linux-kernel - Re: [TRIVIAL PATCH 16/26] x86: Convert print

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Date:	Thu, 13 Dec 2012 10:42:28 -0800
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Borislav Petkov <bp@...en8.de>, Joe Perches <joe@...ches.com>,
	"Luck, Tony" <tony.luck@...el.com>,
	Jiri Kosina <trivial@...nel.org>,
	Jeff Dike <jdike@...toit.com>,
	Richard Weinberger <richard@....at>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-edac@...r.kernel.org" <linux-edac@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"user-mode-linux-devel@...ts.sourceforge.net" 
	<user-mode-linux-devel@...ts.sourceforge.net>,
	"user-mode-linux-user@...ts.sourceforge.net" 
	<user-mode-linux-user@...ts.sourceforge.net>
Subject: Re: [TRIVIAL PATCH 16/26] x86: Convert print_symbol to %pSR

On 12/13/2012 10:37 AM, Borislav Petkov wrote:
>>
>> If appropriate, the code could be changed to
>>
>> 	(void *)(unsigned long)m->ip
> 
> Can we explicitly cast it to what it is so that we can be explicit as to
> what we're casting it? IOW:
> 
> 	(void *)(__u64)m->ip;
> 
> Does that even work on 32bit?
> 
> Also, does the compiler bitch about this useless cast when building with
> W=123?
> 

Uh... no.

The point is that (void *)(unsigned long) casts it to an integer of
pointer size -- in userspace you would to (void *)(size_t) or (void
*)(uintptr_t) -- so that the compiler knows "I meant to do that."

	-hpa


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