From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Tue, 24 Nov 2009 14:25:52 +0100 (CET) Received: from h5.dl5rb.org.uk ([81.2.74.5]:45245 "EHLO h5.dl5rb.org.uk" rhost-flags-OK-OK-OK-OK) by eddie.linux-mips.org with ESMTP id S1492387AbZKXNZp (ORCPT ); Tue, 24 Nov 2009 14:25:45 +0100 Received: from h5.dl5rb.org.uk (localhost.localdomain [127.0.0.1]) by h5.dl5rb.org.uk (8.14.3/8.14.3) with ESMTP id nAODQ2iB028082; Tue, 24 Nov 2009 13:26:02 GMT Received: (from ralf@localhost) by h5.dl5rb.org.uk (8.14.3/8.14.3/Submit) id nAODQ1Y3028080; Tue, 24 Nov 2009 13:26:01 GMT Date: Tue, 24 Nov 2009 13:26:01 +0000 From: Ralf Baechle To: Imre Kaloz Cc: nbd@openwrt.org, linux-mips@linux-mips.org Subject: Re: [PATCH] use __always_inline for __xchg Message-ID: <20091124132601.GA27951@linux-mips.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.19 (2009-01-05) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 25092 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Sat, Jan 29, 2005 at 05:54:44PM +0100, Imre Kaloz wrote: > The following patch changes inline for __xchg to __always_inline in > include/asm-mips/system.h, following the changes in git. Without this > change linking the kernel fails. > > Signed-off-by: Imre Kaloz > Signed-off-by: Felix Fietkau Imre just pointed me at this antique patch again saying it was still needed. Back then I ditched it because I couldn't see what the problem it was trying to fix was - but after a little brainstorming it got obvious. Now I don't like __always_inline which forces the optimizer to do things which may not really be what we want, for example when building with -Os so I found a different fix using BUILD_BUG_ON(). Patch below. Cheers, Ralf From: Ralf Baechle MIPS: Fix build error if __xchg() is not getting inlined. If __xchg() is not getting inlined the outline version of the function will have a reference to __xchg_called_with_bad_pointer() which does not exist remaining. Fixed by using BUILD_BUG_ON() xchg() to check for allowable operand sizes. Signed-off-by: Ralf Baechle diff --git a/arch/mips/include/asm/system.h b/arch/mips/include/asm/system.h index fcf5f98..587a48a 100644 --- a/arch/mips/include/asm/system.h +++ b/arch/mips/include/asm/system.h @@ -193,10 +193,6 @@ extern __u64 __xchg_u64_unsupported_on_32bit_kernels(volatile __u64 * m, __u64 v #define __xchg_u64 __xchg_u64_unsupported_on_32bit_kernels #endif -/* This function doesn't exist, so you'll get a linker error - if something tries to do an invalid xchg(). */ -extern void __xchg_called_with_bad_pointer(void); - static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int size) { switch (size) { @@ -205,11 +201,17 @@ static inline unsigned long __xchg(unsigned long x, volatile void * ptr, int siz case 8: return __xchg_u64(ptr, x); } - __xchg_called_with_bad_pointer(); + return x; } -#define xchg(ptr, x) ((__typeof__(*(ptr)))__xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))) +#define xchg(ptr, x) \ +({ \ + BUILD_BUG_ON(sizeof(*(ptr)) & ~0xc); \ + \ + ((__typeof__(*(ptr))) \ + __xchg((unsigned long)(x), (ptr), sizeof(*(ptr)))); \ +}) extern void set_handler(unsigned long offset, void *addr, unsigned long len); extern void set_uncached_handler(unsigned long offset, void *addr, unsigned long len);