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#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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