Messages in this thread Patch in this message | | | Date | Tue, 10 Oct 2023 10:12:20 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH] x86: Enable IBT in Rust if enabled in C |
| |
On Mon, Oct 09, 2023 at 10:42:54PM +0000, Matthew Maurer wrote: > These flags are not made conditional on compiler support because at the > moment exactly one version of rustc supported, and that one supports > these flags. > > Building without these additional flags will manifest as objtool > printing a large number of errors about missing ENDBR and if CFI is > enabled (not currently possible) will result in incorrectly structured > function prefixes.
Well, I would also imagine running it on actual IBT enabled hardware will get you a non-booting kernel.
> Signed-off-by: Matthew Maurer <mmaurer@google.com> > --- > > Split out the IBT additions as per > https://lkml.kernel.org/linux-fsdevel/CANiq72kK6ppBE7j=z7uua1cJMKaLoR5U3NUAZXT5MrNEs9ZhfQ@mail.gmail.com/ > > arch/x86/Makefile | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/arch/x86/Makefile b/arch/x86/Makefile > index 5bfe5caaa444..941f7abf6dbf 100644 > --- a/arch/x86/Makefile > +++ b/arch/x86/Makefile > @@ -81,6 +81,7 @@ ifeq ($(CONFIG_X86_KERNEL_IBT),y) > # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104816 > # > KBUILD_CFLAGS += $(call cc-option,-fcf-protection=branch -fno-jump-tables) > +KBUILD_RUSTFLAGS += -Zcf-protection=branch -Zno-jump-tables
One question, -Zcf-protection=branch, will that ever emit NOTRACK prefix? The kernel very explicitly does not support (enable) NOTRACK.
> else > KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none) > endif > -- > 2.42.0.609.gbb76f46606-goog >
| |