[ Upstream commit 75b5ab134bb5f657ef7979a59106dce0657e8d87 ]
Clang enables -Wenum-enum-conversion and -Wenum-compare-conditional
under -Wenum-conversion. A recent change in Clang strengthened these
warnings and they appear frequently in common builds, primarily due to
several instances in common headers but there are quite a few drivers
that have individual instances as well.
include/linux/vmstat.h:508:43: warning: arithmetic between different enumeration types ('enum zone_stat_item' and 'enum numa_stat_item') [-Wenum-enum-conversion]
508 | return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
| ~~~~~~~~~~~~~~~~~~~~~ ^
509 | item];
| ~~~~
drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c:955:24: warning: conditional expression between different enumeration types ('enum iwl_mac_beacon_flags' and 'enum iwl_mac_beacon_flags_v1') [-Wenum-compare-conditional]
955 | flags |= is_new_rate ? IWL_MAC_BEACON_CCK
| ^ ~~~~~~~~~~~~~~~~~~
956 | : IWL_MAC_BEACON_CCK_V1;
| ~~~~~~~~~~~~~~~~~~~~~
drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c:1120:21: warning: conditional expression between different enumeration types ('enum iwl_mac_beacon_flags' and 'enum iwl_mac_beacon_flags_v1') [-Wenum-compare-conditional]
1120 | 0) > 10 ?
| ^
1121 | IWL_MAC_BEACON_FILS :
| ~~~~~~~~~~~~~~~~~~~
1122 | IWL_MAC_BEACON_FILS_V1;
| ~~~~~~~~~~~~~~~~~~~~~~
Doing arithmetic between or returning two different types of enums could
be a bug, so each of the instance of the warning needs to be evaluated.
Unfortunately, as mentioned above, there are many instances of this
warning in many different configurations, which can break the build when
CONFIG_WERROR is enabled.
To avoid introducing new instances of the warnings while cleaning up the
disruption for the majority of users, disable these warnings for the
default build while leaving them on for W=1 builds.
Cc: stable@vger.kernel.org
Closes: https://github.com/ClangBuiltLinux/linux/issues/2002
Link: 8c2ae42b3e
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Pull Kbuild updates from Masahiro Yamada:
- Remove potentially incomplete targets when Kbuid is interrupted by
SIGINT etc in case GNU Make may miss to do that when stderr is piped
to another program.
- Rewrite the single target build so it works more correctly.
- Fix rpm-pkg builds with V=1.
- List top-level subdirectories in ./Kbuild.
- Ignore auto-generated __kstrtab_* and __kstrtabns_* symbols in
kallsyms.
- Avoid two different modules in lib/zstd/ having shared code, which
potentially causes building the common code as build-in and modular
back-and-forth.
- Unify two modpost invocations to optimize the build process.
- Remove head-y syntax in favor of linker scripts for placing
particular sections in the head of vmlinux.
- Bump the minimal GNU Make version to 3.82.
- Clean up misc Makefiles and scripts.
* tag 'kbuild-v6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (41 commits)
docs: bump minimal GNU Make version to 3.82
ia64: simplify esi object addition in Makefile
Revert "kbuild: Check if linker supports the -X option"
kbuild: rebuild .vmlinux.export.o when its prerequisite is updated
kbuild: move modules.builtin(.modinfo) rules to Makefile.vmlinux_o
zstd: Fixing mixed module-builtin objects
kallsyms: ignore __kstrtab_* and __kstrtabns_* symbols
kallsyms: take the input file instead of reading stdin
kallsyms: drop duplicated ignore patterns from kallsyms.c
kbuild: reuse mksysmap output for kallsyms
mksysmap: update comment about __crc_*
kbuild: remove head-y syntax
kbuild: use obj-y instead extra-y for objects placed at the head
kbuild: hide error checker logs for V=1 builds
kbuild: re-run modpost when it is updated
kbuild: unify two modpost invocations
kbuild: move vmlinux.o rule to the top Makefile
kbuild: move .vmlinux.objs rule to Makefile.modpost
kbuild: list sub-directories in ./Kbuild
Makefile.compiler: replace cc-ifversion with compiler-specific macros
...
Pull kernel hardening updates from Kees Cook:
"Most of the collected changes here are fixes across the tree for
various hardening features (details noted below).
The most notable new feature here is the addition of the memcpy()
overflow warning (under CONFIG_FORTIFY_SOURCE), which is the next step
on the path to killing the common class of "trivially detectable"
buffer overflow conditions (i.e. on arrays with sizes known at compile
time) that have resulted in many exploitable vulnerabilities over the
years (e.g. BleedingTooth).
This feature is expected to still have some undiscovered false
positives. It's been in -next for a full development cycle and all the
reported false positives have been fixed in their respective trees.
All the known-bad code patterns we could find with Coccinelle are also
either fixed in their respective trees or in flight.
The commit message in commit 54d9469bc5 ("fortify: Add run-time WARN
for cross-field memcpy()") for the feature has extensive details, but
I'll repeat here that this is a warning _only_, and is not intended to
actually block overflows (yet). The many patches fixing array sizes
and struct members have been landing for several years now, and we're
finally able to turn this on to find any remaining stragglers.
Summary:
Various fixes across several hardening areas:
- loadpin: Fix verity target enforcement (Matthias Kaehlcke).
- zero-call-used-regs: Add missing clobbers in paravirt (Bill
Wendling).
- CFI: clean up sparc function pointer type mismatches (Bart Van
Assche).
- Clang: Adjust compiler flag detection for various Clang changes
(Sami Tolvanen, Kees Cook).
- fortify: Fix warnings in arch-specific code in sh, ARM, and xen.
Improvements to existing features:
- testing: improve overflow KUnit test, introduce fortify KUnit test,
add more coverage to LKDTM tests (Bart Van Assche, Kees Cook).
- overflow: Relax overflow type checking for wider utility.
New features:
- string: Introduce strtomem() and strtomem_pad() to fill a gap in
strncpy() replacement needs.
- um: Enable FORTIFY_SOURCE support.
- fortify: Enable run-time struct member memcpy() overflow warning"
* tag 'hardening-v6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (27 commits)
Makefile.extrawarn: Move -Wcast-function-type-strict to W=1
hardening: Remove Clang's enable flag for -ftrivial-auto-var-init=zero
sparc: Unbreak the build
x86/paravirt: add extra clobbers with ZERO_CALL_USED_REGS enabled
x86/paravirt: clean up typos and grammaros
fortify: Convert to struct vs member helpers
fortify: Explicitly check bounds are compile-time constants
x86/entry: Work around Clang __bdos() bug
ARM: decompressor: Include .data.rel.ro.local
fortify: Adjust KUnit test for modular build
sh: machvec: Use char[] for section boundaries
kunit/memcpy: Avoid pathological compile-time string size
lib: Improve the is_signed_type() kunit test
LoadPin: Require file with verity root digests to have a header
dm: verity-loadpin: Only trust verity targets with enforcement
LoadPin: Fix Kconfig doc about format of file with verity digests
um: Enable FORTIFY_SOURCE
lkdtm: Update tests for memcpy() run-time warnings
fortify: Add run-time WARN for cross-field memcpy()
fortify: Use SIZE_MAX instead of (size_t)-1
...
-Wformat was recently re-enabled for builds with clang, then quickly
re-disabled, due to concerns stemming from the frequency of default
argument promotion related warning instances.
commit 258fafcd06 ("Makefile.extrawarn: re-enable -Wformat for clang")
commit 21f9c8a13b ("Revert "Makefile.extrawarn: re-enable -Wformat for clang"")
ISO WG14 has ratified N2562 to address default argument promotion
explicitly for printf, as part of the upcoming ISO C2X standard.
The behavior of clang was changed in clang-16 to not warn for the cited
cases in all language modes.
Add a version check, so that users of clang-16 now get the full effect
of -Wformat. For older clang versions, re-enable flags under the
-Wformat group that way users still get some useful checks related to
format strings, without noisy default argument promotion warnings. I
intentionally omitted -Wformat-y2k and -Wformat-security from being
re-enabled, which are also part of -Wformat in clang-16.
Link: https://github.com/ClangBuiltLinux/linux/issues/378
Link: https://github.com/llvm/llvm-project/issues/57102
Link: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2562.pdf
Suggested-by: Justin Stitt <jstitt007@gmail.com>
Suggested-by: Nathan Chancellor <nathan@kernel.org>
Suggested-by: Youngmin Nam <youngmin.nam@samsung.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are no instances of this warning in the tree across several
difference architectures and configurations. This was added by
commit 26ea6bb1fe ("kbuild, LLVMLinux: Supress warnings unless W=1-3")
back in 2014, where it might have been necessary, but there are no
instances of it now so stop disabling it to increase warning coverage
for clang.
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This reverts commit 258fafcd06.
The clang -Wformat warning is terminally broken, and the clang people
can't seem to get their act together.
This test program causes a warning with clang:
#include <stdio.h>
int main(int argc, char **argv)
{
printf("%hhu\n", 'a');
}
resulting in
t.c:5:19: warning: format specifies type 'unsigned char' but the argument has type 'int' [-Wformat]
printf("%hhu\n", 'a');
~~~~ ^~~
%d
and apparently clang people consider that a feature, because they don't
want to face the reality of how either C character constants, C
arithmetic, and C varargs functions work.
The rest of the world just shakes their head at that kind of
incompetence, and turns off -Wformat for clang again.
And no, the "you should use a pointless cast to shut this up" is not a
valid answer. That warning should not exist in the first place, or at
least be optinal with some "-Wformat-me-harder" kind of option.
[ Admittedly, there's also very little reason to *ever* use '%hh[ud]' in
C, but what little reason there is is entirely about 'I want to see
only the low 8 bits of the argument'. So I would suggest nobody ever
use that format in the first place, but if they do, the clang
behavious is simply always wrong. Because '%hhu' takes an 'int'. It's
that simple. ]
Reported-by: Sudip Mukherjee (Codethink) <sudipm.mukherjee@gmail.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's been an ongoing mission to re-enable the -Wformat warning for
Clang. A previous attempt at enabling the warning showed that there were
many instances of this warning throughout the codebase. The sheer amount
of these warnings really polluted builds and thus -Wno-format was added
to _temporarily_ toggle them off.
After many patches the warning has largely been eradicated for x86,
x86_64, arm, and arm64 on a variety of configs. The time to enable the
warning has never been better as it seems for the first time we are
ahead of them and can now solve them as they appear rather than tackling
from a backlog.
As to the root cause of this large backlog of warnings, Clang seems to
pickup on some more nuanced cases of format warnings caused by implicit
integer conversion as well as default argument promotions from
printf-like functions.
Link: https://github.com/ClangBuiltLinux/linux/issues/378
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
When developing new code/feature, CONFIG_WERROR is most
often turned off, especially for people using make W=12 to
get more warnings.
In such case, turning on -Werror temporarily would require
switching on CONFIG_WERROR in the configuration, building,
then switching off CONFIG_WERROR.
For this use case, this patch introduces a new 'e' modifier
to W= as a short hand for KCFLAGS+=-Werror" so that -Werror
got added to the kernel (built-in) and modules' CFLAGS.
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
As a preparation for moving to -std=gnu11, turn off the
-Wshift-negative-value option. This warning is enabled by gcc when
building with -Wextra for c99 or higher, but not for c89. Since
the kernel already relies on well-defined overflow behavior,
the warning is not helpful and can simply be disabled in
all locations that use -Wextra.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com> # LLVM/Clang v13.0.0 (x86-64)
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
-Wunaligned-access is a new warning in clang that is default enabled for
arm and arm64 under certain circumstances within the clang frontend (see
LLVM commit below). On v5.17-rc2, an ARCH=arm allmodconfig build shows
1284 total/70 unique instances of this warning (most of the instances
are in header files), which is quite noisy.
To keep a normal build green through CONFIG_WERROR, only show this
warning with W=1, which will allow automated build systems to catch new
instances of the warning so that the total number can be driven down to
zero eventually since catching unaligned accesses at compile time would
be generally useful.
Cc: stable@vger.kernel.org
Link: 35737df4dc
Link: https://github.com/ClangBuiltLinux/linux/issues/1569
Link: https://github.com/ClangBuiltLinux/linux/issues/1576
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
The -Wnested-externs warning has become useless with gcc, since
this warns every time that BUILD_BUG_ON() or similar macros
are used.
With clang, the warning option does nothing to start with, so
just remove it entirely.
Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This warning behaves differently depending on the architecture
and compiler. Using x86 gcc, we get no output at all because
gcc knows the architecture can handle unaligned accesses.
Using x86 clang, or gcc on an architecture that needs to
manually deal with unaligned accesses, the build log is
completely flooded with these warnings, as they are commonly
invoked by inline functions of networking headers, e.g.
include/linux/skbuff.h:1426:26: warning: cast increases required alignment of target type [-Wcast-align]
The compiler is correct to point this out, as we are dealing
with undefined behavior that does cause problems in practice,
but there is also no good way to rewrite the code in commonly
included headers to a safer method.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This -Wsign-compare compiler warning can be very noisy
and most of the suggested conversions are unnecessary.
Make the warning W=3 so it's described under the
"can most likely be ignored" block.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Currently, we disable -Wtautological-compare, which in turn disables a
bunch of more specific tautological comparison warnings that are useful
for the kernel such as -Wtautological-bitwise-compare. See clang's
documentation below for the other warnings that are suppressed by
-Wtautological-compare. Now that all of the major/noisy warnings have
been fixed, enable -Wtautological-compare so that more issues can be
caught at build time by various continuous integration setups.
-Wtautological-constant-out-of-range-compare is kept disabled under a
normal build but visible at W=1 because there are places in the kernel
where a constant or variable size can change based on the kernel
configuration. These are not fixed in a clean/concise way and the ones
I have audited so far appear to be harmless. It is not a subgroup but
rather just one warning so we do not lose out on much coverage by
default.
Link: https://github.com/ClangBuiltLinux/linux/issues/488
Link: http://releases.llvm.org/10.0.0/tools/clang/docs/DiagnosticsReference.html#wtautological-compare
Link: https://bugs.llvm.org/show_bug.cgi?id=42666
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
GCC and Clang have different policy for -Wunused-function; GCC does not
warn unused static inline functions at all whereas Clang does if they
are defined in source files instead of included headers although it has
been suppressed since commit abb2ea7dfd ("compiler, clang: suppress
warning for unused static inline functions").
We often miss to delete unused functions where 'static inline' is used
in *.c files since there is no tool to detect them. Unused code remains
until somebody notices. For example, commit 075ddd7568 ("regulator:
core: remove unused rdev_get_supply()").
Let's remove __maybe_unused from the inline macro to allow Clang to
start finding unused static inline functions. For now, we do this only
for W=1 build since it is not a good idea to sprinkle warnings for the
normal build (e.g. 35 warnings for arch/x86/configs/x86_64_defconfig).
My initial attempt was to add -Wno-unused-function for no W= build
(https://lore.kernel.org/patchwork/patch/1120594/)
Nathan Chancellor pointed out that would weaken Clang's checks since
we would no longer get -Wunused-function without W=1. It is true GCC
would catch unused static non-inline functions, but it would weaken
Clang as a standalone compiler, at least.
Hence, here is a counter implementation. The current problem is, W=...
only controls compiler flags, which are globally effective. There is
no way to address only 'static inline' functions.
This commit defines KBUILD_EXTRA_WARN[123] corresponding to W=[123].
When KBUILD_EXTRA_WARN1 is defined, __maybe_unused is omitted from
the 'inline' macro.
The new macro __inline_maybe_unused makes the code a bit uglier, so I
hope we can remove it entirely after fixing most of the warnings.
If you contribute to code clean-up, please run "make CC=clang W=1"
and check -Wunused-function warnings. You will find lots of unused
functions.
Some of them are false-positives because the call-sites are disabled
by #ifdef. I do not like to abuse the inline keyword for suppressing
unused-function warnings because it is intended to be a hint for the
compiler optimization. I prefer #ifdef around the definition, or
__maybe_unused if #ifdef would make the code too ugly.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
KBUILD_ENABLE_EXTRA_GCC_CHECKS started as a switch to add extra warning
options for GCC, but now it is a historical misnomer since we use it
also for Clang, DTC, and even kernel-doc.
Rename it to more sensible, shorter KBUILD_EXTRA_WARN.
For the backward compatibility, KBUILD_ENABLE_EXTRA_GCC_CHECKS is still
supported (but not advertised in the documentation).
I also fixed up 'make help', and updated the documentation.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>
Instead of the warning-[123] magic, let's accumulate compiler options
to KBUILD_CFLAGS directly as the top Makefile does. I think this makes
it easier to understand what is going on in this file.
This commit slightly changes the behavior, I think all of which are OK.
[1] Currently, cc-option calls are needlessly evaluated. For example,
warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
needs evaluating only when W=3, but it is actually evaluated for
W=1, W=2 as well. With this commit, only relevant cc-option calls
will be evaluated. This is a slight optimization.
[2] Currently, unsupported level like W=4 is checked by:
$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
This will no longer be checked, but I do not think it is a big
deal.
[3] Currently, 4 Clang warnings (Winitializer-overrides, Wformat,
Wsign-compare, Wformat-zero-length) are shown by any of W=1, W=2,
and W=3. With this commit, they will be warned only by W=1. I
think this is a more correct behavior since each warning belongs
to only one group.
For understanding this commit correctly:
We have 3 warning groups, W=1, W=2, and W=3. You may think W=3 has a
higher level than W=1, but they are actually independent. If you like,
you can combine them like W=13. To enable all the warnings, you can
pass W=123. It is shown by 'make help', but not noticed much. Since we
support W= combination, there should not exist intersection among the
three groups. If we enable Winitializer-overrides for W=1, we do not
need to for W=2 or W=3. This is the reason why I think the change [3]
makes sense.
The documentation says -Winitializer-overrides is enabled by default.
(https://clang.llvm.org/docs/DiagnosticsReference.html#winitializer-overrides)
We negate it by passing -Wno-initializer-overrides for the normal
build, but we do not do that for W=1. This means, W=1 effectively
enables -Winitializer-overrides by the clang's default. The same for
the other three.
Add comments in case people are confused with the code.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
This flag turns off several other warnings that would
be useful. Most notably -warn_unused_result is disabled.
All of the following warnings are currently disabled:
UnusedValue
|-UnusedComparison
|-warn_unused_comparison
|-UnusedResult
|-warn_unused_result
|-UnevaluatedExpression
|-PotentiallyEvaluatedExpression
|-warn_side_effects_typeid
|-warn_side_effects_unevaluated_context
|-warn_unused_expr
|-warn_unused_voidptr
|-warn_unused_container_subscript_expr
|-warn_unused_call
With this flag removed there are ~10 warnings.
Patches have been submitted for each of these warnings.
Reported-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: clang-built-linux@googlegroups.com
Link: https://github.com/ClangBuiltLinux/linux/issues/520
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
It makes little sense to pass -Waggregate-return these days since large
part of the linux kernel rely on returning struct(s). For instance:
../include/linux/timekeeping.h: In function 'show_uptime':
../include/linux/ktime.h:91:34: error: function call has aggregate value [-Werror=aggregate-return]
#define ktime_to_timespec64(kt) ns_to_timespec64((kt))
^~~~~~~~~~~~~~~~~~~~~~
../include/linux/timekeeping.h:166:8: note: in expansion of macro 'ktime_to_timespec64'
*ts = ktime_to_timespec64(ktime_get_coarse_boottime());
Remove this warning from W=2 completely.
Signed-off-by: Mathieu Malaterre <malat@debian.org>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
We do not support old Clang versions. Upgrade your clang version
if any of these flags is unsupported.
Let's add all flags inside ifdef CONFIG_CC_IS_CLANG unconditionally.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Sedat Dilek <sedat.dilek@gmail.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>
