• Marco Elver's avatar
    kcov: fix generic Kconfig dependencies if ARCH_WANTS_NO_INSTR · bece04b5
    Marco Elver authored
    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 in 540540d0 ("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,
    commit 0f1441b4 ("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 of 0f1441b4, 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.comSigned-off-by: default avatarMarco Elver <elver@google.com>
    Reviewed-by: default avatarNathan Chancellor <nathan@kernel.org>
    Acked-by: default avatarPeter 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: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    bece04b5
Kconfig.debug 86.9 KB