arm64: Kconfig: Make CONFIG_COMPAT a menuconfig entry
Make CONFIG_COMPAT a menuconfig entry so that we can place
CONFIG_KUSER_HELPERS and CONFIG_ARMV8_DEPRECATED underneath it.
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 0861a6f..75c1a07 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -1082,9 +1082,65 @@
This requires the linear region to be mapped down to pages,
which may adversely affect performance in some cases.
+config ARM64_SW_TTBR0_PAN
+ bool "Emulate Privileged Access Never using TTBR0_EL1 switching"
+ help
+ Enabling this option prevents the kernel from accessing
+ user-space memory directly by pointing TTBR0_EL1 to a reserved
+ zeroed area and reserved ASID. The user access routines
+ restore the valid TTBR0_EL1 temporarily.
+
+menuconfig COMPAT
+ bool "Kernel support for 32-bit EL0"
+ depends on ARM64_4K_PAGES || EXPERT
+ select COMPAT_BINFMT_ELF if BINFMT_ELF
+ select HAVE_UID16
+ select OLD_SIGSUSPEND3
+ select COMPAT_OLD_SIGACTION
+ help
+ This option enables support for a 32-bit EL0 running under a 64-bit
+ kernel at EL1. AArch32-specific components such as system calls,
+ the user helper functions, VFP support and the ptrace interface are
+ handled appropriately by the kernel.
+
+ If you use a page size other than 4KB (i.e, 16KB or 64KB), please be aware
+ that you will only be able to execute AArch32 binaries that were compiled
+ with page size aligned segments.
+
+ If you want to execute 32-bit userspace applications, say Y.
+
+if COMPAT
+
+config KUSER_HELPERS
+ bool "Enable kuser helpers page for 32 bit applications"
+ default y
+ help
+ Warning: disabling this option may break 32-bit user programs.
+
+ Provide kuser helpers to compat tasks. The kernel provides
+ helper code to userspace in read only form at a fixed location
+ to allow userspace to be independent of the CPU type fitted to
+ the system. This permits binaries to be run on ARMv4 through
+ to ARMv8 without modification.
+
+ See Documentation/arm/kernel_user_helpers.txt for details.
+
+ However, the fixed address nature of these helpers can be used
+ by ROP (return orientated programming) authors when creating
+ exploits.
+
+ If all of the binaries and libraries which run on your platform
+ are built specifically for your platform, and make no use of
+ these helpers, then you can turn this option off to hinder
+ such exploits. However, in that case, if a binary or library
+ relying on those helpers is run, it will not function correctly.
+
+ Say N here only if you are absolutely certain that you do not
+ need these helpers; otherwise, the safe option is to say Y.
+
+
menuconfig ARMV8_DEPRECATED
bool "Emulate deprecated/obsolete ARMv8 instructions"
- depends on COMPAT
depends on SYSCTL
help
Legacy software support may require certain instructions
@@ -1150,13 +1206,7 @@
If unsure, say Y
endif
-config ARM64_SW_TTBR0_PAN
- bool "Emulate Privileged Access Never using TTBR0_EL1 switching"
- help
- Enabling this option prevents the kernel from accessing
- user-space memory directly by pointing TTBR0_EL1 to a reserved
- zeroed area and reserved ASID. The user access routines
- restore the valid TTBR0_EL1 temporarily.
+endif
menu "ARMv8.1 architectural features"
@@ -1479,53 +1529,6 @@
endmenu
-config COMPAT
- bool "Kernel support for 32-bit EL0"
- depends on ARM64_4K_PAGES || EXPERT
- select COMPAT_BINFMT_ELF if BINFMT_ELF
- select HAVE_UID16
- select OLD_SIGSUSPEND3
- select COMPAT_OLD_SIGACTION
- help
- This option enables support for a 32-bit EL0 running under a 64-bit
- kernel at EL1. AArch32-specific components such as system calls,
- the user helper functions, VFP support and the ptrace interface are
- handled appropriately by the kernel.
-
- If you use a page size other than 4KB (i.e, 16KB or 64KB), please be aware
- that you will only be able to execute AArch32 binaries that were compiled
- with page size aligned segments.
-
- If you want to execute 32-bit userspace applications, say Y.
-
-config KUSER_HELPERS
- bool "Enable kuser helpers page for 32 bit applications."
- depends on COMPAT
- default y
- help
- Warning: disabling this option may break 32-bit user programs.
-
- Provide kuser helpers to compat tasks. The kernel provides
- helper code to userspace in read only form at a fixed location
- to allow userspace to be independent of the CPU type fitted to
- the system. This permits binaries to be run on ARMv4 through
- to ARMv8 without modification.
-
- See Documentation/arm/kernel_user_helpers.txt for details.
-
- However, the fixed address nature of these helpers can be used
- by ROP (return orientated programming) authors when creating
- exploits.
-
- If all of the binaries and libraries which run on your platform
- are built specifically for your platform, and make no use of
- these helpers, then you can turn this option off to hinder
- such exploits. However, in that case, if a binary or library
- relying on those helpers is run, it will not function correctly.
-
- 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 SYSVIPC_COMPAT
def_bool y
depends on COMPAT && SYSVIPC
