From: Nathan Chancellor <natechancellor@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
LKML <linux-kernel@vger.kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux <clang-built-linux@googlegroups.com>,
x86@kernel.org, Arnd Bergmann <arnd@arndb.de>,
Sedat Dilek <sedat.dilek@gmail.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] objtool: Improve UACCESS coverage
Date: Wed, 24 Jul 2019 09:54:46 -0700 [thread overview]
Message-ID: <20190724165446.GA110233@archlinux-threadripper> (raw)
In-Reply-To: <20190724164821.GB31425@hirez.programming.kicks-ass.net>
On Wed, Jul 24, 2019 at 06:48:21PM +0200, Peter Zijlstra wrote:
> On Wed, Jul 24, 2019 at 04:10:40PM +0200, Peter Zijlstra wrote:
> > And that most certainly should trigger...
> >
> > Let me gdb that objtool thing.
>
> ---
> Subject: objtool: Improve UACCESS coverage
>
> A clang build reported an (obvious) double CLAC while a GCC build did
> not; it turns out we only re-visit instructions if the first visit was
> with AC=0. If OTOH the first visit was with AC=1, we completely ignore
> any subsequent visit, even when it has AC=0.
>
> Fix this by using a visited mask, instead of boolean and (explicitly)
> mark the AC state.
>
> $ ./objtool check -b --no-fp --retpoline --uaccess ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o
> ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0x22: redundant UACCESS disable
> ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xea: (alt)
> ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: .altinstr_replacement+0xffffffffffffffff: (branch)
> ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xd9: (alt)
> ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0xb2: (branch)
> ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x39: (branch)
> ../../defconfig-build/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.o: warning: objtool: eb_copy_relocations.isra.34()+0x0: <=== (func)
>
> Reported-by: Josh Poimboeuf <jpoimboe@redhat.com>
> Reported-by: Thomas Gleixner <tglx@linutronix.de>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
This doesn't regress clang and I see the warning on GCC now too.
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
next prev parent reply other threads:[~2019-07-24 16:54 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-18 20:40 x86 - clang / objtool status Thomas Gleixner
2019-07-18 20:58 ` Nathan Chancellor
2019-07-19 6:39 ` Thomas Gleixner
2019-07-19 7:00 ` Arnd Bergmann
2019-07-19 7:03 ` Nathan Chancellor
2019-07-24 16:57 ` Nick Desaulniers
2019-07-18 22:42 ` Nick Desaulniers
2019-07-19 6:44 ` Thomas Gleixner
2019-07-19 11:37 ` Sedat Dilek
2019-07-19 13:48 ` Sedat Dilek
2019-07-22 15:40 ` Sedat Dilek
2019-07-25 6:17 ` Sedat Dilek
2019-07-24 2:43 ` Josh Poimboeuf
2019-07-24 7:47 ` Peter Zijlstra
2019-07-24 12:37 ` Josh Poimboeuf
2019-07-24 12:55 ` Josh Poimboeuf
2019-07-24 13:35 ` Peter Zijlstra
2019-07-24 14:05 ` Josh Poimboeuf
2019-07-24 14:10 ` Peter Zijlstra
2019-07-24 16:48 ` [PATCH] objtool: Improve UACCESS coverage Peter Zijlstra
2019-07-24 16:54 ` Nathan Chancellor [this message]
2019-07-24 16:55 ` Nick Desaulniers
2019-07-24 18:30 ` Sedat Dilek
2019-07-24 18:32 ` Sedat Dilek
2019-07-24 16:52 ` x86 - clang / objtool status Peter Zijlstra
2019-07-24 17:22 ` Nick Desaulniers
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20190724165446.GA110233@archlinux-threadripper \
--to=natechancellor@gmail.com \
--cc=arnd@arndb.de \
--cc=clang-built-linux@googlegroups.com \
--cc=jpoimboe@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=ndesaulniers@google.com \
--cc=peterz@infradead.org \
--cc=sedat.dilek@gmail.com \
--cc=tglx@linutronix.de \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.