arm64: Silence gcc warnings about arch ABI drift

[ Upstream commit ebcc5928c5d925b1c8d968d9c89cdb0d0186db17 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 35649ee8ad56b69b85ddee57a6e29da4a0833156..c12ff63265a946bcd983100421d6709d116e5d3d 100644 (file)
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -51,6 +51,7 @@ endif
 
 KBUILD_CFLAGS  += -mgeneral-regs-only $(lseinstr) $(brokengasinst)
 KBUILD_CFLAGS  += -fno-asynchronous-unwind-tables
+KBUILD_CFLAGS  += -Wno-psabi
 KBUILD_AFLAGS  += $(lseinstr) $(brokengasinst)
 
 KBUILD_CFLAGS  += $(call cc-option,-mabi=lp64)