s390/mm,tlb: safeguard against speculative TLB creation

[linux.git] / arch / s390 / include / asm / mmu_context.h

diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h
index 38149b63dc44a360ab3b0db2dfca4f23e64cc63a..7abf318b1522726eb8858226d3f59b211542b799 100644 (file)
--- a/arch/s390/include/asm/mmu_context.h
+++ b/arch/s390/include/asm/mmu_context.h
@@ -35,7 +35,7 @@ static inline int init_new_context(struct task_struct *tsk,
 #define LCTL_OPCODE "lctlg"
 #endif
 
-static inline void update_mm(struct mm_struct *mm, struct task_struct *tsk)
+static inline void update_user_asce(struct mm_struct *mm)
 {
        pgd_t *pgd = mm->pgd;
 
@@ -45,6 +45,13 @@ static inline void update_mm(struct mm_struct *mm, struct task_struct *tsk)
        set_fs(current->thread.mm_segment);
 }
 
+static inline void clear_user_asce(struct mm_struct *mm)
+{
+       S390_lowcore.user_asce = S390_lowcore.kernel_asce;
+       asm volatile(LCTL_OPCODE" 1,1,%0\n" : : "m" (S390_lowcore.user_asce));
+       asm volatile(LCTL_OPCODE" 7,7,%0\n" : : "m" (S390_lowcore.user_asce));
+}
+
 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
                             struct task_struct *tsk)
 {
@@ -53,11 +60,13 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
        if (prev == next)
                return;
        if (atomic_inc_return(&next->context.attach_count) >> 16) {
-               /* Delay update_mm until all TLB flushes are done. */
+               /* Delay update_user_asce until all TLB flushes are done. */
                set_tsk_thread_flag(tsk, TIF_TLB_WAIT);
+               /* Clear old ASCE by loading the kernel ASCE. */
+               clear_user_asce(next);
        } else {
                cpumask_set_cpu(cpu, mm_cpumask(next));
-               update_mm(next, tsk);
+               update_user_asce(next);
                if (next->context.flush_mm)
                        /* Flush pending TLBs */
                        __tlb_flush_mm(next);
@@ -80,7 +89,7 @@ static inline void finish_arch_post_lock_switch(void)
                cpu_relax();
 
        cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
-       update_mm(mm, tsk);
+       update_user_asce(mm);
        if (mm->context.flush_mm)
                __tlb_flush_mm(mm);
        preempt_enable();