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-rw-r--r--arch/powerpc/lib/vmx-helper.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/powerpc/lib/vmx-helper.c b/arch/powerpc/lib/vmx-helper.c
index f76a50291fd7..d491da8d1838 100644
--- a/arch/powerpc/lib/vmx-helper.c
+++ b/arch/powerpc/lib/vmx-helper.c
@@ -36,7 +36,17 @@ int exit_vmx_usercopy(void)
{
disable_kernel_altivec();
pagefault_enable();
- preempt_enable();
+ preempt_enable_no_resched();
+ /*
+ * Must never explicitly call schedule (including preempt_enable())
+ * while in a kuap-unlocked user copy, because the AMR register will
+ * not be saved and restored across context switch. However preempt
+ * kernels need to be preempted as soon as possible if need_resched is
+ * set and we are preemptible. The hack here is to schedule a
+ * decrementer to fire here and reschedule for us if necessary.
+ */
+ if (IS_ENABLED(CONFIG_PREEMPT) && need_resched())
+ set_dec(1);
return 0;
}