Pull READ/WRITE_ONCE rework from Will Deacon:
"This the READ_ONCE rework I've been working on for a while, which
bumps the minimum GCC version and improves code-gen on arm64 when
stack protector is enabled"
[ Side note: I'm _really_ tempted to raise the minimum gcc version to
4.9, so that we can just say that we require _Generic() support.
That would allow us to more cleanly handle a lot of the cases where we
depend on very complex macros with 'sizeof' or __builtin_choose_expr()
with __builtin_types_compatible_p() etc.
This branch has a workaround for sparse not handling _Generic(),
either, but that was already fixed in the sparse development branch,
so it's really just gcc-4.9 that we'd require. - Linus ]
* 'rwonce/rework' of git://git.kernel.org/pub/scm/linux/kernel/git/will/linux:
compiler_types.h: Use unoptimized __unqual_scalar_typeof for sparse
compiler_types.h: Optimize __unqual_scalar_typeof compilation time
compiler.h: Enforce that READ_ONCE_NOCHECK() access size is sizeof(long)
compiler-types.h: Include naked type in __pick_integer_type() match
READ_ONCE: Fix comment describing 2x32-bit atomicity
gcov: Remove old GCC 3.4 support
arm64: barrier: Use '__unqual_scalar_typeof' for acquire/release macros
locking/barriers: Use '__unqual_scalar_typeof' for load-acquire macros
READ_ONCE: Drop pointer qualifiers when reading from scalar types
READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses
READ_ONCE: Simplify implementations of {READ,WRITE}_ONCE()
arm64: csum: Disable KASAN for do_csum()
fault_inject: Don't rely on "return value" from WRITE_ONCE()
net: tls: Avoid assigning 'const' pointer to non-const pointer
netfilter: Avoid assigning 'const' pointer to non-const pointer
compiler/gcc: Raise minimum GCC version for kernel builds to 4.8
This is the remnant of commit c17d6179ad ("gcc-plugins: remove unused
GCC_PLUGIN_SUBDIR").
The conditional $(if $(findstring /,$(p)),...) is always false because
none of plugins contains '/' in the file name.
Clean up the code.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
It is very rare to see versions of GCC prior to 4.8 being used to build
the mainline kernel. These old compilers are also know to have codegen
issues which can lead to silent miscompilation:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145
Raise the minimum GCC version for kernel build to 4.8 and remove some
tautological Kconfig dependencies as a consequence.
Cc: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Remove "params.h" include, which has been dropped in GCC 10.
Remove is_a_helper() macro, which is now defined in gimple.h, as seen
when running './scripts/gcc-plugin.sh g++ g++ gcc':
In file included from <stdin>:1:
./gcc-plugins/gcc-common.h:852:13: error: redefinition of ‘static bool is_a_helper<T>::test(U*) [with U = const gimple; T = const ggoto*]’
852 | inline bool is_a_helper<const ggoto *>::test(const_gimple gs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from ./gcc-plugins/gcc-common.h:125,
from <stdin>:1:
/usr/lib/gcc/x86_64-redhat-linux/10/plugin/include/gimple.h:1037:1: note: ‘static bool is_a_helper<T>::test(U*) [with U = const gimple; T = const ggoto*]’ previously declared here
1037 | is_a_helper <const ggoto *>::test (const gimple *gs)
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~
Add -Wno-format-diag to scripts/gcc-plugins/Makefile to avoid
meaningless warnings from error() formats used by plugins:
scripts/gcc-plugins/structleak_plugin.c: In function ‘int plugin_init(plugin_name_args*, plugin_gcc_version*)’:
scripts/gcc-plugins/structleak_plugin.c:253:12: warning: unquoted sequence of 2 consecutive punctuation characters ‘'-’ in format [-Wformat-diag]
253 | error(G_("unknown option '-fplugin-arg-%s-%s'"), plugin_name, argv[i].key);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Signed-off-by: Frédéric Pierret (fepitre) <frederic.pierret@qubes-os.org>
Link: https://lore.kernel.org/r/20200407113259.270172-1-frederic.pierret@qubes-os.org
[kees: include -Wno-format-diag for plugin builds]
Signed-off-by: Kees Cook <keescook@chromium.org>
With GCC version >= 8, the cgraph_create_edge() macro argument using
"frequency" goes unused. Instead of assigning a temporary variable for
the argument, pass the compute_call_stmt_bb_frequency() call directly
as the macro argument so that it will just not be called when it is
not wanted by the macros.
Silences the warning:
scripts/gcc-plugins/stackleak_plugin.c:54:6: warning: variable ‘frequency’ set but not used [-Wunused-but-set-variable]
Now builds cleanly with gcc-7 and gcc-9. Both boot and pass
STACKLEAK_ERASING LKDTM test.
Signed-off-by: Kees Cook <keescook@chromium.org>
Nobody was opposed to raising minimum GCC version to 4.8 [1]
So, we will drop GCC <= 4.7 support sooner or later.
We always use C++ compiler for building plugins for GCC >= 4.8.
This commit drops the plugin support for GCC <= 4.7 a bit earlier,
which allows us to dump lots of code.
[1] https://lkml.org/lkml/2020/1/23/545
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Pull SPDX updates from Greg KH:
"Here are three SPDX patches for 5.7-rc1.
One fixes up the SPDX tag for a single driver, while the other two go
through the tree and add SPDX tags for all of the .gitignore files as
needed.
Nothing too complex, but you will get a merge conflict with your
current tree, that should be trivial to handle (one file modified by
two things, one file deleted.)
All three of these have been in linux-next for a while, with no
reported issues other than the merge conflict"
* tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
ASoC: MT6660: make spdxcheck.py happy
.gitignore: add SPDX License Identifier
.gitignore: remove too obvious comments
Pull Kbuild updates from Masahiro Yamada:
"Build system:
- add CONFIG_UNUSED_KSYMS_WHITELIST, which will be useful to define a
fixed set of export symbols for Generic Kernel Image (GKI)
- allow to run 'make dt_binding_check' without .config
- use full schema for checking DT examples in *.yaml files
- make modpost fail for missing MODULE_IMPORT_NS(), which makes more
sense because we know the produced modules are never loadable
- Remove unused 'AS' variable
Kconfig:
- sanitize DEFCONFIG_LIST, and remove ARCH_DEFCONFIG from Kconfig
files
- relax the 'imply' behavior so that symbols implied by 'y' can
become 'm'
- make 'imply' obey 'depends on' in order to make 'imply' really weak
Misc:
- add documentation on building the kernel with Clang/LLVM
- revive __HAVE_ARCH_STRLEN for 32bit sparc to use optimized strlen()
- fix warning from deb-pkg builds when CONFIG_DEBUG_INFO=n
- various script and Makefile cleanups"
* tag 'kbuild-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (34 commits)
Makefile: Update kselftest help information
kbuild: deb-pkg: fix warning when CONFIG_DEBUG_INFO is unset
kbuild: add outputmakefile to no-dot-config-targets
kbuild: remove AS variable
net: wan: wanxl: refactor the firmware rebuild rule
net: wan: wanxl: use $(M68KCC) instead of $(M68KAS) for rebuilding firmware
net: wan: wanxl: use allow to pass CROSS_COMPILE_M68k for rebuilding firmware
kbuild: add comment about grouped target
kbuild: add -Wall to KBUILD_HOSTCXXFLAGS
kconfig: remove unused variable in qconf.cc
sparc: revive __HAVE_ARCH_STRLEN for 32bit sparc
kbuild: refactor Makefile.dtbinst more
kbuild: compute the dtbs_install destination more simply
Makefile: disallow data races on gcc-10 as well
kconfig: make 'imply' obey the direct dependency
kconfig: allow symbols implied by y to become m
net: drop_monitor: use IS_REACHABLE() to guard net_dm_hw_report()
modpost: return error if module is missing ns imports and MODULE_ALLOW_MISSING_NAMESPACE_IMPORTS=n
modpost: rework and consolidate logging interface
kbuild: allow to run dt_binding_check without kernel configuration
...
Add -Wall to catch more warnings for C++ host programs.
When I submitted the previous version, the 0-day bot reported
-Wc++11-compat warnings for old GCC:
HOSTCXX -fPIC scripts/gcc-plugins/latent_entropy_plugin.o
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/tm.h:28:0,
from scripts/gcc-plugins/gcc-common.h:15,
from scripts/gcc-plugins/latent_entropy_plugin.c:78:
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/elfos.h:102:21: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
fprintf ((FILE), "%s"HOST_WIDE_INT_PRINT_UNSIGNED"\n",\
^
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/config/elfos.h:170:24: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n", \
^
In file included from /usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/tm.h:42:0,
from scripts/gcc-plugins/gcc-common.h:15,
from scripts/gcc-plugins/latent_entropy_plugin.c:78:
/usr/lib/gcc/x86_64-linux-gnu/4.8/plugin/include/defaults.h:126:24: warning: C++11 requires a space between string literal and macro [-Wc++11-compat]
fprintf ((FILE), ","HOST_WIDE_INT_PRINT_UNSIGNED",%u\n", \
^
The source of the warnings is in the plugin headers, so we have no
control of it. I just suppressed them by adding -Wno-c++11-compat to
scripts/gcc-plugins/Makefile.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Information about GCC plugins is relevant to kernel building, so move this
document to the kbuild manual.
Acked-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
In old days, the "host-progs" syntax was used for specifying host
programs. It was renamed to the current "hostprogs-y" in 2004.
It is typically useful in scripts/Makefile because it allows Kbuild to
selectively compile host programs based on the kernel configuration.
This commit renames like follows:
always -> always-y
hostprogs-y -> hostprogs
So, scripts/Makefile will look like this:
always-$(CONFIG_BUILD_BIN2C) += ...
always-$(CONFIG_KALLSYMS) += ...
...
hostprogs := $(always-y) $(always-m)
I think this makes more sense because a host program is always a host
program, irrespective of the kernel configuration. We want to specify
which ones to compile by CONFIG options, so always-y will be handier.
The "always", "hostprogs-y", "hostprogs-m" will be kept for backward
compatibility for a while.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
I noticed that randconfig builds with gcc no longer produce a lot of
ccache hits, unlike with clang, and traced this back to plugins
now being enabled unconditionally if they are supported.
I am now working around this by adding
export CCACHE_COMPILERCHECK=/usr/bin/size -A %compiler%
to my top-level Makefile. This changes the heuristic that ccache uses
to determine whether the plugins are the same after a 'make clean'.
However, it also seems that being able to just turn off the plugins is
generally useful, at least for build testing it adds noticeable overhead
but does not find a lot of bugs additional bugs, and may be easier for
ccache users than my workaround.
Fixes: 9f671e5815 ("security: Create "kernel hardening" config area")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20191211133951.401933-1-arnd@arndb.de
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
The gcc_plugins.txt file is already a ReST file. Move it
to the core-api book while renaming it.
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Acked-by: Kees Cook <keescook@chromium.org>
Pull gcc-plugins fix from Kees Cook:
"Handle unusual header environment, fixing a redefined macro error
under a Darwin build host"
* tag 'gcc-plugins-v5.2-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
gcc-plugins: Fix build failures under Darwin host
Add SPDX license identifiers to all Make/Kconfig files which:
- Have no license information of any form
These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:
GPL-2.0-only
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The gcc-common.h file did not take into account certain macros that
might have already been defined in the build environment. This updates
the header to avoid redefining the macros, as seen on a Darwin host
using gcc 4.9.2:
HOSTCXX -fPIC scripts/gcc-plugins/arm_ssp_per_task_plugin.o - due to: scripts/gcc-plugins/gcc-common.h
In file included from scripts/gcc-plugins/arm_ssp_per_task_plugin.c:3:0:
scripts/gcc-plugins/gcc-common.h:153:0: warning: "__unused" redefined
^
In file included from /usr/include/stdio.h:64:0,
from /Users/hns/Documents/Projects/QuantumSTEP/System/Library/Frameworks/System.framework/Versions-jessie/x86_64-apple-darwin15.0.0/gcc/arm-linux-gnueabi/bin/../lib/gcc/arm-linux-gnueabi/4.9.2/plugin/include/system.h:40,
from /Users/hns/Documents/Projects/QuantumSTEP/System/Library/Frameworks/System.framework/Versions-jessie/x86_64-apple-darwin15.0.0/gcc/arm-linux-gnueabi/bin/../lib/gcc/arm-linux-gnueabi/4.9.2/plugin/include/gcc-plugin.h:28,
from /Users/hns/Documents/Projects/QuantumSTEP/System/Library/Frameworks/System.framework/Versions-jessie/x86_64-apple-darwin15.0.0/gcc/arm-linux-gnueabi/bin/../lib/gcc/arm-linux-gnueabi/4.9.2/plugin/include/plugin.h:23,
from scripts/gcc-plugins/gcc-common.h:9,
from scripts/gcc-plugins/arm_ssp_per_task_plugin.c:3:
/usr/include/sys/cdefs.h:161:0: note: this is the location of the previous definition
^
Reported-and-tested-by: "H. Nikolaus Schaller" <hns@goldelico.com>
Fixes: 189af46571 ("ARM: smp: add support for per-task stack canaries")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Use gen_rtx_set instead of gen_rtx_SET. The former is a wrapper macro
that handles the difference between GCC versions implementing
the latter.
This fixes the following error on my system with g++ 5.4.0 as the host
compiler
HOSTCXX -fPIC scripts/gcc-plugins/arm_ssp_per_task_plugin.o
scripts/gcc-plugins/arm_ssp_per_task_plugin.c:42:14: error: macro "gen_rtx_SET" requires 3 arguments, but only 2 given
mask)),
^
scripts/gcc-plugins/arm_ssp_per_task_plugin.c: In function ‘unsigned int arm_pertask_ssp_rtl_execute()’:
scripts/gcc-plugins/arm_ssp_per_task_plugin.c:39:20: error: ‘gen_rtx_SET’ was not declared in this scope
emit_insn_before(gen_rtx_SET
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Fixes: 189af46571 ("ARM: smp: add support for per-task stack canaries")
Cc: stable@vger.kernel.org
Tested-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Right now kernel hardening options are scattered around various Kconfig
files. This can be a central place to collect these kinds of options
going forward. This is initially populated with the memory initialization
options from the gcc-plugins.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Pull gcc-plugins updates from Kees Cook:
"This adds additional type coverage to the existing structleak plugin
and adds a large set of selftests to help evaluate stack variable
zero-initialization coverage.
That can be used to test whatever instrumentation might be performing
zero-initialization: either with the structleak plugin or with Clang's
coming "-ftrivial-auto-var-init=zero" option.
Summary:
- Add scalar and array initialization coverage
- Refactor Kconfig to make options more clear
- Add self-test module for testing automatic initialization"
* tag 'gcc-plugins-v5.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
lib: Introduce test_stackinit module
gcc-plugins: structleak: Generalize to all variable types
Use after scope bugs detector seems to be almost entirely useless for
the linux kernel. It exists over two years, but I've seen only one
valid bug so far [1]. And the bug was fixed before it has been
reported. There were some other use-after-scope reports, but they were
false-positives due to different reasons like incompatibility with
structleak plugin.
This feature significantly increases stack usage, especially with GCC <
9 version, and causes a 32K stack overflow. It probably adds
performance penalty too.
Given all that, let's remove use-after-scope detector entirely.
While preparing this patch I've noticed that we mistakenly enable
use-after-scope detection for clang compiler regardless of
CONFIG_KASAN_EXTRA setting. This is also fixed now.
[1] http://lkml.kernel.org/r/<20171129052106.rhgbjhhis53hkgfn@wfg-t540p.sh.intel.com>
Link: http://lkml.kernel.org/r/20190111185842.13978-1-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Acked-by: Will Deacon <will.deacon@arm.com> [arm64]
Cc: Qian Cai <cai@lca.pw>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This adjusts structleak to also work with non-struct types when they
are passed by reference, since those variables may leak just like
anything else. This is exposed via an improved set of Kconfig options.
(This does mean structleak is slightly misnamed now.)
Building with CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL should give the
kernel complete initialization coverage of all stack variables passed
by reference, including padding (see lib/test_stackinit.c).
Using CONFIG_GCC_PLUGIN_STRUCTLEAK_VERBOSE to count added initializations
under defconfig:
..._BYREF: 5945 added initializations
..._BYREF_ALL: 16606 added initializations
There is virtually no change to text+data size (both have less than 0.05%
growth):
text data bss dec hex filename
19502103 5051456 1917000 26470559 193e89f vmlinux.stock
19513412 5051456 1908808 26473676 193f4cc vmlinux.byref
19516974 5047360 1900616 26464950 193d2b6 vmlinux.byref_all
The measured performance difference is in the noise for hackbench and
kernel build benchmarks:
Stock:
5x hackbench -g 20 -l 1000
Mean: 10.649s
Std Dev: 0.339
5x kernel build (4-way parallel)
Mean: 261.98s
Std Dev: 1.53
CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF:
5x hackbench -g 20 -l 1000
Mean: 10.540s
Std Dev: 0.233
5x kernel build (4-way parallel)
Mean: 260.52s
Std Dev: 1.31
CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL:
5x hackbench -g 20 -l 1000
Mean: 10.320
Std Dev: 0.413
5x kernel build (4-way parallel)
Mean: 260.10
Std Dev: 0.86
This does not yet solve missing padding initialization for structures
on the stack that are never passed by reference (which should be a tiny
minority). Hopefully this will be more easily addressed by upstream
compiler fixes after clarifying the C11 padding initialization
specification.
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
