Messages in this thread | | | Date | Thu, 18 Mar 2021 12:38:42 -0500 | From | Josh Poimboeuf <> | Subject | Re: [PATCH 5/9] objtool: Rework rebuild_reloc logic |
| |
On Thu, Mar 18, 2021 at 06:04:25PM +0100, Peter Zijlstra wrote: > On Thu, Mar 18, 2021 at 11:36:40AM -0500, Josh Poimboeuf wrote: > > > I was thinking you could get a section changed without touching > > > relocations, but while that is theoretically possible, it is exceedingly > > > unlikely (and objtool doesn't do that). > > > > Hm? This is a *relocation* section, not a normal one. So by > > definition, it only changes when its relocations change. > > The way I read this code: > > list_for_each_entry(sec, &elf->sections, list) { > if (sec->changed) { > + if (sec->reloc && > + elf_rebuild_reloc_section(elf, sec->reloc)) { > + WARN_ELF("elf_rebuild_reloc_section"); > + return -1; > + } > > is that we iterate the regular sections (which could be dirtied because > we changed some data), and if that section has a relocation section, we > rebuild that for good measure (even though it might not have altered > relocations). > > Or am I just totally confused ?
Ah, you're right. I'm the one that's confused. I guess I was also confused when I wrote that hunk, but it just happens to work anyway.
It would be cleaner to do something like
if ((is_reloc_sec(sec) && elf_rebuild_reloc_section(elf, sec)) {
so we process the changed reloc section directly, instead of relying on the (most likely) fact that the corresponding text section also changed.
-- Josh
| |