On Wed, 13 Apr 2016, Jessica Yu wrote: > +++ Miroslav Benes [13/04/16 15:01 +0200]: > > On Wed, 13 Apr 2016, Michael Ellerman wrote: > > > > > This series adds live patching support for powerpc (ppc64le only ATM). > > > > > > It's unchanged since the version I posted on March 24, with the exception > > > that > > > I've dropped the first patch, which was a testing-only patch. > > > > > > If there's no further comments I'll put this in a topic branch in the next > > > day > > > or two and Jiri & I will both merge that into next. > > > > Hi, > > > > I'll definitely give it a proper look today or tomorrow, but there is one > > thing that needs to be solved. The patch set from Jessica reworking > > relocations for live patching is now merged in our for-next branch. This > > means that we need to find out if there is something in struct > > mod_arch_specific for powerpc which needs to be preserved and do it. > > > > I took a look around the powerpc module.c code and it looks like the > mod_arch_specific stuff should be fine, since it is statically allocated > in the module struct (unlike the situation in s390, where > mod->arch.syminfo was vmalloc'd and we had to delay the free). > However I'm not familiar with the powerpc code so I need to dig around > a bit more to be 100% sure. I came to the same conclusion. There is only struct bug_entry *bug_table in mod_arch_specific but it looks unimportant wrt relocations. > A second concern I have is that apply_relocate_add() relies on > sections like .stubs and .toc (for 64-bit) and .init.plt and .plt > sections (for 32-bit). In order for apply_relocate_add() to work for > livepatch, we must make sure these sections aren't thrown away and are > not in init module memory since this memory will be freed at the end > of module load (see how INIT_OFFSET_MASK is used in kernel/module.c). > As long as these sections are placed in module core memory, we will be > OK. I need to think about this a bit more. I knew I shouldn't have opened arch/powerpc/kernel/module*.c. We could always hack sh_flags of those sections in module_arch_frob_sections() to make them stay. Miroslav > > Third and unrelated comment: the klp_write_module_reloc stub isn't > needed anymore :-) > > Thanks, > Jessica > -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
