[PATCH] ftrace/x86: Fix arch_syscall_match_sym_name for x86_64

[Jiri Olsa]

Recent commit changed the name prefix of syscalls
for x86_64 (check the 'Fixes:' for commit number).

The names switch from "sys_" prefix to ""__x64_sys_",
which made the default matching function always fail.

Consequently the ftrace syscall __init code could not
match any syscall metadata so the "syscall" events
vanished. This fix returns them back.

Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx>
Fixes: d5a00528b58c ("syscalls/core, syscalls/x86: Rename struct pt_regs-based sys_*() to __x64_sys_*()")
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
---
 arch/x86/include/asm/ftrace.h | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
index 09ad88572746..7b131ad39ee2 100644
--- a/arch/x86/include/asm/ftrace.h
+++ b/arch/x86/include/asm/ftrace.h
@@ -67,6 +67,18 @@ static inline bool arch_trace_is_compat_syscall(struct pt_regs *regs)
 	return false;
 }
 #endif /* CONFIG_FTRACE_SYSCALLS && CONFIG_IA32_EMULATION */
+
+#ifdef CONFIG_X86_64
+#define ARCH_HAS_SYSCALL_MATCH_SYM_NAME 1
+static inline bool arch_syscall_match_sym_name(const char *sym, const char *name)
+{
+	/*
+	 * Skip the __x64_sys_ prefix and compare the
+	 * syscall name only.
+	 */
+	return !strcmp(sym + 9, name + 3);
+}
+#endif /* CONFIG_X86_64 */
 #endif /* !__ASSEMBLY__  && !COMPILE_OFFSETS */
 
 #endif /* _ASM_X86_FTRACE_H */
-- 
2.13.6