Re: [RFC PATCH v2 00/13] objtool: add base support for arm64

[Nick Desaulniers]

On Fri, Mar 5, 2021 at 3:51 PM Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote:
>
> (in response to
> https://lore.kernel.org/linux-arm-kernel/20210303170932.1838634-1-jthierry@xxxxxxxxxx/
> from the command line)
>
> > Changes since v1[2]:
> > - Drop gcc plugin in favor of -fno-jump-tables
>
> Thank you for this!  I built+booted(under emulation) arm64 defconfig and built
> arm64 allmodconfig with LLVM=1 with this series applied.
>
> Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
>
> One thing I noticed was a spew of warnings for allmodconfig, like:
> init/main.o: warning: objtool: asan.module_ctor()+0xc: call without frame pointer save/setup
> init/main.o: warning: objtool: asan.module_dtor()+0xc: call without frame pointer save/setup
>
> I assume those are from the KASAN constructors. See also:
> https://github.com/ClangBuiltLinux/linux/issues/1238
>
> Can we disable HAVE_STACK_PROTECTOR if CC_IS_CLANG and CONFIG_KASAN is set,
> until we can resolve the above issue?

Ah, filtering the logs more, it looks like GCOV is has the same issue
KASAN does (known issue).  Here's a filtered log:
https://gist.github.com/nickdesaulniers/01358015b33bd16ccd7d951c4a8c44e7

I'm curious about the failure to decode certain instructions?

The stack state mismatches are what are valuable to me; we'll need
some help digging into those at some point.  The logs from defconfig
are clean.
-- 
Thanks,
~Nick Desaulniers