Messages in this thread | | | Date | Fri, 4 Mar 2022 22:39:30 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v3 00/39] x86: Kernel IBT |
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On Fri, Mar 04, 2022 at 11:09:58AM -0800, Josh Poimboeuf wrote: > On Thu, Mar 03, 2022 at 12:23:21PM +0100, Peter Zijlstra wrote: > > Hi, another week, another series. > > > > Since last time: > > > > - fixed and tested kexec (redgecomb) > > - s/4*HAS_KERNEL_IBT/ENDBR_INSN_SIZE/ (jpoimboe) > > - re-arranged Xen patches to avoid churn (andyhpp) > > - folded IBT_SEAL Kconfig and objtool options (jpoimboe) > > - dropped direct call/jmp rewrite from objtool (jpoimboe) > > - dropped UD1 poison (jpoimboe) > > - fixed kprobe selftests (masami,naveen) > > - fixed ftrace selftests (rostedt) > > - simplified CET/INT3 selftests (jpoimboe) > > - boot time msg on IBT (kees) > > - objtool WARN_FUNC sym+off fallback (jpoimboe) > > - picked up tags for unchanged patches > > - probably more > > > > Supposedly clang-14-rc2 will work on this series, I'll validate the moment the > > Debian package gets updated. > > > > Patches go on top of tip/master + arm64/for-next/linkage. Also available here: > > > > git://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git x86/wip.ibt > > I'm getting some warnings with CONFIG_X86_KERNEL_IBT=n: > > arch/x86/entry/entry_64.o: warning: objtool: irq_entries_start()+0x7: unreachable instruction > arch/x86/kernel/ftrace_64.o: warning: objtool: return_to_handler()+0x2a: unreachable instruction
Blergh, those are INT3 instructions, the first is the LDT stub padding while the second is that INT3 you asked about earlier.
I can mark then all using SLS style rules, but that then triggers:
arch/x86/kernel/reboot.o: warning: objtool: native_machine_emergency_restart()+0x8f: BUG: why am I validating an ignored function?
which does horrible things on purpose to tickle a tripple fault in order to reboot the machine.
Perhaps we should ignore INT3 by default, just like NOP ?
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