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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Will Deacon <will.deacon@arm.com>,
        Michael Weiser <michael.weiser@gmx.de>
Subject: [PATCH 4.15 39/64] arm64: Remove unimplemented syscall log message
Date:   Mon, 26 Feb 2018 21:22:16 +0100
Message-Id: <20180226202155.121249160@linuxfoundation.org>
In-Reply-To: <20180226202153.453363333@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

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: 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
@@ -526,14 +526,6 @@ 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), regs->syscallno);
-		dump_instr("", regs);
-		if (user_mode(regs))
-			__show_regs(regs);
-	}
-
 	return sys_ni_syscall();
 }