[PATCH 4.9 28/29] arm64: Remove unimplemented syscall log message

Greg Kroah-Hartman
2021-06-08T18:31:27Z

From: Michael Weiser <michael.weiser@gmx.de>

commit 1962682d2b2fbe6cfa995a85c53c069fadda473e upstream.

Stop printing a (ratelimited) kernel message for each instance of an
unimplemented syscall being called. Userland making an unimplemented
syscall is not necessarily misbehaviour and to be expected with a
current userland running on an older kernel. Also, the current message
looks scary to users but does not actually indicate a real problem nor
help them narrow down the cause. Just rely on sys_ni_syscall() to return
-ENOSYS.

Cc: <stable@vger.kernel.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Michael Weiser <michael.weiser@gmx.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/arm64/kernel/traps.c | 8 --------
1 file changed, 8 deletions(-)

--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -543,14 +543,6 @@ asmlinkage long do_ni_syscall(struct pt_
}
#endif

- if (show_unhandled_signals_ratelimited()) {
- pr_info("%s[%d]: syscall %d\n", current->comm,
- task_pid_nr(current), (int)regs->syscallno);
- dump_instr("", regs);
- if (user_mode(regs))
- __show_regs(regs);
- }
-
return sys_ni_syscall();
}