RISC-V: Avoid dereferening NULL regs in die()

stable inclusion
from stable-v5.10.175
commit f9fdb3e7b0758516fbc5ae12e3ec23d9060f7035
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8711T

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f9fdb3e7b0758516fbc5ae12e3ec23d9060f7035



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[ Upstream commit f2913d00 ]

I don't think we can actually die() without a regs pointer, but the
compiler was warning about a NULL check after a dereference.  It seems
prudent to just avoid the possibly-NULL dereference, given that when
die()ing the system is already toast so who knows how we got there.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220920200037.6727-1-palmer@rivosinc.com


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Stable-dep-of: 130aee3f ("riscv: Avoid enabling interrupts in die()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>