[2.6.34-rc6] ARM: build breaks with KPROBES

[2.6.34-rc6] ARM: build breaks with KPROBES

[Shilimkar, Santosh]

Russell,

The latest mainline ARM build breaks with KPROBES enabled. Anand
Gadiyar did git bisect and figured out that below commit breaks the build.
	commit :4260415f6a3b92c5c986398d96c314df37a4ccbf

I tried matching the sections but failed to fix the build error. Below
is the hack patch to keep build working.

Regards,
Santosh

*******************************************************

ARM: Build break with KPROBES enabled

With CONFIG_KPROBES enabled two section are getting created which
leads to below buid break.

LOG:
 AS      arch/arm/kernel/entry-armv.o
arch/arm/kernel/entry-armv.S: Assembler messages:
arch/arm/kernel/entry-armv.S:431: Error: symbol ret_from_exception is in a different section
arch/arm/kernel/entry-armv.S:490: Error: symbol ret_from_exception is in a different section
arch/arm/kernel/entry-armv.S:491: Error: symbol __und_usr_unknown is in a different section


Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reported-by: Anand Gadiyar <gadiyar@ti.com>
---
 arch/arm/kernel/entry-armv.S |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index e6a0fb0..db4ec05 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -679,7 +679,7 @@ do_fpe:
 	.data
 ENTRY(fp_enter)
 	.word	no_fp
-	.text
+	.previous
 
 ENTRY(no_fp)
 	mov	pc, lr
-- 
1.6.0.4

[2.6.34-rc6] ARM: build breaks with KPROBES

[Russell King - ARM Linux]

On Fri, Apr 30, 2010 at 12:51:49PM +0530, Shilimkar, Santosh wrote:
> Russell,
> 
> The latest mainline ARM build breaks with KPROBES enabled. Anand
> Gadiyar did git bisect and figured out that below commit breaks the build.
> 	commit :4260415f6a3b92c5c986398d96c314df37a4ccbf

Did you read the comments in the commit message to understand why
.previous is dangerous?

> I tried matching the sections but failed to fix the build error. Below
> is the hack patch to keep build working.

The previous section is not .text, but:

#ifdef CONFIG_KPROBES
        .section        .kprobes.text,"ax",%progbits
#else
        .text
#endif

Either change the preceding .data to .pushsection .data, and the following
.text to .popsection, or duplicate the above ifdef; .pushsection/.popsection
is _far_ safer than using .previous.

[2.6.34-rc6] ARM: build breaks with KPROBES

[Shilimkar, Santosh]

> -----Original Message-----
> From: Russell King - ARM Linux [mailto:linux at arm.linux.org.uk]
> Sent: Friday, April 30, 2010 1:18 PM
> To: Shilimkar, Santosh
> Cc: linux-arm-kernel at lists.infradead.org; Linux-OMAP
> Subject: Re: [2.6.34-rc6] ARM: build breaks with KPROBES
> 
> On Fri, Apr 30, 2010 at 12:51:49PM +0530, Shilimkar, Santosh wrote:
> > Russell,
> >
> > The latest mainline ARM build breaks with KPROBES enabled. Anand
> > Gadiyar did git bisect and figured out that below commit breaks the build.
> > 	commit :4260415f6a3b92c5c986398d96c314df37a4ccbf
> 
> Did you read the comments in the commit message to understand why
> .previous is dangerous?
> 
> > I tried matching the sections but failed to fix the build error. Below
> > is the hack patch to keep build working.
> 
> The previous section is not .text, but:
> 
> #ifdef CONFIG_KPROBES
>         .section        .kprobes.text,"ax",%progbits
> #else
>         .text
> #endif
> 
> Either change the preceding .data to .pushsection .data, and the following
> .text to .popsection, or duplicate the above ifdef; .pushsection/.popsection
> is _far_ safer than using .previous.
OK.
Here is the updated patch based on your suggestion.

[2.6.34-rc6] ARM: build breaks with KPROBES

[Russell King - ARM Linux]

On Fri, Apr 30, 2010 at 02:57:20PM +0530, Shilimkar, Santosh wrote:
> >From 2660d4ca5d77406fc8d46a5c0f18127332914604 Mon Sep 17 00:00:00 2001
> From: Santosh Shilimkar <santosh.shilimkar@ti.com>
> Date: Fri, 30 Apr 2010 12:41:16 +0530
> Subject: [PATCH] ARM: Fix build break with KPROBES enabled
> 
> With CONFIG_KPROBES enabled two section are getting created which
> leads to below build break.

Ok.