Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
Russell King | d84b471 | 2006-08-21 19:23:38 +0100 | [diff] [blame] | 2 | * linux/arch/arm/mm/context.c |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 3 | * |
| 4 | * Copyright (C) 2002-2003 Deep Blue Solutions Ltd, all rights reserved. |
| 5 | * |
| 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. |
| 9 | */ |
| 10 | #include <linux/init.h> |
| 11 | #include <linux/sched.h> |
| 12 | #include <linux/mm.h> |
Catalin Marinas | 11805bc | 2010-01-26 19:09:42 +0100 | [diff] [blame^] | 13 | #include <linux/smp.h> |
| 14 | #include <linux/percpu.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | |
| 16 | #include <asm/mmu_context.h> |
| 17 | #include <asm/tlbflush.h> |
| 18 | |
Russell King | 8678c1f | 2007-05-08 20:03:09 +0100 | [diff] [blame] | 19 | static DEFINE_SPINLOCK(cpu_asid_lock); |
| 20 | unsigned int cpu_last_asid = ASID_FIRST_VERSION; |
Catalin Marinas | 11805bc | 2010-01-26 19:09:42 +0100 | [diff] [blame^] | 21 | #ifdef CONFIG_SMP |
| 22 | DEFINE_PER_CPU(struct mm_struct *, current_mm); |
| 23 | #endif |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | |
| 25 | /* |
| 26 | * We fork()ed a process, and we need a new context for the child |
| 27 | * to run in. We reserve version 0 for initial tasks so we will |
Catalin Marinas | 9d99df4 | 2007-02-05 14:47:40 +0100 | [diff] [blame] | 28 | * always allocate an ASID. The ASID 0 is reserved for the TTBR |
| 29 | * register changing sequence. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | */ |
| 31 | void __init_new_context(struct task_struct *tsk, struct mm_struct *mm) |
| 32 | { |
| 33 | mm->context.id = 0; |
Catalin Marinas | 11805bc | 2010-01-26 19:09:42 +0100 | [diff] [blame^] | 34 | spin_lock_init(&mm->context.id_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 35 | } |
| 36 | |
Catalin Marinas | 11805bc | 2010-01-26 19:09:42 +0100 | [diff] [blame^] | 37 | static void flush_context(void) |
| 38 | { |
| 39 | /* set the reserved ASID before flushing the TLB */ |
| 40 | asm("mcr p15, 0, %0, c13, c0, 1\n" : : "r" (0)); |
| 41 | isb(); |
| 42 | local_flush_tlb_all(); |
| 43 | if (icache_is_vivt_asid_tagged()) { |
| 44 | __flush_icache_all(); |
| 45 | dsb(); |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | #ifdef CONFIG_SMP |
| 50 | |
| 51 | static void set_mm_context(struct mm_struct *mm, unsigned int asid) |
| 52 | { |
| 53 | unsigned long flags; |
| 54 | |
| 55 | /* |
| 56 | * Locking needed for multi-threaded applications where the |
| 57 | * same mm->context.id could be set from different CPUs during |
| 58 | * the broadcast. This function is also called via IPI so the |
| 59 | * mm->context.id_lock has to be IRQ-safe. |
| 60 | */ |
| 61 | spin_lock_irqsave(&mm->context.id_lock, flags); |
| 62 | if (likely((mm->context.id ^ cpu_last_asid) >> ASID_BITS)) { |
| 63 | /* |
| 64 | * Old version of ASID found. Set the new one and |
| 65 | * reset mm_cpumask(mm). |
| 66 | */ |
| 67 | mm->context.id = asid; |
| 68 | cpumask_clear(mm_cpumask(mm)); |
| 69 | } |
| 70 | spin_unlock_irqrestore(&mm->context.id_lock, flags); |
| 71 | |
| 72 | /* |
| 73 | * Set the mm_cpumask(mm) bit for the current CPU. |
| 74 | */ |
| 75 | cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm)); |
| 76 | } |
| 77 | |
| 78 | /* |
| 79 | * Reset the ASID on the current CPU. This function call is broadcast |
| 80 | * from the CPU handling the ASID rollover and holding cpu_asid_lock. |
| 81 | */ |
| 82 | static void reset_context(void *info) |
| 83 | { |
| 84 | unsigned int asid; |
| 85 | unsigned int cpu = smp_processor_id(); |
| 86 | struct mm_struct *mm = per_cpu(current_mm, cpu); |
| 87 | |
| 88 | /* |
| 89 | * Check if a current_mm was set on this CPU as it might still |
| 90 | * be in the early booting stages and using the reserved ASID. |
| 91 | */ |
| 92 | if (!mm) |
| 93 | return; |
| 94 | |
| 95 | smp_rmb(); |
| 96 | asid = cpu_last_asid + cpu + 1; |
| 97 | |
| 98 | flush_context(); |
| 99 | set_mm_context(mm, asid); |
| 100 | |
| 101 | /* set the new ASID */ |
| 102 | asm("mcr p15, 0, %0, c13, c0, 1\n" : : "r" (mm->context.id)); |
| 103 | isb(); |
| 104 | } |
| 105 | |
| 106 | #else |
| 107 | |
| 108 | static inline void set_mm_context(struct mm_struct *mm, unsigned int asid) |
| 109 | { |
| 110 | mm->context.id = asid; |
| 111 | cpumask_copy(mm_cpumask(mm), cpumask_of(smp_processor_id())); |
| 112 | } |
| 113 | |
| 114 | #endif |
| 115 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 116 | void __new_context(struct mm_struct *mm) |
| 117 | { |
| 118 | unsigned int asid; |
| 119 | |
Russell King | 8678c1f | 2007-05-08 20:03:09 +0100 | [diff] [blame] | 120 | spin_lock(&cpu_asid_lock); |
Catalin Marinas | 11805bc | 2010-01-26 19:09:42 +0100 | [diff] [blame^] | 121 | #ifdef CONFIG_SMP |
| 122 | /* |
| 123 | * Check the ASID again, in case the change was broadcast from |
| 124 | * another CPU before we acquired the lock. |
| 125 | */ |
| 126 | if (unlikely(((mm->context.id ^ cpu_last_asid) >> ASID_BITS) == 0)) { |
| 127 | cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm)); |
| 128 | spin_unlock(&cpu_asid_lock); |
| 129 | return; |
| 130 | } |
| 131 | #endif |
| 132 | /* |
| 133 | * At this point, it is guaranteed that the current mm (with |
| 134 | * an old ASID) isn't active on any other CPU since the ASIDs |
| 135 | * are changed simultaneously via IPI. |
| 136 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 137 | asid = ++cpu_last_asid; |
| 138 | if (asid == 0) |
Russell King | 8678c1f | 2007-05-08 20:03:09 +0100 | [diff] [blame] | 139 | asid = cpu_last_asid = ASID_FIRST_VERSION; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | |
| 141 | /* |
| 142 | * If we've used up all our ASIDs, we need |
| 143 | * to start a new version and flush the TLB. |
| 144 | */ |
Russell King | 8678c1f | 2007-05-08 20:03:09 +0100 | [diff] [blame] | 145 | if (unlikely((asid & ~ASID_MASK) == 0)) { |
Catalin Marinas | 11805bc | 2010-01-26 19:09:42 +0100 | [diff] [blame^] | 146 | asid = cpu_last_asid + smp_processor_id() + 1; |
| 147 | flush_context(); |
| 148 | #ifdef CONFIG_SMP |
| 149 | smp_wmb(); |
| 150 | smp_call_function(reset_context, NULL, 1); |
| 151 | #endif |
| 152 | cpu_last_asid += NR_CPUS; |
Catalin Marinas | 9d99df4 | 2007-02-05 14:47:40 +0100 | [diff] [blame] | 153 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 154 | |
Catalin Marinas | 11805bc | 2010-01-26 19:09:42 +0100 | [diff] [blame^] | 155 | set_mm_context(mm, asid); |
| 156 | spin_unlock(&cpu_asid_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 157 | } |