Re: [PATCH] powerpc: Add jump label support

Re: [PATCH] powerpc: Add jump label support

[Steven Rostedt]

On Mon, 2010-11-08 at 15:12 +1100, Michael Ellerman wrote:
> This patch adds support for the new "jump label" feature.

Darn it! I wanted to port this!!!

;-)

> 
> Built for 64 & 32 bit, tested on 64 bit. Survives a kernel build under
> perf with all tracepoints enabled, and manual inspection of the patched
> code looks right. But still, lightly tested, YMMV.
> 
> Unlike x86 and sparc we just merrily patch the code with no locks etc,
> as far as I know this is safe, but I'm not really sure what the x86/sparc
> code is protecting against so maybe it's not.

Thanks, I'll give it a test on my electra as soon as I get a gcc 4.5.1
cross compiler working.

-- Steve

Re: [PATCH] powerpc: Add jump label support

[Stephen Rothwell]

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Hi Michael,

Just a trivial note ...

On Mon,  8 Nov 2010 15:12:46 +1100 (EST) Michael Ellerman <michael@ellerman.id.au> wrote:
>
> diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
> new file mode 100644
> index 0000000..feffb86
> --- /dev/null
> +++ b/arch/powerpc/include/asm/jump_label.h
> @@ -0,0 +1,46 @@
> +#ifndef _ASM_POWERPC_JUMP_LABEL_H
> +#define _ASM_POWERPC_JUMP_LABEL_H
> +
> +/*
> + * Copyright 2010 Michael Ellerman, IBM Corp.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +
> +#ifdef __KERNEL__

You don't need this protection in a file that is not exported to user
space.

-- 
Cheers,
Stephen Rothwell                    sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/

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Re: [PATCH] powerpc: Add jump label support

[Michael Ellerman]

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On Mon, 2010-11-08 at 09:18 -0500, Steven Rostedt wrote:
> On Mon, 2010-11-08 at 15:12 +1100, Michael Ellerman wrote:
> > This patch adds support for the new "jump label" feature.
> 
> Darn it! I wanted to port this!!!
> 
> ;-)

Sorry! I've been locked in a dark room for ages and this was a nice
chance to work on some upstream code for a change :)

> > Built for 64 & 32 bit, tested on 64 bit. Survives a kernel build under
> > perf with all tracepoints enabled, and manual inspection of the patched
> > code looks right. But still, lightly tested, YMMV.
> > 
> > Unlike x86 and sparc we just merrily patch the code with no locks etc,
> > as far as I know this is safe, but I'm not really sure what the x86/sparc
> > code is protecting against so maybe it's not.
> 
> Thanks, I'll give it a test on my electra as soon as I get a gcc 4.5.1
> cross compiler working.

Thanks.

cheers



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Re: [PATCH] powerpc: Add jump label support

[Michael Ellerman]

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On Tue, 2010-11-09 at 13:35 +1100, Stephen Rothwell wrote:
> Hi Michael,
> 
> Just a trivial note ...
> 
> On Mon,  8 Nov 2010 15:12:46 +1100 (EST) Michael Ellerman <michael@ellerman.id.au> wrote:
> >
> > diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
> > new file mode 100644
> > index 0000000..feffb86
> > --- /dev/null
> > +++ b/arch/powerpc/include/asm/jump_label.h
> > @@ -0,0 +1,46 @@
> > +#ifndef _ASM_POWERPC_JUMP_LABEL_H
> > +#define _ASM_POWERPC_JUMP_LABEL_H
> > +
> > +/*
> > + * Copyright 2010 Michael Ellerman, IBM Corp.
> > + *
> > + * This program is free software; you can redistribute it and/or
> > + * modify it under the terms of the GNU General Public License
> > + * as published by the Free Software Foundation; either version
> > + * 2 of the License, or (at your option) any later version.
> > + */
> > +
> > +#ifdef __KERNEL__
> 
> You don't need this protection in a file that is not exported to user
> space.

Ah true. I'll respin after I've heard if anyone has tested it :)

cheers



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Re: [PATCH] powerpc: Add jump label support

[Steven Rostedt]

On Tue, 2010-11-09 at 14:33 +1100, Michael Ellerman wrote:

> > You don't need this protection in a file that is not exported to user
> > space.
> 
> Ah true. I'll respin after I've heard if anyone has tested it :)

Don't wait for me. I'm stuck debugging some other crap. Getting a 4.5
PPC compiler working is very low on my priority list, unfortunately. :-(

-- Steve

Re: [PATCH] powerpc: Add jump label support

[Michael Ellerman]

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On Mon, 2010-11-08 at 22:41 -0500, Steven Rostedt wrote:
> On Tue, 2010-11-09 at 14:33 +1100, Michael Ellerman wrote:
> 
> > > You don't need this protection in a file that is not exported to user
> > > space.
> > 
> > Ah true. I'll respin after I've heard if anyone has tested it :)
> 
> Don't wait for me. I'm stuck debugging some other crap. Getting a 4.5
> PPC compiler working is very low on my priority list, unfortunately. :-(

No worries, testing is for sissies anyway.

There are 4.5.0 crosses on kernel.org, I think they're the same as the
ones I'm using, which seem to work on powerpc at least.

http://kernel.org/pub/tools/crosstool/files/bin/x86_64/4.5.0/

cheers


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