mirror of https://github.com/OpenIPC/firmware.git
80 lines
3.6 KiB
Diff
80 lines
3.6 KiB
Diff
diff -drupN a/arch/x86/Makefile b/arch/x86/Makefile
|
|
--- a/arch/x86/Makefile 2018-08-06 17:23:04.000000000 +0300
|
|
+++ b/arch/x86/Makefile 2022-06-12 05:28:14.000000000 +0300
|
|
@@ -11,6 +11,16 @@ else
|
|
KBUILD_DEFCONFIG := $(ARCH)_defconfig
|
|
endif
|
|
|
|
+# For gcc stack alignment is specified with -mpreferred-stack-boundary,
|
|
+# clang has the option -mstack-alignment for that purpose.
|
|
+ifneq ($(call cc-option, -mpreferred-stack-boundary=4),)
|
|
+ cc_stack_align4 := -mpreferred-stack-boundary=2
|
|
+ cc_stack_align8 := -mpreferred-stack-boundary=3
|
|
+else ifneq ($(call cc-option, -mstack-alignment=16),)
|
|
+ cc_stack_align4 := -mstack-alignment=4
|
|
+ cc_stack_align8 := -mstack-alignment=8
|
|
+endif
|
|
+
|
|
# How to compile the 16-bit code. Note we always compile for -march=i386;
|
|
# that way we can complain to the user if the CPU is insufficient.
|
|
#
|
|
@@ -24,10 +34,11 @@ REALMODE_CFLAGS := $(M16_CFLAGS) -g -Os
|
|
-DDISABLE_BRANCH_PROFILING \
|
|
-Wall -Wstrict-prototypes -march=i386 -mregparm=3 \
|
|
-fno-strict-aliasing -fomit-frame-pointer -fno-pic \
|
|
- -mno-mmx -mno-sse \
|
|
- $(call cc-option, -ffreestanding) \
|
|
- $(call cc-option, -fno-stack-protector) \
|
|
- $(call cc-option, -mpreferred-stack-boundary=2)
|
|
+ -mno-mmx -mno-sse
|
|
+
|
|
+REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -ffreestanding)
|
|
+REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), -fno-stack-protector)
|
|
+REALMODE_CFLAGS += $(call __cc-option, $(CC), $(REALMODE_CFLAGS), $(cc_stack_align4))
|
|
export REALMODE_CFLAGS
|
|
|
|
# BITS is used as extension for files which are available in a 32 bit
|
|
@@ -64,8 +75,10 @@ ifeq ($(CONFIG_X86_32),y)
|
|
# with nonstandard options
|
|
KBUILD_CFLAGS += -fno-pic
|
|
|
|
- # prevent gcc from keeping the stack 16 byte aligned
|
|
- KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=2)
|
|
+ # Align the stack to the register width instead of using the default
|
|
+ # alignment of 16 bytes. This reduces stack usage and the number of
|
|
+ # alignment instructions.
|
|
+ KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align4))
|
|
|
|
# Disable unit-at-a-time mode on pre-gcc-4.0 compilers, it makes gcc use
|
|
# a lot more stack due to the lack of sharing of stacklots:
|
|
@@ -88,17 +101,25 @@ else
|
|
KBUILD_CFLAGS += -m64
|
|
|
|
# Align jump targets to 1 byte, not the default 16 bytes:
|
|
- KBUILD_CFLAGS += -falign-jumps=1
|
|
+ KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
|
|
|
|
# Pack loops tightly as well:
|
|
- KBUILD_CFLAGS += -falign-loops=1
|
|
+ KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
|
|
|
|
# Don't autogenerate traditional x87 instructions
|
|
KBUILD_CFLAGS += $(call cc-option,-mno-80387)
|
|
KBUILD_CFLAGS += $(call cc-option,-mno-fp-ret-in-387)
|
|
|
|
- # Use -mpreferred-stack-boundary=3 if supported.
|
|
- KBUILD_CFLAGS += $(call cc-option,-mpreferred-stack-boundary=3)
|
|
+ KBUILD_CFLAGS += -fno-pic
|
|
+
|
|
+ # By default gcc and clang use a stack alignment of 16 bytes for x86.
|
|
+ # However the standard kernel entry on x86-64 leaves the stack on an
|
|
+ # 8-byte boundary. If the compiler isn't informed about the actual
|
|
+ # alignment it will generate extra alignment instructions for the
|
|
+ # default alignment which keep the stack *mis*aligned.
|
|
+ # Furthermore an alignment to the register width reduces stack usage
|
|
+ # and the number of alignment instructions.
|
|
+ KBUILD_CFLAGS += $(call cc-option,$(cc_stack_align8))
|
|
|
|
# Use -mskip-rax-setup if supported.
|
|
KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)
|