Source to osfmk/kern/syscall_emulation.c
/*
* Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* The contents of this file constitute Original Code as defined in and
* are subject to the Apple Public Source License Version 1.1 (the
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* http://www.apple.com/publicsource and read it before using this file.
*
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* License for the specific language governing rights and limitations
* under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
/*
* @OSF_COPYRIGHT@
*/
/*
* Mach Operating System
* Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and ditribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or [email protected]
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie Mellon
* the rights to redistribute these changes.
*/
/*
*/
#include <mach/error.h>
#include <mach/vm_param.h>
#include <mach/boolean.h>
#include <kern/misc_protos.h>
#include <kern/syscall_emulation.h>
#include <kern/task.h>
#include <kern/kalloc.h>
#include <vm/vm_kern.h>
#include <machine/thread.h> /* for syscall_emulation_sync */
/*
* Exported interface
*/
/*
* WARNING:
* This code knows that kalloc() allocates memory most efficiently
* in sizes that are powers of 2, and asks for those sizes.
*/
/*
* Go from number of entries to size of struct eml_dispatch and back.
*/
#define base_size (sizeof(struct eml_dispatch) - sizeof(eml_routine_t))
#define count_to_size(count) \
(base_size + sizeof(vm_offset_t) * (count))
#define size_to_count(size) \
( ((size) - base_size) / sizeof(vm_offset_t) )
/* Forwards */
kern_return_t
task_set_emulation_vector_internal(
task_t task,
int vector_start,
emulation_vector_t emulation_vector,
mach_msg_type_number_t emulation_vector_count);
/*
* eml_init: initialize user space emulation code
*/
void
eml_init(void)
{
}
/*
* eml_task_reference() [Exported]
*
* Bumps the reference count on the common emulation
* vector.
*/
void
eml_task_reference(
task_t task,
task_t parent)
{
register eml_dispatch_t eml;
if (parent == TASK_NULL)
eml = EML_DISPATCH_NULL;
else
eml = parent->eml_dispatch;
if (eml != EML_DISPATCH_NULL) {
mutex_lock(&eml->lock);
eml->ref_count++;
mutex_unlock(&eml->lock);
}
task->eml_dispatch = eml;
}
/*
* eml_task_deallocate() [Exported]
*
* Cleans up after the emulation code when a process exits.
*/
void
eml_task_deallocate(
task_t task)
{
register eml_dispatch_t eml;
eml = task->eml_dispatch;
if (eml != EML_DISPATCH_NULL) {
int count;
mutex_lock(&eml->lock);
count = --eml->ref_count;
mutex_unlock(&eml->lock);
if (count == 0)
kfree((vm_offset_t)eml, count_to_size(eml->disp_count));
task->eml_dispatch = EML_DISPATCH_NULL;
}
}
/*
* task_set_emulation_vector: [Server Entry]
* set a list of emulated system calls for this task.
*/
kern_return_t
task_set_emulation_vector_internal(
task_t task,
int vector_start,
emulation_vector_t emulation_vector,
mach_msg_type_number_t emulation_vector_count)
{
eml_dispatch_t cur_eml, new_eml, old_eml;
vm_size_t new_size;
int cur_start, cur_end;
int new_start, new_end;
int vector_end;
if (task == TASK_NULL)
return EML_BAD_TASK;
vector_end = vector_start + (int) emulation_vector_count;
/*
* We try to re-use the existing emulation vetor
* if possible. We can reuse the vector if it
* is not shared with another task and if it is
* large enough to contain the entries we are
* supplying.
*
* We must grab the lock on the task to check whether
* there is an emulation vector.
* If the vector is shared or not large enough, we
* need to drop the lock and allocate a new emulation
* vector.
*
* While the lock is dropped, the emulation vector
* may be released by all other tasks (giving us
* exclusive use), or may be enlarged by another
* task_set_emulation_vector call. Therefore,
* after allocating the new emulation vector, we
* must grab the lock again to check whether we
* really need the new vector we just allocated.
*
* Since an emulation vector cannot be altered
* if it is in use by more than one task, the
* task lock is sufficient to protect the vector`s
* start, count, and contents. The lock in the
* vector protects only the reference count.
*/
old_eml = EML_DISPATCH_NULL; /* vector to discard */
new_eml = EML_DISPATCH_NULL; /* new vector */
for (;;) {
/*
* Find the current emulation vector.
* See whether we can overwrite it.
*/
task_lock(task);
cur_eml = task->eml_dispatch;
if (cur_eml != EML_DISPATCH_NULL) {
cur_start = cur_eml->disp_min;
cur_end = cur_eml->disp_count + cur_start;
mutex_lock(&cur_eml->lock);
if (cur_eml->ref_count == 1 &&
cur_start <= vector_start &&
cur_end >= vector_end)
{
/*
* Can use the existing emulation vector.
* Discard any new one we allocated.
*/
mutex_unlock(&cur_eml->lock);
old_eml = new_eml;
break;
}
if (new_eml != EML_DISPATCH_NULL &&
new_start <= cur_start &&
new_end >= cur_end)
{
/*
* A new vector was allocated, and it is large enough
* to hold all the entries from the current vector.
* Copy the entries to the new emulation vector,
* deallocate the current one, and use the new one.
*/
bcopy((char *)&cur_eml->disp_vector[0],
(char *)&new_eml->disp_vector[cur_start-new_start],
cur_eml->disp_count * sizeof(vm_offset_t));
if (--cur_eml->ref_count == 0)
old_eml = cur_eml; /* discard old vector */
mutex_unlock(&cur_eml->lock);
task->eml_dispatch = new_eml;
syscall_emulation_sync(task);
cur_eml = new_eml;
break;
}
mutex_unlock(&cur_eml->lock);
/*
* Need a new emulation vector.
* Ensure it will hold all the entries from
* both the old and new emulation vectors.
*/
new_start = vector_start;
if (new_start > cur_start)
new_start = cur_start;
new_end = vector_end;
if (new_end < cur_end)
new_end = cur_end;
}
else {
/*
* There is no curren emulation vector.
* If a new one was allocated, use it.
*/
if (new_eml != EML_DISPATCH_NULL) {
task->eml_dispatch = new_eml;
cur_eml = new_eml;
break;
}
/*
* Compute the size needed for the new vector.
*/
new_start = vector_start;
new_end = vector_end;
}
/*
* Have no vector (or one that is no longer large enough).
* Drop all the locks and allocate a new vector.
* Repeat the loop to check whether the old vector was
* changed while we didn`t hold the locks.
*/
task_unlock(task);
if (new_eml != EML_DISPATCH_NULL)
kfree((vm_offset_t)new_eml, count_to_size(new_eml->disp_count));
new_size = count_to_size(new_end - new_start);
new_eml = (eml_dispatch_t) kalloc(new_size);
bzero((char *)new_eml, new_size);
mutex_init(&new_eml->lock, ETAP_MISC_EMULATE);
new_eml->ref_count = 1;
new_eml->disp_min = new_start;
new_eml->disp_count = new_end - new_start;
continue;
}
/*
* We have the emulation vector.
* Install the new emulation entries.
*/
bcopy((char *)&emulation_vector[0],
(char *)&cur_eml->disp_vector[vector_start - cur_eml->disp_min],
emulation_vector_count * sizeof(vm_offset_t));
task_unlock(task);
/*
* Discard any old emulation vector we don`t need.
*/
if (old_eml)
kfree((vm_offset_t) old_eml, count_to_size(old_eml->disp_count));
return KERN_SUCCESS;
}
/*
* task_set_emulation_vector: [Server Entry]
*
* Set the list of emulated system calls for this task.
* The list is out-of-line.
*/
kern_return_t
task_set_emulation_vector(
task_t task,
int vector_start,
emulation_vector_t emulation_vector,
mach_msg_type_number_t emulation_vector_count)
{
kern_return_t kr;
vm_offset_t emul_vector_addr;
if (task == TASK_NULL)
return EML_BAD_TASK; /* XXX sb KERN_INVALID_ARGUMENT */
/*
* XXX - [email protected].
* If emulation_vector_count is NULL, discard the emulation
* vectors.
* We need a way to do that for emulator-less servers started
* from a classic server. There seems to be no way to get rid
* of or to avoid inheriting the emulation vector !?
*/
if (emulation_vector_count == 0) {
eml_task_deallocate(task);
return KERN_SUCCESS;
}
/*
* The emulation vector is really a vm_map_copy_t.
*/
kr = vm_map_copyout(ipc_kernel_map, &emul_vector_addr,
(vm_map_copy_t) emulation_vector);
if (kr != KERN_SUCCESS)
return kr;
/*
* Can't fault while we hold locks.
*/
kr = vm_map_wire(ipc_kernel_map,
trunc_page(emul_vector_addr),
round_page(emul_vector_addr +
emulation_vector_count *
sizeof(eml_dispatch_t)),
VM_PROT_READ|VM_PROT_WRITE, FALSE);
assert(kr == KERN_SUCCESS);
/*
* Do the work.
*/
kr = task_set_emulation_vector_internal(
task,
vector_start,
(emulation_vector_t) emul_vector_addr,
emulation_vector_count);
assert(kr == KERN_SUCCESS);
/*
* Discard the memory
*/
(void) kmem_free(ipc_kernel_map,
emul_vector_addr,
emulation_vector_count * sizeof(eml_dispatch_t));
return KERN_SUCCESS;
}
/*
* task_get_emulation_vector: [Server Entry]
*
* Get the list of emulated system calls for this task.
* List is returned out-of-line.
*/
kern_return_t
task_get_emulation_vector(
task_t task,
int *vector_start, /* out */
emulation_vector_t *emulation_vector, /* out */
mach_msg_type_number_t *emulation_vector_count) /* out */
{
eml_dispatch_t eml;
vm_size_t vector_size, size;
vm_offset_t addr;
if (task == TASK_NULL)
return EML_BAD_TASK;
addr = 0;
size = 0;
for(;;) {
vm_size_t size_needed;
task_lock(task);
eml = task->eml_dispatch;
if (eml == EML_DISPATCH_NULL) {
task_unlock(task);
if (addr)
(void) kmem_free(ipc_kernel_map, addr, size);
*vector_start = 0;
*emulation_vector = 0;
*emulation_vector_count = 0;
return KERN_SUCCESS;
}
/*
* Do we have the memory we need?
*/
vector_size = eml->disp_count * sizeof(vm_offset_t);
size_needed = round_page(vector_size);
if (size_needed <= size)
break;
/*
* If not, unlock the task and allocate more memory.
*/
task_unlock(task);
if (size != 0)
kmem_free(ipc_kernel_map, addr, size);
size = size_needed;
if (kmem_alloc(ipc_kernel_map, &addr, size) != KERN_SUCCESS)
return KERN_RESOURCE_SHORTAGE;
}
/*
* Copy out the dispatch addresses
*/
*vector_start = eml->disp_min;
*emulation_vector_count = eml->disp_count;
bcopy((char *)eml->disp_vector,
(char *)addr,
vector_size);
/*
* Unlock the task and free any memory we did not need
*/
task_unlock(task);
{
vm_size_t size_used, size_left;
vm_map_copy_t memory;
/*
* Free any unused memory beyond the end of the last page used
*/
size_used = round_page(vector_size);
if (size_used != size)
(void) kmem_free(ipc_kernel_map,
addr + size_used,
size - size_used);
/*
* Zero the remainder of the page being returned.
*/
size_left = size_used - vector_size;
if (size_left > 0)
bzero((char *)addr + vector_size, size_left);
/*
* Unwire and make memory into copyin form.
*/
(void) vm_map_unwire(ipc_kernel_map, addr, addr + size_used, FALSE);
(void) vm_map_copyin(ipc_kernel_map, addr, vector_size,
TRUE, &memory);
*emulation_vector = (emulation_vector_t) memory;
}
return KERN_SUCCESS;
}
/*
* task_set_emulation: [Server Entry]
* set up for user space emulation of syscalls within this task.
*/
kern_return_t
task_set_emulation(
task_t task,
vm_offset_t routine_entry_pt,
int routine_number)
{
return task_set_emulation_vector_internal(task, routine_number,
&routine_entry_pt, 1);
}