[PATCH 1/4] arm64: capabilities: add nopti command line argument
From: Mark Langsdorf <hidden>
Date: 2018-05-24 19:09:29
Subsystem:
arm64 port (aarch64 architecture), documentation, the rest · Maintainers:
Catalin Marinas, Will Deacon, Jonathan Corbet, Linus Torvalds
The x86 kernel and the documentation use 'nopti' as the kernel command line argument to disable kernel page table isolation, so add nopti to the arm64 kernel for compatibility. Signed-off-by: Mark Langsdorf <redacted> --- Documentation/admin-guide/kernel-parameters.txt | 6 +++--- arch/arm64/kernel/cpufeature.c | 11 ++++++++++- 2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index f2040d4..a987725 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt@@ -3342,8 +3342,8 @@ pt. [PARIDE] See Documentation/blockdev/paride.txt. - pti= [X86_64] Control Page Table Isolation of user and - kernel address spaces. Disabling this feature + pti= [X86_64, ARM64] Control Page Table Isolation of user + and kernel address spaces. Disabling this feature removes hardening, but improves performance of system calls and interrupts.
@@ -3354,7 +3354,7 @@ Not specifying this option is equivalent to pti=auto. - nopti [X86_64] + nopti [X86_64, ARM64] Equivalent to pti=off pty.legacy_count=
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 9d1b06d..7c5d8712 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c@@ -934,10 +934,19 @@ static int __init parse_kpti(char *str) if (ret) return ret; - __kpti_forced = enabled ? 1 : -1; + if (!__kpti_forced) + __kpti_forced = enabled ? 1 : -1; return 0; } __setup("kpti=", parse_kpti); + +/* for compatibility with documentation and x86 nopti command line arg */ +static int __init force_nokpti(char *arg) +{ + __kpti_forced = -1; + return 0; +} +early_param("nopti", force_nokpti); #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */ #ifdef CONFIG_ARM64_HW_AFDBM
--
2.9.5