diff options
| -rw-r--r-- | arch/arm64/Kconfig | 25 | ||||
| -rw-r--r-- | arch/arm64/Makefile | 35 | ||||
| -rw-r--r-- | arch/arm64/kernel/Makefile | 3 |
3 files changed, 61 insertions, 2 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index a72be105b83a..2e9931d9f1e4 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1234,6 +1234,31 @@ config KEYS_COMPAT def_bool y depends on COMPAT && KEYS +config COMPAT_VDSO + bool "32-bit vDSO" + depends on COMPAT + select ARM_ARCH_TIMER_VCT_ACCESS + default n + help + Warning: a 32-bit toolchain is necessary to build the vDSO. You + must explicitly define which toolchain should be used by setting + CROSS_COMPILE_ARM32 to the prefix of the 32-bit toolchain (same format + as CROSS_COMPILE). If CROSS_COMPILE_ARM32 is empty, a warning will be + printed and the kernel will be built as if COMPAT_VDSO had not been + set. If CROSS_COMPILE_ARM32 is set to an invalid prefix, compilation + will be aborted. + + Provide a vDSO to 32-bit processes. It includes the symbols provided + by the vDSO from the 32-bit kernel, so that a 32-bit libc can use + the compat vDSO without modification. It also provides sigreturn + trampolines, replacing the sigreturn page. + +config CROSS_COMPILE_ARM32 + string "32-bit toolchain prefix" + help + Same as setting CROSS_COMPILE_ARM32 in the environment, but saved for + future builds. The environment variable overrides this config option. + endmenu menu "Power management options" diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index e8361ff258f2..6a5994163f24 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -30,6 +30,35 @@ $(warning LSE atomics not supported by binutils) endif endif +ifeq ($(CONFIG_COMPAT_VDSO), y) + CROSS_COMPILE_ARM32 ?= $(CONFIG_CROSS_COMPILE_ARM32:"%"=%) + + # Check that the user has provided a valid prefix for the 32-bit toolchain. + # To prevent selecting the system $(cc-name) by default, the prefix is not + # allowed to be empty, unlike CROSS_COMPILE. In the unlikely event that the + # system $(cc-name) is actually the 32-bit ARM compiler to be used, the + # variable can be set to the dirname (e.g. CROSS_COMPILE_ARM32=/usr/bin/). + # Note: this Makefile is read both before and after regenerating the config + # (if needed). Any warning appearing before the config has been regenerated + # should be ignored. If the error is triggered and you set + # CONFIG_CROSS_COMPILE_ARM32, set CROSS_COMPILE_ARM32 to an appropriate value + # when invoking make and fix CONFIG_CROSS_COMPILE_ARM32. + ifeq ($(CROSS_COMPILE_ARM32),) + $(warning CROSS_COMPILE_ARM32 not defined or empty, the compat vDSO will not be built) + else ifeq ($(cc-name),clang) + export CLANG_TRIPLE_ARM32 ?= $(CROSS_COMPILE_ARM32) + export CLANG_TARGET_ARM32 := --target=$(notdir $(CLANG_TRIPLE_ARM32:%-=%)) + export CONFIG_VDSO32 := y + vdso32 := -DCONFIG_VDSO32=1 + else ifeq ($(shell which $(CROSS_COMPILE_ARM32)$(cc-name) 2> /dev/null),) + $(error $(CROSS_COMPILE_ARM32)$(cc-name) not found, check CROSS_COMPILE_ARM32) + else + export CROSS_COMPILE_ARM32 + export CONFIG_VDSO32 := y + vdso32 := -DCONFIG_VDSO32=1 + endif +endif + ifeq ($(cc-name),clang) # This is a workaround for https://bugs.llvm.org/show_bug.cgi?id=30792. # TODO: revert when this is fixed in LLVM. @@ -37,11 +66,11 @@ KBUILD_CFLAGS += -mno-implicit-float else KBUILD_CFLAGS += -mgeneral-regs-only endif -KBUILD_CFLAGS += $(lseinstr) +KBUILD_CFLAGS += $(lseinstr) $(vdso32) KBUILD_CFLAGS += -fno-pic KBUILD_CFLAGS += $(call cc-option, -mpc-relative-literal-loads) KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -KBUILD_AFLAGS += $(lseinstr) +KBUILD_AFLAGS += $(lseinstr) $(vdso32) ifeq ($(CONFIG_CPU_BIG_ENDIAN), y) KBUILD_CPPFLAGS += -mbig-endian @@ -152,6 +181,8 @@ archclean: prepare: vdso_prepare vdso_prepare: prepare0 $(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso include/generated/vdso-offsets.h + $(if $(CONFIG_VDSO32),$(Q)$(MAKE) $(build)=arch/arm64/kernel/vdso32 \ + include/generated/vdso32-offsets.h) define archhelp echo '* Image.gz - Compressed kernel image (arch/$(ARCH)/boot/Image.gz)' diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile index 89de53410f3a..18938199a838 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -27,7 +27,9 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE arm64-obj-$(CONFIG_COMPAT) += sys32.o signal32.o \ sys_compat.o entry32.o +ifneq ($(CONFIG_VDSO32),y) arm64-obj-$(CONFIG_COMPAT) += sigreturn32.o +endif arm64-obj-$(CONFIG_KUSER_HELPERS) += kuser32.o arm64-obj-$(CONFIG_FUNCTION_TRACER) += ftrace.o entry-ftrace.o arm64-obj-$(CONFIG_MODULES) += arm64ksyms.o module.o @@ -56,6 +58,7 @@ arm64-obj-$(CONFIG_HARDEN_BRANCH_PREDICTOR) += bpi.o endif obj-y += $(arm64-obj-y) vdso/ probes/ +obj-$(CONFIG_VDSO32) += vdso32/ obj-m += $(arm64-obj-m) head-y := head.o extra-y += $(head-y) vmlinux.lds |