linux/arch/x86
Josh Poimboeuf 3d9606b0e0 x86/kvm: Fix "missing ENDBR" BUG for fastop functions
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: 6649fa876d ("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>
2022-08-19 04:05:42 -04:00
..
boot x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments 2022-08-10 18:30:09 -07:00
coco x86/tdx: Handle load_unaligned_zeropad() page-cross to a shared page 2022-06-17 15:37:33 -07:00
configs efi: vars: Remove deprecated 'efivars' sysfs interface 2022-06-24 20:40:19 +02:00
crypto SPDX changes for 6.0-rc1 2022-08-04 12:12:54 -07:00
entry x86: link vdso and boot with -z noexecstack --no-warn-rwx-segments 2022-08-10 18:30:09 -07:00
events ARM: 2022-08-04 14:59:54 -07:00
hyperv ARM: 2022-08-04 14:59:54 -07:00
ia32 x86: Remove a.out support 2022-04-11 18:04:27 +02:00
include x86/ibt, objtool: Add IBT_NOSEAL() 2022-08-19 04:05:42 -04:00
kernel Fix the "IBPB mitigated RETBleed" mode of operation on AMD CPUs 2022-08-13 14:24:12 -07:00
kvm x86/kvm: Fix "missing ENDBR" BUG for fastop functions 2022-08-19 04:05:42 -04:00
lib x86/retbleed: Add fine grained Kconfig knobs 2022-06-29 17:43:41 +02:00
math-emu x86/32: Remove lazy GS macros 2022-04-14 14:09:43 +02:00
mm mm/hugetlb: make pud_huge() and follow_huge_pud() aware of non-present pud entry 2022-08-08 18:06:43 -07:00
net Merge https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2022-07-22 16:55:44 -07:00
pci x86/PCI: Revert "x86/PCI: Clip only host bridge windows for E820 regions" 2022-06-17 14:24:14 -05:00
platform Bitmap patches for v6.0-rc1 2022-08-07 17:52:35 -07:00
power x86/cpu: Load microcode during restore_processor_state() 2022-04-19 19:37:05 +02:00
purgatory x86/purgatory: Omit use of bin2c 2022-07-25 10:32:32 +02:00
ras
realmode Intel Trust Domain Extensions 2022-05-23 17:51:12 -07:00
tools
um Misc fixes: 2022-08-06 17:45:37 -07:00
video
virt/vmx/tdx
xen x86/xen: Add support for HVMOP_set_evtchn_upcall_vector 2022-08-12 11:28:21 +02:00
.gitignore x86/purgatory: Omit use of bin2c 2022-07-25 10:32:32 +02:00
Kbuild
Kconfig - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
Kconfig.assembler
Kconfig.cpu
Kconfig.debug arch: make TRACE_IRQFLAGS_NMI_SUPPORT generic 2022-06-23 15:39:21 +01:00
Makefile lkdtm: Disable return thunks in rodata.c 2022-07-20 19:24:53 +02:00
Makefile_32.cpu
Makefile.um