compiler_attributes.h: define __no_profile, add to noinstr

noinstr implies that we would like the compiler to avoid instrumenting a
function.  Add support for the compiler attribute
no_profile_instrument_function to compiler_attributes.h, then add
__no_profile to the definition of noinstr.

Link: https://lore.kernel.org/lkml/20210614162018.GD68749@worktop.programming.kicks-ass.net/
Link: https://reviews.llvm.org/D104257
Link: https://reviews.llvm.org/D104475
Link: https://reviews.llvm.org/D104658
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80223Reviewed-by: Fangrui Song <maskray@google.com>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210621231822.2848305-2-ndesaulniers@google.com

include/linux/compiler_attributes.h

@@ -33,6 +33,7 @@
 # define __GCC4_has_attribute___externally_visible__  1
 # define __GCC4_has_attribute___no_caller_saved_registers__ 0
 # define __GCC4_has_attribute___noclone__             1
+# define __GCC4_has_attribute___no_profile_instrument_function__ 0
 # define __GCC4_has_attribute___nonstring__           0
 # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
 # define __GCC4_has_attribute___no_sanitize_undefined__ (__GNUC_MINOR__ >= 9)
@@ -237,6 +238,18 @@
 # define __nonstring
 #endif
 
+/*
+ * Optional: only supported since GCC >= 7.1, clang >= 13.0.
+ *
+ *      gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute
+ *    clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function
+ */
+#if __has_attribute(__no_profile_instrument_function__)
+# define __no_profile                  __attribute__((__no_profile_instrument_function__))
+#else
+# define __no_profile
+#endif
+
 /*
  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
  * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn

include/linux/compiler_types.h

@@ -210,7 +210,7 @@ struct ftrace_likely_data {
 /* Section for code which can't be instrumented at all */
 #define noinstr								\
 	noinline notrace __attribute((__section__(".noinstr.text")))	\
-	__no_kcsan __no_sanitize_address
+	__no_kcsan __no_sanitize_address __no_profile
 
 #endif /* __KERNEL__ */