plucky (2) PR_SET_SPECULATION_CTRL.2const.gz

Provided by: manpages-dev_6.9.1-1_all bug

NAME
       PR_SET_SPECULATION_CTRL - set the state of a speculation misfeature for the calling thread


LIBRARY
       Standard C library (libc, -lc)


SYNOPSIS
       #include <linux/prctl.h>  /* Definition of PR_* constants */
       #include <sys/prctl.h>

       int prctl(PR_SET_SPECULATION_CTRL, long misfeature, long val, 0L, 0L);


DESCRIPTION
       Sets  the  state  of  the  speculation  misfeature  specified  in misfeature.  The speculation-misfeature
       settings are per-thread attributes.

       Currently, misfeature must be one of:

       PR_SPEC_STORE_BYPASS
              Set the state of the speculative store bypass misfeature.

       PR_SPEC_INDIRECT_BRANCH (since Linux 4.20)
              Set the state of the indirect branch speculation misfeature.

       The val argument is used to hand in the control value, which is one of the following:

       PR_SPEC_ENABLE
              The speculation feature is enabled, mitigation is disabled.

       PR_SPEC_DISABLE
              The speculation feature is disabled, mitigation is enabled.

       PR_SPEC_FORCE_DISABLE
              Same as PR_SPEC_DISABLE, but cannot be undone.

       PR_SPEC_DISABLE_NOEXEC (since Linux 5.1)
              Same as PR_SPEC_DISABLE, but the state will be cleared on execve(2).  Currently only supported for
              PR_SPEC_STORE_BYPASS.

       The  speculation  feature  can  also be controlled by the spec_store_bypass_disable boot parameter.  This
       parameter may enforce a read-only policy which will result in the prctl() call  failing  with  the  error
       ENXIO.  For further details, see the kernel source file Documentation/admin-guide/kernel-parameters.txt.


RETURN VALUE
       On success, 0 is returned.  On error, -1 is returned, and errno is set to indicate the error.


ERRORS
       ENODEV The kernel or CPU does not support the requested speculation misfeature.

       ENXIO  The  control  of the selected speculation misfeature is not possible.  See PR_GET_SPECULATION_CTRL
              for the bit fields to determine which option is available.

       EPERM  The speculation was disabled with PR_SPEC_FORCE_DISABLE and caller tried to enable it again.

       ERANGE misfeature is not a valid value.


STANDARDS
       Linux.


HISTORY
       Linux 4.17.


SEE ALSO
       prctl(2), PR_GET_SPECULATION_CTRL(2const)