microblaze: switch to generic sigaltstack

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/microblaze/Kconfig

@@ -27,6 +27,7 @@ config MICROBLAZE
 	select GENERIC_CLOCKEVENTS
 	select MODULES_USE_ELF_RELA
 	select CLONE_BACKWARDS
+	select GENERIC_SIGALTSTACK
 
 config SWAP
 	def_bool n

arch/microblaze/kernel/signal.c

@@ -41,13 +41,6 @@
 #include <asm/cacheflush.h>
 #include <asm/syscalls.h>
 
-asmlinkage long
-sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
-		struct pt_regs *regs)
-{
-	return do_sigaltstack(uss, uoss, regs->r1);
-}
-
 /*
  * Do a signal return; undo the signal stack.
  */
@@ -109,9 +102,7 @@ asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 	if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
 		goto badframe;
 
-	/* It is more difficult to avoid calling this function than to
-	 call it and ignore errors. */
-	if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->r1) == -EFAULT)
+	if (restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
 
 	return rval;
@@ -194,11 +185,7 @@ static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
 	/* Create the ucontext. */
 	err |= __put_user(0, &frame->uc.uc_flags);
 	err |= __put_user(NULL, &frame->uc.uc_link);
-	err |= __put_user((void __user *)current->sas_ss_sp,
-			&frame->uc.uc_stack.ss_sp);
-	err |= __put_user(sas_ss_flags(regs->r1),
-			&frame->uc.uc_stack.ss_flags);
-	err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
+	err |= __save_altstack(&frame->uc.uc_stack, regs->r1);
 	err |= setup_sigcontext(&frame->uc.uc_mcontext,
 			regs, set->sig[0]);
 	err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));