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From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: x86@kernel.org, joao@overdrivepizza.com, hjl.tools@gmail.com,
	andrew.cooper3@citrix.com, linux-kernel@vger.kernel.org,
	ndesaulniers@google.com, keescook@chromium.org,
	samitolvanen@google.com, mark.rutland@arm.com,
	alyssa.milburn@intel.com, mbenes@suse.cz, rostedt@goodmis.org,
	mhiramat@kernel.org, alexei.starovoitov@gmail.com
Subject: Re: [PATCH v3 00/39] x86: Kernel IBT
Date: Fri, 4 Mar 2022 22:39:30 +0100	[thread overview]
Message-ID: <20220304213930.GS11184@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20220304190958.comlw5wt7zdgeakc@treble>

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 ?

      parent reply	other threads:[~2022-03-04 21:39 UTC|newest]

Thread overview: 64+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-03 11:23 [PATCH v3 00/39] x86: Kernel IBT Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 01/39] static_call: Avoid building empty .static_call_sites Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 02/39] x86/module: Fix the paravirt vs alternative order Peter Zijlstra
2022-03-08 13:58   ` [tip: x86/urgent] " tip-bot2 for Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 03/39] objtool: Add --dry-run Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 04/39] x86/ibt: Base IBT bits Peter Zijlstra
2022-03-07 11:17   ` Peter Zijlstra
2022-03-07 12:25     ` Joao Moreira
2022-03-07 18:19       ` Nick Desaulniers
2022-03-03 11:23 ` [PATCH v3 05/39] x86/ibt: Add ANNOTATE_NOENDBR Peter Zijlstra
2022-03-04 18:59   ` Josh Poimboeuf
2022-03-04 20:22     ` Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 06/39] x86/text-patching: Make text_gen_insn() play nice with ANNOTATE_NOENDBR Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 07/39] x86/ibt,paravirt: Use text_gen_insn() for paravirt_patch() Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 08/39] x86/entry: Cleanup PARAVIRT Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 09/39] x86/entry,xen: Early rewrite of restore_regs_and_return_to_kernel() Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 10/39] x86/ibt,xen: Sprinkle the ENDBR Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 11/39] x86/ibt,entry: Sprinkle ENDBR dust Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 12/39] x86/linkage: Add ENDBR to SYM_FUNC_START*() Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 13/39] x86/ibt,paravirt: Sprinkle ENDBR Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 14/39] x86/ibt,crypto: Add ENDBR for the jump-table entries Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 15/39] x86/ibt,kvm: Add ENDBR to fastops Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 16/39] x86/ibt,ftrace: Search for __fentry__ location Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 17/39] x86/livepatch: Validate " Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 18/39] x86/ibt,ftrace: Make function-graph play nice Peter Zijlstra
2022-03-04 17:51   ` Josh Poimboeuf
2022-03-04 19:48     ` Peter Zijlstra
2022-03-04 21:03       ` Josh Poimboeuf
2022-03-04 21:44         ` Peter Zijlstra
2022-03-04 22:05           ` Josh Poimboeuf
2022-03-04 23:08       ` David Laight
2022-03-03 11:23 ` [PATCH v3 19/39] x86/ibt,kprobes: Cure sym+0 equals fentry woes Peter Zijlstra
2022-03-07  9:44   ` Masami Hiramatsu
2022-03-03 11:23 ` [PATCH v3 20/39] x86/ibt,bpf: Add ENDBR instructions to prologue and trampoline Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 21/39] x86/ibt,ftrace: Add ENDBR to samples/ftrace Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 22/39] x86/ibt: Add IBT feature, MSR and #CP handling Peter Zijlstra
2022-03-04 17:57   ` Josh Poimboeuf
2022-03-04 20:38     ` Peter Zijlstra
2022-03-04 18:07   ` Josh Poimboeuf
2022-03-04 20:39     ` Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 23/39] x86/alternative: Simplify int3_selftest_ip Peter Zijlstra
2022-03-04 18:02   ` Josh Poimboeuf
2022-03-04 18:09     ` Josh Poimboeuf
2022-03-03 11:23 ` [PATCH v3 24/39] x86/ibt: Disable IBT around firmware Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 25/39] x86/bugs: Disable Retpoline when IBT Peter Zijlstra
2022-03-04 17:39   ` Josh Poimboeuf
2022-03-03 11:23 ` [PATCH v3 26/39] x86/ibt: Annotate text references Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 27/39] x86/ibt,ftrace: Annotate ftrace code patching Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 28/39] x86/ibt,sev: Annotations Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 29/39] x86/ibt: Dont generate ENDBR in .discard.text Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 30/39] x86/ibt: Ensure module init/exit points have references Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 31/39] objtool: Rename --duplicate to --lto Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 32/39] Kbuild: Allow whole module objtool runs Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 33/39] objtool: Read the NOENDBR annotation Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 34/39] objtool: Have WARN_FUNC fall back to sym+off Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 35/39] objtool: Add IBT/ENDBR decoding Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 36/39] objtool: Validate IBT assumptions Peter Zijlstra
2022-03-03 11:23 ` [PATCH v3 37/39] objtool: Optionally WARN about unused ANNOTATE_NOENDBR Peter Zijlstra
2022-03-04 18:27   ` Josh Poimboeuf
2022-03-03 11:23 ` [PATCH v3 38/39] objtool: Find unused ENDBR instructions Peter Zijlstra
2022-03-03 11:24 ` [PATCH v3 39/39] x86/alternative: Use .ibt_endbr_seal to seal indirect calls Peter Zijlstra
2022-03-04 19:09 ` [PATCH v3 00/39] x86: Kernel IBT Josh Poimboeuf
2022-03-04 20:22   ` Peter Zijlstra
2022-03-04 21:39   ` Peter Zijlstra [this message]

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