From: Alexander Graf <agraf@suse.de>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>, Richard Brown <rbrown@suse.de>,
Matthias Brugger <mbrugger@suse.com>
Subject: [PATCH v2] arm64: Make kpti command line options x86 compatible
Date: Tue, 13 Nov 2018 16:29:06 +0100 [thread overview]
Message-ID: <20181113152906.55802-1-agraf@suse.de> (raw)
I've already stumbled over 2 cases where people got confused about how to
disable kpti on AArch64. In both cases, they used existing x86_64 options
and just applied that to an AArch64 system, expecting it to work.
I think it makes a lot of sense to have compatible kernel command line
parameters whenever we can have them be compatible.
So this patch adds the pti= and no_pti kernel command line options, mapping
them into the existing kpti= command line framework. It preserves the old
syntax to maintain compatibility with older command lines.
While at it, the patch also marks the respective options as dual-arch.
Reported-by: Richard Brown <rbrown@suse.de>
Signed-off-by: Alexander Graf <agraf@suse.de>
---
v1 -> v2:
- Actually make it compile. Sorry for the sloppy v1.
---
Documentation/admin-guide/kernel-parameters.txt | 6 +++---
arch/arm64/kernel/cpufeature.c | 20 +++++++++++++++++++-
2 files changed, 22 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 81d1d5a74728..4a1c6bcfcdb5 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3522,8 +3522,8 @@
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.
@@ -3534,7 +3534,7 @@
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 af50064dea51..a67b4b563a7c 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -978,13 +978,31 @@ static int __init parse_kpti(char *str)
bool enabled;
int ret = strtobool(str, &enabled);
- if (ret)
+ if (ret) {
+ if (!strncmp(str, "auto", 4)) {
+ __kpti_forced = 0;
+ return 0;
+ }
return ret;
+ }
__kpti_forced = enabled ? 1 : -1;
return 0;
}
early_param("kpti", parse_kpti);
+
+static int __init parse_pti(char *str)
+{
+ return parse_kpti(str);
+}
+early_param("pti", parse_pti);
+
+static int __init parse_no_pti(char *p)
+{
+ __kpti_forced = -1;
+ return 0;
+}
+early_param("nopti", parse_no_pti);
#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
#ifdef CONFIG_ARM64_HW_AFDBM
--
2.12.3
next reply other threads:[~2018-11-13 15:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-13 15:29 Alexander Graf [this message]
2018-11-15 15:47 ` [PATCH v2] arm64: Make kpti command line options x86 compatible Will Deacon
2018-11-15 16:49 ` Alexander Graf
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