linux-kernel - Re: [PATCH] linkage.h: fix build breakage due to symbol prefix handling

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Date:	Thu, 2 May 2013 13:37:37 +1000
From:	Stephen Rothwell <sfr@...b.auug.org.au>
To:	Rusty Russell <rusty@...tcorp.com.au>
Cc:	James Hogan <james.hogan@...tec.com>,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	Al Viro <viro@...iv.linux.org.uk>,
	Mike Frysinger <vapier@...too.org>,
	uclinux-dist-devel@...ckfin.uclinux.org
Subject: Re: [PATCH] linkage.h: fix build breakage due to symbol prefix
 handling

Hi all,

On Thu, 02 May 2013 09:58:08 +0930 Rusty Russell <rusty@...tcorp.com.au> wrote:
>
> James Hogan <james.hogan@...tec.com> writes:
> > Al's commit e1b5bb6d1236d4ad2084c53aa83dde7cdf6f8eea ("consolidate
> > cond_syscall and SYSCALL_ALIAS declarations") broke the build on
> > blackfin and metag due to the following code:
> >
> >   #ifndef SYMBOL_NAME
> >   #ifdef CONFIG_SYMBOL_PREFIX
> >   #define SYMBOL_NAME(x) CONFIG_SYMBOL_PREFIX ## x
> >   #else
> >   #define SYMBOL_NAME(x) x
> >   #endif
> >   #endif
> >   #define __SYMBOL_NAME(x) __stringify(SYMBOL_NAME(x))
> >
> > __stringify literally stringifies CONFIG_SYMBOL_PREFIX ##x, so you get
> > lines like this in kernel/sys_ni.s:
> >
> >   .weak CONFIG_SYMBOL_PREFIXsys_quotactl
> >   .set CONFIG_SYMBOL_PREFIXsys_quotactl,CONFIG_SYMBOL_PREFIXsys_ni_syscall
> >
> > The patches in Rusty's modules-next tree such as "CONFIG_SYMBOL_PREFIX:
> > cleanup." clean up the whole mess around symbol prefixes, so this patch
> > just attempts to fix the build in the mean time. The intermediate
> > definition of SYMBOL_NAME above isn't used and is incorrect when
> > CONFIG_SYMBOL_PREFIX is defined as CONFIG_SYMBOL_PREFIX is a quoted
> > string literal, so define __SYMBOL_NAME directly depending on
> > CONFIG_SYMBOL_PREFIX.
> 
> I just pushed my modules-next tree to Linus, so hopefully the nightmare
> is over soon!

This is the merge fix patch I have been carrying in linux-next since
March 14: (this probably does not quite apply any more but, hey ...)

From: Stephen Rothwell <sfr@...b.auug.org.au>
Date: Thu, 14 Mar 2013 17:14:41 +1100
Subject: [PATCH] cond_syscall and SYSCALL_ALIAS merge fixup

Signed-off-by: Stephen Rothwell <sfr@...b.auug.org.au>
---
 include/linux/linkage.h | 20 ++++++--------------
 1 file changed, 6 insertions(+), 14 deletions(-)

diff --git a/include/linux/linkage.h b/include/linux/linkage.h
index 829d66c..bedcddf 100644
--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -2,7 +2,7 @@
 #define _LINUX_LINKAGE_H
 
 #include <linux/compiler.h>
-#include <linux/stringify.h>
+#include <linux/export.h>
 #include <asm/linkage.h>
 
 #ifdef __cplusplus
@@ -15,24 +15,16 @@
 #define asmlinkage CPP_ASMLINKAGE
 #endif
 
-#ifndef SYMBOL_NAME
-#ifdef CONFIG_SYMBOL_PREFIX
-#define SYMBOL_NAME(x) CONFIG_SYMBOL_PREFIX ## x
-#else
-#define SYMBOL_NAME(x) x
-#endif
-#endif
-#define __SYMBOL_NAME(x) __stringify(SYMBOL_NAME(x))
-
 #ifndef cond_syscall
-#define cond_syscall(x) asm(".weak\t" __SYMBOL_NAME(x) \
-	"\n\t.set\t" __SYMBOL_NAME(x) "," __SYMBOL_NAME(sys_ni_syscall));
+#define cond_syscall(x) asm(".weak\t" VMLINUX_SYMBOL_STR(x) "\n\t"	\
+			    ".set\t" VMLINUX_SYMBOL_STR(x) ","	\
+			    VMLINUX_SYMBOL_STR(sys_ni_syscall))
 #endif
 
 #ifndef SYSCALL_ALIAS
 #define SYSCALL_ALIAS(alias, name)				\
-	asm ("\t.globl " __SYMBOL_NAME(alias)			\
-	"\n\t.set\t" __SYMBOL_NAME(alias) "," __SYMBOL_NAME(name))
+	asm ("\t.globl " VMLINUX_SYMBOL_STR(alias)			\
+	"\n\t.set\t" VMLINUX_SYMBOL_STR(alias) "," VMLINUX_SYMBOL_STR(name))
 #endif
 
 #define __page_aligned_data	__section(.data..page_aligned) __aligned(PAGE_SIZE)
-- 
1.8.1

-- 
Cheers,
Stephen Rothwell                    sfr@...b.auug.org.au

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