[RFC][PATCH] Update -Wattribute-alias for gcc9

[Laura Abbott <labbott@redhat.com>]

Commit bee20031772a ("disable -Wattribute-alias warning for
SYSCALL_DEFINEx()") disabled -Wattribute-alias with gcc8.
gcc9 changed the format of -Wattribute-alias to take a parameter.
This doesn't quite match with the existing disabling mechanism
so update for gcc9 to match with the default (-Wattribute-alias=1).

Signed-off-by: Laura Abbott <labbott@redhat.com>
---
This is RFC because it feels ugly. I went ahead and did the obvious fixup
but it's worth discussing if we're going to end up with an explosion or
if there's a better way to handle this in one macro.
---
 include/linux/compat.h       | 2 ++
 include/linux/compiler-gcc.h | 7 ++++++-
 include/linux/syscalls.h     | 2 ++
 3 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 056be0d03722..d5d7700f26a6 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -75,6 +75,8 @@
 	__diag_push();								\
 	__diag_ignore(GCC, 8, "-Wattribute-alias",				\
 		      "Type aliasing is used to sanitize syscall arguments");\
+	__diag_ignore(GCC, 9, "-Wattribute-alias=1",				\
+		      "Type aliasing is used to sanitize syscall arguments");\
 	asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__));	\
 	asmlinkage long compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))	\
 		__attribute__((alias(__stringify(__se_compat_sys##name))));	\
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index e8579412ad21..75079668344c 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -165,8 +165,13 @@
 #define __diag_str(s)		__diag_str1(s)
 #define __diag(s)		_Pragma(__diag_str(GCC diagnostic s))
 
-#if GCC_VERSION >= 80000
+#if GCC_VERSION >= 90000
+#define __diag_GCC_8(s)
+#define __diag_GCC_9(s)		__diag(s)
+#elif GCC_VERSION >= 80000
 #define __diag_GCC_8(s)		__diag(s)
+#define __diag_GCC_9(s)
 #else
 #define __diag_GCC_8(s)
+#define __diag_GCC_9(s)
 #endif
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 257cccba3062..a08059e1ccf4 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -236,6 +236,8 @@ static inline int is_syscall_trace_event(struct trace_event_call *tp_event)
 	__diag_push();							\
 	__diag_ignore(GCC, 8, "-Wattribute-alias",			\
 		      "Type aliasing is used to sanitize syscall arguments");\
+	__diag_ignore(GCC, 9, "-Wattribute-alias=1",			\
+		      "Type aliasing is used to sanitize syscall arguments");\
 	asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))	\
 		__attribute__((alias(__stringify(__se_sys##name))));	\
 	ALLOW_ERROR_INJECTION(sys##name, ERRNO);			\
-- 
2.20.1