From: Peter Zijlstra <peterz@infradead.org>
To: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, x86@kernel.org,
mhiramat@kernel.org, mbenes@suse.cz, brgerst@gmail.com
Subject: Re: [PATCH v3 18/26] objtool: Fix !CFI insn_state propagation
Date: Tue, 24 Mar 2020 23:11:09 +0100 [thread overview]
Message-ID: <20200324221109.GU2452@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20200324214006.tlanaff5q6gkgk2a@treble>
On Tue, Mar 24, 2020 at 04:40:06PM -0500, Josh Poimboeuf wrote:
> On Tue, Mar 24, 2020 at 04:31:31PM +0100, Peter Zijlstra wrote:
> > + if (!save_insn->visited) {
> > + /*
> > + * Oops, no state to copy yet.
> > + * Hopefully we can reach this
> > + * instruction from another branch
> > + * after the save insn has been
> > + * visited.
> > + */
> > + if (insn == first)
> > + return 0; // XXX
>
> Yeah, moving this code out to apply_insn_hint() seems like a nice idea,
> but it wouldn't be worth it if it breaks this case. TBH I don't
> remember if this check was for a real-world case. Might be worth
> looking at... If this case doesn't exist in reality then we could just
> remove this check altogether.
I'll go run a bunch of builds with a print on it, that should tell us I
suppose.
> > +
> > + WARN_FUNC("objtool isn't smart enough to handle this CFI save/restore combo",
> > + sec, insn->offset);
> > + return 1;
> > + }
> > +
> > + insn->state = save_insn->state;
> > + }
> > +
> > + *state = insn->state;
>
> This would have been easier to review if apply_insn_hint() were added in
> a separate patch.
27 it will be!
> > +
> > + /* restore !CFI state */
> > + state->df = old.df;
> > + state->uaccess = old.uaccess;
> > + state->uaccess_stack = old.uaccess_stack;
>
> Maybe we should just move the CFI stuff into a state->cfi substruct.
> That would remove the need for these bits and probably also the comment
> above the insn_state declaration.
Indeed!
next prev parent reply other threads:[~2020-03-24 22:11 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-24 15:31 [PATCH v3 00/26] objtool: vmlinux.o and noinstr validation Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 01/26] objtool: Introduce validate_return() Peter Zijlstra
2020-03-25 8:39 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 02/26] objtool: Rename func_for_each_insn() Peter Zijlstra
2020-03-25 8:43 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 03/26] objtool: Rename func_for_each_insn_all() Peter Zijlstra
2020-03-25 8:44 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 04/26] x86/kexec: Use RIP relative addressing Peter Zijlstra
2020-03-25 9:34 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 05/26] x86/kexec: Make relocate_kernel_64.S objtool clean Peter Zijlstra
2020-03-24 20:55 ` Josh Poimboeuf
2020-03-25 9:56 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 06/26] objtool: Optimize find_symbol_by_index() Peter Zijlstra
2020-03-25 10:01 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 07/26] objtool: Add a statistics mode Peter Zijlstra
2020-03-25 10:10 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 08/26] objtool: Optimize find_section_by_index() Peter Zijlstra
2020-03-25 10:12 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 09/26] objtool: Optimize find_section_by_name() Peter Zijlstra
2020-03-25 10:18 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 10/26] objtool: Optimize find_symbol_*() and read_symbols() Peter Zijlstra
2020-03-25 10:20 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 11/26] objtool: Rename find_containing_func() Peter Zijlstra
2020-03-25 10:21 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 12/26] objtool: Resize insn_hash Peter Zijlstra
2020-03-25 10:21 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 13/26] objtool: Optimize find_symbol_by_name() Peter Zijlstra
2020-03-25 10:25 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 14/26] objtool: Optimize read_sections() Peter Zijlstra
2020-03-25 12:10 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-04-21 14:47 ` [PATCH v3 14/26] " youling257
2020-04-21 15:49 ` Peter Zijlstra
2020-04-21 15:57 ` Borislav Petkov
2020-04-21 17:50 ` youling 257
2020-03-24 15:31 ` [PATCH v3 15/26] objtool: Delete cleanup() Peter Zijlstra
2020-03-25 12:11 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 16/26] objtool: Optimize find_rela_by_dest_range() Peter Zijlstra
2020-03-25 12:19 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 17/26] objtool: Re-arrange validate_functions() Peter Zijlstra
2020-03-24 21:10 ` Josh Poimboeuf
2020-03-24 21:15 ` Peter Zijlstra
2020-03-25 12:22 ` Miroslav Benes
2020-03-26 10:08 ` [tip: core/objtool] " tip-bot2 for Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 18/26] objtool: Fix !CFI insn_state propagation Peter Zijlstra
2020-03-24 21:40 ` Josh Poimboeuf
2020-03-24 22:11 ` Peter Zijlstra [this message]
2020-03-24 23:00 ` Peter Zijlstra
2020-03-25 14:39 ` Josh Poimboeuf
2020-03-25 14:41 ` [PATCH v3.1 18a/26] objtool: Remove CFI save/restore special case Peter Zijlstra
2020-03-25 14:42 ` [PATCH v3.1 18b/26] objtool: Factor out CFI hints Peter Zijlstra
2020-03-25 14:43 ` [PATCH v3.1 18c/26] objtool: Rename struct cfi_state Peter Zijlstra
2020-03-25 14:43 ` [PATCH v3.1 18d/26] objtool: Fix !CFI insn_state propagation Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 19/26] objtool: Implement noinstr validation Peter Zijlstra
2020-03-24 21:41 ` Josh Poimboeuf
2020-03-25 14:44 ` [PATCH v3.1 " Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 20/26] objtool: Optimize !vmlinux.o again Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 21/26] objtool: Use sec_offset_hash() for insn_hash Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 22/26] objtool: Detect loading function pointers across noinstr Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 23/26] kbuild/objtool: Add objtool-vmlinux.o pass Peter Zijlstra
2020-03-24 22:03 ` Josh Poimboeuf
2020-03-24 22:05 ` Peter Zijlstra
2020-03-24 15:31 ` [PATCH v3 24/26] objtool: Avoid iterating !text section symbols Peter Zijlstra
2020-03-24 22:09 ` Josh Poimboeuf
2020-03-24 15:31 ` [PATCH v3 25/26] objtool: Rearrange validate_section() Peter Zijlstra
2020-03-24 22:10 ` Josh Poimboeuf
2020-03-24 15:31 ` [PATCH v3 26/26] objtool: Add STT_NOTYPE noinstr validation Peter Zijlstra
2020-03-24 22:16 ` Josh Poimboeuf
2020-03-24 22:34 ` Peter Zijlstra
2020-03-25 14:42 ` Josh Poimboeuf
2020-03-25 15:53 ` Peter Zijlstra
2020-03-25 16:40 ` Josh Poimboeuf
2020-03-25 16:50 ` Peter Zijlstra
2020-03-26 8:01 ` Julien Thierry
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