powerpc: Suppress .eh_frame generation

GCC v8 defaults to enabling -fasynchronous-unwind-tables due to
https://gcc.gnu.org/r259298, which results in .eh_frame section being
generated. This results in additional disk usage by the build, as well
as the kernel modules. Since the kernel has no use for this, this
section is discarded.

Add -fno-asynchronous-unwind-tables to KBUILD_CFLAGS to suppress
generation of .eh_frame section. Note that our VDSOs need .eh_frame, but
are not affected by this change since our VDSO code are all in assembly.

Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1ed7cd84a7d1a3180b30c0c60e70eed8bb8b40c3.1583415544.git.naveen.n.rao@linux.vnet.ibm.com

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 89956c4f1ce3b137140a101bd310230cecbec93e..f310c32e88a4ecacb0ad5f075402ce88288e848c 100644 (file)
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -239,6 +239,9 @@ KBUILD_CFLAGS += $(call cc-option,-mno-vsx)
 KBUILD_CFLAGS += $(call cc-option,-mno-spe)
 KBUILD_CFLAGS += $(call cc-option,-mspe=no)
 
+# Don't emit .eh_frame since we have no use for it
+KBUILD_CFLAGS += -fno-asynchronous-unwind-tables
+
 # Never use string load/store instructions as they are
 # often slow when they are implemented at all
 KBUILD_CFLAGS          += $(call cc-option,-mno-string)