*
* More scalable flush, from Andi Kleen
*
- * To avoid global state use 8 different call vectors.
- * Each CPU uses a specific vector to trigger flushes on other
- * CPUs. Depending on the received vector the target CPUs look into
- * the right array slot for the flush data.
- *
- * With more than 8 CPUs they are hashed to the 8 available
- * vectors. The limited global vector space forces us to this right now.
- * In future when interrupts are split into per CPU domains this could be
- * fixed, at the cost of triggering multiple IPIs in some cases.
+ * Implement flush IPI by CALL_FUNCTION_VECTOR, Alex Shi
*/
-union smp_flush_state {
- struct {
- struct mm_struct *flush_mm;
- unsigned long flush_start;
- unsigned long flush_end;
- raw_spinlock_t tlbstate_lock;
- DECLARE_BITMAP(flush_cpumask, NR_CPUS);
- };
- char pad[INTERNODE_CACHE_BYTES];
-} ____cacheline_internodealigned_in_smp;
-
-/* State is put into the per CPU data section, but padded
- to a full cache line because other CPUs can access it and we don't
- want false sharing in the per cpu data segment. */
-static union smp_flush_state flush_state[NUM_INVALIDATE_TLB_VECTORS];
-
-static DEFINE_PER_CPU_READ_MOSTLY(int, tlb_vector_offset);
+struct flush_tlb_info {
+ struct mm_struct *flush_mm;
+ unsigned long flush_start;
+ unsigned long flush_end;
+};
/*
* We cannot call mmdrop() because we are in interrupt context,
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 mmu_state to TLBSTATE_OK
- * Now the smp_invalidate_interrupt won't call leave_mm if cpu0
- * was in lazy tlb mode.
- * 1a3) update cpu active_mm
+ * 1a1) set cpu_tlbstate to TLBSTATE_OK
+ * Now the tlb flush NMI handler flush_tlb_func won't call leave_mm
+ * if cpu0 was in lazy tlb mode.
+ * 1a2) update cpu active_mm
* Now cpu0 accepts tlb flushes for the new mm.
- * 1a4) cpu_set(cpu, new_mm->cpu_vm_mask);
+ * 1a3) cpu_set(cpu, new_mm->cpu_vm_mask);
* Now the other cpus will send tlb flush ipis.
* 1a4) change cr3.
+ * 1a5) cpu_clear(cpu, old_mm->cpu_vm_mask);
+ * Stop ipi delivery for the old mm. This is not synchronized with
+ * the other cpus, but flush_tlb_func ignore flush ipis for the wrong
+ * mm, and in the worst case we perform a superfluous tlb flush.
* 1b) thread switch without mm change
- * cpu active_mm is correct, cpu0 already handles
- * flush ipis.
- * 1b1) set cpu mmu_state to TLBSTATE_OK
+ * cpu 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.
* runs in kernel space, the cpu could load tlb entries for user space
* pages.
*
- * The good news is that cpu mmu_state is local to each cpu, no
+ * The good news is that cpu_tlbstate is local to each cpu, no
* write/read ordering problems.
*/
/*
- * TLB flush IPI:
- *
+ * TLB flush funcation:
* 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.
- *
- * Interrupts are disabled.
- */
-
-/*
- * FIXME: use of asmlinkage is not consistent. On x86_64 it's noop
- * but still used for documentation purpose but the usage is slightly
- * inconsistent. On x86_32, asmlinkage is regparm(0) but interrupt
- * entry calls in with the first parameter in %eax. Maybe define
- * intrlinkage?
*/
-#ifdef CONFIG_X86_64
-asmlinkage
-#endif
-void smp_invalidate_interrupt(struct pt_regs *regs)
+static void flush_tlb_func(void *info)
{
- unsigned int cpu;
- unsigned int sender;
- union smp_flush_state *f;
-
- cpu = smp_processor_id();
- /*
- * orig_rax contains the negated interrupt vector.
- * Use that to determine where the sender put the data.
- */
- sender = ~regs->orig_ax - INVALIDATE_TLB_VECTOR_START;
- f = &flush_state[sender];
-
- if (!cpumask_test_cpu(cpu, to_cpumask(f->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 (f->flush_mm == this_cpu_read(cpu_tlbstate.active_mm)) {
- if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
- if (f->flush_end == TLB_FLUSH_ALL
- || !cpu_has_invlpg)
- local_flush_tlb();
- else if (!f->flush_end)
- __flush_tlb_single(f->flush_start);
- else {
- unsigned long addr;
- addr = f->flush_start;
- while (addr < f->flush_end) {
- __flush_tlb_single(addr);
- addr += PAGE_SIZE;
- }
- }
- } else
- leave_mm(cpu);
- }
-out:
- ack_APIC_irq();
- smp_mb__before_clear_bit();
- cpumask_clear_cpu(cpu, to_cpumask(f->flush_cpumask));
- smp_mb__after_clear_bit();
- inc_irq_stat(irq_tlb_count);
-}
+ struct flush_tlb_info *f = info;
-static void flush_tlb_others_ipi(const struct cpumask *cpumask,
- struct mm_struct *mm, unsigned long start,
- unsigned long end)
-{
- unsigned int sender;
- union smp_flush_state *f;
-
- /* Caller has disabled preemption */
- sender = this_cpu_read(tlb_vector_offset);
- f = &flush_state[sender];
-
- if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS)
- raw_spin_lock(&f->tlbstate_lock);
-
- f->flush_mm = mm;
- f->flush_start = start;
- f->flush_end = end;
- if (cpumask_andnot(to_cpumask(f->flush_cpumask), cpumask, cpumask_of(smp_processor_id()))) {
- /*
- * We have to send the IPI only to
- * CPUs affected.
- */
- apic->send_IPI_mask(to_cpumask(f->flush_cpumask),
- INVALIDATE_TLB_VECTOR_START + sender);
-
- while (!cpumask_empty(to_cpumask(f->flush_cpumask)))
- cpu_relax();
- }
+ if (f->flush_mm != this_cpu_read(cpu_tlbstate.active_mm))
+ return;
+
+ if (this_cpu_read(cpu_tlbstate.state) == TLBSTATE_OK) {
+ if (f->flush_end == TLB_FLUSH_ALL || !cpu_has_invlpg)
+ local_flush_tlb();
+ else if (!f->flush_end)
+ __flush_tlb_single(f->flush_start);
+ else {
+ unsigned long addr;
+ addr = f->flush_start;
+ while (addr < f->flush_end) {
+ __flush_tlb_single(addr);
+ addr += PAGE_SIZE;
+ }
+ }
+ } else
+ leave_mm(smp_processor_id());
- f->flush_mm = NULL;
- f->flush_start = 0;
- f->flush_end = 0;
- if (nr_cpu_ids > NUM_INVALIDATE_TLB_VECTORS)
- raw_spin_unlock(&f->tlbstate_lock);
}
void native_flush_tlb_others(const struct cpumask *cpumask,
struct mm_struct *mm, unsigned long start,
unsigned long end)
{
+ struct flush_tlb_info info;
+ info.flush_mm = mm;
+ info.flush_start = start;
+ info.flush_end = end;
+
if (is_uv_system()) {
unsigned int cpu;
cpu = smp_processor_id();
cpumask = uv_flush_tlb_others(cpumask, mm, start, end, cpu);
if (cpumask)
- flush_tlb_others_ipi(cpumask, mm, start, end);
+ smp_call_function_many(cpumask, flush_tlb_func,
+ &info, 1);
return;
}
- flush_tlb_others_ipi(cpumask, mm, start, end);
-}
-
-static void __cpuinit calculate_tlb_offset(void)
-{
- int cpu, node, nr_node_vecs, idx = 0;
- /*
- * we are changing tlb_vector_offset for each CPU in runtime, but this
- * will not cause inconsistency, as the write is atomic under X86. we
- * might see more lock contentions in a short time, but after all CPU's
- * tlb_vector_offset are changed, everything should go normal
- *
- * Note: if NUM_INVALIDATE_TLB_VECTORS % nr_online_nodes !=0, we might
- * waste some vectors.
- **/
- if (nr_online_nodes > NUM_INVALIDATE_TLB_VECTORS)
- nr_node_vecs = 1;
- else
- nr_node_vecs = NUM_INVALIDATE_TLB_VECTORS/nr_online_nodes;
-
- for_each_online_node(node) {
- int node_offset = (idx % NUM_INVALIDATE_TLB_VECTORS) *
- nr_node_vecs;
- int cpu_offset = 0;
- for_each_cpu(cpu, cpumask_of_node(node)) {
- per_cpu(tlb_vector_offset, cpu) = node_offset +
- cpu_offset;
- cpu_offset++;
- cpu_offset = cpu_offset % nr_node_vecs;
- }
- idx++;
- }
-}
-
-static int __cpuinit tlb_cpuhp_notify(struct notifier_block *n,
- unsigned long action, void *hcpu)
-{
- switch (action & 0xf) {
- case CPU_ONLINE:
- case CPU_DEAD:
- calculate_tlb_offset();
- }
- return NOTIFY_OK;
-}
-
-static int __cpuinit init_smp_flush(void)
-{
- int i;
-
- for (i = 0; i < ARRAY_SIZE(flush_state); i++)
- raw_spin_lock_init(&flush_state[i].tlbstate_lock);
-
- calculate_tlb_offset();
- hotcpu_notifier(tlb_cpuhp_notify, 0);
- return 0;
+ smp_call_function_many(cpumask, flush_tlb_func, &info, 1);
}
-core_initcall(init_smp_flush);
void flush_tlb_current_task(void)
{
projects / users / hch / configfs.git / commitdiff