2 * linux/arch/arm/mm/context.c
4 * Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved.
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
10 #include <linux/init.h>
11 #include <linux/sched.h>
13 #include <linux/smp.h>
14 #include <linux/percpu.h>
16 #include <asm/mmu_context.h>
17 #include <asm/thread_notify.h>
18 #include <asm/tlbflush.h>
20 static DEFINE_RAW_SPINLOCK(cpu_asid_lock);
21 unsigned int cpu_last_asid = ASID_FIRST_VERSION;
23 #ifdef CONFIG_ARM_LPAE
24 void cpu_set_reserved_ttbr0(void)
26 unsigned long ttbl = __pa(swapper_pg_dir);
27 unsigned long ttbh = 0;
30 * Set TTBR0 to swapper_pg_dir which contains only global entries. The
34 " mcrr p15, 0, %0, %1, c2 @ set TTBR0\n"
36 : "r" (ttbl), "r" (ttbh));
40 void cpu_set_reserved_ttbr0(void)
43 /* Copy TTBR1 into TTBR0 */
45 " mrc p15, 0, %0, c2, c0, 1 @ read TTBR1\n"
46 " mcr p15, 0, %0, c2, c0, 0 @ set TTBR0\n"
52 #ifdef CONFIG_PID_IN_CONTEXTIDR
53 static int contextidr_notifier(struct notifier_block *unused, unsigned long cmd,
58 struct thread_info *thread = t;
60 if (cmd != THREAD_NOTIFY_SWITCH)
63 pid = task_pid_nr(thread->task) << ASID_BITS;
65 " mrc p15, 0, %0, c13, c0, 1\n"
66 " bfi %1, %0, #0, %2\n"
67 " mcr p15, 0, %1, c13, c0, 1\n"
68 : "=r" (contextidr), "+r" (pid)
75 static struct notifier_block contextidr_notifier_block = {
76 .notifier_call = contextidr_notifier,
79 static int __init contextidr_notifier_init(void)
81 return thread_register_notifier(&contextidr_notifier_block);
83 arch_initcall(contextidr_notifier_init);
87 * We fork()ed a process, and we need a new context for the child
90 void __init_new_context(struct task_struct *tsk, struct mm_struct *mm)
93 raw_spin_lock_init(&mm->context.id_lock);
96 static void flush_context(void)
98 cpu_set_reserved_ttbr0();
99 local_flush_tlb_all();
100 if (icache_is_vivt_asid_tagged()) {
101 __flush_icache_all();
108 static void set_mm_context(struct mm_struct *mm, unsigned int asid)
113 * Locking needed for multi-threaded applications where the
114 * same mm->context.id could be set from different CPUs during
115 * the broadcast. This function is also called via IPI so the
116 * mm->context.id_lock has to be IRQ-safe.
118 raw_spin_lock_irqsave(&mm->context.id_lock, flags);
119 if (likely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) {
121 * Old version of ASID found. Set the new one and
122 * reset mm_cpumask(mm).
124 mm->context.id = asid;
125 cpumask_clear(mm_cpumask(mm));
127 raw_spin_unlock_irqrestore(&mm->context.id_lock, flags);
130 * Set the mm_cpumask(mm) bit for the current CPU.
132 cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
136 * Reset the ASID on the current CPU. This function call is broadcast
137 * from the CPU handling the ASID rollover and holding cpu_asid_lock.
139 static void reset_context(void *info)
142 unsigned int cpu = smp_processor_id();
143 struct mm_struct *mm = current->active_mm;
146 asid = cpu_last_asid + cpu + 1;
149 set_mm_context(mm, asid);
151 /* set the new ASID */
152 cpu_switch_mm(mm->pgd, mm);
157 static inline void set_mm_context(struct mm_struct *mm, unsigned int asid)
159 mm->context.id = asid;
160 cpumask_copy(mm_cpumask(mm), cpumask_of(smp_processor_id()));
165 void __new_context(struct mm_struct *mm)
169 raw_spin_lock(&cpu_asid_lock);
172 * Check the ASID again, in case the change was broadcast from
173 * another CPU before we acquired the lock.
175 if (unlikely(((mm->context.id ^ cpu_last_asid) >> ASID_BITS) == 0)) {
176 cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
177 raw_spin_unlock(&cpu_asid_lock);
182 * At this point, it is guaranteed that the current mm (with
183 * an old ASID) isn't active on any other CPU since the ASIDs
184 * are changed simultaneously via IPI.
186 asid = ++cpu_last_asid;
188 asid = cpu_last_asid = ASID_FIRST_VERSION;
191 * If we've used up all our ASIDs, we need
192 * to start a new version and flush the TLB.
194 if (unlikely((asid & ~ASID_MASK) == 0)) {
195 asid = cpu_last_asid + smp_processor_id() + 1;
199 smp_call_function(reset_context, NULL, 1);
201 cpu_last_asid += NR_CPUS;
204 set_mm_context(mm, asid);
205 raw_spin_unlock(&cpu_asid_lock);