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authorLinus Torvalds <torvalds@linux-foundation.org>2021-02-07 20:37:37 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-02-07 20:37:37 +0300
commit2db138bb9fa10f5652f55d3c3f427af54626a086 (patch)
tree1c4764f9cb8c03ac90cbc534b48ace2065f8ca84 /Documentation
parent825b5991a46ef28a05a4646c8fe1ae5cef7c7828 (diff)
parentefe6e3068067212b85c2d0474b5ee3b2d0c7adab (diff)
downloadlinux-2db138bb9fa10f5652f55d3c3f427af54626a086.tar.xz
Merge tag 'kbuild-fixes-v5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild fixes from Masahiro Yamada: - Use the 'python3' command to invoke python scripts because some distributions do not provide the 'python' command any more. - Clean-up and update documents - Use pkg-config to search libcrypto - Fix duplicated debug flags - Ignore some more stubs in scripts/kallsyms.c * tag 'kbuild-fixes-v5.11-2' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: kallsyms: fix nonconverging kallsyms table with lld kbuild: fix duplicated flags in DEBUG_CFLAGS scripts/clang-tools: switch explicitly to Python 3 kbuild: remove PYTHON variable Documentation/llvm: Add a section about supported architectures Revert "checkpatch: add check for keyword 'boolean' in Kconfig definitions" scripts: use pkg-config to locate libcrypto kconfig: mconf: fix HOSTCC call doc: gcc-plugins: update gcc-plugins.rst kbuild: simplify GCC_PLUGINS enablement in dummy-tools/gcc Documentation/Kbuild: Remove references to gcc-plugin.sh scripts: switch explicitly to Python 3
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/Makefile2
-rw-r--r--Documentation/kbuild/gcc-plugins.rst47
-rw-r--r--Documentation/kbuild/llvm.rst44
-rw-r--r--Documentation/kbuild/makefiles.rst2
4 files changed, 67 insertions, 28 deletions
diff --git a/Documentation/Makefile b/Documentation/Makefile
index 61a7310b49e0..9c42dde97671 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -75,7 +75,7 @@ quiet_cmd_sphinx = SPHINX $@ --> file://$(abspath $(BUILDDIR)/$3/$4)
cmd_sphinx = $(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/userspace-api/media $2 && \
PYTHONDONTWRITEBYTECODE=1 \
BUILDDIR=$(abspath $(BUILDDIR)) SPHINX_CONF=$(abspath $(srctree)/$(src)/$5/$(SPHINX_CONF)) \
- $(PYTHON) $(srctree)/scripts/jobserver-exec \
+ $(PYTHON3) $(srctree)/scripts/jobserver-exec \
$(SHELL) $(srctree)/Documentation/sphinx/parallel-wrapper.sh \
$(SPHINXBUILD) \
-b $2 \
diff --git a/Documentation/kbuild/gcc-plugins.rst b/Documentation/kbuild/gcc-plugins.rst
index 4b1c10f88e30..3349966f213d 100644
--- a/Documentation/kbuild/gcc-plugins.rst
+++ b/Documentation/kbuild/gcc-plugins.rst
@@ -11,16 +11,13 @@ compiler [1]_. They are useful for runtime instrumentation and static analysis.
We can analyse, change and add further code during compilation via
callbacks [2]_, GIMPLE [3]_, IPA [4]_ and RTL passes [5]_.
-The GCC plugin infrastructure of the kernel supports all gcc versions from
-4.5 to 6.0, building out-of-tree modules, cross-compilation and building in a
-separate directory.
-Plugin source files have to be compilable by both a C and a C++ compiler as well
-because gcc versions 4.5 and 4.6 are compiled by a C compiler,
-gcc-4.7 can be compiled by a C or a C++ compiler,
-and versions 4.8+ can only be compiled by a C++ compiler.
+The GCC plugin infrastructure of the kernel supports building out-of-tree
+modules, cross-compilation and building in a separate directory.
+Plugin source files have to be compilable by a C++ compiler.
-Currently the GCC plugin infrastructure supports only the x86, arm, arm64 and
-powerpc architectures.
+Currently the GCC plugin infrastructure supports only some architectures.
+Grep "select HAVE_GCC_PLUGINS" to find out which architectures support
+GCC plugins.
This infrastructure was ported from grsecurity [6]_ and PaX [7]_.
@@ -47,20 +44,13 @@ Files
This is a compatibility header for GCC plugins.
It should be always included instead of individual gcc headers.
-**$(src)/scripts/gcc-plugin.sh**
-
- This script checks the availability of the included headers in
- gcc-common.h and chooses the proper host compiler to build the plugins
- (gcc-4.7 can be built by either gcc or g++).
-
**$(src)/scripts/gcc-plugins/gcc-generate-gimple-pass.h,
$(src)/scripts/gcc-plugins/gcc-generate-ipa-pass.h,
$(src)/scripts/gcc-plugins/gcc-generate-simple_ipa-pass.h,
$(src)/scripts/gcc-plugins/gcc-generate-rtl-pass.h**
These headers automatically generate the registration structures for
- GIMPLE, SIMPLE_IPA, IPA and RTL passes. They support all gcc versions
- from 4.5 to 6.0.
+ GIMPLE, SIMPLE_IPA, IPA and RTL passes.
They should be preferred to creating the structures by hand.
@@ -68,21 +58,25 @@ Usage
=====
You must install the gcc plugin headers for your gcc version,
-e.g., on Ubuntu for gcc-4.9::
+e.g., on Ubuntu for gcc-10::
- apt-get install gcc-4.9-plugin-dev
+ apt-get install gcc-10-plugin-dev
Or on Fedora::
dnf install gcc-plugin-devel
-Enable a GCC plugin based feature in the kernel config::
+Enable the GCC plugin infrastructure and some plugin(s) you want to use
+in the kernel config::
- CONFIG_GCC_PLUGIN_CYC_COMPLEXITY = y
+ CONFIG_GCC_PLUGINS=y
+ CONFIG_GCC_PLUGIN_CYC_COMPLEXITY=y
+ CONFIG_GCC_PLUGIN_LATENT_ENTROPY=y
+ ...
-To compile only the plugin(s)::
+To compile the minimum tool set including the plugin(s)::
- make gcc-plugins
+ make scripts
or just run the kernel make and compile the whole kernel with
the cyclomatic complexity GCC plugin.
@@ -91,7 +85,8 @@ the cyclomatic complexity GCC plugin.
4. How to add a new GCC plugin
==============================
-The GCC plugins are in $(src)/scripts/gcc-plugins/. You can use a file or a directory
-here. It must be added to $(src)/scripts/gcc-plugins/Makefile,
-$(src)/scripts/Makefile.gcc-plugins and $(src)/arch/Kconfig.
+The GCC plugins are in scripts/gcc-plugins/. You need to put plugin source files
+right under scripts/gcc-plugins/. Creating subdirectories is not supported.
+It must be added to scripts/gcc-plugins/Makefile, scripts/Makefile.gcc-plugins
+and a relevant Kconfig file.
See the cyc_complexity_plugin.c (CONFIG_GCC_PLUGIN_CYC_COMPLEXITY) GCC plugin.
diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst
index 21c847890d03..b18401d2ba82 100644
--- a/Documentation/kbuild/llvm.rst
+++ b/Documentation/kbuild/llvm.rst
@@ -63,6 +63,50 @@ They can be enabled individually. The full list of the parameters: ::
Currently, the integrated assembler is disabled by default. You can pass
``LLVM_IAS=1`` to enable it.
+Supported Architectures
+-----------------------
+
+LLVM does not target all of the architectures that Linux supports and
+just because a target is supported in LLVM does not mean that the kernel
+will build or work without any issues. Below is a general summary of
+architectures that currently work with ``CC=clang`` or ``LLVM=1``. Level
+of support corresponds to "S" values in the MAINTAINERS files. If an
+architecture is not present, it either means that LLVM does not target
+it or there are known issues. Using the latest stable version of LLVM or
+even the development tree will generally yield the best results.
+An architecture's ``defconfig`` is generally expected to work well,
+certain configurations may have problems that have not been uncovered
+yet. Bug reports are always welcome at the issue tracker below!
+
+.. list-table::
+ :widths: 10 10 10
+ :header-rows: 1
+
+ * - Architecture
+ - Level of support
+ - ``make`` command
+ * - arm
+ - Supported
+ - ``LLVM=1``
+ * - arm64
+ - Supported
+ - ``LLVM=1``
+ * - mips
+ - Maintained
+ - ``CC=clang``
+ * - powerpc
+ - Maintained
+ - ``CC=clang``
+ * - riscv
+ - Maintained
+ - ``CC=clang``
+ * - s390
+ - Maintained
+ - ``CC=clang``
+ * - x86
+ - Supported
+ - ``LLVM=1``
+
Getting Help
------------
diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst
index 9f6a11881951..300d8edcb994 100644
--- a/Documentation/kbuild/makefiles.rst
+++ b/Documentation/kbuild/makefiles.rst
@@ -755,7 +755,7 @@ more details, with real examples.
bits on the scripts nonetheless.
Kbuild provides variables $(CONFIG_SHELL), $(AWK), $(PERL),
- $(PYTHON) and $(PYTHON3) to refer to interpreters for the respective
+ and $(PYTHON3) to refer to interpreters for the respective
scripts.
Example::