xtensa: switch to generic sigaltstack

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/arch/xtensa/include/asm/syscall.h b/arch/xtensa/include/asm/syscall.h
index 08a23dd..3673ff1 100644
--- a/arch/xtensa/include/asm/syscall.h
+++ b/arch/xtensa/include/asm/syscall.h
@@ -12,7 +12,6 @@
 asmlinkage long xtensa_ptrace(long, long, long, long);
 asmlinkage long xtensa_sigreturn(struct pt_regs*);
 asmlinkage long xtensa_rt_sigreturn(struct pt_regs*);
-asmlinkage long xtensa_sigaltstack(struct pt_regs *regs);
 asmlinkage long xtensa_shmat(int, char __user *, int);
 asmlinkage long xtensa_fadvise64_64(int, int,
 				    unsigned long long, unsigned long long);
diff --git a/arch/xtensa/include/uapi/asm/unistd.h b/arch/xtensa/include/uapi/asm/unistd.h
index 5162418..19fac3f 100644
--- a/arch/xtensa/include/uapi/asm/unistd.h
+++ b/arch/xtensa/include/uapi/asm/unistd.h
@@ -483,7 +483,7 @@
 #define __NR_restart_syscall 			223
 __SYSCALL(223, sys_restart_syscall, 0)
 #define __NR_sigaltstack 			224
-__SYSCALL(224, xtensa_sigaltstack, 2)
+__SYSCALL(224, sys_sigaltstack, 2)
 #define __NR_rt_sigreturn 			225
 __SYSCALL(225, xtensa_rt_sigreturn, 1)
 #define __NR_rt_sigaction 			226