kernel: use KCFLAGS for passing EXTRA_OPTIMIZATION flags

This uses kernel's generic variable and doesn't require patching it with
a custom Makefile change. It's expected *not* to change any behaviour.

Signed-off-by: Rafał Miłecki <[email protected]>
(cherry picked from commit 1d42af720c6b6dcfcdd0b89bce386fca1607dcb3)
Signed-off-by: Kevin Darbyshire-Bryant <[email protected]>
(cherry picked from commit 24e27bec9a6df1511a504cf04cd9578a23e74657)

include/kernel.mk

@@ -101,7 +101,7 @@ endif
 KERNEL_MAKE = $(MAKE) $(KERNEL_MAKEOPTS)
 
 KERNEL_MAKE_FLAGS = \
-	KCFLAGS="$(call iremap,$(BUILD_DIR),$(notdir $(BUILD_DIR)))" \
+	KCFLAGS="$(call iremap,$(BUILD_DIR),$(notdir $(BUILD_DIR))) $(filter-out -fno-plt,$(call qstrip,$(CONFIG_EXTRA_OPTIMIZATION)))" \
 	HOSTCFLAGS="$(HOST_CFLAGS) -Wall -Wmissing-prototypes -Wstrict-prototypes" \
 	CROSS_COMPILE="$(KERNEL_CROSS)" \
 	ARCH="$(LINUX_KARCH)" \

rules.mk

@@ -62,7 +62,6 @@ ARCH_PACKAGES:=$(call qstrip,$(CONFIG_TARGET_ARCH_PACKAGES))
 BOARD:=$(call qstrip,$(CONFIG_TARGET_BOARD))
 SUBTARGET:=$(call qstrip,$(CONFIG_TARGET_SUBTARGET))
 TARGET_OPTIMIZATION:=$(call qstrip,$(CONFIG_TARGET_OPTIMIZATION))
-export EXTRA_OPTIMIZATION:=$(filter-out -fno-plt,$(call qstrip,$(CONFIG_EXTRA_OPTIMIZATION)))
 TARGET_SUFFIX=$(call qstrip,$(CONFIG_TARGET_SUFFIX))
 BUILD_SUFFIX:=$(call qstrip,$(CONFIG_BUILD_SUFFIX))
 SUBDIR:=$(patsubst $(TOPDIR)/%,%,${CURDIR})

target/linux/generic/pending-5.4/201-extra_optimization.patch

@@ -14,18 +14,12 @@ Signed-off-by: Felix Fietkau <[email protected]>
 
 --- a/Makefile
 +++ b/Makefile
-@@ -719,11 +719,11 @@ KBUILD_CFLAGS	+= $(call cc-disable-warni
- KBUILD_CFLAGS	+= $(call cc-disable-warning, address-of-packed-member)
-
- ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE
--KBUILD_CFLAGS += -O2
-+KBUILD_CFLAGS += -O2 $(EXTRA_OPTIMIZATION)
+@@ -723,7 +723,7 @@ KBUILD_CFLAGS += -O2
  else ifdef CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE_O3
--KBUILD_CFLAGS += -O3
-+KBUILD_CFLAGS += -O3 $(EXTRA_OPTIMIZATION)
+ KBUILD_CFLAGS += -O3
  else ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
 -KBUILD_CFLAGS += -Os
-+KBUILD_CFLAGS += -Os -fno-reorder-blocks -fno-tree-ch $(EXTRA_OPTIMIZATION)
++KBUILD_CFLAGS += -Os -fno-reorder-blocks -fno-tree-ch
  endif
 
  # Tell gcc to never replace conditional load with a non-conditional one