vm_map_protect9
Apply protection bits to a virtual memory region
Usage
#include <sys/param.h>
#include <vm/vm.h>
#include <vm/vm_map.h>
int
vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end, vm_prot_t new_prot, vm_prot_t new_maxprot, int flags);
Overview
The vm_map_protect() function sets the protection bits and maximum protection bits of the address region bounded by start and end within the map map.
If the flags argument has the VM_MAP_PROTECT_SET_PROT bit set, then the effective protection is set to new_prot.
If the flags argument has the VM_MAP_PROTECT_SET_MAXPROT bit set, then the maximum protection is set to new_maxprot. Protection bits not included into new_maxprot will be cleared from existing entries.
The values specified by new_prot and new_maxprot are not allowed to include any protection bits that are not set in existing max_protection on every entry within the range. The operation will fail if this condition is violated. For instance, this prevents upgrading a shared mapping of a read-only file from read-only to read-write.
The specified range must not contain sub-maps.
Implementation notes
The function acquires a lock on the map for the duration, by calling vm_map_lock(9). Also, any in-progress wiring operation on the map affecting the specified range will cause vm_map_protect to sleep, waiting for completion.
Return values
- KERN_SUCCESS
-
The specified protection bits were set successfully.
- KERN_INVALID_ARGUMENT
-
A sub-map entry was encountered in the range,
- KERN_PROTECTION_FAILURE
-
The value of new_prot or new_maxprot exceed max_protection for an entry within the range.
- KERN_PROTECTION_FAILURE
-
The map does not allow simultaneous setting of write and execute permissions, but new_prot has both VM_PROT_WRITE and VM_PROT_EXECUTE set.
- KERN_RESOURCE_SHORTAGE
-
A copy-on-write mapping is transitioned from read-only to read-write, and not enough swap space is available to back the copied pages.
- KERN_OUT_OF_BOUNDS
-
Both new protection and new maximum protection updates were requested, but the specified new_prot is not a subset of new_maxprot.
Releases
54 releases since FreeBSD 5.2-RELEASE; the text changed 36 times.