linux-kernel - Re: [PATCH] binfmt_flat: minimum support for theBlackfin relocations

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Date:	Thu, 20 Sep 2007 14:04:26 +0200
From:	Bernd Schmidt <bernds_cb1@...nline.de>
To:	Paul Mundt <lethal@...ux-sh.org>,
	David McCullough <David_Mccullough@...urecomputing.com>,
	Robin Getz <rgetz@...ckfin.uclinux.org>,
	uclinux-dist-devel@...ckfin.uclinux.org, bryan.wu@...log.com,
	Bernd Schmidt <bernd.schmidt@...log.com>,
	Greg Ungerer <gerg@...pgear.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	ysato@...rs.sourceforge.jp, miles@....nec.co.jp,
	linux-m32r@...linux-m32r.org
Subject: Re: [PATCH] binfmt_flat: minimum support for theBlackfin relocations

Paul Mundt wrote:
> I find it a bit disconcerting that blackfin already depends on this
> in-tree without there being any earlier discussion on making these
> changes.

Parts of the initial submission were picked up (the include/asm 
directory), other's weren't.  Little we can do about that.

>>>>  	 */
>>>>  	if (rev > OLD_FLAT_VERSION) {
>>>> +		unsigned long persistent = 0;
>>>>  		for (i=0; i < relocs; i++) {
>>>>  			unsigned long addr, relval;
>>>>  
>>>> @@ -749,6 +750,8 @@ static int load_flat_file(struct linux_binprm * bprm,
>>>>  			   relocated (of course, the address has to be
>>>>  			   relocated first).  */
>>>>  			relval = ntohl(reloc[i]);
>>>> +			if (flat_set_persistent (relval, &persistent))
>>>> +				continue;
>>>>  			addr = flat_get_relocate_addr(relval);
>>>>  			rp = (unsigned long *) calc_reloc(addr, libinfo, id, 1);
>>>>  			if (rp == (unsigned long *)RELOC_FAILED) {
> 
> I don't much care for this API. It's shuffling around a temporary
> variable for the architecture code that's set for certain relocations
> that are otherwise unhandled.
> 
> Since all the architecture is interested in is the relval that has
> associated "persistent" data encoded in it, why don't we just have a stub
> to give the architecture a chance to validate the relval before the
> flat_get_relocate_addr() and move this stuff there instead? ie, blackfin
> takes this out-of-line and manages its persistent value there.

What is flat_set_persistent other than a stub to validate the relval? 
I'm not at all sure what you're proposing or how it would be different.

> load_flat_file() is ugly enough without dumping more architecture
> callback abuses in it.

The other maintainers who have spoken up didn't seem to think this was 
ugly, or an abuse.  I'm surprised to hear language like that when 
discussing a patch that adds an if statement, a local variable and one 
parameter in a function call.


Bernd
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