linux-kernel - PROBLEM: objtool: __x64_sys_exit_group()+0x14: unreachable instruction

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Message-ID: <20191112223300.GA17891@debian>
Date:   Wed, 13 Nov 2019 04:03:00 +0530
From:   Jeffrin Jose <jeffrin@...agiritech.edu.in>
To:     akpm@...ux-foundation.org, oleg@...hat.com, christian@...uner.io,
        tj@...nel.org, peterz@...radead.org, prsood@...eaurora.org,
        avagin@...il.com, aarcange@...hat.com
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        jeffrin@...agiritech.edu.in
Subject: PROBLEM: objtool: __x64_sys_exit_group()+0x14: unreachable
 instruction

hello all,

i found a warning during kernel build (5.3.11-rc1+).
-----------------x----------x-----------------
kernel/exit.o: warning: objtool: __x64_sys_exit_group()+0x14: unreachable instruction
-------------------x---------------x-----------

Related details:
---------------

$uname -a
Linux debian 5.3.11-rc1+ #6 SMP Tue Nov 12 01:23:06 IST 2019 x86_64 GNU/Linux
$

$gcc --version
gcc (Debian 9.2.1-14) 9.2.1 20191025
------x---has-been-cut-here--x------



(gdb) l __x64_sys_exit_group
987	/*
988	 * this kills every thread in the thread group. Note that any externally
989	 * wait4()-ing process will get the correct exit code - even if this
990	 * thread is not the thread group leader.
991	 */
992	SYSCALL_DEFINE1(exit_group, int, error_code)
993	{
994		do_group_exit((error_code & 0xff) << 8);
995		/* NOTREACHED */
996		return 0;
(gdb) 

(gdb) l *__x64_sys_exit_group+0x14
0xffffffff81085404 is in __x64_sys_exit_group (kernel/exit.c:996).
991	 */
992	SYSCALL_DEFINE1(exit_group, int, error_code)
993	{
994		do_group_exit((error_code & 0xff) << 8);
995		/* NOTREACHED */
996		return 0;
997	}
998	
999	struct waitid_info {
1000		pid_t pid;
(gdb) 


(gdb) l *__x64_sys_exit_group
0xffffffff810853f0 is in __x64_sys_exit_group (kernel/exit.c:992).
987	/*
988	 * this kills every thread in the thread group. Note that any externally
989	 * wait4()-ing process will get the correct exit code - even if this
990	 * thread is not the thread group leader.
991	 */
992	SYSCALL_DEFINE1(exit_group, int, error_code)
993	{
994		do_group_exit((error_code & 0xff) << 8);
995		/* NOTREACHED */
996		return 0;
(gdb) 

--------------------x-------------x-----------------------------

objdump -r -S -l --disassemble kernel/exit.o   output is attached

--
software engineer
rajagiri school of engineering and technology







View attachment "objoutput.txt" of type "text/plain" (263873 bytes)