From: Ingo Molnar <mingo@elte.hu>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: Yinghai Lu <yinghai@kernel.org>,
David Howells <dhowells@redhat.com>,
Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Stephen Rothwell <sfr@canb.auug.org.au>,
linux-next@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
mel@csn.ul.ie
Subject: [PATCH] kbuild, sparseirq: work around GCC bug with __weak aliases
Date: Fri, 26 Dec 2008 14:42:18 +0100 [thread overview]
Message-ID: <20081226134218.GA1054@elte.hu> (raw)
In-Reply-To: <20081226133354.GC29265@elte.hu>
* Ingo Molnar <mingo@elte.hu> wrote:
> > I recall David Howells had a similar issue with the bootparamter patch
> > set. The workaround he used was to add a barrier(); call in the weak
> > function to avoid the inline.
>
> could we add some extra attribute to __weak that would have a similar
> effect? Something like __attribute__((noinline)), or something silly
> like __attribute__((deprecated)) - just to keep gcc from screwing up
> __weak functions? Perhaps adding a section attribute would have a
> similar effect? (putting weak definitions into an extra section is
> probably helpful anyway)
I've applied the patch below to tip/irq/sparseirq - could someone with an
affected GCC version please check whether this solves the crash?
Ingo
------------------->
>From 0d41e654c877a0de441448ca2f63a72ed11c5d84 Mon Sep 17 00:00:00 2001
From: Ingo Molnar <mingo@elte.hu>
Date: Fri, 26 Dec 2008 14:39:51 +0100
Subject: [PATCH] kbuild, sparseirq: work around GCC bug with __weak aliases
Impact: fix panic on null pointer with sparseirq
Certain versions of GCC inline the weak global functions.
Work it around by marking __weak functions as noinline.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
include/linux/compiler-gcc.h | 8 +++++++-
1 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 5c8351b..1ad72e6 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -41,11 +41,17 @@
#define __deprecated __attribute__((deprecated))
#define __packed __attribute__((packed))
-#define __weak __attribute__((weak))
#define __naked __attribute__((naked))
#define __noreturn __attribute__((noreturn))
/*
+ * Mark weak aliases also noinline, because some GCC versions
+ * incorrectly inline weak aliases (even when a non-weak variant
+ * is there) and thus cause crashes:
+ */
+#define __weak __attribute__((weak)) noinline
+
+/*
* From the GCC manual:
*
* Many functions have no effects except the return value and their
next prev parent reply other threads:[~2008-12-26 13:44 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-16 11:37 linux-next: Tree for December 16 Stephen Rothwell
2008-12-16 23:26 ` Andrew Morton
2008-12-17 6:59 ` linux-next: mtd tree build failures (Was: Re: linux-next: Tree for December 16) Stephen Rothwell
2008-12-17 9:32 ` Artem Bityutskiy
2008-12-17 9:57 ` Stephen Rothwell
2008-12-17 7:07 ` linux-next: Tree for December 16 Artem Bityutskiy
2008-12-17 7:08 ` next-20081216 - powerpc link error 'dynreloc miscount' Kamalesh Babulal
2008-12-17 7:08 ` Kamalesh Babulal
2008-12-17 7:28 ` Sam Ravnborg
2008-12-17 7:28 ` Sam Ravnborg
2008-12-17 7:30 ` Stephen Rothwell
2008-12-19 10:54 ` [BUG] next-20081216 - WARNING: at kernel/smp.c:333 smp_call_function_mask Kamalesh Babulal
2008-12-19 11:51 ` Yinghai Lu
2008-12-19 13:46 ` Kamalesh Babulal
2008-12-19 21:02 ` Yinghai Lu
2008-12-23 13:21 ` Kamalesh Babulal
2008-12-23 21:09 ` Yinghai Lu
2008-12-24 16:34 ` Kamalesh Babulal
2008-12-24 20:34 ` Yinghai Lu
2008-12-26 9:12 ` Kamalesh Babulal
2008-12-26 10:05 ` Yinghai Lu
2008-12-26 10:27 ` Sam Ravnborg
2008-12-26 13:33 ` Ingo Molnar
2008-12-26 13:42 ` Ingo Molnar [this message]
2008-12-27 4:09 ` [PATCH] kbuild, sparseirq: work around GCC bug with __weak aliases Paul Mackerras
2008-12-27 10:59 ` Ingo Molnar
2008-12-28 23:27 ` Paul Mackerras
2008-12-26 15:28 ` [BUG] next-20081216 - WARNING: at kernel/smp.c:333 smp_call_function_mask Kamalesh Babulal
2008-12-26 15:33 ` Ingo Molnar
2008-12-26 17:04 ` Kamalesh Babulal
2008-12-26 18:17 ` Ingo Molnar
2008-12-27 7:11 ` Kamalesh Babulal
2008-12-27 7:14 ` Yinghai Lu
2008-12-27 7:39 ` Yinghai Lu
2008-12-27 8:37 ` Ingo Molnar
2008-12-27 8:39 ` Ingo Molnar
2008-12-27 11:21 ` Kamalesh Babulal
2008-12-27 11:24 ` Ingo Molnar
2008-12-27 11:57 ` Kamalesh Babulal
2008-12-27 12:26 ` Ingo Molnar
2008-12-27 15:29 ` Kamalesh Babulal
2008-12-27 21:10 ` Yinghai Lu
2008-12-27 21:10 ` Yinghai Lu
2008-12-28 12:55 ` Ingo Molnar
2008-12-28 16:11 ` Kamalesh Babulal
2008-12-28 23:09 ` Yinghai Lu
2008-12-27 5:05 ` [PATCH] perf_counter: more barrier in blank weak function Yinghai Lu
2008-12-27 5:06 ` [PATCH] kgdb: " Yinghai Lu
2008-12-27 8:17 ` Ingo Molnar
2008-12-27 8:34 ` Andrew Morton
2008-12-27 6:07 ` [PATCH] perf_counter: " KOSAKI Motohiro
2008-12-27 9:46 ` [BUG] next-20081216 - WARNING: at kernel/smp.c:333 smp_call_function_mask David Howells
2008-12-27 9:50 ` Ingo Molnar
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