[PATCH 1/2] compiler_attributes.h: define __no_profile, add to noinstr

Nick Desaulniers
2021-06-18T23:30:50Z

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

Cc: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Link: https://lore.kernel.org/lkml/20210614162018.GD68749@worktop.programming.kicks-ass.net/
Link: https://reviews.llvm.org/D104475
Link: https://reviews.llvm.org/D104257
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80223
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
---
include/linux/compiler_attributes.h | 12 ++++++++++++
include/linux/compiler_types.h | 2 +-
2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/linux/compiler_attributes.h b/include/linux/compiler_attributes.h
index c043b8d2b17b..cf584a1908b3 100644
--- a/include/linux/compiler_attributes.h
+++ b/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 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 +238,17 @@
# define __nonstring
#endif

+/*
+ * Optional: only supported since clang >= 13
+ * gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80223
+ * clang: https://clang.llvm.org/docs/AttributeReference.html#no_profile
+ */
+#if __has_attribute(__no_profile__)
+# define __no_profile __attribute__((__no_profile__))
+#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
diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
index d29bda7f6ebd..d509169860f1 100644
--- a/include/linux/compiler_types.h
+++ b/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__ */

--
2.32.0.288.g62a8d224e6-goog