Messages in this thread | | | From | Masahiro Yamada <> | Date | Tue, 31 Oct 2023 21:20:33 +0900 | Subject | Re: [PATCH] x86: Let AS_WRUSS depend on X86_64 |
| |
On Tue, Oct 31, 2023 at 8:26 PM Borislav Petkov <bp@alien8.de> wrote: > > + linux-kbuild@vger.kernel.org > > On Tue, Oct 31, 2023 at 11:21:11AM +0100, Jiri Slaby (SUSE) wrote: > > Since commit 18e66b695e78 ("x86/shstk: Add Kconfig option for shadow > > stack"), AS_WRUSS is set even in 32-bit .configs. It is due to how > > Kbuild works. .config is not considered during make oldconfig (and other > > make *config), so standard (64-bit) gcc is invoked from 'as-instr' > > Kbuild tests.
I do not mind either way.
Please note "depends on X86_64" cannot prevent gcc from running here.
$(as-instr,wrussq %rax$(comma)(%rbx)) is replaced with 'y' while parsing the Kconfig files.
I want to change it in the future, but that is how Kconfig works now.
You don't save the cost of running the compiler.
> And such gcc indeed reports that wruss is supported, so > > AS_WRUSS=y is set. > > > > Provided the wruss instruction is 64-bit only (and used in pure 64-bit > > X86_USER_SHADOW_STACK), it has little sense to have AS_WRUSS=y set on > > 32-bit. > > > > Therefore, make the whole test dependent on X86_64 to ensure it's set > > only on 64-bit. > > > > Signed-off-by: Jiri Slaby (SUSE) <jirislaby@kernel.org> > > Cc: Yu-cheng Yu <yu-cheng.yu@intel.com> > > Cc: Rick Edgecombe <rick.p.edgecombe@intel.com> > > Cc: Dave Hansen <dave.hansen@linux.intel.com> > > Cc: Borislav Petkov (AMD) <bp@alien8.de> > > Cc: Kees Cook <keescook@chromium.org> > > Cc: Mike Rapoport (IBM) <rppt@kernel.org> > > Cc: Pengfei Xu <pengfei.xu@intel.com> > > Cc: John Allen <john.allen@amd.com> > > Cc: Kees Cook <keescook@chromium.org> > > Cc: Thomas Gleixner <tglx@linutronix.de> > > Cc: Ingo Molnar <mingo@redhat.com> > > Cc: "H. Peter Anvin" <hpa@zytor.com> > > Cc: x86@kernel.org > > --- > > arch/x86/Kconfig.assembler | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/arch/x86/Kconfig.assembler b/arch/x86/Kconfig.assembler > > index 8ad41da301e5..a5b5241711e3 100644 > > --- a/arch/x86/Kconfig.assembler > > +++ b/arch/x86/Kconfig.assembler > > @@ -27,5 +27,6 @@ config AS_GFNI > > > > config AS_WRUSS > > def_bool $(as-instr,wrussq %rax$(comma)(%rbx)) > > + depends on X86_64 > > help > > Supported by binutils >= 2.31 and LLVM integrated assembler > > -- > > 2.42.0 > > > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette
-- Best Regards Masahiro Yamada
| |