[PATCH v4 3/5] powerpc/vdso: Refactor CFLAGS for CVDSO build

Christophe Leroy
2024-09-02T12:04:59Z

In order to avoid two much duplication when we add new VDSO
functionnalities in C like getrandom, refactor common CFLAGS.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
v3: Also refactor removed flags
---
arch/powerpc/kernel/vdso/Makefile | 32 +++++++++++++------------------
1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/arch/powerpc/kernel/vdso/Makefile b/arch/powerpc/kernel/vdso/Makefile
index c07a425b8f78..67fe79d26fae 100644
--- a/arch/powerpc/kernel/vdso/Makefile
+++ b/arch/powerpc/kernel/vdso/Makefile
@@ -10,28 +10,11 @@ obj-vdso64 = sigtramp64-64.o gettimeofday-64.o datapage-64.o cacheflush-64.o not

ifneq ($(c-gettimeofday-y),)
CFLAGS_vgettimeofday-32.o += -include $(c-gettimeofday-y)
- CFLAGS_vgettimeofday-32.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
- CFLAGS_vgettimeofday-32.o += $(call cc-option, -fno-stack-protector)
- CFLAGS_vgettimeofday-32.o += -DDISABLE_BRANCH_PROFILING
- CFLAGS_vgettimeofday-32.o += -ffreestanding -fasynchronous-unwind-tables
- CFLAGS_REMOVE_vgettimeofday-32.o = $(CC_FLAGS_FTRACE)
- CFLAGS_REMOVE_vgettimeofday-32.o += -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc
- # This flag is supported by clang for 64-bit but not 32-bit so it will cause
- # an unused command line flag warning for this file.
- ifdef CONFIG_CC_IS_CLANG
- CFLAGS_REMOVE_vgettimeofday-32.o += -fno-stack-clash-protection
- endif
- CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y)
- CFLAGS_vgettimeofday-64.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
- CFLAGS_vgettimeofday-64.o += $(call cc-option, -fno-stack-protector)
- CFLAGS_vgettimeofday-64.o += -DDISABLE_BRANCH_PROFILING
- CFLAGS_vgettimeofday-64.o += -ffreestanding -fasynchronous-unwind-tables
- CFLAGS_REMOVE_vgettimeofday-64.o = $(CC_FLAGS_FTRACE)
# Go prior to 1.16.x assumes r30 is not clobbered by any VDSO code. That used to be true
# by accident when the VDSO was hand-written asm code, but may not be now that the VDSO is
# compiler generated. To avoid breaking Go tell GCC not to use r30. Impact on code
# generation is minimal, it will just use r29 instead.
- CFLAGS_vgettimeofday-64.o += $(call cc-option, -ffixed-r30)
+ CFLAGS_vgettimeofday-64.o += -include $(c-gettimeofday-y) $(call cc-option, -ffixed-r30)
endif

# Build rules
@@ -49,6 +32,11 @@ targets += $(obj-vdso64) vdso64.so.dbg vgettimeofday-64.o
obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))

ccflags-y := -fno-common -fno-builtin
+ccflags-y += $(DISABLE_LATENT_ENTROPY_PLUGIN)
+ccflags-y += $(call cc-option, -fno-stack-protector)
+ccflags-y += -DDISABLE_BRANCH_PROFILING
+ccflags-y += -ffreestanding -fasynchronous-unwind-tables
+ccflags-remove-y := $(CC_FLAGS_FTRACE)
ldflags-y := -Wl,--hash-style=both -nostdlib -shared -z noexecstack $(CLANG_FLAGS)
ldflags-$(CONFIG_LD_IS_LLD) += $(call cc-option,--ld-path=$(LD),-fuse-ld=lld)
ldflags-$(CONFIG_LD_ORPHAN_WARN) += -Wl,--orphan-handling=$(CONFIG_LD_ORPHAN_WARN_LEVEL)
@@ -57,6 +45,12 @@ ldflags-$(CONFIG_LD_ORPHAN_WARN) += -Wl,--orphan-handling=$(CONFIG_LD_ORPHAN_WAR
ldflags-y += $(filter-out $(CC_AUTO_VAR_INIT_ZERO_ENABLER) $(CC_FLAGS_FTRACE) -Wa$(comma)%, $(KBUILD_CFLAGS))

CC32FLAGS := -m32
+CC32FLAGSREMOVE := -mcmodel=medium -mabi=elfv1 -mabi=elfv2 -mcall-aixdesc
+ # This flag is supported by clang for 64-bit but not 32-bit so it will cause
+ # an unused command line flag warning for this file.
+ifdef CONFIG_CC_IS_CLANG
+CC32FLAGSREMOVE += -fno-stack-clash-protection
+endif
LD32FLAGS := -Wl,-soname=linux-vdso32.so.1
AS32FLAGS := -D__VDSO32__

@@ -105,7 +99,7 @@ quiet_cmd_vdso32ld_and_check = VDSO32L $@
quiet_cmd_vdso32as = VDSO32A $@
cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) $(AS32FLAGS) -c -o $@ $<
quiet_cmd_vdso32cc = VDSO32C $@
- cmd_vdso32cc = $(VDSOCC) $(c_flags) $(CC32FLAGS) -c -o $@ $<
+ cmd_vdso32cc = $(VDSOCC) $(filter-out $(CC32FLAGSREMOVE), $(c_flags)) $(CC32FLAGS) -c -o $@ $<

quiet_cmd_vdso64ld_and_check = VDSO64L $@
cmd_vdso64ld_and_check = $(VDSOCC) $(ldflags-y) $(LD64FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^); $(cmd_vdso_check)
--
2.44.0