LoongArch: Export some signal functions

So that they can be called in the kernel modules to do something.

Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Binbin Zhou <zhoubinbin@loongson.cn>

Author: AaronDot

arch/loongarch/kernel/Makefile

@@ -7,6 +7,7 @@ OBJECT_FILES_NON_STANDARD_head.o := y
 
 extra-y		:= vmlinux.lds
 
+obj-y		+= extern.o
 obj-y		+= head.o cpu-probe.o cacheinfo.o env.o setup.o entry.o genex.o \
 		   traps.o irq.o idle.o process.o dma.o mem.o io.o reset.o switch.o \
 		   elf.o syscall.o signal.o time.o topology.o inst.o ptrace.o vdso.o \

arch/loongarch/kernel/extern.c

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/signal.h>
+
+void loongarch_set_current_blocked(sigset_t *newset);
+int loongarch_copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from);
+int loongarch___save_altstack(stack_t __user *uss, unsigned long sp);
+int loongarch_restore_altstack(const stack_t __user *uss);
+
+void loongarch_set_current_blocked(sigset_t *newset)
+{
+	return set_current_blocked(newset);
+}
+EXPORT_SYMBOL_GPL(loongarch_set_current_blocked);
+
+int loongarch_copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
+{
+	return copy_siginfo_to_user(to, from);
+}
+EXPORT_SYMBOL_GPL(loongarch_copy_siginfo_to_user);
+
+int loongarch___save_altstack(stack_t __user *uss, unsigned long sp)
+{
+	return __save_altstack(uss, sp);
+}
+EXPORT_SYMBOL_GPL(loongarch___save_altstack);
+
+int loongarch_restore_altstack(const stack_t __user *uss)
+{
+	return restore_altstack(uss);
+}
+EXPORT_SYMBOL_GPL(loongarch_restore_altstack);