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Message-ID: <CAGXu5jJ=9zX8d3f30vMb-DC5AM3fHPFL0fxYh+CnpvAwvTtEKQ@mail.gmail.com>
Date: Tue, 1 Mar 2016 11:16:23 -0800
From: Kees Cook <keescook@...omium.org>
To: Emese Revfy <re.emese@...il.com>
Cc: linux-kbuild <linux-kbuild@...r.kernel.org>, PaX Team <pageexec@...email.hu>,
Brad Spengler <spender@...ecurity.net>,
"kernel-hardening@...ts.openwall.com" <kernel-hardening@...ts.openwall.com>, Michal Marek <mmarek@...e.com>,
Rasmus Villemoes <linux@...musvillemoes.dk>, Fengguang Wu <fengguang.wu@...el.com>
Subject: Re: [PATCH v4 0/3] Introduce GCC plugin infrastructure
On Tue, Mar 1, 2016 at 11:09 AM, Kees Cook <keescook@...omium.org> wrote:
> On Tue, Mar 1, 2016 at 9:14 AM, Emese Revfy <re.emese@...il.com> wrote:
>> This patch set introduce the GCC plugin infrastructure with examples for testing
>> and documentation.
>>
>> GCC plugins are loadable modules that provide extra features to the compiler.
>> They are useful for runtime instrumentation and static analysis.
>>
>> The infrastructure supports all gcc versions from 4.5 to 6.0, building
>> out-of-tree modules and building in a separate directory. Cross-compilation
>> is supported too but currently only the x86 architecture enables plugins.
>>
>> This infrastructure was ported from grsecurity/PaX. It is a CII project
>> supported by the Linux Foundation.
Oh, for future submissions, please include lkml itself too, just to
get some more eyes on it. I'm intending to carry this for -next, so I
don't want to unduly surprise anyone. :)
-Kees
>>
>> Emese Revfy (3):
>> GCC plugin infrastructure
>> Add Cyclomatic complexity plugin
>> Documentations of the GCC plugin infrastructre
>>
>>
>> Changes from v3:
>> * Fix some indentation related warnings
>> (Suggested by checkpatch.pl)
>> * Add maintainer entries
>> * Don't run gcc_plugin.sh when the GCC_PLUGINS option is disabled or unsupported
>> (Reported-by: Fengguang Wu <fengguang.wu@...el.com>)
>>
>> I found a kbuild bug (or feature?) related to this patch. When a config option is disabled
>> then the symbol gets undefined only when you run make clean.
>> The easiest way to reproduce it is with e.g., CC_STACKPROTECTOR_STRONG:
>
> Yeah, I fought this when adding _STRONG. It seems there are two
> "phases" of Kbuild where it rebuilds the .config during phase 1 then
> does the actual build in phase 2. I couldn't make the stack protector
> detection kill the build because it would kill the config rewriter
> too. So I had to leave it a warning and let the compiler die later
> instead.
>
> -Kees
>
>>
>> * patch in warning here:
>>
>> diff --git a/Makefile b/Makefile
>> index a1a7708..9e6961f 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -664,6 +664,7 @@ ifdef CONFIG_CC_STACKPROTECTOR_REGULAR
>> else
>> ifdef CONFIG_CC_STACKPROTECTOR_STRONG
>> stackp-flag := -fstack-protector-strong
>> + $(warning AAAAAAAA)
>> ifeq ($(call cc-option, $(stackp-flag)),)
>> $(warning Cannot use CONFIG_CC_STACKPROTECTOR_STRONG: \
>> -fstack-protector-strong not supported by compiler)
>>
>> * enable CC_STACKPROTECTOR_STRONG in menuconfig
>> * run make and it prints out the "AAAAAAAA"
>> * enable CC_STACKPROTECTOR_NONE in menuconfig
>> * run make and it prints out the "AAAAAAAA"
>> * run make clean, run make again and it doesn't print out the "AAAAAAAA"
>>
>>
>> Changes from v2:
>> * Fixed incorrectly encoded characters
>> * Generate the GIMPLE, IPA, SIMPLE_IPA and RTL pass structures
>> (Suggested-by: Rasmus Villemoes <linux@...musvillemoes.dk>)
>> * Write plugin related warning messages to stderr instead of stdout
>> (Suggested-by: Kees Cook <keescook@...omium.org>)
>> * Mention the installation of the gcc plugin headers (Documentation)
>>
>>
>> Changes from v1:
>> * Move the gcc-plugins make target into a separate Makefile because there may
>> be a lot of plugins (Suggested-by: Rasmus Villemoes)
>> * Simplify the dependencies of the plugin related config option
>> (Suggested-by: Kees Cook <keescook@...omium.org>)
>> * Removed the unnecessary example plugin
>> ---
>> Documentation/dontdiff | 1 +
>> Documentation/gcc-plugins.txt | 82 ++++
>> MAINTAINERS | 8 +
>> Makefile | 41 +-
>> arch/Kconfig | 24 +
>> arch/x86/Kconfig | 1 +
>> init/Makefile | 3 +
>> scripts/Makefile.build | 2 +-
>> scripts/Makefile.clean | 3 +-
>> scripts/Makefile.gcc-plugins | 32 ++
>> scripts/Makefile.host | 69 ++-
>> scripts/gcc-plugin.sh | 51 ++
>> scripts/link-vmlinux.sh | 2 +-
>> scripts/package/builddeb | 1 +
>> tools/gcc/Makefile | 19 +
>> tools/gcc/cyc_complexity_plugin.c | 73 +++
>> tools/gcc/gcc-common.h | 803 +++++++++++++++++++++++++++++++
>> tools/gcc/gcc-generate-gimple-pass.h | 173 +++++++
>> tools/gcc/gcc-generate-ipa-pass.h | 287 +++++++++++
>> tools/gcc/gcc-generate-rtl-pass.h | 173 +++++++
>> tools/gcc/gcc-generate-simple_ipa-pass.h | 173 +++++++
>> 21 files changed, 2006 insertions(+), 15 deletions(-)
>
>
>
> --
> Kees Cook
> Chrome OS & Brillo Security
--
Kees Cook
Chrome OS & Brillo Security
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