* [tip:x86/asm] x86, binutils, xen: Fix another wrong size directive
2011-03-11 20:59 x86_64, xen: fix another wrong size directive Alexander van Heukelum
@ 2011-03-12 8:04 ` tip-bot for Alexander van Heukelum
0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Alexander van Heukelum @ 2011-03-12 8:04 UTC (permalink / raw)
To: linux-tip-commits
Cc: linux-kernel, hpa, mingo, torvalds, heukelum, jeremy, akpm,
jbeulich, kees.cook, tglx, mingo, hjl.tools
Commit-ID: 371c394af27ab7d1e58a66bc19d9f1f3ac1f67b4
Gitweb: http://git.kernel.org/tip/371c394af27ab7d1e58a66bc19d9f1f3ac1f67b4
Author: Alexander van Heukelum <heukelum@fastmail.fm>
AuthorDate: Fri, 11 Mar 2011 21:59:38 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Sat, 12 Mar 2011 09:02:29 +0100
x86, binutils, xen: Fix another wrong size directive
The latest binutils (2.21.0.20110302/Ubuntu) breaks the build
yet another time, under CONFIG_XEN=y due to a .size directive that
refers to a slightly differently named (hence, to the now very
strict and unforgiving assembler, non-existent) symbol.
[ mingo:
This unnecessary build breakage caused by new binutils
version 2.21 gets escallated back several kernel releases spanning
several years of Linux history, affecting over 130,000 upstream
kernel commits (!), on CONFIG_XEN=y 64-bit kernels (i.e. essentially
affecting all major Linux distro kernel configs).
Git annotate tells us that this slight debug symbol code mismatch
bug has been introduced in 2008 in commit 3d75e1b8:
3d75e1b8 (Jeremy Fitzhardinge 2008-07-08 15:06:49 -0700 1231) ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
The 'bug' is just a slight assymetry in ENTRY()/END()
debug-symbols sequences, with lots of assembly code between the
ENTRY() and the END():
ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
...
END(do_hypervisor_callback)
Human reviewers almost never catch such small mismatches, and binutils
never even warned about it either.
This new binutils version thus breaks the Xen build on all upstream kernels
since v2.6.27, out of the blue.
This makes a straightforward Git bisection of all 64-bit Xen-enabled kernels
impossible on such binutils, for a bisection window of over hundred
thousand historic commits. (!)
This is a major fail on the side of binutils and binutils needs to turn
this show-stopper build failure into a warning ASAP. ]
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Jan Beulich <jbeulich@novell.com>
Cc: H.J. Lu <hjl.tools@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <kees.cook@canonical.com>
LKML-Reference: <1299877178-26063-1-git-send-email-heukelum@fastmail.fm>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
arch/x86/kernel/entry_64.S | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/kernel/entry_64.S b/arch/x86/kernel/entry_64.S
index aed1ffb..bbd5c80 100644
--- a/arch/x86/kernel/entry_64.S
+++ b/arch/x86/kernel/entry_64.S
@@ -1248,7 +1248,7 @@ ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)
decl PER_CPU_VAR(irq_count)
jmp error_exit
CFI_ENDPROC
-END(do_hypervisor_callback)
+END(xen_do_hypervisor_callback)
/*
* Hypervisor uses this for application faults while it executes.
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