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This patch allows to build the whole kernel with GCC plugins. It was ported from
grsecurity/PaX. The infrastructure supports building out-of-tree modules and
building in a separate directory. Cross-compilation is supported too.
Currently the x86, arm, arm64 and uml architectures enable plugins.
The directory of the gcc plugins is scripts/gcc-plugins. You can use a file or a directory
there. The plugins compile with these options:
* -fno-rtti: gcc is compiled with this option so the plugins must use it too
* -fno-exceptions: this is inherited from gcc too
* -fasynchronous-unwind-tables: this is inherited from gcc too
* -ggdb: it is useful for debugging a plugin (better backtrace on internal
errors)
* -Wno-narrowing: to suppress warnings from gcc headers (ipa-utils.h)
* -Wno-unused-variable: to suppress warnings from gcc headers (gcc_version
variable, plugin-version.h)
The infrastructure introduces a new Makefile target called gcc-plugins. It
supports all gcc versions from 4.5 to 6.0. The scripts/gcc-plugin.sh script
chooses the proper host compiler (gcc-4.7 can be built by either gcc or g++).
This script also checks the availability of the included headers in
scripts/gcc-plugins/gcc-common.h.
The gcc-common.h header contains frequently included headers for GCC plugins
and it has a compatibility layer for the supported gcc versions.
The gcc-generate-*-pass.h headers automatically generate the registration
structures for GIMPLE, SIMPLE_IPA, IPA and RTL passes.
Note that 'make clean' keeps the *.so files (only the distclean or mrproper
targets clean all) because they are needed for out-of-tree modules.
Based on work created by the PaX Team.
Signed-off-by: Emese Revfy <re.emese@gmail.com>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michal Marek <mmarek@suse.com>
88 lines
2.9 KiB
Plaintext
88 lines
2.9 KiB
Plaintext
GCC plugin infrastructure
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=========================
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1. Introduction
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===============
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GCC plugins are loadable modules that provide extra features to the
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compiler [1]. They are useful for runtime instrumentation and static analysis.
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We can analyse, change and add further code during compilation via
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callbacks [2], GIMPLE [3], IPA [4] and RTL passes [5].
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The GCC plugin infrastructure of the kernel supports all gcc versions from
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4.5 to 6.0, building out-of-tree modules, cross-compilation and building in a
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separate directory.
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Plugin source files have to be compilable by both a C and a C++ compiler as well
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because gcc versions 4.5 and 4.6 are compiled by a C compiler,
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gcc-4.7 can be compiled by a C or a C++ compiler,
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and versions 4.8+ can only be compiled by a C++ compiler.
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Currently the GCC plugin infrastructure supports only the x86, arm and arm64
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architectures.
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This infrastructure was ported from grsecurity [6] and PaX [7].
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--
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[1] https://gcc.gnu.org/onlinedocs/gccint/Plugins.html
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[2] https://gcc.gnu.org/onlinedocs/gccint/Plugin-API.html#Plugin-API
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[3] https://gcc.gnu.org/onlinedocs/gccint/GIMPLE.html
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[4] https://gcc.gnu.org/onlinedocs/gccint/IPA.html
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[5] https://gcc.gnu.org/onlinedocs/gccint/RTL.html
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[6] https://grsecurity.net/
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[7] https://pax.grsecurity.net/
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2. Files
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========
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$(src)/scripts/gcc-plugins
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This is the directory of the GCC plugins.
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$(src)/scripts/gcc-plugins/gcc-common.h
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This is a compatibility header for GCC plugins.
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It should be always included instead of individual gcc headers.
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$(src)/scripts/gcc-plugin.sh
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This script checks the availability of the included headers in
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gcc-common.h and chooses the proper host compiler to build the plugins
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(gcc-4.7 can be built by either gcc or g++).
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$(src)/scripts/gcc-plugins/gcc-generate-gimple-pass.h
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$(src)/scripts/gcc-plugins/gcc-generate-ipa-pass.h
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$(src)/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h
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$(src)/scripts/gcc-plugins/gcc-generate-rtl-pass.h
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These headers automatically generate the registration structures for
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GIMPLE, SIMPLE_IPA, IPA and RTL passes. They support all gcc versions
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from 4.5 to 6.0.
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They should be preferred to creating the structures by hand.
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3. Usage
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========
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You must install the gcc plugin headers for your gcc version,
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e.g., on Ubuntu for gcc-4.9:
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apt-get install gcc-4.9-plugin-dev
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Enable a GCC plugin based feature in the kernel config:
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CONFIG_GCC_PLUGIN_CYC_COMPLEXITY = y
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To compile only the plugin(s):
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make gcc-plugins
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or just run the kernel make and compile the whole kernel with
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the cyclomatic complexity GCC plugin.
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4. How to add a new GCC plugin
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==============================
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The GCC plugins are in $(src)/scripts/gcc-plugins/. You can use a file or a directory
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here. It must be added to $(src)/scripts/gcc-plugins/Makefile,
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$(src)/scripts/Makefile.gcc-plugins and $(src)/arch/Kconfig.
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See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin.
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