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authorKees Cook <keescook@chromium.org>2018-05-03 14:37:54 -0700
committerThomas Gleixner <tglx@linutronix.de>2018-05-05 00:51:45 +0200
commitf21b53b20c754021935ea43364dbf53778eeba32 (patch)
tree56c873b4f7dc9b7561858f8e7e4a6bfc2ba8eeeb /Documentation
parent8bf37d8c067bb7eb8e7c381bdadf9bd89182b6bc (diff)
downloadlinux-f21b53b20c754021935ea43364dbf53778eeba32.tar.bz2
x86/speculation: Make "seccomp" the default mode for Speculative Store Bypass
Unless explicitly opted out of, anything running under seccomp will have SSB mitigations enabled. Choosing the "prctl" mode will disable this. [ tglx: Adjusted it to the new arch_seccomp_spec_mitigate() mechanism ] Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt26
1 files changed, 17 insertions, 9 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index a8d2ae1e335b..f2040d46f095 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4049,19 +4049,27 @@
This parameter controls whether the Speculative Store
Bypass optimization is used.
- on - Unconditionally disable Speculative Store Bypass
- off - Unconditionally enable Speculative Store Bypass
- auto - Kernel detects whether the CPU model contains an
- implementation of Speculative Store Bypass and
- picks the most appropriate mitigation.
- prctl - Control Speculative Store Bypass per thread
- via prctl. Speculative Store Bypass is enabled
- for a process by default. The state of the control
- is inherited on fork.
+ on - Unconditionally disable Speculative Store Bypass
+ off - Unconditionally enable Speculative Store Bypass
+ auto - Kernel detects whether the CPU model contains an
+ implementation of Speculative Store Bypass and
+ picks the most appropriate mitigation. If the
+ CPU is not vulnerable, "off" is selected. If the
+ CPU is vulnerable the default mitigation is
+ architecture and Kconfig dependent. See below.
+ prctl - Control Speculative Store Bypass per thread
+ via prctl. Speculative Store Bypass is enabled
+ for a process by default. The state of the control
+ is inherited on fork.
+ seccomp - Same as "prctl" above, but all seccomp threads
+ will disable SSB unless they explicitly opt out.
Not specifying this option is equivalent to
spec_store_bypass_disable=auto.
+ Default mitigations:
+ X86: If CONFIG_SECCOMP=y "seccomp", otherwise "prctl"
+
spia_io_base= [HW,MTD]
spia_fio_base=
spia_pedr=