[RFC PATCH riscv/for-next 1/4] riscv: align ftrace to 4 Byte boundary and increase ftrace prologue size

[Andy Chiu]

We are introducing a new ftrace mechanism in order to phase out
stop_machine() and enable kernel preemption. The new mechanism requires
ftrace patchable function entries to be 24 bytes and aligned to 4 Byte
boundaries.

Before applying this patch, the size of the kernel code, with 43432 of
ftrace entries, was at 12.31 MB. Under the same configuration, the size
has increased to 12.68 MB after applying this patch set.

Signed-off-by: Andy Chiu <andy.chiu at sifive.com>
Reviewed-by: Greentime Hu <greentime.hu at sifive.com>
Reviewed-by: Zong Li <zong.li at sifive.com>
---
 arch/riscv/Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile
index 1f19bdac6767..cb6cfdffc49c 100644
--- a/arch/riscv/Makefile
+++ b/arch/riscv/Makefile
@@ -11,7 +11,7 @@ LDFLAGS_vmlinux :=
 ifeq ($(CONFIG_DYNAMIC_FTRACE),y)
 	LDFLAGS_vmlinux := --no-relax
 	KBUILD_CPPFLAGS += -DCC_USING_PATCHABLE_FUNCTION_ENTRY
-	CC_FLAGS_FTRACE := -fpatchable-function-entry=8
+	CC_FLAGS_FTRACE := -fpatchable-function-entry=12  -falign-functions=4
 endif
 
 ifeq ($(CONFIG_CMODEL_MEDLOW),y)
-- 
2.36.0