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prctl.2: Various fixups to Konrad Rzeszutek Wilk's text 

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Michael Kerrisk 2018-05-28 12:49:23 +02:00
parent 2feab5d3b1
commit a01c1cbcc3
1 changed files with 27 additions and 29 deletions
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56
man2/prctl.2
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@ -1009,10 +1009,9 @@ See
.BR capabilities (7).
.TP
.BR PR_GET_SPECULATION_CTRL
Returns the state of the speculation misfeature which is selected with
the value of
.IR arg2 ,
which must be
Returns the state of the speculation misfeature specified in
.IR arg2 .
Currently, the only permitted value for this argument is
.BR PR_SPEC_STORE_BYPASS
(otherwise the call fails with the error
.BR ENODEV ).
@ -1045,26 +1044,27 @@ is set, then per-thread control of the mitigation is available.
If not set,
.BR prctl ()
for the speculation misfeature will fail.
In the above operation
.IP
The
.IR arg3 ,
.IR arg4 ,
and
.I arg5
must be specified as 0, otherwise the call fails with the error
arguments must be specified as 0; otherwise the call fails with the error
.BR EINVAL .
.TP
.BR PR_SET_SPECULATION_CTRL
Sets the state of the speculation misfeature which is selected with
the value of
.IR arg2 ,
which must be
Sets the state of the speculation misfeature specified in
.IR arg2 .
Currently, the only permitted value for this argument is
.B PR_SPEC_STORE_BYPASS
(otherwise the call fails with the error
.BR ENODEV ).
This control is per thread.
This setting is a per-thread attribute.
The
.IR arg3
argument is used to hand in the control value, which can be either:
argument is used to hand in the control value,
which is one of the following:
.RS
.TP
.BR PR_SPEC_ENABLE
@ -1088,23 +1088,23 @@ Any other value in
.IR arg3
will result in the call failing with the error
.BR ERANGE .
Also
.IP
The
.I arg4
and
.I arg5
must be specified as 0, otherwise the call fails with the rror
arguments must be specified as 0; otherwise the call fails with the error
.BR EINVAL .
.IP
Furtheremore this speculation feature can also be controlled by the boot-time
parameter of
.B
spec_store_bypass_disable=
Which could enforce a read-only policy which will result in the call failure
with the error
The speculation feature can also be controlled by the
.B spec_store_bypass_disable
boot parameter.
This parameter may enforce a read-only policy which will result in the
.BR prctl (2)
call failing with the error
.BR ENXIO .
Consult the
.B PR_GET_SPECULATION_CTRL
for details on the possible enumerations.
For further details, see the kernel source file
.IR Documentation/admin-guide/kernel-parameters.txt .
.TP
.BR PR_SET_THP_DISABLE " (since Linux 3.15)"
.\" commit a0715cc22601e8830ace98366c0c2bd8da52af52
@ -1698,13 +1698,11 @@ was
.BR PR_SET_SPECULATION_CTRL
and
.IR arg3
is incorrect - neither
.B PR_SPEC_ENABLE
is neither
.BR PR_SPEC_ENABLE ,
.BR PR_SPEC_DISABLE ,
nor
.B PR_SPEC_DISABLE
nor
.B PR_SPEC_FORCE_DISABLE
was choosen
.BR PR_SPEC_FORCE_DISABLE .
.TP
.B EINVAL
.I option