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Commit cc657f53 authored by Paul Mackerras's avatar Paul Mackerras
Browse files

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: default avatarPaul Mackerras <paulus@samba.org>
parent 493f25ef

arch/powerpc/kernel/signal_32.c

+5 −2
Original line number Diff line number Diff line
@@ -403,8 +403,6 @@ static int save_user_regs(struct pt_regs *regs, struct mcontext __user *frame, 
		    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 @@ static int handle_rt_signal(unsigned long sig, struct k_sigaction *ka, 
			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 @@ static int handle_signal(unsigned long sig, struct k_sigaction *ka, 
		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;

arch/powerpc/kernel/signal_64.c

+3 −3
Original line number Diff line number Diff line
@@ -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;