From: Arvind Sankar <nivedita@alum.mit.edu>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Arvind Sankar <nivedita@alum.mit.edu>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Fangrui Song <maskray@google.com>,
clang-built-linux <clang-built-linux@googlegroups.com>,
e5ten.arch@gmail.com,
"maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
<x86@kernel.org>, "H. Peter Anvin" <hpa@zytor.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Ard Biesheuvel <ardb@kernel.org>,
Kees Cook <keescook@chromium.org>,
LKML <linux-kernel@vger.kernel.org>,
"# 3.4.x" <stable@vger.kernel.org>
Subject: Re: [PATCH] x86/boot/compressed: Disable relocation relaxation for non-pie link
Date: Tue, 11 Aug 2020 20:41:58 -0400 [thread overview]
Message-ID: <20200812004158.GA1447296@rani.riverdale.lan> (raw)
In-Reply-To: <CAKwvOdn5gCjcAVHZ3jHU+q=mD5rmFAHpEyHyLf7ixtdaQ3Z-PQ@mail.gmail.com>
On Tue, Aug 11, 2020 at 04:51:23PM -0700, Nick Desaulniers wrote:
> On Tue, Aug 11, 2020 at 4:43 PM Arvind Sankar <nivedita@alum.mit.edu> wrote:
> >
> > On Tue, Aug 11, 2020 at 04:04:40PM -0700, Nick Desaulniers wrote:
> > > On Tue, Aug 11, 2020 at 3:44 PM Arvind Sankar <nivedita@alum.mit.edu> wrote:
> > > >
> > > > On Tue, Aug 11, 2020 at 10:58:40AM -0700, Nick Desaulniers wrote:
> > > > > > Cc: stable@vger.kernel.org # 4.19.x
> > > > >
> > > > > Thanks Arvind, good write up. Just curious about this stable tag, how
> > > > > come you picked 4.19? I can see boot failures in our CI for x86+LLD
> > > > > back to 4.9. Can we amend that tag to use `# 4.9`? I'd be happy to
> > > > > help submit backports should they fail to apply cleanly.
> > > > > https://travis-ci.com/github/ClangBuiltLinux/continuous-integration/builds/179237488
> > > > >
> > > >
> > > > 4.19 renamed LDFLAGS to KBUILD_LDFLAGS. For 4.4, 4.9 and 4.14 the patch
> > > > needs to be modified, KBUILD_LDFLAGS -> LDFLAGS, so I figured we should
> > > > submit backports separately. For 4.19 onwards, it should apply without
> > > > changes I think.
> > >
> > > Cool, sounds good. I'll keep an eye out for when stable goes to pick this up.
> > >
> > > tglx, Ingo, BP, can we pretty please get this in tip/urgent for
> > > inclusion into 5.9?
> > > --
> > > Thanks,
> > > ~Nick Desaulniers
> >
> > Another alternative is to just do this unconditionally instead of even
> > checking for the -pie flag. None of the GOTPCRELs are in the
> > decompressor, so they shouldn't be performance-sensitive at all.
> >
> > It still wouldn't apply cleanly to all the stable versions, but
> > backporting would be even simpler.
> >
> > What do you think?
> >
> > diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> > index 3962f592633d..10c2ba59d192 100644
> > --- a/arch/x86/boot/compressed/Makefile
> > +++ b/arch/x86/boot/compressed/Makefile
> > @@ -43,6 +43,7 @@ KBUILD_CFLAGS += -Wno-pointer-sign
> > KBUILD_CFLAGS += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
> > KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
> > KBUILD_CFLAGS += -D__DISABLE_EXPORTS
> > +KBUILD_CFLAGS += $(call as-option,-Wa$(comma)-mrelax-relocations=no)
>
> We'd still want it for KBUILD_AFLAGS, too, just to be safe. Maybe a
KBUILD_CFLAGS gets included into KBUILD_AFLAGS, so this already does
that.
> one line comment to the effect of `# remove me once we can link as
> -pie` would help us rip off this band-aid in the future? It's more
> obvious that the added hunk can be reverted once -pie linkage is
> achieved with the current patch; either are fine by me. Thanks!
>
> >
> > KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
> > GCOV_PROFILE := n
>
>
>
> --
> Thanks,
> ~Nick Desaulniers
next prev parent reply other threads:[~2020-08-12 0:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-07 19:41 [PATCH] x86/boot: avoid relaxable symbols with Clang Nick Desaulniers
2020-08-07 21:29 ` Arvind Sankar
2020-08-07 21:54 ` Nick Desaulniers
2020-08-08 1:43 ` Arvind Sankar
2020-08-10 18:32 ` Nick Desaulniers
2020-08-11 17:36 ` [PATCH] x86/boot/compressed: Disable relocation relaxation for non-pie link Arvind Sankar
2020-08-11 17:58 ` Nick Desaulniers
2020-08-11 22:44 ` Arvind Sankar
2020-08-11 23:04 ` Nick Desaulniers
2020-08-11 23:43 ` Arvind Sankar
2020-08-11 23:51 ` Nick Desaulniers
2020-08-12 0:41 ` Arvind Sankar [this message]
2020-08-12 0:43 ` [PATCH v2] x86/boot/compressed: Disable relocation relaxation Arvind Sankar
2020-08-12 17:42 ` Nick Desaulniers
2020-08-15 15:49 ` Sedat Dilek
2020-08-15 20:56 ` Nick Desaulniers
2020-08-15 21:09 ` Sedat Dilek
2020-08-25 14:56 ` Arvind Sankar
2020-09-04 15:23 ` Arvind Sankar
2020-09-13 22:34 ` Arvind Sankar
2020-09-14 5:43 ` Ard Biesheuvel
2020-09-14 9:16 ` Ingo Molnar
2020-09-14 9:35 ` Sedat Dilek
2020-09-14 17:16 ` [tip: x86/urgent] " tip-bot2 for Arvind Sankar
2020-08-12 17:39 ` [PATCH] x86/boot/compressed: Disable relocation relaxation for non-pie link Nick Desaulniers
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