BSD syscalls: Virtual memory

Dispatch and catalog guide · Every number and configuration alternative

This page is generated from syscalls.master and authored descriptions.json. The signature is the master declaration, not the internal handler's (proc, args, retval) ABI. Descriptions identify selected local mechanisms; they do not claim every branch was audited.

65: msync

int msync(caddr_ut addr, size_ut len, int flags) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_MSYNC.

Synchronize mapped memory according to the requested flags.

Implementation: msync. msync_nocancel sanitizes the range and calls mach_vm_msync; the ordinary wrapper first tests cancellation. This operation is distinct from descriptor fsync.

73: munmap

int munmap(caddr_ut addr, size_ut len) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_MUNMAP.

Remove a process virtual-address range.

Implementation: munmap. munmap_sanitize checks/normalizes the range before mach_vm_deallocate_kernel removes it from the current map; error conversion is handled at the BSD boundary.

74: mprotect

int mprotect(caddr_ut addr, size_ut len, int prot) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_MPROTECT.

Change requested protections on a virtual range.

Implementation: mprotect. Sanitizes range/protection, applies MAC/code-signing checks and invokes mach_vm_protect; maximum protection and map/pmap policy can reject the change.

75: madvise

int madvise(caddr_ut addr, size_ut len, int behav);

Declaration: syscalls.master · Condition: always · Audit event: AUE_MADVISE.

Apply a virtual-memory behavior/advice request to a range.

Implementation: madvise. madvise_sanitize validates the behavior/range, then mach_vm_behavior_set selects the VM operation; advice modes have different reclaim/read-ahead semantics.

78: mincore

int mincore(caddr_ut addr, size_ut len, user_addr_t vec);

Declaration: syscalls.master · Condition: always · Audit event: AUE_MINCORE.

Report per-page residency/status information for a virtual range.

Implementation: mincore. Sanitizes the range, queries batches with vm_map_page_range_info_internal, translates page-state bits and copies the result vector out.

85: swapon

int swapon(void);

Declaration: syscalls.master · Condition: always · Audit event: AUE_SWAPON.

Preserve a historical swap-enable entry point.

Implementation: swapon. The body returns ENOTSUP; actual compressor/swap lifecycle is not configured through this legacy syscall here.

197: mmap

user_addr_t mmap(caddr_ut addr, size_ut len, int prot, int flags, int fd, off_t pos) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_MMAP.

Create a process virtual mapping from anonymous memory or a supported descriptor.

Implementation: mmap. Sanitizes address/size/protection/flags, resolves file or shared-memory backing and authorization, then enters Mach VM mapping with translated inheritance/copy/protection options; the returned address is copied through the syscall result ABI.

203: mlock

int mlock(caddr_ut addr, size_ut len);

Declaration: syscalls.master · Condition: always · Audit event: AUE_MLOCK.

Wire a user virtual-address range into memory.

Implementation: mlock. Calls vm_map_wire_kernel for the current map with user-wiring semantics and translated protection; accounting, faults and resource-limit failures remain VM responsibilities.

204: munlock

int munlock(caddr_ut addr, size_ut len);

Declaration: syscalls.master · Condition: always · Audit event: AUE_MUNLOCK.

Remove user wiring from a range.

Implementation: munlock. Calls vm_map_unwire for the current map/range; releasing a wiring claim is not necessarily freeing the physical page.

250: minherit

int minherit(caddr_ut addr, size_ut len, int inherit);

Declaration: syscalls.master · Condition: always · Audit event: AUE_MINHERIT.

Change a mapping's fork inheritance behavior.

Implementation: minherit. Sanitizes the range and inheritance value and calls mach_vm_inherit; later task/map copying interprets the resulting entry policy.

294: shared_region_check_np

int shared_region_check_np(uint64_t *start_address) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_NULL.

Query/establish the process's shared-region association and start address.

Implementation: shared_region_check_np. Uses vm_shared_region_get and shared-region validation/removal paths, considers task address width and mapping state, then returns the shared-region address through user output.

296: vm_pressure_monitor

int vm_pressure_monitor(int wait_for_pressure, int nsecs_monitored, uint32_t *pages_reclaimed);

Declaration: syscalls.master · Condition: always · Audit event: AUE_NULL.

Query or wait for virtual-memory pressure information.

Implementation: vm_pressure_monitor. Calls mach_vm_pressure_monitor with the requested wait/duration policy and copies pressure/reclaim information to the supplied output pointers.

324: mlockall

int mlockall(int how);

Declaration: syscalls.master · Condition: always · Audit event: AUE_MLOCKALL.

Preserve declared whole-address-space wiring entry points without a local implementation.

Implementation: mlockall. Each handler immediately returns ENOSYS; these numbers do not provide functioning whole-map lock/unlock operations in this checkout.

325: munlockall

int munlockall(int how);

Declaration: syscalls.master · Condition: always · Audit event: AUE_MUNLOCKALL.

Preserve declared whole-address-space wiring entry points without a local implementation.

Implementation: munlockall. Each handler immediately returns ENOSYS; these numbers do not provide functioning whole-map lock/unlock operations in this checkout.

405: msync_nocancel

int msync_nocancel(caddr_ut addr, size_ut len, int flags) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_MSYNC.

Synchronize mapped memory according to the requested flags.

Implementation: msync_nocancel. msync_nocancel sanitizes the range and calls mach_vm_msync; the ordinary wrapper first tests cancellation. This operation is distinct from descriptor fsync.

439: kas_info

int kas_info(int selector, void *value, size_t *size);

Declaration: syscalls.master · Condition: always · Audit event: AUE_NULL.

Query selected kernel address-space layout information under privilege and configuration gates.

Implementation: kas_info. The selector dispatch checks CONFIG_KAS_INFO, credentials/MAC and user-width/size inputs before copying slide or segment information; unsupported selectors/configurations fail rather than exposing arbitrary kernel memory.

440: memorystatus_control

int memorystatus_control(uint32_t command, int32_t pid, uint32_t flags, user_addr_t buffer, size_t buffersize);

Declaration: syscalls.master · Condition: (CONFIG_MEMORYSTATUS) · Audit event: AUE_NULL.

Query or change process memory-status, limits, priority and related jetsam/freezer policy.

Implementation: memorystatus_control. Checks credentials/entitlements/MAC and dispatches the command to memorystatus_cmd_* helpers; list/snapshot queries, limit updates and process actions have different payload/ownership contracts.

453: memorystatus_get_level

int memorystatus_get_level(user_addr_t level);

Declaration: syscalls.master · Condition: (CONFIG_MEMORYSTATUS) · Audit event: AUE_NULL.

Read the current memorystatus level.

Implementation: memorystatus_get_level. Copies the maintained level value to the supplied user address; it does not initiate pressure collection or freeze a process.

489: mremap_encrypted

int mremap_encrypted(caddr_ut addr, size_ut len, uint32_t cryptid, uint32_t cputype, uint32_t cpusubtype);

Declaration: syscalls.master · Condition: (CONFIG_CODE_DECRYPTION) · Audit event: AUE_MPROTECT.

Install encrypted-image mapping/decryption handling for a virtual range.

Implementation: mremap_encrypted. Sanitizes the range, resolves the mapped vnode/offset identity and selects registered decryption/pager handling; cryptographic provider internals are outside this local frontend.

534: memorystatus_available_memory

uint64_t memorystatus_available_memory(void) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_NULL.

Estimate memory available to the current process under memorystatus policy.

Implementation: memorystatus_available_memory. Returns memorystatus_available_memory_internal through the 64-bit syscall result path, incorporating local limits/availability policy rather than raw free-page count alone.

536: shared_region_map_and_slide_2_np

int shared_region_map_and_slide_2_np(uint32_t files_count, const struct shared_file_np *files, uint32_t mappings_count, const shared_file_mapping_slide_np_ut *mappings_u) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_NULL.

Map a collection of shared-cache files and slide/fixup metadata into the shared region.

Implementation: shared_region_map_and_slide_2_np. Imports bounded file/mapping arrays through shared_region_copyin, validates descriptor-backed mappings, and enters the shared-region map/slide machinery; dyld's external cache production is outside this body.

550: map_with_linking_np

int map_with_linking_np(void *regions, uint32_t region_count, void *link_info, uint32_t link_info_size) NO_SYSCALL_STUB;

Declaration: syscalls.master · Condition: always · Audit event: AUE_NULL.

Map file-backed regions with kernel-assisted linking metadata.

Implementation: map_with_linking_np. Imports region/linking information, resolves vnode-backed descriptors and UBC objects, applies mmap policy and enters the VM map/linking path; the syscall consumes metadata rather than performing arbitrary userspace linking.