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PR_GET_SPECULATION_CTRL(2const) — Linux manual page

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | STANDARDS | HISTORY | SEE ALSO | COLOPHON 

PR_GET_SPECULATION_CTRL(2const)          PR_GET_SPECULATION_CTRL(2const)

NAME         top

       PR_GET_SPECULATION_CTRL - get the state of a speculation
       misfeature for the calling thread

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

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

       int prctl(PR_GET_SPECULATION_CTRL, long misfeature, 0L, 0L, 0L);

DESCRIPTION         top

       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         top

       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         top

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

STANDARDS         top

       Linux.

HISTORY         top

       Linux 4.17.

SEE ALSO         top

       prctl(2), PR_SET_SPECULATION_CTRL(2const)

COLOPHON         top

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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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