[linux-next:master 9681/11059] arch/mips/kernel/traps.c:416 die() warn: variable dereferenced before check 'regs' (see line 404)

[linux-next:master 9681/11059] arch/mips/kernel/traps.c:416 die() warn: variable dereferenced before check 'regs' (see line 404)

[kernel test robot]

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CC: kbuild-all(a)lists.01.org
CC: Linux Memory Management List <linux-mm@kvack.org>
TO: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
CC: Christoph Hellwig <hch@lst.de>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   6145d80cfc62e3ed8f16ff584d6287e6d88b82b9
commit: 45deb5faeb9e02951361ceba5ffee721745661c3 [9681/11059] MIPS: uaccess: Remove get_fs/set_fs call sites
:::::: branch date: 10 hours ago
:::::: commit date: 2 days ago
config: mips-randconfig-m031-20210408 (attached as .config)
compiler: mips64el-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

New smatch warnings:
arch/mips/kernel/traps.c:416 die() warn: variable dereferenced before check 'regs' (see line 404)

Old smatch warnings:
arch/mips/kernel/traps.c:1996 nmi_exception_handler() warn: ignoring unreachable code.

vim +/regs +416 arch/mips/kernel/traps.c

^1da177e4c3f41 Linus Torvalds  2005-04-16  387  
ce384d83d00ee4 Yury Polyanskiy 2010-04-26  388  void __noreturn die(const char *str, struct pt_regs *regs)
^1da177e4c3f41 Linus Torvalds  2005-04-16  389  {
^1da177e4c3f41 Linus Torvalds  2005-04-16  390  	static int die_counter;
ce384d83d00ee4 Yury Polyanskiy 2010-04-26  391  	int sig = SIGSEGV;
^1da177e4c3f41 Linus Torvalds  2005-04-16  392  
8742cd23471635 Nathan Lynch    2011-09-30  393  	oops_enter();
8742cd23471635 Nathan Lynch    2011-09-30  394  
e3b28831c18c6c Ralf Baechle    2015-07-28  395  	if (notify_die(DIE_OOPS, str, regs, 0, current->thread.trap_nr,
dc73e4c1b6df27 Ralf Baechle    2013-10-09  396  		       SIGSEGV) == NOTIFY_STOP)
10423c91ffc8e5 Ralf Baechle    2011-05-13  397  		sig = 0;
5dd11d5d47d248 Jason Wessel    2010-05-20  398  
^1da177e4c3f41 Linus Torvalds  2005-04-16  399  	console_verbose();
4d85f6afa43d36 Wu Zhangjin     2011-07-23  400  	raw_spin_lock_irq(&die_lock);
41c594ab65fc89 Ralf Baechle    2006-04-05  401  	bust_spinlocks(1);
ce384d83d00ee4 Yury Polyanskiy 2010-04-26  402  
178086c86ac973 Ralf Baechle    2005-10-13  403  	printk("%s[#%d]:\n", str, ++die_counter);
^1da177e4c3f41 Linus Torvalds  2005-04-16 @404  	show_registers(regs);
373d4d099761cb Rusty Russell   2013-01-21  405  	add_taint(TAINT_DIE, LOCKDEP_NOW_UNRELIABLE);
4d85f6afa43d36 Wu Zhangjin     2011-07-23  406  	raw_spin_unlock_irq(&die_lock);
d4fd1989ea142b Maxime Bizon    2006-07-20  407  
8742cd23471635 Nathan Lynch    2011-09-30  408  	oops_exit();
8742cd23471635 Nathan Lynch    2011-09-30  409  
d4fd1989ea142b Maxime Bizon    2006-07-20  410  	if (in_interrupt())
d4fd1989ea142b Maxime Bizon    2006-07-20  411  		panic("Fatal exception in interrupt");
d4fd1989ea142b Maxime Bizon    2006-07-20  412  
99a7a234c89017 Aaro Koskinen   2016-03-09  413  	if (panic_on_oops)
d4fd1989ea142b Maxime Bizon    2006-07-20  414  		panic("Fatal exception");
d4fd1989ea142b Maxime Bizon    2006-07-20  415  
7aa1c8f47e7e79 Ralf Baechle    2012-10-11 @416  	if (regs && kexec_should_crash(current))
7aa1c8f47e7e79 Ralf Baechle    2012-10-11  417  		crash_kexec(regs);
7aa1c8f47e7e79 Ralf Baechle    2012-10-11  418  
ce384d83d00ee4 Yury Polyanskiy 2010-04-26  419  	do_exit(sig);
^1da177e4c3f41 Linus Torvalds  2005-04-16  420  }
^1da177e4c3f41 Linus Torvalds  2005-04-16  421  

:::::: The code at line 416 was first introduced by commit
:::::: 7aa1c8f47e7e792d11f898cbdddaf6fa21ff08cc MIPS: kdump: Add support

:::::: TO: Ralf Baechle <ralf@linux-mips.org>
:::::: CC: Ralf Baechle <ralf@linux-mips.org>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all(a)lists.01.org

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