On Mon, Jun 21, 2021 at 04:18:22PM -0700, Nick Desaulniers wrote: > We don't want compiler instrumentation to touch noinstr functions, which > are annotated with the no_profile_instrument_function function > attribute. Add a Kconfig test for this and make PGO and GCOV depend on > it. > > If an architecture is using noinstr, it should denote that via this > Kconfig value. That makes Kconfigs that depend on noinstr able to > express dependencies in an architecturally agnostic way. > > Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx> > Cc: Peter Oberparleiter <oberpar@xxxxxxxxxxxxx> > Link: https://lore.kernel.org/lkml/YMTn9yjuemKFLbws@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > Link: https://lore.kernel.org/lkml/YMcssV%2Fn5IBGv4f0@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ > Suggested-by: Nathan Chancellor <nathan@xxxxxxxxxx> > Suggested-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Signed-off-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> FWIW, this looks good to me: Acked-by: Mark Rutland <mark.rutland@xxxxxxx> Catalin, Will, are you happy iwth the arm64 bit? Thanks, Makr. > --- > Changes V1 -> V2: > * Add ARCH_WANTS_NO_INSTR > * Change depdendencies to be !ARCH_WANTS_NO_INSTR || CC_HAS_NO_PROFILE_FN_ATTR > rather than list architectures explicitly, as per Nathan. > * s/no_profile/no_profile_instrument_function/ > > arch/Kconfig | 7 +++++++ > arch/arm64/Kconfig | 1 + > arch/s390/Kconfig | 1 + > arch/x86/Kconfig | 1 + > init/Kconfig | 3 +++ > kernel/gcov/Kconfig | 1 + > kernel/pgo/Kconfig | 3 ++- > 7 files changed, 16 insertions(+), 1 deletion(-) > > diff --git a/arch/Kconfig b/arch/Kconfig > index 2b4109b0edee..2113c6b3b801 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -285,6 +285,13 @@ config ARCH_THREAD_STACK_ALLOCATOR > config ARCH_WANTS_DYNAMIC_TASK_STRUCT > bool > > +config ARCH_WANTS_NO_INSTR > + bool > + help > + An architecure should select this if the noinstr macro is being used on > + functions to denote that the toolchain should avoid instrumenting such > + functions and is required for correctness. > + > config ARCH_32BIT_OFF_T > bool > depends on !64BIT > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 9f1d8566bbf9..39bf982b06f8 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -93,6 +93,7 @@ config ARM64 > select ARCH_WANT_FRAME_POINTERS > select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || (ARM64_16K_PAGES && !ARM64_VA_BITS_36) > select ARCH_WANT_LD_ORPHAN_WARN > + select ARCH_WANTS_NO_INSTR > select ARCH_HAS_UBSAN_SANITIZE_ALL > select ARM_AMBA > select ARM_ARCH_TIMER > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig > index b4c7c34069f8..bd60310f33b9 100644 > --- a/arch/s390/Kconfig > +++ b/arch/s390/Kconfig > @@ -117,6 +117,7 @@ config S390 > select ARCH_USE_BUILTIN_BSWAP > select ARCH_USE_CMPXCHG_LOCKREF > select ARCH_WANTS_DYNAMIC_TASK_STRUCT > + select ARCH_WANTS_NO_INSTR > select ARCH_WANT_DEFAULT_BPF_JIT > select ARCH_WANT_IPC_PARSE_VERSION > select BUILDTIME_TABLE_SORT > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig > index da43fd046149..7d6a44bb9b0e 100644 > --- a/arch/x86/Kconfig > +++ b/arch/x86/Kconfig > @@ -114,6 +114,7 @@ config X86 > select ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH > select ARCH_WANT_DEFAULT_BPF_JIT if X86_64 > select ARCH_WANTS_DYNAMIC_TASK_STRUCT > + select ARCH_WANTS_NO_INSTR > select ARCH_WANT_HUGE_PMD_SHARE > select ARCH_WANT_LD_ORPHAN_WARN > select ARCH_WANTS_THP_SWAP if X86_64 > diff --git a/init/Kconfig b/init/Kconfig > index 1ea12c64e4c9..31397a7a45fb 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -83,6 +83,9 @@ config TOOLS_SUPPORT_RELR > config CC_HAS_ASM_INLINE > def_bool $(success,echo 'void foo(void) { asm inline (""); }' | $(CC) -x c - -c -o /dev/null) > > +config CC_HAS_NO_PROFILE_FN_ATTR > + def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror) > + > config CONSTRUCTORS > bool > > diff --git a/kernel/gcov/Kconfig b/kernel/gcov/Kconfig > index 58f87a3092f3..053447183ac5 100644 > --- a/kernel/gcov/Kconfig > +++ b/kernel/gcov/Kconfig > @@ -5,6 +5,7 @@ config GCOV_KERNEL > bool "Enable gcov-based kernel profiling" > depends on DEBUG_FS > depends on !CC_IS_CLANG || CLANG_VERSION >= 110000 > + depends on !ARCH_WANTS_NO_INSTR || CC_HAS_NO_PROFILE_FN_ATTR > select CONSTRUCTORS > default n > help > diff --git a/kernel/pgo/Kconfig b/kernel/pgo/Kconfig > index d2053df1111c..ce7fe04f303d 100644 > --- a/kernel/pgo/Kconfig > +++ b/kernel/pgo/Kconfig > @@ -8,7 +8,8 @@ config PGO_CLANG > bool "Enable clang's PGO-based kernel profiling" > depends on DEBUG_FS > depends on ARCH_SUPPORTS_PGO_CLANG > - depends on CC_IS_CLANG && CLANG_VERSION >= 120000 > + depends on CC_IS_CLANG > + depends on !ARCH_WANTS_NO_INSTR || CC_HAS_NO_PROFILE_FN_ATTR > help > This option enables clang's PGO (Profile Guided Optimization) based > code profiling to better optimize the kernel. > -- > 2.32.0.288.g62a8d224e6-goog >
