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Mon, 01 Oct 2018 11:04:56 -0700 (PDT) From: Mark Salyzyn To: linux-kernel@vger.kernel.org Subject: RESEND [PATCH v2 6/6] arm64: Wire up and expose the new compat vDSO Date: Mon, 1 Oct 2018 10:58:43 -0700 Message-Id: <20181001175845.168430-24-salyzyn@android.com> X-Mailer: git-send-email 2.19.0.605.g01d371f741-goog In-Reply-To: <20181001175845.168430-1-salyzyn@android.com> References: <20181001175845.168430-1-salyzyn@android.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181001_110509_477750_0A5C2C8C X-CRM114-Status: GOOD ( 23.57 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , Laura Abbott , Kees Cook , Ard Biesheuvel , Marc Zyngier , Catalin Marinas , Kevin Brodsky , Will Deacon , Russell King , Jeremy Linton , Mark Salyzyn , android-kernel@android.com, Masahiro Yamada , James Morse , Andrew Pinski , Dmitry Safonov , Andy Gross , John Stultz , Thomas Gleixner , Andy Lutomirski , linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP From: Kevin Brodsky Expose the new compat vDSO via the COMPAT_VDSO config option. The option is not enabled in defconfig because we really need a 32-bit compiler this time, and we rely on the user to provide it themselves by setting CROSS_COMPILE_ARM32. Therefore enabling the option by default would make little sense, since the user must explicitly set a non-standard environment variable anyway. CONFIG_COMPAT_VDSO is not directly used in the code, because we want to ignore it (build as if it were not set) if the user didn't set CROSS_COMPILE_ARM32. If the variable has been set to a valid prefix, CONFIG_VDSO32 will be set; this is the option that the code and Makefiles test. For more flexibility, like CROSS_COMPILE, CROSS_COMPILE_ARM32 can also be set via CONFIG_CROSS_COMPILE_ARM32 (the environment variable overrides the config option, as expected). Signed-off-by: Kevin Brodsky Signed-off-by: Mark Salyzyn Tested-by: Mark Salyzyn Cc: James Morse Cc: Russell King Cc: Catalin Marinas Cc: Will Deacon Cc: Andy Lutomirski Cc: Dmitry Safonov Cc: John Stultz Cc: Mark Rutland Cc: Laura Abbott Cc: Kees Cook Cc: Ard Biesheuvel Cc: Andy Gross Cc: Andrew Pinski Cc: Thomas Gleixner Cc: linux-kernel@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org Cc: Jeremy Linton Cc: android-kernel@android.com v2: rebase --- arch/arm64/Kconfig | 24 ++++++++++++++++++++++++ arch/arm64/Makefile | 36 ++++++++++++++++++++++++++++++++++-- arch/arm64/kernel/Makefile | 3 +++ 3 files changed, 61 insertions(+), 2 deletions(-) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6e61f01108cb..4ed2f93a9607 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1335,6 +1335,30 @@ config SYSVIPC_COMPAT def_bool y depends on COMPAT && SYSVIPC +config COMPAT_VDSO + bool "32-bit vDSO" + depends on COMPAT + 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. + menu "Power management options" source "kernel/power/Kconfig" diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 106039d25e2f..ed6c3c6fb8f8 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -49,9 +49,39 @@ $(warning Detected assembler with broken .inst; disassembly will be unreliable) endif endif -KBUILD_CFLAGS += -mgeneral-regs-only $(lseinstr) $(brokengasinst) +ifeq ($(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),) + $(error CROSS_COMPILE_ARM32 not defined or empty, the compat vDSO will not be built) + else ifeq ($(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 + +KBUILD_CFLAGS += -mgeneral-regs-only $(lseinstr) $(brokengasinst) $(vdso32) KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -KBUILD_AFLAGS += $(lseinstr) $(brokengasinst) +KBUILD_CFLAGS += $(call cc-option, -mpc-relative-literal-loads) +KBUILD_AFLAGS += $(lseinstr) $(brokengasinst) $(vdso32) KBUILD_CFLAGS += $(call cc-option,-mabi=lp64) KBUILD_AFLAGS += $(call cc-option,-mabi=lp64) @@ -156,6 +186,8 @@ 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 1c2bd2210f58..6eca683fc5a8 100644 --- a/arch/arm64/kernel/Makefile +++ b/arch/arm64/kernel/Makefile @@ -29,7 +29,9 @@ $(obj)/%.stub.o: $(obj)/%.o FORCE arm64-obj-$(CONFIG_COMPAT) += sys32.o signal32.o \ sys_compat.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-$(CONFIG_MODULES) += arm64ksyms.o module.o @@ -61,6 +63,7 @@ arm64-obj-$(CONFIG_ARM_SDE_INTERFACE) += sdei.o arm64-obj-$(CONFIG_ARM64_SSBD) += ssbd.o 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