MIPS: Use arch specific syscall name match function

On MIPS system, most of the syscall function name begin with prefix
sys_. Some syscalls are special such as clone/fork, function name of
these begin with __sys_. Since scratch registers need be saved in
stack when these system calls happens.

With ftrace system call method, system call functions are declared with
SYSCALL_DEFINEx, metadata of the system call symbol name begins with
sys_. Here mips specific function arch_syscall_match_sym_name is used to
compare function name between sys_call_table[] and metadata of syscall
symbol.

Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

Author: bibo-mao

arch/mips/include/asm/ftrace.h

@@ -91,4 +91,20 @@ void prepare_ftrace_return(unsigned long *parent_ra_addr, unsigned long self_ra,
 
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
+
+#ifdef CONFIG_FTRACE_SYSCALLS
+#ifndef __ASSEMBLY__
+/*
+ * Some syscall entry functions on mips start with "__sys_" (fork and clone,
+ * for instance). We should also match the sys_ variant with those.
+ */
+#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME
+static inline bool arch_syscall_match_sym_name(const char *sym,
+					       const char *name)
+{
+	return !strcmp(sym, name) ||
+		(!strncmp(sym, "__sys_", 6) && !strcmp(sym + 6, name + 4));
+}
+#endif /* __ASSEMBLY__ */
+#endif /* CONFIG_FTRACE_SYSCALLS */
 #endif /* _ASM_MIPS_FTRACE_H */