From: Alexander van Heukelum Date: Fri, 11 Mar 2011 20:59:38 +0000 (+0100) Subject: x86, binutils, xen: Fix another wrong size directive X-Git-Tag: v2.6.39-rc1~506^2 X-Git-Url: http://git.itanic.dy.fi/?p=linux-stable;a=commitdiff_plain;h=371c394af27ab7d1e58a66bc19d9f1f3ac1f67b4 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 Cc: Jeremy Fitzhardinge Cc: Jan Beulich Cc: H.J. Lu Cc: Linus Torvalds Cc: Andrew Morton Cc: "H. Peter Anvin" Cc: Kees Cook LKML-Reference: <1299877178-26063-1-git-send-email-heukelum@fastmail.fm> Signed-off-by: Ingo Molnar --- 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.