Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux

[linux.git] / arch / powerpc / kernel / process.c

diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index 75b6676c1a0b911b72b7af5a8dc7761173e638e8..646bf4d222c1caeda5c7851de74fbbe0ad0d65d9 100644 (file)
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -551,6 +551,24 @@ static void tm_reclaim_thread(struct thread_struct *thr,
                msr_diff &= MSR_FP | MSR_VEC | MSR_VSX | MSR_FE0 | MSR_FE1;
        }
 
+       /*
+        * Use the current MSR TM suspended bit to track if we have
+        * checkpointed state outstanding.
+        * On signal delivery, we'd normally reclaim the checkpointed
+        * state to obtain stack pointer (see:get_tm_stackpointer()).
+        * This will then directly return to userspace without going
+        * through __switch_to(). However, if the stack frame is bad,
+        * we need to exit this thread which calls __switch_to() which
+        * will again attempt to reclaim the already saved tm state.
+        * Hence we need to check that we've not already reclaimed
+        * this state.
+        * We do this using the current MSR, rather tracking it in
+        * some specific thread_struct bit, as it has the additional
+        * benifit of checking for a potential TM bad thing exception.
+        */
+       if (!MSR_TM_SUSPENDED(mfmsr()))
+               return;
+
        tm_reclaim(thr, thr->regs->msr, cause);
 
        /* Having done the reclaim, we now have the checkpointed