Re: enabling COMPILE_TEST support for GCC plugins in v4.11

[Kees Cook]

On Fri, Dec 9, 2016 at 3:33 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Thursday, December 8, 2016 11:00:42 AM CET Kees Cook wrote:
>> Hi,
>>
>> I'd like to get the GCC plugins building under
>> allyesconfig/allmodconfig for -next soon (with the intention of
>> landing the change in v4.11). Specifically, I intend to revert
>> a519167e753e ("gcc-plugins: disable under COMPILE_TEST").
>>
>> Right now the plugins are only supported on x86, arm, and arm64,
>> though powerpc may happen in either v4.10 or v4.11 as well. This means
>> that the autobuilders for these architectures need to have the "gcc
>> plugin development" package installed which contains the GCC headers
>> needed for the plugins. For Debian/Ubuntu, this is gcc-$N-plugin-dev
>> (and for cross compilers: gcc-$N-plugin-dev-$arch-linux-$abi). For
>> Fedora, it is gcc-plugin-devel (though I'm not sure the naming for
>> cross compilers). Manual builds of compilers should already have these
>> headers installed.
>>
>> The "noisy" plugin, cyc_complexity, is just an example, and I have
>> disabled it (which is pending[1] for v4.10). The remaining ones
>> (sancov and latent_entropy) are what I'm hoping to see tested
>> tree-wide (with the expectation that more are coming down the road:
>> initify, randstruct, structleak, constify, ...)
>>
>> IIUC, the 0day builder already has the headers installed. I tried to
>> look through linux-next to find all the other folks that do
>> autobuilding on these architectures; apologies if I've missed anyone.
>>
>> If you have a moment, applying 215e2aa6c024[1] and reverting
>> a519167e753e for an allyesconfig/allmodconfig build should let you
>> know if things are working correctly with headers installed. If anyone
>> sees any problems, please let me know and I can queue up fixes.
>>
>> Thanks!
>>
>> -Kees
>>
>> [1] http://git.kernel.org/cgit/linux/kernel/git/kees/linux.git/commit/?h=for-next/gcc-plugins&id=215e2aa6c024d27cdbe88e2ea88cb59dcab588eb
>
> This is what I got on x86-64 with a gcc-7.0.0 snapshot:
>
> In file included from /git/arm-soc/scripts/gcc-plugins/gcc-common.h:42:0,
>                  from <stdin>:1:
> /home/arnd/cross-gcc/lib/gcc/x86_64-linux/7.0.0/plugin/include/emit-rtl.h:371:41: error: use of enum âmemmodelâ without previous declaration
>  extern bool need_atomic_barrier_p (enum memmodel, bool);
>                                          ^
> In file included from /git/arm-soc/scripts/gcc-plugins/gcc-common.h:94:0,
>                  from <stdin>:1:
> /home/arnd/cross-gcc/lib/gcc/x86_64-linux/7.0.0/plugin/include/tree-ssanames.h:70:40: error: use of enum âvalue_range_typeâ without previous declaration
>  extern void set_range_info (tree, enum value_range_type, const wide_int_ref &,
>                                         ^
> /home/arnd/cross-gcc/lib/gcc/x86_64-linux/7.0.0/plugin/include/tree-ssanames.h:73:13: error: use of enum âvalue_range_typeâ without previous declaration
>  extern enum value_range_type get_range_info (const_tree, wide_int *,
>              ^
> /home/arnd/cross-gcc/lib/gcc/x86_64-linux/7.0.0/plugin/include/tree-ssanames.h:98:55: error: use of enum âvalue_range_typeâ without previous declaration
>  extern void duplicate_ssa_name_range_info (tree, enum value_range_type,
>                                                        ^
> Cannot use CONFIG_GCC_PLUGINS: your gcc installation does not support plugins, perhaps the necessary headers are missing?
> scripts/Makefile.gcc-plugins:51: recipe for target 'gcc-plugins-check' failed
>
> I manually fixed up the gcc header files to include the ones with the
> definition for now, to address those, but I don't know if that change is
> correct.

What was needed?

-Kees

-- 
Kees Cook
Nexus Security