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540540d06e
Until now no compiler supported an attribute to disable coverage
instrumentation as used by KCOV.
To work around this limitation on x86, noinstr functions have their
coverage instrumentation turned into nops by objtool. However, this
solution doesn't scale automatically to other architectures, such as
arm64, which are migrating to use the generic entry code.
Clang [1] and GCC [2] have added support for the attribute recently.
[1] 280333021e
[2] https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=cec4d4a6782c9bd8d071839c50a239c49caca689
The changes will appear in Clang 13 and GCC 12.
Add __no_sanitize_coverage for both compilers, and add it to noinstr.
Note: In the Clang case, __has_feature(coverage_sanitizer) is only true if
the feature is enabled, and therefore we do not require an additional
defined(CONFIG_KCOV) (like in the GCC case where __has_attribute(..) is
always true) to avoid adding redundant attributes to functions if KCOV is
off. That being said, compilers that support the attribute will not
generate errors/warnings if the attribute is redundantly used; however,
where possible let's avoid it as it reduces preprocessed code size and
associated compile-time overheads.
[elver@google.com: Implement __has_feature(coverage_sanitizer) in Clang]
Link: https://lkml.kernel.org/r/20210527162655.3246381-1-elver@google.com
[elver@google.com: add comment explaining __has_feature() in Clang]
Link: https://lkml.kernel.org/r/20210527194448.3470080-1-elver@google.com
Link: https://lkml.kernel.org/r/20210525175819.699786-1-elver@google.com
Signed-off-by: Marco Elver <elver@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Will Deacon <will@kernel.org>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
84 lines
2.8 KiB
C
84 lines
2.8 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_COMPILER_TYPES_H
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#error "Please don't include <linux/compiler-clang.h> directly, include <linux/compiler.h> instead."
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#endif
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/* Compiler specific definitions for Clang compiler */
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/* same as gcc, this was present in clang-2.6 so we can assume it works
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* with any version that can compile the kernel
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*/
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#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
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/* all clang versions usable with the kernel support KASAN ABI version 5 */
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#define KASAN_ABI_VERSION 5
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/*
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* Note: Checking __has_feature(*_sanitizer) is only true if the feature is
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* enabled. Therefore it is not required to additionally check defined(CONFIG_*)
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* to avoid adding redundant attributes in other configurations.
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*/
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#if __has_feature(address_sanitizer) || __has_feature(hwaddress_sanitizer)
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/* Emulate GCC's __SANITIZE_ADDRESS__ flag */
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#define __SANITIZE_ADDRESS__
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#define __no_sanitize_address \
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__attribute__((no_sanitize("address", "hwaddress")))
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#else
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#define __no_sanitize_address
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#endif
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#if __has_feature(thread_sanitizer)
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/* emulate gcc's __SANITIZE_THREAD__ flag */
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#define __SANITIZE_THREAD__
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#define __no_sanitize_thread \
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__attribute__((no_sanitize("thread")))
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#else
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#define __no_sanitize_thread
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#endif
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#if defined(CONFIG_ARCH_USE_BUILTIN_BSWAP)
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#define __HAVE_BUILTIN_BSWAP32__
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#define __HAVE_BUILTIN_BSWAP64__
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#define __HAVE_BUILTIN_BSWAP16__
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#endif /* CONFIG_ARCH_USE_BUILTIN_BSWAP */
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#if __has_feature(undefined_behavior_sanitizer)
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/* GCC does not have __SANITIZE_UNDEFINED__ */
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#define __no_sanitize_undefined \
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__attribute__((no_sanitize("undefined")))
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#else
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#define __no_sanitize_undefined
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#endif
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/*
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* Support for __has_feature(coverage_sanitizer) was added in Clang 13 together
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* with no_sanitize("coverage"). Prior versions of Clang support coverage
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* instrumentation, but cannot be queried for support by the preprocessor.
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*/
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#if __has_feature(coverage_sanitizer)
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#define __no_sanitize_coverage __attribute__((no_sanitize("coverage")))
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#else
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#define __no_sanitize_coverage
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#endif
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/*
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* Not all versions of clang implement the type-generic versions
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* of the builtin overflow checkers. Fortunately, clang implements
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* __has_builtin allowing us to avoid awkward version
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* checks. Unfortunately, we don't know which version of gcc clang
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* pretends to be, so the macro may or may not be defined.
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*/
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#if __has_builtin(__builtin_mul_overflow) && \
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__has_builtin(__builtin_add_overflow) && \
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__has_builtin(__builtin_sub_overflow)
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#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
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#endif
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#if __has_feature(shadow_call_stack)
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# define __noscs __attribute__((__no_sanitize__("shadow-call-stack")))
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#endif
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#define __nocfi __attribute__((__no_sanitize__("cfi")))
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#define __cficanonical __attribute__((__cfi_canonical_jump_table__))
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