On Wed, Jun 24, 2020 at 08:57:12AM +0100, Will Deacon wrote: > On Tue, Jun 23, 2020 at 06:49:40PM -0700, Kees Cook wrote: > > We don't want to depend on the linker's orphan section placement > > heuristics as these can vary between linkers, and may change between > > versions. All sections need to be explicitly named in the linker > > script. > > > > Avoid .eh_frame* by making sure both -fno-asychronous-unwind-tables and > > -fno-unwind-tables are present in both CFLAGS and AFLAGS. Remove one > > last instance of .eh_frame by removing the needless Call Frame Information > > annotations from arch/arm64/kernel/smccc-call.S. > > > > Add .plt, .data.rel.ro, .igot.*, and .iplt to discards as they are not > > actually used. While .got.plt is also not used, it must be included > > otherwise ld.bfd will fail to link with the error: > > > > aarch64-linux-gnu-ld: discarded output section: `.got.plt' > > > > However, as it'd be better to validate that it stays effectively empty, > > add an assert. > > > > Explicitly include debug sections when they're present. > > > > Fix a case of needless quotes in __section(), which Clang doesn't like. > > > > Finally, enable orphan section warnings. > > > > Thanks to Ard Biesheuvel for many hints on correct ways to handle > > mysterious sections. :) > > Sorry to be a pain, but this patch is doing 3 or 4 independent things at > once. Please could you split it up a bit? > e.g. > > - Removal of cfi directives from smccc macro > - Removal of quotes around section name for clang > - Avoid generating .eh_frame > - Ensure all sections are accounted for in linker script and warn on orphans > > That way it's a bit easier to manage, we can revert/backport bits later if > necessary and you get more patches in the kernel ;) Yeah, this one patch did grow a bit. ;) I've split it up now. > You can also add my Ack on all the patches: > > Acked-by: Will Deacon <will@xxxxxxxxxx> Thanks! -- Kees Cook
