linux-kernel - [tip:core/urgent] objtool, compiler.h: Fix _

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Message-ID: <tip-55149d06534ae2a7ba5f7a078353deb89b3fe891@git.kernel.org>
Date:   Wed, 1 Mar 2017 05:24:51 -0800
From:   tip-bot for Josh Poimboeuf <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...nel.org, peterz@...radead.org,
        hpa@...or.com, linux-kernel@...r.kernel.org,
        a.p.zijlstra@...llo.nl, jpoimboe@...hat.com,
        torvalds@...ux-foundation.org
Subject: [tip:core/urgent] objtool, compiler.h: Fix __unreachable section
 relocation size

Commit-ID:  55149d06534ae2a7ba5f7a078353deb89b3fe891
Gitweb:     http://git.kernel.org/tip/55149d06534ae2a7ba5f7a078353deb89b3fe891
Author:     Josh Poimboeuf <jpoimboe@...hat.com>
AuthorDate: Wed, 1 Mar 2017 00:05:04 -0600
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Wed, 1 Mar 2017 14:20:18 +0100

objtool, compiler.h: 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
kernel addresses.  Use relative addresses instead:

  ".long %c0b - .\t\n"

Suggested-by: Linus Torvalds <torvalds@...ux-foundation.org>
Reported-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.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@...nel.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..b6bb901 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"						\
+	    ".long %c0b - .\t\n"					\
 	    ".popsection\t\n" : : "i" (__LINE__));			\
 })
 #else