| Message ID | 20220802133009.1282520-3-Ben.Wolsieffer@hefring.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Add support for FDPIC binaries on ARM | expand |
On 02/08/2022 15:30, Ben Wolsieffer wrote: > Linux on ARM supports FDPIC binaries intended for use on no-MMU systems. > This patch enables support for building a toolchain that produces FDPIC > binaries. > > Unfortunately, the target name for an FDPIC toolchain is a bit > idiosyncratic and must be arm-<vendor>-uclinuxfdpiceabi. This requires a > few special cases in the target construction code, since there is no > separate TARGET_OS field. > > According to the kernel help for CONFIG_BINFMT_ELF_FDPIC, "It is also > possible to run FDPIC ELF binaries on MMU linux," so FDPIC support is > available on all ARM platforms, not just no-MMU. > > Signed-off-by: Ben Wolsieffer <Ben.Wolsieffer@hefring.com> > --- > arch/Config.in | 1 + > package/Makefile.in | 30 +++++++++++++++++++++--------- > 2 files changed, 22 insertions(+), 9 deletions(-) > > diff --git a/arch/Config.in b/arch/Config.in > index c5d481b9e5..8dab58cf04 100644 > --- a/arch/Config.in > +++ b/arch/Config.in > @@ -39,6 +39,7 @@ config BR2_arceb > > config BR2_arm > bool "ARM (little endian)" > + select BR2_ARCH_HAS_FDPIC_SUPPORT > # MMU support is set by the subarchitecture file, arch/Config.in.arm > help > ARM is a 32-bit reduced instruction set computer (RISC) > diff --git a/package/Makefile.in b/package/Makefile.in > index ff60f85092..d75f620d82 100644 > --- a/package/Makefile.in > +++ b/package/Makefile.in > @@ -36,18 +36,21 @@ $(error BR2_TOOLCHAIN_BUILDROOT_VENDOR cannot be 'unknown'. \ > It might be confused with the native toolchain) > endif > > -# Compute GNU_TARGET_NAME > -GNU_TARGET_NAME = $(ARCH)-$(TARGET_VENDOR)-$(TARGET_OS)-$(LIBC)$(ABI) > - > # FLAT binary format needs uclinux, except RISC-V 64-bits which needs > # the regular linux name. > ifeq ($(BR2_BINFMT_FLAT):$(BR2_RISCV_64),y:) > TARGET_OS = uclinux > +# FDPIC binary format requires no OS field in target > +else ifeq ($(BR2_BINFMT_FDPIC),y) > +TARGET_OS = > else > TARGET_OS = linux > endif > > -ifeq ($(BR2_TOOLCHAIN_USES_UCLIBC),y) > +# FDPIC suffix must be -uclinuxfdpiceabi > +ifeq ($(BR2_BINFMT_FDPIC),y) > +LIBC = uclinux > +else ifeq ($(BR2_TOOLCHAIN_USES_UCLIBC),y) > LIBC = uclibc > else ifeq ($(BR2_TOOLCHAIN_USES_MUSL),y) > LIBC = musl > @@ -59,12 +62,14 @@ else > $(error No C library enabled, this is not possible.) > endif > > -# The ABI suffix is a bit special on ARM, as it needs to be > -# -uclibcgnueabi for uClibc EABI, and -gnueabi for glibc EABI. > -# This means that the LIBC and ABI aren't strictly orthogonal, > -# which explains why we need the test on LIBC below. > +# The ABI suffix is a bit special on ARM, as it needs to be -uclibcgnueabi > +# for uClibc EABI, -gnueabi for glibc EABI and -uclinuxfdpiceabi if FDPIC is > +# used. This means that the LIBC and ABI aren't strictly orthogonal, which > +# explains why we need the test on LIBC below. > ifeq ($(BR2_arm)$(BR2_armeb),y) > -ifeq ($(LIBC),uclibc) > +ifeq ($(BR2_BINFMT_FDPIC),y) > +ABI = fdpiceabi > +else ifeq ($(LIBC),uclibc) > ABI = gnueabi > else > ABI = eabi > @@ -90,6 +95,13 @@ TARGET_ABI += -mabi=spe -mfloat-gprs=double -Wa,-me500mc > endif > endif > > +# Compute GNU_TARGET_NAME > +ifeq ($(TARGET_OS),) > +GNU_TARGET_NAME = $(ARCH)-$(TARGET_VENDOR)-$(LIBC)$(ABI) > +else > +GNU_TARGET_NAME = $(ARCH)-$(TARGET_VENDOR)-$(TARGET_OS)-$(LIBC)$(ABI) > +endif I think all the special-casing for TARGET_OS, LIBC and ABI are way too complicated. None of these are used anywhere else (except LIBC which is also used in rust.mk - but Rust won't support FDPIC ever I think). So I think you should just put the special-casing here in GNU_TARGET_NAME itself: # The tuple for FDPIC on ARM is very special: it doesn't have the OS part, and # it must end with -uclinuxfdpiceabi ifeq ($(BR2_BINFMT_FDPIC),y) GNU_TARGET_NAME = $(ARCH)-$(TARGET_VENDOR)-uclinuxfdpiceabi else GNU_TARGET_NAME = $(ARCH)-$(TARGET_VENDOR)-$(TARGET_OS)-$(LIBC)$(ABI) endif If we ever add other architectures with FDPIC (RISC-V is a likely candidate), we may revisit that again, but for now this is sufficient. Regards, Arnout > + > # Use longcalls option for Xtensa globally. > # The 'longcalls' option allows calls across a greater range of addresses, > # and is required for some packages. While this option can degrade both
diff --git a/arch/Config.in b/arch/Config.in index c5d481b9e5..8dab58cf04 100644 --- a/arch/Config.in +++ b/arch/Config.in @@ -39,6 +39,7 @@ config BR2_arceb config BR2_arm bool "ARM (little endian)" + select BR2_ARCH_HAS_FDPIC_SUPPORT # MMU support is set by the subarchitecture file, arch/Config.in.arm help ARM is a 32-bit reduced instruction set computer (RISC) diff --git a/package/Makefile.in b/package/Makefile.in index ff60f85092..d75f620d82 100644 --- a/package/Makefile.in +++ b/package/Makefile.in @@ -36,18 +36,21 @@ $(error BR2_TOOLCHAIN_BUILDROOT_VENDOR cannot be 'unknown'. \ It might be confused with the native toolchain) endif -# Compute GNU_TARGET_NAME -GNU_TARGET_NAME = $(ARCH)-$(TARGET_VENDOR)-$(TARGET_OS)-$(LIBC)$(ABI) - # FLAT binary format needs uclinux, except RISC-V 64-bits which needs # the regular linux name. ifeq ($(BR2_BINFMT_FLAT):$(BR2_RISCV_64),y:) TARGET_OS = uclinux +# FDPIC binary format requires no OS field in target +else ifeq ($(BR2_BINFMT_FDPIC),y) +TARGET_OS = else TARGET_OS = linux endif -ifeq ($(BR2_TOOLCHAIN_USES_UCLIBC),y) +# FDPIC suffix must be -uclinuxfdpiceabi +ifeq ($(BR2_BINFMT_FDPIC),y) +LIBC = uclinux +else ifeq ($(BR2_TOOLCHAIN_USES_UCLIBC),y) LIBC = uclibc else ifeq ($(BR2_TOOLCHAIN_USES_MUSL),y) LIBC = musl @@ -59,12 +62,14 @@ else $(error No C library enabled, this is not possible.) endif -# The ABI suffix is a bit special on ARM, as it needs to be -# -uclibcgnueabi for uClibc EABI, and -gnueabi for glibc EABI. -# This means that the LIBC and ABI aren't strictly orthogonal, -# which explains why we need the test on LIBC below. +# The ABI suffix is a bit special on ARM, as it needs to be -uclibcgnueabi +# for uClibc EABI, -gnueabi for glibc EABI and -uclinuxfdpiceabi if FDPIC is +# used. This means that the LIBC and ABI aren't strictly orthogonal, which +# explains why we need the test on LIBC below. ifeq ($(BR2_arm)$(BR2_armeb),y) -ifeq ($(LIBC),uclibc) +ifeq ($(BR2_BINFMT_FDPIC),y) +ABI = fdpiceabi +else ifeq ($(LIBC),uclibc) ABI = gnueabi else ABI = eabi @@ -90,6 +95,13 @@ TARGET_ABI += -mabi=spe -mfloat-gprs=double -Wa,-me500mc endif endif +# Compute GNU_TARGET_NAME +ifeq ($(TARGET_OS),) +GNU_TARGET_NAME = $(ARCH)-$(TARGET_VENDOR)-$(LIBC)$(ABI) +else +GNU_TARGET_NAME = $(ARCH)-$(TARGET_VENDOR)-$(TARGET_OS)-$(LIBC)$(ABI) +endif + # Use longcalls option for Xtensa globally. # The 'longcalls' option allows calls across a greater range of addresses, # and is required for some packages. While this option can degrade both
Linux on ARM supports FDPIC binaries intended for use on no-MMU systems. This patch enables support for building a toolchain that produces FDPIC binaries. Unfortunately, the target name for an FDPIC toolchain is a bit idiosyncratic and must be arm-<vendor>-uclinuxfdpiceabi. This requires a few special cases in the target construction code, since there is no separate TARGET_OS field. According to the kernel help for CONFIG_BINFMT_ELF_FDPIC, "It is also possible to run FDPIC ELF binaries on MMU linux," so FDPIC support is available on all ARM platforms, not just no-MMU. Signed-off-by: Ben Wolsieffer <Ben.Wolsieffer@hefring.com> --- arch/Config.in | 1 + package/Makefile.in | 30 +++++++++++++++++++++--------- 2 files changed, 22 insertions(+), 9 deletions(-)