arm64: Kconfig: Make CONFIG_COMPAT_VDSO a proper Kconfig option

CONFIG_COMPAT_VDSO is defined by passing '-DCONFIG_COMPAT_VDSO' to the
compiler when the generic compat vDSO code is in use. It's much cleaner
and simpler to expose this as a proper Kconfig option (like x86 does),
so do that and remove the bodge.

Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
[bwh: Backported to 5.3: adjust context]

Gbp-Pq: Topic bugfix/arm64
Gbp-Pq: Name arm64-kconfig-make-config_compat_vdso-a-proper-kconf.patch

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index f63b824cdc2d3f79ff591986d9d0b9bd1f190a48..12326062cc01d5f608852bfc8faa5cade5552ece 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -111,7 +111,6 @@ config ARM64
        select GENERIC_STRNLEN_USER
        select GENERIC_TIME_VSYSCALL
        select GENERIC_GETTIMEOFDAY
-       select GENERIC_COMPAT_VDSO if (!CPU_BIG_ENDIAN && COMPAT && "$(CROSS_COMPILE_COMPAT)" != "")
        select HANDLE_DOMAIN_IRQ
        select HARDIRQS_SW_RESEND
        select HAVE_PCI
@@ -1149,7 +1148,7 @@ menuconfig COMPAT
 if COMPAT
 
 config KUSER_HELPERS
-       bool "Enable kuser helpers page for 32 bit applications"
+       bool "Enable kuser helpers page for 32-bit applications"
        default y
        help
          Warning: disabling this option may break 32-bit user programs.
@@ -1175,6 +1174,18 @@ config KUSER_HELPERS
          Say N here only if you are absolutely certain that you do not
          need these helpers; otherwise, the safe option is to say Y.
 
+config COMPAT_VDSO
+       bool "Enable vDSO for 32-bit applications"
+       depends on !CPU_BIG_ENDIAN && "$(CROSS_COMPILE_COMPAT)" != ""
+       select GENERIC_COMPAT_VDSO
+       default y
+       help
+         Place in the process address space of 32-bit applications an
+         ELF shared object providing fast implementations of gettimeofday
+         and clock_gettime.
+
+         You must have a 32-bit build of glibc 2.22 or later for programs
+         to seamlessly take advantage of this.
 
 menuconfig ARMV8_DEPRECATED
        bool "Emulate deprecated/obsolete ARMv8 instructions"

diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile
index 5858d6e4492681202b4fd9b7200f690970a19f07..47f2c00db90e81fbcc7851ba395ea9b240fc7eda 100644 (file)
--- a/arch/arm64/Makefile
+++ b/arch/arm64/Makefile
@@ -54,11 +54,6 @@ COMPATCC ?= $(CROSS_COMPILE_COMPAT)gcc
 endif
 export COMPATCC
 
-ifeq ($(CONFIG_GENERIC_COMPAT_VDSO), y)
-  export CONFIG_COMPAT_VDSO := y
-  compat_vdso := -DCONFIG_COMPAT_VDSO=1
-endif
-
 KBUILD_CFLAGS  += -mgeneral-regs-only $(lseinstr) $(brokengasinst) $(compat_vdso)
 KBUILD_CFLAGS  += -fno-asynchronous-unwind-tables
 KBUILD_CFLAGS  += $(call cc-disable-warning, psabi)