sparc: Allow handling signals when stack is corrupted.

If we can't push the pending register windows onto the user's stack,
we disallow signal delivery even if the signal would be delivered on a
valid seperate signal stack.

Add a register window save area in the signal frame, and store any
unsavable windows there.

On sigreturn, if any windows are still queued up in the signal frame,
try to push them back onto the stack and if that fails we kill the
process immediately.

This allows the debug/tst-longjmp_chk2 glibc test case to pass.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 120 insertions, 0 deletions

diff --git a/arch/sparc/kernel/sigutil_32.c b/arch/sparc/kernel/sigutil_32.c
new file mode 100644
index 000000000000..35c7897b009a
--- /dev/null
+++ b/arch/sparc/kernel/sigutil_32.c
@@ -0,0 +1,120 @@
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/thread_info.h>
+#include <linux/uaccess.h>
+#include <linux/sched.h>
+
+#include <asm/sigcontext.h>
+#include <asm/fpumacro.h>
+#include <asm/ptrace.h>
+
+#include "sigutil.h"
+
+int save_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
+{
+	int err = 0;
+#ifdef CONFIG_SMP
+	if (test_tsk_thread_flag(current, TIF_USEDFPU)) {
+		put_psr(get_psr() | PSR_EF);
+		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
+		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
+		regs->psr &= ~(PSR_EF);
+		clear_tsk_thread_flag(current, TIF_USEDFPU);
+	}
+#else
+	if (current == last_task_used_math) {
+		put_psr(get_psr() | PSR_EF);
+		fpsave(&current->thread.float_regs[0], &current->thread.fsr,
+		       &current->thread.fpqueue[0], &current->thread.fpqdepth);
+		last_task_used_math = NULL;
+		regs->psr &= ~(PSR_EF);
+	}
+#endif
+	err |= __copy_to_user(&fpu->si_float_regs[0],
+			      &current->thread.float_regs[0],
+			      (sizeof(unsigned long) * 32));
+	err |= __put_user(current->thread.fsr, &fpu->si_fsr);
+	err |= __put_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
+	if (current->thread.fpqdepth != 0)
+		err |= __copy_to_user(&fpu->si_fpqueue[0],
+				      &current->thread.fpqueue[0],
+				      ((sizeof(unsigned long) +
+				      (sizeof(unsigned long *)))*16));
+	clear_used_math();
+	return err;
+}
+
+int restore_fpu_state(struct pt_regs *regs, __siginfo_fpu_t __user *fpu)
+{
+	int err;
+#ifdef CONFIG_SMP
+	if (test_tsk_thread_flag(current, TIF_USEDFPU))
+		regs->psr &= ~PSR_EF;
+#else
+	if (current == last_task_used_math) {
+		last_task_used_math = NULL;
+		regs->psr &= ~PSR_EF;
+	}
+#endif
+	set_used_math();
+	clear_tsk_thread_flag(current, TIF_USEDFPU);
+
+	if (!access_ok(VERIFY_READ, fpu, sizeof(*fpu)))
+		return -EFAULT;
+
+	err = __copy_from_user(&current->thread.float_regs[0], &fpu->si_float_regs[0],
+			       (sizeof(unsigned long) * 32));
+	err |= __get_user(current->thread.fsr, &fpu->si_fsr);
+	err |= __get_user(current->thread.fpqdepth, &fpu->si_fpqdepth);
+	if (current->thread.fpqdepth != 0)
+		err |= __copy_from_user(&current->thread.fpqueue[0],
+					&fpu->si_fpqueue[0],
+					((sizeof(unsigned long) +
+					(sizeof(unsigned long *)))*16));
+	return err;
+}
+
+int save_rwin_state(int wsaved, __siginfo_rwin_t __user *rwin)
+{
+	int i, err = __put_user(wsaved, &rwin->wsaved);
+
+	for (i = 0; i < wsaved; i++) {
+		struct reg_window32 *rp;
+		unsigned long fp;
+
+		rp = &current_thread_info()->reg_window[i];
+		fp = current_thread_info()->rwbuf_stkptrs[i];
+		err |= copy_to_user(&rwin->reg_window[i], rp,
+				    sizeof(struct reg_window32));
+		err |= __put_user(fp, &rwin->rwbuf_stkptrs[i]);
+	}
+	return err;
+}
+
+int restore_rwin_state(__siginfo_rwin_t __user *rp)
+{
+	struct thread_info *t = current_thread_info();
+	int i, wsaved, err;
+
+	__get_user(wsaved, &rp->wsaved);
+	if (wsaved > NSWINS)
+		return -EFAULT;
+
+	err = 0;
+	for (i = 0; i < wsaved; i++) {
+		err |= copy_from_user(&t->reg_window[i],
+				      &rp->reg_window[i],
+				      sizeof(struct reg_window32));
+		err |= __get_user(t->rwbuf_stkptrs[i],
+				  &rp->rwbuf_stkptrs[i]);
+	}
+	if (err)
+		return err;
+
+	t->w_saved = wsaved;
+	synchronize_user_stack();
+	if (t->w_saved)
+		return -EFAULT;
+	return 0;
+
+}