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Documentation: Add powerpc options for spec_store_bypass_disable 

Document the support for spec_store_bypass_disable that was added for
powerpc in commit a048a07d7f ("powerpc/64s: Add support for a store
forwarding barrier at kernel entry/exit").

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
This commit is contained in:
Michael Ellerman 2018-07-10 12:08:36 +10:00 committed by Jonathan Corbet
parent 9ac8c3bd50
commit 6b4c1360e8
1 changed files with 13 additions and 3 deletions
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16
Documentation/admin-guide/kernel-parameters.txt
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@ -4060,6 +4060,8 @@
This parameter controls whether the Speculative Store
Bypass optimization is used.
On x86 the options are:
on - Unconditionally disable Speculative Store Bypass
off - Unconditionally enable Speculative Store Bypass
auto - Kernel detects whether the CPU model contains an
@ -4075,12 +4077,20 @@
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"
On powerpc the options are:
on,auto - On Power8 and Power9 insert a store-forwarding
barrier on kernel entry and exit. On Power7
perform a software flush on kernel entry and
exit.
off - No action.
Not specifying this option is equivalent to
spec_store_bypass_disable=auto.
spia_io_base= [HW,MTD]
spia_fio_base=
spia_pedr=