linux-kernel - Re: [RFC PATCH v2 4/6] livepatch: reuse module loader code to write relocations

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Date:	Thu, 10 Dec 2015 20:56:27 +0100 (CET)
From:	Jiri Kosina <jikos@...nel.org>
To:	Minfei Huang <mnfhuang@...il.com>
cc:	Jessica Yu <jeyu@...hat.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Seth Jennings <sjenning@...hat.com>,
	Vojtech Pavlik <vojtech@...e.com>,
	Jonathan Corbet <corbet@....net>,
	Miroslav Benes <mbenes@...e.cz>, linux-api@...r.kernel.org,
	live-patching@...r.kernel.org, x86@...nel.org,
	linux-kernel@...r.kernel.org, linux-s390@...r.kernel.org,
	linux-doc@...r.kernel.org
Subject: Re: [RFC PATCH v2 4/6] livepatch: reuse module loader code to write
 relocations

On Thu, 10 Dec 2015, Minfei Huang wrote:

> > +	klp_for_each_reloc_sec(obj, reloc_sec) {
> > +		relindex = reloc_sec->index;
> > +		num_relas = pmod->sechdrs[relindex].sh_size / sizeof(Elf_Rela);
> > +		rela = (Elf_Rela *) pmod->sechdrs[relindex].sh_addr;
> > +
> > +		/* For each rela in this __klp_rela section */
> > +		for (i = 0; i < num_relas; i++, rela++) {
> > +			sym = symtab + ELF_R_SYM(rela->r_info);
> > +			symname = pmod->core_strtab + sym->st_name;
> > +
> > +			if (sym->st_shndx == SHN_LIVEPATCH) {
> > +				if (sym->st_info == 'K')
> > +					ret = klp_find_external_symbol(pmod, symname, &addr);
> > +				else
> > +					ret = klp_find_object_symbol(obj->name, symname, &addr);
> > +				if (ret)
> > +					return ret;
> > +				sym->st_value = addr;
> > +			}
> >  		}
> > +		ret = apply_relocate_add(pmod->sechdrs, pmod->core_strtab,
> > +					 pmod->index.sym, relindex, pmod);
> 
> It is more appropiate to test the ret.

And if error is encountered ... then you'd propose to do what?

The code is correct as is; the return value is propagated properly to 
caller, and all the existing callers have proper error handling.

-- 
Jiri Kosina
SUSE Labs

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