BACKPORT: compiler_types.h: Remove __compiletime_object_size()

Since all compilers support __builtin_object_size(), and there is only
one user of __compiletime_object_size, remove it to avoid the needless
indirection. This lets Clang reason about check_copy_size() correctly.

Link: ClangBuiltLinux/linux#1179
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Sedat Dilek <sedat.dilek@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: Arvind Sankar <nivedita@alum.mit.edu>
Cc: Masahiro Yamada <masahiroy@kernel.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Sami Tolvanen <samitolvanen@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Gabriel Krisman Bertazi <krisman@collabora.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: UtsavBalar1231 <utsavbalar1231@gmail.com>
Change-Id: Iaa0e99edc8a081aa31cc32d7684644e5833d9864
Signed-off-by: UtsavBalar1231 <utsavbalar1231@gmail.com>

include/linux/compiler-gcc.h

@@ -60,8 +60,6 @@
 
 #define __optimize(level)	__attribute__((__optimize__(level)))
 
-#define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
-
 #ifndef __CHECKER__
 #define __compiletime_warning(message) __attribute__((warning(message)))
 #define __compiletime_error(message) __attribute__((error(message)))

include/linux/compiler.h

@@ -328,10 +328,6 @@ static inline void *offset_to_ptr(const int *off)
 #define __noreorder
 #endif
 
-/* Compile time object size, -1 for unknown */
-#ifndef __compiletime_object_size
-# define __compiletime_object_size(obj) -1
-#endif
 #ifndef __compiletime_warning
 # define __compiletime_warning(message)
 #endif

include/linux/thread_info.h

@@ -137,7 +137,7 @@ static inline void copy_overflow(int size, unsigned long count)
 static __always_inline bool
 check_copy_size(const void *addr, size_t bytes, bool is_source)
 {
-	int sz = __compiletime_object_size(addr);
+	int sz = __builtin_object_size(addr, 0);
 	if (unlikely(sz >= 0 && sz < bytes)) {
 		if (!__builtin_constant_p(bytes))
 			copy_overflow(sz, bytes);