powerpc: Fix clearing of the FPSCR when invoking a signal handler

As pointed out by Gary Byers, we were clearing the image of the FPSCR
(floating point status and control register) in the thread_struct before
copying it to the user stack when invoking a signal.  Thus the task
would see its FPSCR getting cleared when it took a signal.

While fixing it I noticed that our swapcontext system call was also
clearing FPSCR.  It shouldn't, so I fixed that too.

Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 58194e150711..1decf2785530 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -131,9 +131,6 @@ static long setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 
 	flush_fp_to_thread(current);
 
-	/* Make sure signal doesn't get spurrious FP exceptions */
-	current->thread.fpscr.val = 0;
-
 #ifdef CONFIG_ALTIVEC
 	err |= __put_user(v_regs, &sc->v_regs);
 
@@ -423,6 +420,9 @@ static int setup_rt_frame(int signr, struct k_sigaction *ka, siginfo_t *info,
 	if (err)
 		goto badframe;
 
+	/* Make sure signal handler doesn't get spurious FP exceptions */
+	current->thread.fpscr.val = 0;
+
 	/* Set up to return from userspace. */
 	if (vdso64_rt_sigtramp && current->thread.vdso_base) {
 		regs->link = current->thread.vdso_base + vdso64_rt_sigtramp;