From: Marco Elver <elver@xxxxxxxxxx>
Subject: 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,
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/20211201152604.3984495-1-elver@xxxxxxxxxx
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/Kconfig | 2 +-
lib/Kconfig.debug | 2 ++
2 files changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/Kconfig~kcov-fix-generic-kconfig-dependencies-if-arch_wants_no_instr
+++ a/arch/x86/Kconfig
@@ -78,7 +78,7 @@ config X86
select ARCH_HAS_FILTER_PGPROT
select ARCH_HAS_FORTIFY_SOURCE
select ARCH_HAS_GCOV_PROFILE_ALL
- select ARCH_HAS_KCOV if X86_64 && STACK_VALIDATION
+ select ARCH_HAS_KCOV if X86_64
select ARCH_HAS_MEM_ENCRYPT
select ARCH_HAS_MEMBARRIER_SYNC_CORE
select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
--- a/lib/Kconfig.debug~kcov-fix-generic-kconfig-dependencies-if-arch_wants_no_instr
+++ a/lib/Kconfig.debug
@@ -1979,6 +1979,8 @@ config KCOV
bool "Code coverage for fuzzing"
depends on ARCH_HAS_KCOV
depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
+ depends on !ARCH_WANTS_NO_INSTR || STACK_VALIDATION || \
+ GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
select DEBUG_FS
select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
help
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