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291 lines
7.6 KiB
291 lines
7.6 KiB
#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/spinlock.h>
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#include <linux/smp.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <asm/tlbflush.h>
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#include <asm/mmu_context.h>
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#include <asm/cache.h>
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#include <asm/apic.h>
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#include <asm/uv/uv.h>
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DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate)
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= { &init_mm, 0, };
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/*
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* Smarter SMP flushing macros.
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* c/o Linus Torvalds.
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*
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* These mean you can really definitely utterly forget about
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* writing to user space from interrupts. (Its not allowed anyway).
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*
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* Optimizations Manfred Spraul <manfred@colorfullife.com>
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*
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* More scalable flush, from Andi Kleen
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*
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* To avoid global state use 8 different call vectors.
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* Each CPU uses a specific vector to trigger flushes on other
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* CPUs. Depending on the received vector the target CPUs look into
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* the right array slot for the flush data.
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*
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* With more than 8 CPUs they are hashed to the 8 available
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* vectors. The limited global vector space forces us to this right now.
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* In future when interrupts are split into per CPU domains this could be
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* fixed, at the cost of triggering multiple IPIs in some cases.
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*/
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union smp_flush_state {
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struct {
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struct mm_struct *flush_mm;
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unsigned long flush_va;
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raw_spinlock_t tlbstate_lock;
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DECLARE_BITMAP(flush_cpumask, NR_CPUS);
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};
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char pad[INTERNODE_CACHE_BYTES];
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} ____cacheline_internodealigned_in_smp;
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/* State is put into the per CPU data section, but padded
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to a full cache line because other CPUs can access it and we don't
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want false sharing in the per cpu data segment. */
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static union smp_flush_state flush_state[NUM_INVALIDATE_TLB_VECTORS];
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/*
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* We cannot call mmdrop() because we are in interrupt context,
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* instead update mm->cpu_vm_mask.
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*/
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void leave_mm(int cpu)
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{
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if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK)
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BUG();
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cpumask_clear_cpu(cpu,
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mm_cpumask(percpu_read(cpu_tlbstate.active_mm)));
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load_cr3(swapper_pg_dir);
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}
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EXPORT_SYMBOL_GPL(leave_mm);
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/*
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*
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* The flush IPI assumes that a thread switch happens in this order:
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* [cpu0: the cpu that switches]
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* 1) switch_mm() either 1a) or 1b)
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* 1a) thread switch to a different mm
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* 1a1) cpu_clear(cpu, old_mm->cpu_vm_mask);
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* Stop ipi delivery for the old mm. This is not synchronized with
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* the other cpus, but smp_invalidate_interrupt ignore flush ipis
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* for the wrong mm, and in the worst case we perform a superfluous
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* tlb flush.
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* 1a2) set cpu mmu_state to TLBSTATE_OK
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* Now the smp_invalidate_interrupt won't call leave_mm if cpu0
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* was in lazy tlb mode.
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* 1a3) update cpu active_mm
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* Now cpu0 accepts tlb flushes for the new mm.
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* 1a4) cpu_set(cpu, new_mm->cpu_vm_mask);
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* Now the other cpus will send tlb flush ipis.
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* 1a4) change cr3.
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* 1b) thread switch without mm change
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* cpu active_mm is correct, cpu0 already handles
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* flush ipis.
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* 1b1) set cpu mmu_state to TLBSTATE_OK
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* 1b2) test_and_set the cpu bit in cpu_vm_mask.
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* Atomically set the bit [other cpus will start sending flush ipis],
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* and test the bit.
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* 1b3) if the bit was 0: leave_mm was called, flush the tlb.
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* 2) switch %%esp, ie current
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*
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* The interrupt must handle 2 special cases:
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* - cr3 is changed before %%esp, ie. it cannot use current->{active_,}mm.
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* - the cpu performs speculative tlb reads, i.e. even if the cpu only
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* runs in kernel space, the cpu could load tlb entries for user space
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* pages.
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*
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* The good news is that cpu mmu_state is local to each cpu, no
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* write/read ordering problems.
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*/
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/*
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* TLB flush IPI:
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*
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* 1) Flush the tlb entries if the cpu uses the mm that's being flushed.
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* 2) Leave the mm if we are in the lazy tlb mode.
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*
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* Interrupts are disabled.
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*/
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/*
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* FIXME: use of asmlinkage is not consistent. On x86_64 it's noop
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* but still used for documentation purpose but the usage is slightly
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* inconsistent. On x86_32, asmlinkage is regparm(0) but interrupt
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* entry calls in with the first parameter in %eax. Maybe define
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* intrlinkage?
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*/
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#ifdef CONFIG_X86_64
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asmlinkage
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#endif
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void smp_invalidate_interrupt(struct pt_regs *regs)
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{
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unsigned int cpu;
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unsigned int sender;
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union smp_flush_state *f;
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cpu = smp_processor_id();
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/*
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* orig_rax contains the negated interrupt vector.
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* Use that to determine where the sender put the data.
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*/
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sender = ~regs->orig_ax - INVALIDATE_TLB_VECTOR_START;
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f = &flush_state[sender];
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if (!cpumask_test_cpu(cpu, to_cpumask(f->flush_cpumask)))
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goto out;
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/*
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* This was a BUG() but until someone can quote me the
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* line from the intel manual that guarantees an IPI to
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* multiple CPUs is retried _only_ on the erroring CPUs
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* its staying as a return
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*
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* BUG();
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*/
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if (f->flush_mm == percpu_read(cpu_tlbstate.active_mm)) {
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if (percpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
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if (f->flush_va == TLB_FLUSH_ALL)
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local_flush_tlb();
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else
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__flush_tlb_one(f->flush_va);
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} else
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leave_mm(cpu);
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}
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out:
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ack_APIC_irq();
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smp_mb__before_clear_bit();
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cpumask_clear_cpu(cpu, to_cpumask(f->flush_cpumask));
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smp_mb__after_clear_bit();
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inc_irq_stat(irq_tlb_count);
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}
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static void flush_tlb_others_ipi(const struct cpumask *cpumask,
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struct mm_struct *mm, unsigned long va)
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{
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unsigned int sender;
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union smp_flush_state *f;
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/* Caller has disabled preemption */
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sender = smp_processor_id() % NUM_INVALIDATE_TLB_VECTORS;
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f = &flush_state[sender];
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/*
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* Could avoid this lock when
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* num_online_cpus() <= NUM_INVALIDATE_TLB_VECTORS, but it is
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* probably not worth checking this for a cache-hot lock.
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*/
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raw_spin_lock(&f->tlbstate_lock);
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f->flush_mm = mm;
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f->flush_va = va;
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if (cpumask_andnot(to_cpumask(f->flush_cpumask), cpumask, cpumask_of(smp_processor_id()))) {
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/*
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* We have to send the IPI only to
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* CPUs affected.
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*/
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apic->send_IPI_mask(to_cpumask(f->flush_cpumask),
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INVALIDATE_TLB_VECTOR_START + sender);
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while (!cpumask_empty(to_cpumask(f->flush_cpumask)))
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cpu_relax();
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}
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f->flush_mm = NULL;
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f->flush_va = 0;
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raw_spin_unlock(&f->tlbstate_lock);
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}
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void native_flush_tlb_others(const struct cpumask *cpumask,
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struct mm_struct *mm, unsigned long va)
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{
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if (is_uv_system()) {
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unsigned int cpu;
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cpu = get_cpu();
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cpumask = uv_flush_tlb_others(cpumask, mm, va, cpu);
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if (cpumask)
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flush_tlb_others_ipi(cpumask, mm, va);
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put_cpu();
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return;
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}
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flush_tlb_others_ipi(cpumask, mm, va);
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}
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static int __cpuinit init_smp_flush(void)
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{
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int i;
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for (i = 0; i < ARRAY_SIZE(flush_state); i++)
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raw_spin_lock_init(&flush_state[i].tlbstate_lock);
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return 0;
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}
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core_initcall(init_smp_flush);
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void flush_tlb_current_task(void)
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{
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struct mm_struct *mm = current->mm;
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preempt_disable();
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local_flush_tlb();
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if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
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flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL);
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preempt_enable();
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}
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void flush_tlb_mm(struct mm_struct *mm)
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{
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preempt_disable();
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if (current->active_mm == mm) {
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if (current->mm)
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local_flush_tlb();
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else
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leave_mm(smp_processor_id());
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}
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if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
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flush_tlb_others(mm_cpumask(mm), mm, TLB_FLUSH_ALL);
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preempt_enable();
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}
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void flush_tlb_page(struct vm_area_struct *vma, unsigned long va)
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{
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struct mm_struct *mm = vma->vm_mm;
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preempt_disable();
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if (current->active_mm == mm) {
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if (current->mm)
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__flush_tlb_one(va);
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else
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leave_mm(smp_processor_id());
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}
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if (cpumask_any_but(mm_cpumask(mm), smp_processor_id()) < nr_cpu_ids)
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flush_tlb_others(mm_cpumask(mm), mm, va);
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preempt_enable();
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}
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static void do_flush_tlb_all(void *info)
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{
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unsigned long cpu = smp_processor_id();
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__flush_tlb_all();
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if (percpu_read(cpu_tlbstate.state) == TLBSTATE_LAZY)
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leave_mm(cpu);
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}
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void flush_tlb_all(void)
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{
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on_each_cpu(do_flush_tlb_all, NULL, 1);
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}
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