unicore32: switch to generic sigaltstack

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

arch/unicore32/Kconfig

@@ -16,6 +16,7 @@ config UNICORE32
 	select ARCH_WANT_FRAME_POINTERS
 	select GENERIC_IOMAP
 	select MODULES_USE_ELF_REL
+	select GENERIC_SIGALTSTACK
 	help
 	  UniCore-32 is 32-bit Instruction Set Architecture,
 	  including a series of low-power-consumption RISC chip

arch/unicore32/kernel/entry.S

@@ -674,11 +674,6 @@ ENTRY(sys_rt_sigreturn)
 		b	__sys_rt_sigreturn
 ENDPROC(sys_rt_sigreturn)
 
-ENTRY(sys_sigaltstack)
-		ldw	r2, [sp+], #S_OFF + S_SP
-		b	do_sigaltstack
-ENDPROC(sys_sigaltstack)
-
 	__INIT
 
 /*

arch/unicore32/kernel/signal.c

@@ -123,8 +123,7 @@ asmlinkage int __sys_rt_sigreturn(struct pt_regs *regs)
 	if (restore_sigframe(regs, &frame->sig))
 		goto badframe;
 
-	if (do_sigaltstack(&frame->sig.uc.uc_stack, NULL, regs->UCreg_sp)
-			== -EFAULT)
+	if (restore_altstack(&frame->sig.uc.uc_stack))
 		goto badframe;
 
 	return regs->UCreg_00;
@@ -265,7 +264,6 @@ static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 {
 	struct rt_sigframe __user *frame =
 			get_sigframe(ka, regs, sizeof(*frame));
-	stack_t stack;
 	int err = 0;
 
 	if (!frame)
@@ -275,13 +273,7 @@ static int setup_rt_frame(int usig, struct k_sigaction *ka, siginfo_t *info,
 
 	err |= __put_user(0, &frame->sig.uc.uc_flags);
 	err |= __put_user(NULL, &frame->sig.uc.uc_link);
-
-	memset(&stack, 0, sizeof(stack));
-	stack.ss_sp = (void __user *)current->sas_ss_sp;
-	stack.ss_flags = sas_ss_flags(regs->UCreg_sp);
-	stack.ss_size = current->sas_ss_size;
-	err |= __copy_to_user(&frame->sig.uc.uc_stack, &stack, sizeof(stack));
-
+	err |= __save_altstack(&frame->sig.uc.uc_stack, regs->UCreg_sp);
 	err |= setup_sigframe(&frame->sig, regs, set);
 	if (err == 0)
 		err |= setup_return(regs, ka, frame->sig.retcode, frame, usig);