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| author | Catalin Marinas <catalin.marinas@arm.com> | 2016-07-01 18:25:31 +0100 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2016-11-21 18:48:55 +0000 |
| commit | ba42822af1c287f038aa550f3578c61c212a892e (patch) | |
| tree | 7697e71a152e5294568b1a43695adcfeac08f166 /arch/arm64/Kconfig | |
| parent | 9cf09d68b89ae5fe0261dcc69464bcc676900af6 (diff) | |
| download | lwn-ba42822af1c287f038aa550f3578c61c212a892e.tar.gz lwn-ba42822af1c287f038aa550f3578c61c212a892e.zip | |
arm64: Enable CONFIG_ARM64_SW_TTBR0_PAN
This patch adds the Kconfig option to enable support for TTBR0 PAN
emulation. The option is default off because of a slight performance hit
when enabled, caused by the additional TTBR0_EL1 switching during user
access operations or exception entry/exit code.
Cc: Will Deacon <will.deacon@arm.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/Kconfig')
| -rw-r--r-- | arch/arm64/Kconfig | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 0b8227f23eed..e8dd55e7db38 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -794,6 +794,14 @@ config SETEND_EMULATION 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. + menu "ARMv8.1 architectural features" config ARM64_HW_AFDBM |