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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 | #include <linux/spinlock.h>
#include <linux/cpu.h>
#include <linux/interrupt.h>
#include <asm/tlbflush.h>
DEFINE_PER_CPU(struct tlb_state, cpu_tlbstate)
____cacheline_aligned = { &init_mm, 0, };
/* must come after the send_IPI functions above for inlining */
#include <mach_ipi.h>
/*
* Smarter SMP flushing macros.
* c/o Linus Torvalds.
*
* These mean you can really definitely utterly forget about
* writing to user space from interrupts. (Its not allowed anyway).
*
* Optimizations Manfred Spraul <manfred@colorfullife.com>
*/
static cpumask_t flush_cpumask;
static struct mm_struct *flush_mm;
static unsigned long flush_va;
static DEFINE_SPINLOCK(tlbstate_lock);
/*
* We cannot call mmdrop() because we are in interrupt context,
* instead update mm->cpu_vm_mask.
*
* We need to reload %cr3 since the page tables may be going
* away from under us..
*/
void leave_mm(int cpu)
{
if (per_cpu(cpu_tlbstate, cpu).state == TLBSTATE_OK)
BUG();
cpu_clear(cpu, per_cpu(cpu_tlbstate, cpu).active_mm->cpu_vm_mask);
load_cr3(swapper_pg_dir);
}
EXPORT_SYMBOL_GPL(leave_mm);
/*
*
* The flush IPI assumes that a thread switch happens in this order:
* [cpu0: the cpu that switches]
* 1) switch_mm() either 1a) or 1b)
* 1a) thread switch to a different mm
* 1a1) cpu_clear(cpu, old_mm->cpu_vm_mask);
* Stop ipi delivery for the old mm. This is not synchronized with
* the other cpus, but smp_invalidate_interrupt ignore flush ipis
* for the wrong mm, and in the worst case we perform a superfluous
* tlb flush.
* 1a2) set cpu_tlbstate to TLBSTATE_OK
* Now the smp_invalidate_interrupt won't call leave_mm if cpu0
* was in lazy tlb mode.
* 1a3) update cpu_tlbstate[].active_mm
* Now cpu0 accepts tlb flushes for the new mm.
* 1a4) cpu_set(cpu, new_mm->cpu_vm_mask);
* Now the other cpus will send tlb flush ipis.
* 1a4) change cr3.
* 1b) thread switch without mm change
* cpu_tlbstate[].active_mm is correct, cpu0 already handles
* flush ipis.
* 1b1) set cpu_tlbstate to TLBSTATE_OK
* 1b2) test_and_set the cpu bit in cpu_vm_mask.
* Atomically set the bit [other cpus will start sending flush ipis],
* and test the bit.
* 1b3) if the bit was 0: leave_mm was called, flush the tlb.
* 2) switch %%esp, ie current
*
* The interrupt must handle 2 special cases:
* - cr3 is changed before %%esp, ie. it cannot use current->{active_,}mm.
* - the cpu performs speculative tlb reads, i.e. even if the cpu only
* runs in kernel space, the cpu could load tlb entries for user space
* pages.
*
* The good news is that cpu_tlbstate is local to each cpu, no
* write/read ordering problems.
*/
/*
* TLB flush IPI:
*
* 1) Flush the tlb entries if the cpu uses the mm that's being flushed.
* 2) Leave the mm if we are in the lazy tlb mode.
*/
void smp_invalidate_interrupt(struct pt_regs *regs)
{
unsigned long cpu;
cpu = get_cpu();
if (!cpu_isset(cpu, flush_cpumask))
goto out;
/*
* This was a BUG() but until someone can quote me the
* line from the intel manual that guarantees an IPI to
* multiple CPUs is retried _only_ on the erroring CPUs
* its staying as a return
*
* BUG();
*/
if (flush_mm == per_cpu(cpu_tlbstate, cpu).active_mm) {
if (per_cpu(cpu_tlbstate, cpu).state == TLBSTATE_OK) {
if (flush_va == TLB_FLUSH_ALL)
local_flush_tlb();
else
__flush_tlb_one(flush_va);
} else
leave_mm(cpu);
}
ack_APIC_irq();
smp_mb__before_clear_bit();
cpu_clear(cpu, flush_cpumask);
smp_mb__after_clear_bit();
out:
put_cpu_no_resched();
__get_cpu_var(irq_stat).irq_tlb_count++;
}
void native_flush_tlb_others(const cpumask_t *cpumaskp, struct mm_struct *mm,
unsigned long va)
{
cpumask_t cpumask = *cpumaskp;
/*
* A couple of (to be removed) sanity checks:
*
* - current CPU must not be in mask
* - mask must exist :)
*/
BUG_ON(cpus_empty(cpumask));
BUG_ON(cpu_isset(smp_processor_id(), cpumask));
BUG_ON(!mm);
#ifdef CONFIG_HOTPLUG_CPU
/* If a CPU which we ran on has gone down, OK. */
cpus_and(cpumask, cpumask, cpu_online_map);
if (unlikely(cpus_empty(cpumask)))
return;
#endif
/*
* i'm not happy about this global shared spinlock in the
* MM hot path, but we'll see how contended it is.
* AK: x86-64 has a faster method that could be ported.
*/
spin_lock(&tlbstate_lock);
flush_mm = mm;
flush_va = va;
cpus_or(flush_cpumask, cpumask, flush_cpumask);
/*
* We have to send the IPI only to
* CPUs affected.
*/
send_IPI_mask(cpumask, INVALIDATE_TLB_VECTOR);
while (!cpus_empty(flush_cpumask))
/* nothing. lockup detection does not belong here */
cpu_relax();
flush_mm = NULL;
flush_va = 0;
spin_unlock(&tlbstate_lock);
}
void flush_tlb_current_task(void)
{
struct mm_struct *mm = current->mm;
cpumask_t cpu_mask;
preempt_disable();
cpu_mask = mm->cpu_vm_mask;
cpu_clear(smp_processor_id(), cpu_mask);
local_flush_tlb();
if (!cpus_empty(cpu_mask))
flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);
preempt_enable();
}
void flush_tlb_mm(struct mm_struct *mm)
{
cpumask_t cpu_mask;
preempt_disable();
cpu_mask = mm->cpu_vm_mask;
cpu_clear(smp_processor_id(), cpu_mask);
if (current->active_mm == mm) {
if (current->mm)
local_flush_tlb();
else
leave_mm(smp_processor_id());
}
if (!cpus_empty(cpu_mask))
flush_tlb_others(cpu_mask, mm, TLB_FLUSH_ALL);
preempt_enable();
}
void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
{
struct mm_struct *mm = vma->vm_mm;
cpumask_t cpu_mask;
preempt_disable();
cpu_mask = mm->cpu_vm_mask;
cpu_clear(smp_processor_id(), cpu_mask);
if (current->active_mm == mm) {
if (current->mm)
__flush_tlb_one(va);
else
leave_mm(smp_processor_id());
}
if (!cpus_empty(cpu_mask))
flush_tlb_others(cpu_mask, mm, va);
preempt_enable();
}
EXPORT_SYMBOL(flush_tlb_page);
static void do_flush_tlb_all(void *info)
{
unsigned long cpu = smp_processor_id();
__flush_tlb_all();
if (per_cpu(cpu_tlbstate, cpu).state == TLBSTATE_LAZY)
leave_mm(cpu);
}
void flush_tlb_all(void)
{
on_each_cpu(do_flush_tlb_all, NULL, 1);
}
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