications where the
+ * same mm->context.id could be set from different CPUs during
+ * the broadcast. This function is also called via IPI so the
+ * mm->context.id_lock has to be IRQ-safe.
+ */
+ raw_spin_lock_irqsave(&mm->context.id_lock, flags);
+ if (likely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) {
+ /*
+ * Old version of ASID found. Set the new one and
+ * reset mm_cpumask(mm).
+ */
+ mm->context.id = asid;
+ cpumask_clear(mm_cpumask(mm));
+ }
+ raw_spin_unlock_irqrestore(&mm->context.id_lock, flags);
+
+ /*
+ * Set the mm_cpumask(mm) bit for the current CPU.
+ */
+ cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
+}
+
+/*
+ * Reset the ASID on the current CPU. This function call is broadcast
+ * from the CPU handling the ASID rollover and holding cpu_asid_lock.
+ */
+static void reset_context(void *info)
+{
+ unsigned int asid;
+ unsigned int cpu = smp_processor_id();
+ struct mm_struct *mm = current->active_mm;
+
+ smp_rmb();
+ asid = cpu_last_asid + cpu + 1;
+
+ flush_context();
+ set_mm_context(mm, asid);
+
+ /* set the new ASID */
+ cpu_switch_mm(mm->pgd, mm);
+}
+
+#else
+
+static inline void set_mm_context(struct mm_struct *mm, unsigned int asid)
+{
+ mm->context.id = asid;
+ cpumask_copy(mm_cpumask(mm), cpumask_of(smp_processor_id()));
+}
+
+#endif
+
+void __new_context(struct mm_struct *mm)
+{
+ unsigned int asid;
+
+ raw_spin_lock(&cpu_asid_lock);
+#ifdef CONFIG_SMP
+ /*
+ * Check the ASID again, in case the change was broadcast from
+ * another CPU before we acquired the lock.
+ */
+ if (unlikely(((mm->context.id ^ cpu_last_asid) >> ASID_BITS) == 0)) {
+ cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
+ raw_spin_unlock(&cpu_asid_lock);
+ return;
+ }
+#endif
+ /*
+ * At this point, it is guaranteed that the current mm (with
+ * an old ASID) isn't active on any other CPU since the ASIDs
+ * are changed simultaneously via IPI.
+ */
+ asid = ++cpu_last_asid;
+ if (asid == 0)
+ asid = cpu_last_asid = ASID_FIRST_VERSION;
+
+ /*
+ * If we've used up all our ASIDs, we need
+ * to start a new version and flush the TLB.
+ */
+ if (unlikely((asid & ~ASID_MASK) == 0)) {
+ asid = cpu_last_asid + smp_processor_id() + 1;
+ flush_context();
+#ifdef CONFIG_SMP
+ smp_wmb();
+ smp_call_function(reset_context, NULL, 1);
+#endif
+ cpu_last_asid += NR_CPUS;
+ }
+
+ set_mm_context(mm, asid);
+ raw_spin_unlock(&cpu_asid_lock);
+}