]> Git Repo - linux.git/commit
kcov: fix generic Kconfig dependencies if ARCH_WANTS_NO_INSTR
authorMarco Elver <[email protected]>
Thu, 20 Jan 2022 02:10:31 +0000 (18:10 -0800)
committerLinus Torvalds <[email protected]>
Thu, 20 Jan 2022 06:52:55 +0000 (08:52 +0200)
commitbece04b5b41dd7730dd06aec0d6b15c53d1fbb5a
tree80e2c0030164cc60b37aff27866f922067315081
parentbbd2e05fad3e692ff2495895975bd0fce02bdbae
kcov: fix generic Kconfig dependencies if ARCH_WANTS_NO_INSTR

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 540540d06e9d9 ("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 0f1441b44e823 ("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 0f1441b44e823, 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/[email protected]
Signed-off-by: Marco Elver <[email protected]>
Reviewed-by: Nathan Chancellor <[email protected]>
Acked-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Mark Rutland <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Nick Desaulniers <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Andrey Konovalov <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
arch/x86/Kconfig
lib/Kconfig.debug
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