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NAME

     vm_map_stack, vm_map_growstack — manage process stacks

SYNOPSIS

     #include <sys/param.h>
     #include <vm/vm.h>
     #include <vm/vm_map.h>

     int
     vm_map_stack(vm_map_t map, vm_offset_t addrbos, vm_size_t max_ssize, vm_prot_t prot,
         vm_prot_t max, int cow);

     int
     vm_map_growstack(struct proc *p, vm_offset_t addr);

DESCRIPTION

     The vm_map_stack() function maps a process stack for a new process image.  The stack is
     mapped addrbos in map, with a maximum size of max_ssize.  Copy-on-write flags passed in cow
     are also applied to the new mapping.  Protection bits are supplied by prot and max.

     It is typically called by execve(2).

     The vm_map_growstack() function is responsible for growing a stack for the process p to the
     desired address addr, similar to the legacy sbrk(2) call.

IMPLEMENTATION NOTES

     The vm_map_stack() function calls vm_map_insert(9) to create its mappings.

     The vm_map_growstack() function acquires the Giant lock, and the process lock on p, for the
     duration of the call.

RETURN VALUES

     The vm_map_stack() function returns KERN_SUCCESS if the mapping was allocated successfully.

     Otherwise, if mapping the stack would exceed the process's VMEM resource limit, or if the
     specified bottom-of-stack address is out of range for the map, or if there is already a
     mapping at the address which would result, or if max_ssize could not be accommodated within
     the current mapping, KERN_NO_SPACE is returned.

     Other possible return values for this function are documented in vm_map_insert(9).

     The vm_map_growstack() function returns KERN_SUCCESS if addr is already mapped, or if the
     stack was grown successfully.

     It also returns KERN_SUCCESS if addr is outside the stack range; this is done in order to
     preserve compatibility with the deprecated grow() function previously located in the file
     vm_machdep.c.

SEE ALSO

     vm_map(9), vm_map_insert(9)

AUTHORS

     This manual page was written by Bruce M Simpson <bms@spc.org>.