PR_SET_SPECULATION_CTRL(2const) — Linux manual page

PR_SET_SPECULATION_CTRL(2const)          PR_SET_SPECULATION_CTRL(2const)

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)

COLOPHON

       This page is part of the man-pages (Linux kernel and C library
       user-space interface documentation) project.  Information about
       the project can be found at 
       ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report
       for this manual page, see
       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
       This page was obtained from the tarball man-pages-6.9.1.tar.gz
       fetched from
       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
       2024-06-26.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-
       to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to
       man-pages@man7.org

Linux man-pages 6.9.1          2024-06-01PR_SET_SPECULATION_CTRL(2const)

Pages that refer to this page: prctl(2), PR_GET_SPECULATION_CTRL(2const)

---