x86/mm/64: Enable vmapped stacks (CONFIG_HAVE_ARCH_VMAP_STACK=y)

[cascardo/linux.git] / arch / x86 / mm / tlb.c

diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
index 4dbe656..a7655f6 100644 (file)
--- a/arch/x86/mm/tlb.c
+++ b/arch/x86/mm/tlb.c
@@ -77,10 +77,25 @@ void switch_mm_irqs_off(struct mm_struct *prev, struct mm_struct *next,
        unsigned cpu = smp_processor_id();
 
        if (likely(prev != next)) {
+               if (IS_ENABLED(CONFIG_VMAP_STACK)) {
+                       /*
+                        * If our current stack is in vmalloc space and isn't
+                        * mapped in the new pgd, we'll double-fault.  Forcibly
+                        * map it.
+                        */
+                       unsigned int stack_pgd_index = pgd_index(current_stack_pointer());
+
+                       pgd_t *pgd = next->pgd + stack_pgd_index;
+
+                       if (unlikely(pgd_none(*pgd)))
+                               set_pgd(pgd, init_mm.pgd[stack_pgd_index]);
+               }
+
 #ifdef CONFIG_SMP
                this_cpu_write(cpu_tlbstate.state, TLBSTATE_OK);
                this_cpu_write(cpu_tlbstate.active_mm, next);
 #endif
+
                cpumask_set_cpu(cpu, mm_cpumask(next));
 
                /*