arm64: Kill 32-bit applications scheduled on 64-bit-only CPUs

[linux-2.6-block.git] / arch / arm64 / kernel / signal.c

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 6237486ff6bb73db074d6e275c7d739548a1a7d0..f8192f4ae0b8a0a9cbd21a7d0037940a263fa0b6 100644 (file)
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -911,6 +911,19 @@ static void do_signal(struct pt_regs *regs)
        restore_saved_sigmask();
 }
 
+static bool cpu_affinity_invalid(struct pt_regs *regs)
+{
+       if (!compat_user_mode(regs))
+               return false;
+
+       /*
+        * We're preemptible, but a reschedule will cause us to check the
+        * affinity again.
+        */
+       return !cpumask_test_cpu(raw_smp_processor_id(),
+                                system_32bit_el0_cpumask());
+}
+
 asmlinkage void do_notify_resume(struct pt_regs *regs,
                                 unsigned long thread_flags)
 {
@@ -938,6 +951,19 @@ asmlinkage void do_notify_resume(struct pt_regs *regs,
                        if (thread_flags & _TIF_NOTIFY_RESUME) {
                                tracehook_notify_resume(regs);
                                rseq_handle_notify_resume(NULL, regs);
+
+                               /*
+                                * If we reschedule after checking the affinity
+                                * then we must ensure that TIF_NOTIFY_RESUME
+                                * is set so that we check the affinity again.
+                                * Since tracehook_notify_resume() clears the
+                                * flag, ensure that the compiler doesn't move
+                                * it after the affinity check.
+                                */
+                               barrier();
+
+                               if (cpu_affinity_invalid(regs))
+                                       force_sig(SIGKILL);
                        }
 
                        if (thread_flags & _TIF_FOREIGN_FPSTATE)