1 files changed, 243 insertions, 0 deletions
diff --git a/arch/x86/kernel/tlb_32.c b/arch/x86/kernel/tlb_32.c
new file mode 100644
index 00000000000..9bb2363851a
--- /dev/null
+++ b/arch/x86/kernel/tlb_32.c
@@ -0,0 +1,243 @@
+#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, 1);
+}
+