linux-kernel - Re: [PATCH 00/21] objtool: vmlinux.o and CLANG LTO support

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Date:   Fri, 15 Jan 2021 14:59:20 -0600
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Sedat Dilek <sedat.dilek@...il.com>
Cc:     Sami Tolvanen <samitolvanen@...gle.com>, X86 ML <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Kees Cook <keescook@...omium.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Miroslav Benes <mbenes@...e.cz>
Subject: Re: [PATCH 00/21] objtool: vmlinux.o and CLANG LTO support

On Fri, Jan 15, 2021 at 09:19:16PM +0100, Sedat Dilek wrote:
> > > vmlinux.o: warning: objtool: balance_leaf_when_delete()+0x17d4: stack
> > > state mismatch: cfa1=7+192 cfa2=7+176
> > > vmlinux.o: warning: objtool: internal_move_pointers_items()+0x9f7:
> > > stack state mismatch: cfa1=7+160 cfa2=7+176
> > > vmlinux.o: warning: objtool: strncpy_from_user()+0x181: call to
> > > do_strncpy_from_user() with UACCESS enabled
> > > vmlinux.o: warning: objtool: strnlen_user()+0x12b: call to
> > > do_strnlen_user() with UACCESS enabled
> > > vmlinux.o: warning: objtool: i915_gem_execbuffer2_ioctl()+0x390: call
> > > to __ubsan_handle_negate_overflow() with UACCESS enabled
> > > vmlinux.o: warning: objtool: .text.snd_trident_free_voice: unexpected
> > > end of section
> > >
> > > I haven't had a chance to take a closer look yet, but some of these
> > > are probably related to
> > > https://github.com/ClangBuiltLinux/linux/issues/1192. However, I can
> > > reproduce these also with ToT Clang, not just with Clang 11.
> >
> > Thanks, I'm able to reproduce these.  Will take a look.
> >
> 
> AFAICS, that misses the v2 diff (see attachment) you sent me when
> dealing with objtool-vmlinux and clang-cfi.
> It does not cleanly apply with the combination of your objtool-vmlinux
> Git and clang-cfi Git.

Patches 11 and 12 should in theory have the same functionality as that
diff.  I just refactored the code a bit before posting.

-- 
Josh