f5b5faedc4
[ Upstream commit 3d9606b0e0f3aed4dfb61d0853ebf432fead7bba ] The following BUG was reported: traps: Missing ENDBR: andw_ax_dx+0x0/0x10 [kvm] ------------[ cut here ]------------ kernel BUG at arch/x86/kernel/traps.c:253! invalid opcode: 0000 [#1] PREEMPT SMP NOPTI <TASK> asm_exc_control_protection+0x2b/0x30 RIP: 0010:andw_ax_dx+0x0/0x10 [kvm] Code: c3 cc cc cc cc 0f 1f 44 00 00 66 0f 1f 00 48 19 d0 c3 cc cc cc cc 0f 1f 40 00 f3 0f 1e fa 20 d0 c3 cc cc cc cc 0f 1f 44 00 00 <66> 0f 1f 00 66 21 d0 c3 cc cc cc cc 0f 1f 40 00 66 0f 1f 00 21 d0 ? andb_al_dl+0x10/0x10 [kvm] ? fastop+0x5d/0xa0 [kvm] x86_emulate_insn+0x822/0x1060 [kvm] x86_emulate_instruction+0x46f/0x750 [kvm] complete_emulated_mmio+0x216/0x2c0 [kvm] kvm_arch_vcpu_ioctl_run+0x604/0x650 [kvm] kvm_vcpu_ioctl+0x2f4/0x6b0 [kvm] ? wake_up_q+0xa0/0xa0 The BUG occurred because the ENDBR in the andw_ax_dx() fastop function had been incorrectly "sealed" (converted to a NOP) by apply_ibt_endbr(). Objtool marked it to be sealed because KVM has no compile-time references to the function. Instead KVM calculates its address at runtime. Prevent objtool from annotating fastop functions as sealable by creating throwaway dummy compile-time references to the functions. Fixes: 6649fa876da4 ("x86/ibt,kvm: Add ENDBR to fastops") Reported-by: Pengfei Xu <pengfei.xu@intel.com> Debugged-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org> Message-Id: <0d4116f90e9d0c1b754bb90c585e6f0415a1c508.1660837839.git.jpoimboe@kernel.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.