Commit e91946d6 authored by Nathan Chancellor's avatar Nathan Chancellor Committed by Thomas Bogendoerfer
Browse files

MIPS: VDSO: Move disabling the VDSO logic to Kconfig 



After commit 9553d16f ("init/kconfig: Add LD_VERSION Kconfig"), we
have access to GNU ld's version at configuration time. As a result, we
can make it clearer under what configuration circumstances the MIPS VDSO
needs to be disabled.

This is a prerequisite for getting rid of the MIPS VDSO binutils
warning and linking the VDSO when LD is ld.lld. Wrapping the call to
ld-ifversion with CONFIG_LD_IS_LLD does not work because the config
values are wiped away during 'make clean'.

Signed-off-by: default avatarNathan Chancellor <natechancellor@gmail.com>
Signed-off-by: default avatarThomas Bogendoerfer <tsbogend@alpha.franken.de>
parent b744b43f

arch/mips/Kconfig

+2 −0
Original line number Diff line number Diff line
@@ -3214,3 +3214,5 @@ endmenu 
source "drivers/firmware/Kconfig"



source "arch/mips/kvm/Kconfig"



source "arch/mips/vdso/Kconfig"

arch/mips/vdso/Kconfig

0 → 100644
+18 −0
Original line number Diff line number Diff line 
# For the pre-R6 code in arch/mips/vdso/vdso.h for locating

# the base address of VDSO, the linker will emit a R_MIPS_PC32

# relocation in binutils > 2.25 but it will fail with older versions

# because that relocation is not supported for that symbol. As a result

# of which we are forced to disable the VDSO symbols when building

# with < 2.25 binutils on pre-R6 kernels. For more references on why we

# can't use other methods to get the base address of VDSO please refer to

# the comments on that file.

#

# GCC (at least up to version 9.2) appears to emit function calls that make use

# of the GOT when targeting microMIPS, which we can't use in the VDSO due to

# the lack of relocations. As such, we disable the VDSO for microMIPS builds.



config MIPS_LD_CAN_LINK_VDSO

	def_bool LD_VERSION >= 225000000



config MIPS_DISABLE_VDSO

	def_bool CPU_MICROMIPS || (!CPU_MIPSR6 && !MIPS_LD_CAN_LINK_VDSO)

arch/mips/vdso/Makefile

+2 −28
Original line number Diff line number Diff line
@@ -52,37 +52,11 @@ endif 


CFLAGS_REMOVE_vgettimeofday.o = -pg



DISABLE_VDSO := n



#

# For the pre-R6 code in arch/mips/vdso/vdso.h for locating

# the base address of VDSO, the linker will emit a R_MIPS_PC32

# relocation in binutils > 2.25 but it will fail with older versions

# because that relocation is not supported for that symbol. As a result

# of which we are forced to disable the VDSO symbols when building

# with < 2.25 binutils on pre-R6 kernels. For more references on why we

# can't use other methods to get the base address of VDSO please refer to

# the comments on that file.

#

ifndef CONFIG_CPU_MIPSR6

  ifeq ($(call ld-ifversion, -lt, 225000000, y),y)

ifdef CONFIG_MIPS_DISABLE_VDSO

  ifndef CONFIG_MIPS_LD_CAN_LINK_VDSO

    $(warning MIPS VDSO requires binutils >= 2.25)

    DISABLE_VDSO := y

  endif

endif



#

# GCC (at least up to version 9.2) appears to emit function calls that make use

# of the GOT when targeting microMIPS, which we can't use in the VDSO due to

# the lack of relocations. As such, we disable the VDSO for microMIPS builds.

#

ifdef CONFIG_CPU_MICROMIPS

  DISABLE_VDSO := y

endif



ifeq ($(DISABLE_VDSO),y)

  obj-vdso-y := $(filter-out vgettimeofday.o, $(obj-vdso-y))

  ccflags-vdso += -DDISABLE_MIPS_VDSO

endif



# VDSO linker flags.

arch/mips/vdso/vdso.lds.S

+1 −1
Original line number Diff line number Diff line
@@ -91,7 +91,7 @@ PHDRS 
VERSION

{

	LINUX_2.6 {

#ifndef DISABLE_MIPS_VDSO

#ifndef CONFIG_MIPS_DISABLE_VDSO

	global:

		__vdso_clock_gettime;

		__vdso_gettimeofday;

CRA Git | Maintained and supported by SUSTech CRA and CCSE