From: Josh Poimboeuf <jpoimboe@redhat.com>
To: hpa@zytor.com
Cc: linux-tip-commits@vger.kernel.org,
tip-bot for Josh Poimboeuf <tipbot@zytor.com>,
a.p.zijlstra@chello.nl, torvalds@linux-foundation.org,
tglx@linutronix.de, linux-kernel@vger.kernel.org,
peterz@infradead.org, mingo@kernel.org
Subject: Re: [tip:core/urgent] objtool: Fix __unreachable section relocation size
Date: Wed, 1 Mar 2017 06:41:21 -0600 [thread overview]
Message-ID: <20170301124121.urubwf7jo2s45wt2@treble> (raw)
In-Reply-To: <1A185271-A629-43C0-9A1B-9EDB75630057@zytor.com>
On Wed, Mar 01, 2017 at 12:15:38AM -0800, hpa@zytor.com wrote:
> On March 1, 2017 12:10:59 AM PST, tip-bot for Josh Poimboeuf <tipbot@zytor.com> wrote:
> >Commit-ID: 90a7e63a31b8f7d630d12ef0d8d37d3ab87f76e5
> >Gitweb:
> >http://git.kernel.org/tip/90a7e63a31b8f7d630d12ef0d8d37d3ab87f76e5
> >Author: Josh Poimboeuf <jpoimboe@redhat.com>
> >AuthorDate: Wed, 1 Mar 2017 00:05:04 -0600
> >Committer: Ingo Molnar <mingo@kernel.org>
> >CommitDate: Wed, 1 Mar 2017 07:38:25 +0100
> >
> >objtool: Fix __unreachable section relocation size
> >
> >Linus reported the following commit broke module loading on his laptop:
> >
> >d1091c7fa3d5 ("objtool: Improve detection of BUG() and other dead
> >ends")
> >
> >It showed errors like the following:
> >
> > module: overflow in relocation type 10 val ffffffffc02afc81
> > module: 'nvme' likely not compiled with -mcmodel=kernel
> >
> >The problem is that the __unreachable section addresses are stored
> >using
> >the '.long' asm directive, which isn't big enough for .text section
> >relative kernel addresses. Use '.quad' instead.
> >
> >Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
> >Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
> >Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
> >Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
> >Cc: Peter Zijlstra <peterz@infradead.org>
> >Cc: Thomas Gleixner <tglx@linutronix.de>
> >Fixes: d1091c7fa3d5 ("objtool: Improve detection of BUG() and other
> >dead ends")
> >Link: http://lkml.kernel.org/r/20170301060504.oltm3iws6fmubnom@treble
> >Signed-off-by: Ingo Molnar <mingo@kernel.org>
> >---
> > include/linux/compiler-gcc.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> >diff --git a/include/linux/compiler-gcc.h
> >b/include/linux/compiler-gcc.h
> >index 76e28c2..91a77a5 100644
> >--- a/include/linux/compiler-gcc.h
> >+++ b/include/linux/compiler-gcc.h
> >@@ -201,7 +201,7 @@
> > #define annotate_unreachable() ({ \
> > asm("%c0:\t\n" \
> > ".pushsection __unreachable, \"a\"\t\n" \
> >- ".long %c0b\t\n" \
> >+ ".quad %c0b\t\n" \
> > ".popsection\t\n" : : "i" (__LINE__)); \
> > })
> > #else
>
> Or perhaps better use relative addresses, so:
>
> .long foo - (.+4)
Hm, yeah, something like that would indeed be better as it only needs 4
bytes instead of 8. For this use case, the following seems to work:
".long %c0b - .\t\n"
It produces the same relocation section+addend as before but with a
X86_64_PC32 relocation.
It looks like the above patch was already merged so I'll add that change
to the TODO list unless Ingo can squash it with the above patch.
--
Josh
next prev parent reply other threads:[~2017-03-01 12:51 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-28 7:53 [GIT PULL] objtool fixes Ingo Molnar
2017-03-01 1:55 ` Linus Torvalds
2017-03-01 6:05 ` Josh Poimboeuf
2017-03-01 8:10 ` [tip:core/urgent] objtool: Fix __unreachable section relocation size tip-bot for Josh Poimboeuf
2017-03-01 8:15 ` hpa
2017-03-01 12:41 ` Josh Poimboeuf [this message]
2017-03-01 12:44 ` [PATCH] objtool, compiler.h: " Ingo Molnar
2017-03-01 12:56 ` Josh Poimboeuf
2017-03-01 10:37 ` [tip:core/urgent] objtool: " Ingo Molnar
2017-03-01 12:43 ` Josh Poimboeuf
2017-03-01 12:45 ` [tip:core/urgent] objtool, compiler.h: " tip-bot for Josh Poimboeuf
2017-03-01 13:24 ` tip-bot for Josh Poimboeuf
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