freebsd-skq/share/man/man9/vm_map_protect.9
dougm bde6cfd229 Document the KERN_PROTECTION_FAILURE return value from vm_map_protect().
Reviewed by: alc (earlier version)
Approved by: kib, markj (mentors)
Differential Revision: https://reviews.freebsd.org/D20751
2019-06-25 17:27:37 +00:00

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.Dd June 20, 2019
.Dt VM_MAP_PROTECT 9
.Os
.Sh NAME
.Nm vm_map_protect
.Nd apply protection bits to a virtual memory region
.Sh SYNOPSIS
.In sys/param.h
.In vm/vm.h
.In vm/vm_map.h
.Ft int
.Fo vm_map_protect
.Fa "vm_map_t map" "vm_offset_t start" "vm_offset_t end" "vm_prot_t new_prot"
.Fa "boolean_t set_max"
.Fc
.Sh DESCRIPTION
The
.Fn vm_map_protect
function sets the protection bits of the address region bounded by
.Fa start
and
.Fa end
within the map
.Fa map
to
.Fa new_prot .
The value specified by
.Fa new_prot
may not include any protection bits that are not set in
.Va max_protection
on every entry within the range.
.Pp
If
.Fa set_max
is TRUE,
.Fa new_prot
is treated as the new
.Va max_protection
setting for each underlying entry.
Protection bits not included
.Fa new_prot
will be cleared from existing entries.
If
.Fa set_max
is FALSE only the
.Va protection
field is affected.
.Pp
The range MUST be contiguous, and MUST NOT contain sub-maps.
.Sh IMPLEMENTATION NOTES
The function acquires a lock on the
.Fa map
for the duration, by calling
.Xr vm_map_lock 9 .
.Sh RETURN VALUES
The
.Fn vm_map_protect
function returns
.Dv KERN_SUCCESS
if the protection bits could be set successfully.
.Pp
If a sub-map entry was encountered in the range,
.Dv KERN_INVALID_ARGUMENT
is returned.
If the value of
.Fa new_prot
would exceed
.Va max_protection
for an entry within the range,
.Dv KERN_PROTECTION_FAILURE
is returned.
If a copy-on-write mapping is transitioned from read-only to
read-write, and too little swap space is available for backing the
copied pages,
.Dv KERN_RESOURCE_SHORTAGE
is returned.
.Sh SEE ALSO
.Xr vm_map 9
.Sh AUTHORS
This manual page was written by
.An Bruce M Simpson Aq Mt bms@spc.org .