linux/arch
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
..
alpha Bitmap patches for v6.0-rc1 2022-08-07 17:52:35 -07:00
arc Kbuild updates for v5.20 2022-08-10 10:40:41 -07:00
arm Merge 'irq/loongarch', 'pci/ctrl/loongson' and 'pci/header-cleanup-immutable' 2022-08-11 21:06:14 +08:00
arm64 KVM: Rename mmu_notifier_* to mmu_invalidate_* 2022-08-19 04:05:41 -04:00
csky Merge 'irq/loongarch', 'pci/ctrl/loongson' and 'pci/header-cleanup-immutable' 2022-08-11 21:06:14 +08:00
hexagon Bitmap patches for v6.0-rc1 2022-08-07 17:52:35 -07:00
ia64 Bitmap patches for v6.0-rc1 2022-08-07 17:52:35 -07:00
loongarch LoongArch changes for v5.20 2022-08-12 09:44:23 -07:00
m68k Fixes include: 2022-08-09 09:39:25 -07:00
microblaze - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe 2022-08-05 16:32:45 -07:00
mips KVM: Rename mmu_notifier_* to mmu_invalidate_* 2022-08-19 04:05:41 -04:00
nios2 nios2: drop definition of PGD_ORDER 2022-07-17 17:14:43 -07:00
openrisc Updates to various subsystems which I help look after. lib, ocfs2, 2022-08-07 10:03:24 -07:00
parisc Merge 'irq/loongarch', 'pci/ctrl/loongson' and 'pci/header-cleanup-immutable' 2022-08-11 21:06:14 +08:00
powerpc KVM: Rename mmu_notifier_* to mmu_invalidate_* 2022-08-19 04:05:41 -04:00
riscv KVM: Rename mmu_notifier_* to mmu_invalidate_* 2022-08-19 04:05:41 -04:00
s390 Merge 'irq/loongarch', 'pci/ctrl/loongson' and 'pci/header-cleanup-immutable' 2022-08-11 21:06:14 +08:00
sh Merge 'irq/loongarch', 'pci/ctrl/loongson' and 'pci/header-cleanup-immutable' 2022-08-11 21:06:14 +08:00
sparc Merge 'irq/loongarch', 'pci/ctrl/loongson' and 'pci/header-cleanup-immutable' 2022-08-11 21:06:14 +08:00
um virtio: fatures, fixes 2022-08-12 09:50:34 -07:00
x86 x86/kvm: Fix "missing ENDBR" BUG for fastop functions 2022-08-19 04:05:42 -04:00
xtensa Merge 'irq/loongarch', 'pci/ctrl/loongson' and 'pci/header-cleanup-immutable' 2022-08-11 21:06:14 +08:00
.gitignore
Kconfig asm-generic: updates for 6.0 2022-08-05 10:07:23 -07:00