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>
diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c
index 8bdf95b..5a2eba6 100644
--- a/arch/powerpc/kernel/signal_32.c
+++ b/arch/powerpc/kernel/signal_32.c
@@ -403,8 +403,6 @@
ELF_NFPREG * sizeof(double)))
return 1;
- current->thread.fpscr.val = 0; /* turn off all fp exceptions */
-
#ifdef CONFIG_ALTIVEC
/* save altivec registers */
if (current->thread.used_vr) {
@@ -818,6 +816,9 @@
goto badframe;
regs->link = (unsigned long) frame->tramp;
}
+
+ current->thread.fpscr.val = 0; /* turn off all fp exceptions */
+
if (put_user(regs->gpr[1], (u32 __user *)newsp))
goto badframe;
regs->gpr[1] = newsp;
@@ -1097,6 +1098,8 @@
regs->link = (unsigned long) frame->mctx.tramp;
}
+ current->thread.fpscr.val = 0; /* turn off all fp exceptions */
+
if (put_user(regs->gpr[1], (u32 __user *)newsp))
goto badframe;
regs->gpr[1] = newsp;
diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c
index 58194e1..1decf27 100644
--- a/arch/powerpc/kernel/signal_64.c
+++ b/arch/powerpc/kernel/signal_64.c
@@ -131,9 +131,6 @@
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 @@
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;