arm64: Silence gcc warnings about arch ABI drift

Since GCC 9, the compiler warns about evolution of the
platform-specific ABI, in particular relating for the marshaling of
certain structures involving bitfields.

The kernel is a standalone binary, and of course nobody would be
so stupid as to expose structs containing bitfields as function
arguments in ABI.  (Passing a pointer to such a struct, however
inadvisable, should be unaffected by this change.  perf and various
drivers rely on that.)

So these warnings do more harm than good: turn them off.

We may miss warnings about future ABI drift, but that's too bad.
Future ABI breaks of this class will have to be debugged and fixed
the traditional way unless the compiler evolves finer-grained
diagnostics.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
[sw0312.kim: backport mainline commit ebcc5928c5d9 for gcc 9 build]
Signed-off-by: Seung-Woo Kim <sw0312.kim@samsung.com>
Change-Id: I42f221ba946ed70fe770eb3d501a48e837f0377d

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 0c5f70e..80b8f0b 100644 (file)
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -52,6 +52,7 @@ endif
 KBUILD_CFLAGS  += -mgeneral-regs-only $(lseinstr) $(brokengasinst)
 KBUILD_CFLAGS  += -fno-asynchronous-unwind-tables
 KBUILD_CFLAGS  += $(call cc-option, -mpc-relative-literal-loads)
+KBUILD_CFLAGS  += -Wno-psabi
 KBUILD_AFLAGS  += $(lseinstr) $(brokengasinst)
 
 KBUILD_CFLAGS  += $(call cc-option,-mabi=lp64)