On Mon, 31 Aug 2020 at 13:43, Masahiro Yamada <masahi...@kernel.org> wrote: > > On Mon, Aug 31, 2020 at 6:47 PM Jessica Yu <j...@kernel.org> wrote: > > > > +++ Will Deacon [21/08/20 13:30 +0100]: > > [snipped] > > >> > > > So module_enforce_rwx_sections() is already called after > > >> > > > module_frob_arch_sections() - which really baffled me at first, > > >> > > > since > > >> > > > sh_type and sh_flags should have been set already in > > >> > > > module_frob_arch_sections(). > > >> > > > > > >> > > > I added some debug prints to see which section the module code was > > >> > > > tripping on, and it was .text.ftrace_trampoline. See this snippet > > >> > > > from > > >> > > > arm64's module_frob_arch_sections(): > > >> > > > > > >> > > > else if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && > > >> > > > !strcmp(secstrings + sechdrs[i].sh_name, > > >> > > > ".text.ftrace_trampoline")) > > >> > > > tramp = sechdrs + i; > > >> > > > > > >> > > > Since Mauro's config doesn't have CONFIG_DYNAMIC_FTRACE enabled, > > >> > > > tramp > > >> > > > is never set here and the if (tramp) check at the end of the > > >> > > > function > > >> > > > fails, so its section flags are never set, so they remain WAX and > > >> > > > fail > > >> > > > the rwx check. > > >> > > > > >> > > Right. Our module.lds does not go through the preprocessor, so we > > >> > > cannot add the #ifdef check there currently. So we should either drop > > >> > > the IS_ENABLED() check here, or simply rename the section, dropping > > >> > > the .text prefix (which doesn't seem to have any significance outside > > >> > > this context) > > >> > > > > >> > > I'll leave it to Will to make the final call here. > > >> > > > >> > Why don't we just preprocess the linker script, like we do for the main > > >> > kernel? > > >> > > > >> > > >> That should work as well, I just haven't checked how straight-forward > > >> it is to change that. > > > > > >Ok, if it's _not_ straightforward, then let's just drop the IS_ENABLED() > > >altogether. > > > > Unfortunately I've been getting more reports about this issue, so let's just > > get the aforementioned workaround merged first. Does the following look OK? > > > > diff --git a/arch/arm64/kernel/module-plts.c > > b/arch/arm64/kernel/module-plts.c > > index 0ce3a28e3347..2e224435c024 100644 > > --- a/arch/arm64/kernel/module-plts.c > > +++ b/arch/arm64/kernel/module-plts.c > > @@ -305,8 +305,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr > > *sechdrs, > > mod->arch.core.plt_shndx = i; > > else if (!strcmp(secstrings + sechdrs[i].sh_name, > > ".init.plt")) > > mod->arch.init.plt_shndx = i; > > - else if (IS_ENABLED(CONFIG_DYNAMIC_FTRACE) && > > - !strcmp(secstrings + sechdrs[i].sh_name, > > + else if (!strcmp(secstrings + sechdrs[i].sh_name, > > ".text.ftrace_trampoline")) > > tramp = sechdrs + i; > > else if (sechdrs[i].sh_type == SHT_SYMTAB) > > > > If so I'll turn it into a formal patch and we can get that merged in the > > next -rc. > > > > Thanks, > > > > Jessica > > > > Sorry for the delay. > > Please try the attached patch. >
Thanks Masahiro, I'll leave it to the maintainers to make the final call, but this does look rather intrusive to me, especially for an -rc. Renaming scripts/module-common.lds to scripts/module.lds means that the distros may have to update their scripts to generate the linux-headers packages etc, so if we do this at all, we'd better do it between releases.