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 540540d ("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 0f1441b ("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 0f1441b, 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]>

Author: melver

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

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