linux-kernel - [PATCH] MIPS: Use arch specific syscall name match function

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Date:   Tue,  9 Jun 2020 10:54:35 +0800
From:   Bibo Mao <maobibo@...ngson.cn>
To:     Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Steven Rostedt <rostedt@...dmis.org>,
        Ingo Molnar <mingo@...hat.com>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] 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@...ngson.cn>
---
 arch/mips/include/asm/ftrace.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/mips/include/asm/ftrace.h b/arch/mips/include/asm/ftrace.h
index b463f2a..9b42115 100644
--- a/arch/mips/include/asm/ftrace.h
+++ b/arch/mips/include/asm/ftrace.h
@@ -87,4 +87,20 @@ struct dyn_arch_ftrace {
 #endif /*  CONFIG_DYNAMIC_FTRACE */
 #endif /* __ASSEMBLY__ */
 #endif /* CONFIG_FUNCTION_TRACER */
+
+#ifndef __ASSEMBLY__
+#ifdef CONFIG_FTRACE_SYSCALLS
+/*
+ * 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 /* CONFIG_FTRACE_SYSCALLS */
+#endif /* __ASSEMBLY__ */
 #endif /* _ASM_MIPS_FTRACE_H */
-- 
1.8.3.1