On Fri, Dec 9, 2016 at 2:40 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote: > On Thursday, December 8, 2016 11:00:42 AM CET Kees Cook wrote: > >> 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. > > Using gcc-4.9.3 or gcc-5.3.1 for an ARM allmodconfig build, I get tons of > errors such as this one: > > /git/arm-soc/init/initramfs.c: In function 'error': > /git/arm-soc/init/initramfs.c:50:1: error: unrecognizable insn: > } > ^ > (insn 26 25 27 5 (set (reg:SI 111 [ local_entropy.243 ]) > (rotatert:SI (reg:SI 116 [ local_entropy.243 ]) > (const_int -30 [0xffffffffffffffe2]))) -1 > (nil)) > *** WARNING *** there are active plugins, do not report this as a bug unless you can reproduce it without enabling any plugins. > Event | Plugins > PLUGIN_ATTRIBUTES | latent_entropy_plugin > PLUGIN_START_UNIT | latent_entropy_plugin > /git/arm-soc/init/initramfs.c:50:1: internal compiler error: in extract_insn, at recog.c:2202 > /git/arm-soc/arch/arm/vfp/vfpmodule.c: In function 'vfp_init': > /git/arm-soc/arch/arm/vfp/vfpmodule.c:824:1: error: unrecognizable insn: > } > ^ > (insn 138 137 139 17 (set (reg:SI 165 [ local_entropy.93 ]) > (rotatert:SI (reg:SI 150 [ local_entropy.93 ]) > (const_int -9 [0xfffffffffffffff7]))) -1 > (nil)) > *** WARNING *** there are active plugins, do not report this as a bug unless you can reproduce it without enabling any plugins. Well that's exciting! :P > > Using gcc-6.1.1 or gcc-7.0.0, everything works fine as far as I > can tell. With some older Ubuntu binary toolchains, I get this one: > > In file included from <stdin>:1:0: > /git/arm-soc/scripts/gcc-plugins/gcc-common.h:4:22: fatal error: bversion.h: No such file or directory > compilation terminated. > Cannot use CONFIG_GCC_PLUGINS: your gcc installation does not support plugins, perhaps the necessary headers are missing? > > and I can't find the packages for the headers (I still get them for > gcc-5, but not older versions). On very old toolchains (e.g. gcc-4.3), > I get this one: > > Cannot use CONFIG_GCC_PLUGINS: your gcc version does not support plugins, you should upgrade it to at least gcc 4.5 > scripts/Makefile.gcc-plugins:54: recipe for target 'gcc-plugins-check' failed I'm starting to wonder if we need to expose the compiler version to Kconfig so that "all*config" builds for earlier compiler will automatically leave things like plugins off. But I have no idea what the right approach for that might be. I'm not a fan of silently disabling stuff (like is done, for example, for KCOV). If you've selected a Kconfig that your compiler can't build, it should fail to build, but that's different from the allyesconfig etc, since that's about compile tests not a sane kernel image. Perhaps if COMPILE_TEST is enabled, and there is something unsupported by the compiler, only then would it warn and continue, instead of killing build? -Kees -- Kees Cook Nexus Security -- To unsubscribe from this list: send the line "unsubscribe linux-next" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
