Messages in this thread | | | From | Masahiro Yamada <> | Date | Tue, 30 Oct 2018 18:39:24 +0900 | Subject | Re: [PATCH 1/3] retpolines: Only enable retpoline when compiler support it |
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Hi,
On Tue, Oct 30, 2018 at 3:57 PM Zhenzhong Duan <zhenzhong.duan@oracle.com> wrote: > > Since retpoline capable compilers are widely available, make > CONFIG_RETPOLINE hard depend on it. > > Change KBUILD to use CONFIG_RETPOLINE_SUPPORT to avoid conflict with > CONFIG_RETPOLINE which is used by kernel. > > With all that stuff, the check of RETPOLINE is changed to > CONFIG_RETPOLINE. > > This change is based on suggestion in https://lkml.org/lkml/2018/9/18/1016 > > Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Borislav Petkov <bp@suse.de> > Cc: Daniel Borkmann <daniel@iogearbox.net> > Cc: David Woodhouse <dwmw@amazon.co.uk> > Cc: H. Peter Anvin <hpa@zytor.com> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > Cc: Andy Lutomirski <luto@kernel.org> > Cc: Masahiro Yamada <yamada.masahiro@socionext.com> > Cc: Michal Marek <michal.lkml@markovi.net> > ---
Instead of adding another CONFIG option, does it make sense to add compiler support checks to 'depends on' syntax ?
config RETPOLINE bool "Avoid speculative indirect branches in kernel" depends on $(cc-option,-mindirect-branch=thunk-extern -mindirect-branch-register) || \ $(cc-option,-mretpoline-external-thunk) default y select STACK_VALIDATION if HAVE_STACK_VALIDATION
-- Best Regards Masahiro Yamada
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