PR_GET_SPECULATION_CTRL(2const) — Linux manual page

PR_GET_SPECULATION_CTRL(2const)          PR_GET_SPECULATION_CTRL(2const)

NAME

       PR_GET_SPECULATION_CTRL - get 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_GET_SPECULATION_CTRL, long misfeature, 0L, 0L, 0L);

DESCRIPTION

       Return the state of the speculation misfeature specified in
       misfeature.

       Currently, misfeature must be one of:

       PR_SPEC_STORE_BYPASS
              Get the state of the speculative store bypass misfeature.

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

       The return value uses bits 0-4 with the following meaning:

       PR_SPEC_PRCTL
              Mitigation can be controlled per thread by
              PR_SET_SPECULATION_CTRL(2const).

       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).

       If all bits are 0, then the CPU is not affected by the
       speculation misfeature.

       If PR_SPEC_PRCTL is set, then per-thread control of the
       mitigation is available.  If not set,
       PR_SET_SPECULATION_CTRL(2const) for the speculation misfeature
       will fail.

RETURN VALUE

       On success, PR_GET_SPECULATION_CTRL returns the nonnegative value
       described above.  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.

STANDARDS

       Linux.

HISTORY

       Linux 4.17.

SEE ALSO

       prctl(2), PR_SET_SPECULATION_CTRL(2const)

COLOPHON

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

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

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