bece04b5b4
Until recent versions of GCC and Clang, it was not possible to disable KCOV instrumentation via a function attribute. The relevant function attribute was introduced in540540d06e("kcov: add __no_sanitize_coverage to fix noinstr for all architectures"). x86 was the first architecture to want a working noinstr, and at the time no compiler support for the attribute existed yet. Therefore, commit0f1441b44e("objtool: Fix noinstr vs KCOV") introduced the ability to NOP __sanitizer_cov_*() calls in .noinstr.text. However, this doesn't work for other architectures like arm64 and s390 that want a working noinstr per ARCH_WANTS_NO_INSTR. At the time of0f1441b44e, we didn't yet have ARCH_WANTS_NO_INSTR, but now we can move the Kconfig dependency checks to the generic KCOV option. KCOV will be available if: - architecture does not care about noinstr, OR - we have objtool support (like on x86), OR - GCC is 12.0 or newer, OR - Clang is 13.0 or newer. Link: https://lkml.kernel.org/r/20211201152604.3984495-1-elver@google.com Signed-off-by: Marco Elver <elver@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Nick Desaulniers <ndesaulniers@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.