powerpc: Build kernel with -mcmodel=medium
Finally remove the two level TOC and build with -mcmodel=medium.
Unfortunately we can't build modules with -mcmodel=medium due to
the tricks the kernel module loader plays with percpu data:
# -mcmodel=medium breaks modules because it uses 32bit offsets from
# the TOC pointer to create pointers where possible. Pointers into the
# percpu data area are created by this method.
#
# The kernel module loader relocates the percpu data section from the
# original location (starting with 0xd...) to somewhere in the base
# kernel percpu data space (starting with 0xc...). We need a full
# 64bit relocation for this to work, hence -mcmodel=large.
On older kernels we fall back to the two level TOC (-mminimal-toc)
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 78c2b02..31d8965 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -67,7 +67,24 @@
LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie
LDFLAGS_vmlinux := $(LDFLAGS_vmlinux-y)
-CFLAGS-$(CONFIG_PPC64) := -mminimal-toc -mtraceback=no -mcall-aixdesc
+ifeq ($(CONFIG_PPC64),y)
+ifeq ($(call cc-option-yn,-mcmodel=medium),y)
+ # -mcmodel=medium breaks modules because it uses 32bit offsets from
+ # the TOC pointer to create pointers where possible. Pointers into the
+ # percpu data area are created by this method.
+ #
+ # The kernel module loader relocates the percpu data section from the
+ # original location (starting with 0xd...) to somewhere in the base
+ # kernel percpu data space (starting with 0xc...). We need a full
+ # 64bit relocation for this to work, hence -mcmodel=large.
+ KBUILD_CFLAGS_MODULE += -mcmodel=large
+else
+ export NO_MINIMAL_TOC := -mno-minimal-toc
+endif
+endif
+
+CFLAGS-$(CONFIG_PPC64) := -mtraceback=no -mcall-aixdesc
+CFLAGS-$(CONFIG_PPC64) += $(call cc-option,-mcmodel=medium,-mminimal-toc)
CFLAGS-$(CONFIG_PPC32) := -ffixed-r2 -mmultiple
CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power7,-mtune=power4)