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    Subject[PATCH 1/2] prctl: Add PR_SET_MM option description
    Date
    Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
    CC: Tejun Heo <tj@kernel.org>
    CC: Pavel Emelyanov <xemul@parallels.com>
    ---
    man2/prctl.2 | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
    1 files changed, 104 insertions(+), 0 deletions(-)

    diff --git a/man2/prctl.2 b/man2/prctl.2
    index effad2a..4d6244f 100644
    --- a/man2/prctl.2
    +++ b/man2/prctl.2
    @@ -378,6 +378,110 @@ Return the current per-process machine check kill policy.
    All unused
    .BR prctl ()
    arguments must be zero.
    +.TP
    +.BR PR_SET_MM " (since Linux 3.3)"
    +Allows a user to modify certain kernel memory map descriptor fields
    +of the calling process.
    +Usually these fields are set by the kernel and dynamic loader (see
    +.BR ld.so (8)
    +for more information) and a regular application should not use this feature.
    +Still there are cases such as self-modifying programs, where a program might
    +find it useful to change its own memory map.
    +The kernel must be built with
    +.BR CONFIG_CHECKPOINT_RESTORE
    +option turned on, otherwise this feature will not be accessible
    +from a user space level.
    +The calling process must have
    +.BR CAP_SYS_ADMIN
    +(see
    +.BR capabilities (7)
    +for details) capability granted.
    +The value in
    +.I arg2
    +is one of the options below, while
    +.I arg3
    +provides a new value for this option.
    +
    +.BR PR_SET_MM_START_CODE
    +to set the address above which program text can run.
    +The corresponding memory area must be readable and executable,
    +but not writable or shareable (see
    +.BR mprotect (2)
    +and
    +.BR mmap (2)
    +for more information).
    +
    +.BR PR_SET_MM_END_CODE
    +to set the address below which program text can run.
    +The corresponding memory area must be readable and executable,
    +but not writable or shareable.
    +
    +.BR PR_SET_MM_START_DATA
    +to set the address above which program data+bss is placed.
    +The corresponding memory area must be readable and writable,
    +but not executable or shareable.
    +
    +.B PR_SET_MM_END_DATA
    +to set the address below which program data+bss is placed.
    +The corresponding memory area must be readable and writable,
    +but not executable or shareable.
    +
    +.BR PR_SET_MM_START_STACK
    +to set the start address of the stack.
    +The corresponding memory area must be readable and writable.
    +
    +.BR PR_SET_MM_START_BRK
    +to set the address above which program heap can be expanded with
    +.BR brk (2)
    +call.
    +The address must not be greater than ending address of
    +the current program data segment, neither it may exceed
    +resource limit for data (see
    +.BR setrlimit (2)
    +for more information).
    +
    +.BR PR_SET_MM_BRK
    +to set the current
    +.BR brk (2)
    +value.
    +The requirements for address are the same as for
    +.BR PR_SET_MM_START_BRK
    +option.
    +
    +.BR PR_SET_MM_ARG_START
    +to set the address above which program command line is placed.
    +
    +.BR PR_SET_MM_ARG_END
    +to set the address below which program command line is placed.
    +
    +.BR PR_SET_MM_ENV_START
    +to set the address above which program environment is placed.
    +
    +.BR PR_SET_MM_ENV_END
    +to set the address below which program environment is placed.
    +
    +The address passed with
    +.BR PR_SET_MM_ARG_START ,
    +.BR PR_SET_MM_ARG_END ,
    +.BR PR_SET_MM_ENV_START ,
    +.BR PR_SET_MM_ENV_END ,
    +should belong to a process stack area, thus corresponding memory area
    +must be readable, writable and (depending on the kernel
    +configuration) has
    +.BR MAP_GROWSDOWN
    +attribute set (see
    +.BR mmap (2)
    +for details).
    +
    +.BR PR_SET_MM_AUXV
    +to set a new auxiliary vector.
    +The
    +.I arg3
    +argument should provide the address of the vector.
    +The
    +.I arg4
    +is the size of the vector.
    +.\"
    .SH "RETURN VALUE"
    On success,
    .BR PR_GET_DUMPABLE ,
    --
    1.7.7.6


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