/*
* User LDT management.
- * Each thread in a task may have its own LDT.
+ * Each task may have its own LDT.
*/
#include <kern/kalloc.h>
#include <i386/seg.h>
#include <i386/thread.h>
#include <i386/user_ldt.h>
+#include <i386/mp_desc.h>
+#include <i386/proc_reg.h>
+#include <i386/machdep_call.h>
+#include <i386/mp.h>
+#include <i386/machine_routines.h>
-char acc_type[8][3] = {
- /* code stack data */
- { 0, 0, 1 }, /* data */
- { 0, 1, 1 }, /* data, writable */
- { 0, 0, 1 }, /* data, expand-down */
- { 0, 1, 1 }, /* data, writable, expand-down */
- { 1, 0, 0 }, /* code */
- { 1, 0, 1 }, /* code, readable */
- { 1, 0, 0 }, /* code, conforming */
- { 1, 0, 1 }, /* code, readable, conforming */
-};
-
-#if 0
-/* Forward */
-
-extern boolean_t selector_check(
- thread_t thread,
- int sel,
- int type);
-
-boolean_t
-selector_check(
- thread_t thread,
- int sel,
- int type)
-{
- struct user_ldt *ldt;
- int access;
-
- ldt = thread->machine.pcb->ims.ldt;
- if (ldt == 0) {
- switch (type) {
- case S_CODE:
- return sel == USER_CS;
- case S_STACK:
- return sel == USER_DS;
- case S_DATA:
- return sel == 0 ||
- sel == USER_CS ||
- sel == USER_DS;
- }
- }
+#include <sys/errno.h>
- if (type != S_DATA && sel == 0)
- return FALSE;
- if ((sel & (SEL_LDTS|SEL_PL)) != (SEL_LDTS|SEL_PL_U)
- || sel > ldt->desc.limit_low)
- return FALSE;
-
- access = ldt->ldt[sel_idx(sel)].access;
-
- if ((access & (ACC_P|ACC_PL|ACC_TYPE_USER))
- != (ACC_P|ACC_PL_U|ACC_TYPE_USER))
- return FALSE;
- /* present, pl == pl.user, not system */
-
- return acc_type[(access & 0xe)>>1][type];
-}
+static void user_ldt_set_action(void *);
/*
* Add the descriptors to the LDT, starting with
* the descriptor for 'first_selector'.
*/
-kern_return_t
+int
i386_set_ldt(
- thread_t thr_act,
- int first_selector,
- descriptor_list_t desc_list,
- mach_msg_type_number_t count)
+ int *retval,
+ uint32_t start_sel,
+ uint32_t descs, /* out */
+ uint32_t num_sels)
{
- user_ldt_t new_ldt, old_ldt, temp;
+ user_ldt_t new_ldt, old_ldt;
struct real_descriptor *dp;
- int i;
- int min_selector = 0;
- pcb_t pcb;
- vm_size_t ldt_size_needed;
- int first_desc = sel_idx(first_selector);
- vm_map_copy_t old_copy_object;
- thread_t thread;
-
- if (first_desc < min_selector || first_desc > 8191)
- return KERN_INVALID_ARGUMENT;
- if (first_desc + count >= 8192)
- return KERN_INVALID_ARGUMENT;
- if (thr_act == THREAD_NULL)
- return KERN_INVALID_ARGUMENT;
- if ((thread = act_lock_thread(thr_act)) == THREAD_NULL) {
- act_unlock_thread(thr_act);
- return KERN_INVALID_ARGUMENT;
- }
- if (thread == current_thread())
- min_selector = LDTSZ;
- act_unlock_thread(thr_act);
+ unsigned int i;
+ unsigned int min_selector = LDTSZ_MIN; /* do not allow the system selectors to be changed */
+ task_t task = current_task();
+ unsigned int ldt_count;
+ kern_return_t err;
- /*
- * We must copy out desc_list to the kernel map, and wire
- * it down (we touch it while the PCB is locked).
- *
- * We make a copy of the copyin object, and clear
- * out the old one, so that the MIG stub will have a
- * a empty (but valid) copyin object to discard.
- */
- {
- kern_return_t kr;
- vm_map_offset_t dst_addr;
-
- old_copy_object = (vm_map_copy_t) desc_list;
-
- kr = vm_map_copyout(ipc_kernel_map, &dst_addr,
- vm_map_copy_copy(old_copy_object));
- if (kr != KERN_SUCCESS)
- return kr;
-
- (void) vm_map_wire(ipc_kernel_map,
- vm_map_trunc_page(dst_addr),
- vm_map_round_page(dst_addr +
- count * sizeof(struct real_descriptor)),
- VM_PROT_READ|VM_PROT_WRITE, FALSE);
- desc_list = CAST_DOWN(descriptor_list_t, dst_addr);
- }
+ if (start_sel != LDT_AUTO_ALLOC
+ && (start_sel != 0 || num_sels != 0)
+ && (start_sel < min_selector || start_sel >= LDTSZ))
+ return EINVAL;
+ if (start_sel != LDT_AUTO_ALLOC
+ && start_sel + num_sels > LDTSZ)
+ return EINVAL;
- for (i = 0, dp = (struct real_descriptor *) desc_list;
- i < count;
- i++, dp++)
- {
- switch (dp->access & ~ACC_A) {
- case 0:
- case ACC_P:
- /* valid empty descriptor */
- break;
- case ACC_P | ACC_CALL_GATE:
- /* Mach kernel call */
- *dp = *(struct real_descriptor *)
- &ldt[sel_idx(USER_SCALL)];
- break;
- case ACC_P | ACC_PL_U | ACC_DATA:
- case ACC_P | ACC_PL_U | ACC_DATA_W:
- case ACC_P | ACC_PL_U | ACC_DATA_E:
- case ACC_P | ACC_PL_U | ACC_DATA_EW:
- case ACC_P | ACC_PL_U | ACC_CODE:
- case ACC_P | ACC_PL_U | ACC_CODE_R:
- case ACC_P | ACC_PL_U | ACC_CODE_C:
- case ACC_P | ACC_PL_U | ACC_CODE_CR:
- case ACC_P | ACC_PL_U | ACC_CALL_GATE_16:
- case ACC_P | ACC_PL_U | ACC_CALL_GATE:
- break;
- default:
- (void) vm_map_remove(ipc_kernel_map,
- vm_map_trunc_page(desc_list),
- vm_map_round_page(&desc_list[count]),
- VM_MAP_REMOVE_KUNWIRE);
- return KERN_INVALID_ARGUMENT;
+ task_lock(task);
+
+ old_ldt = task->i386_ldt;
+
+ if (start_sel == LDT_AUTO_ALLOC) {
+ if (old_ldt) {
+ unsigned int null_count;
+ struct real_descriptor null_ldt;
+
+ bzero(&null_ldt, sizeof(null_ldt));
+
+ /*
+ * Look for null selectors among the already-allocated
+ * entries.
+ */
+ null_count = 0;
+ i = 0;
+ while (i < old_ldt->count)
+ {
+ if (!memcmp(&old_ldt->ldt[i++], &null_ldt, sizeof(null_ldt))) {
+ null_count++;
+ if (null_count == num_sels)
+ break; /* break out of while loop */
+ } else {
+ null_count = 0;
+ }
+ }
+
+ /*
+ * If we broke out of the while loop, i points to the selector
+ * after num_sels null selectors. Otherwise it points to the end
+ * of the old LDTs, and null_count is the number of null selectors
+ * at the end.
+ *
+ * Either way, there are null_count null selectors just prior to
+ * the i-indexed selector, and either null_count >= num_sels,
+ * or we're at the end, so we can extend.
+ */
+ start_sel = old_ldt->start + i - null_count;
+ } else {
+ start_sel = LDTSZ_MIN;
+ }
+
+ if (start_sel + num_sels > LDTSZ) {
+ task_unlock(task);
+ return ENOMEM;
}
}
- ldt_size_needed = sizeof(struct real_descriptor)
- * (first_desc + count);
-
- pcb = thr_act->machine.pcb;
- new_ldt = 0;
- Retry:
- simple_lock(&pcb->lock);
- old_ldt = pcb->ims.ldt;
- if (old_ldt == 0 ||
- old_ldt->desc.limit_low + 1 < ldt_size_needed)
- {
+
+ if (start_sel == 0 && num_sels == 0) {
+ new_ldt = NULL;
+ } else {
/*
- * No old LDT, or not big enough
+ * Allocate new LDT
*/
- if (new_ldt == 0) {
- simple_unlock(&pcb->lock);
-
- new_ldt = (user_ldt_t) kalloc(ldt_size_needed
- + sizeof(struct real_descriptor));
- new_ldt->desc.limit_low = ldt_size_needed - 1;
- new_ldt->desc.limit_high = 0;
- new_ldt->desc.base_low =
- ((vm_offset_t)&new_ldt->ldt[0]) & 0xffff;
- new_ldt->desc.base_med =
- (((vm_offset_t)&new_ldt->ldt[0]) >> 16)
- & 0xff;
- new_ldt->desc.base_high =
- ((vm_offset_t)&new_ldt->ldt[0]) >> 24;
- new_ldt->desc.access = ACC_P | ACC_LDT;
- new_ldt->desc.granularity = 0;
-
- goto Retry;
+
+ unsigned int begin_sel = start_sel;
+ unsigned int end_sel = begin_sel + num_sels;
+
+ if (old_ldt != NULL) {
+ if (old_ldt->start < begin_sel)
+ begin_sel = old_ldt->start;
+ if (old_ldt->start + old_ldt->count > end_sel)
+ end_sel = old_ldt->start + old_ldt->count;
+ }
+
+ ldt_count = end_sel - begin_sel;
+
+ new_ldt = (user_ldt_t)kalloc(sizeof(struct user_ldt) + (ldt_count * sizeof(struct real_descriptor)));
+ if (new_ldt == NULL) {
+ task_unlock(task);
+ return ENOMEM;
}
+ new_ldt->start = begin_sel;
+ new_ldt->count = ldt_count;
+
/*
* Have new LDT. If there was a an old ldt, copy descriptors
- * from old to new. Otherwise copy the default ldt.
+ * from old to new.
*/
if (old_ldt) {
- bcopy((char *)&old_ldt->ldt[0],
- (char *)&new_ldt->ldt[0],
- old_ldt->desc.limit_low + 1);
+ bcopy(&old_ldt->ldt[0],
+ &new_ldt->ldt[old_ldt->start - begin_sel],
+ old_ldt->count * sizeof(struct real_descriptor));
+
+ /*
+ * If the old and new LDTs are non-overlapping, fill the
+ * center in with null selectors.
+ */
+
+ if (old_ldt->start + old_ldt->count < start_sel)
+ bzero(&new_ldt->ldt[old_ldt->count],
+ (start_sel - (old_ldt->start + old_ldt->count)) * sizeof(struct real_descriptor));
+ else if (old_ldt->start > start_sel + num_sels)
+ bzero(&new_ldt->ldt[num_sels],
+ (old_ldt->start - (start_sel + num_sels)) * sizeof(struct real_descriptor));
}
- else if (thr_act == current_thread()) {
- struct real_descriptor template = {0, 0, 0, ACC_P, 0, 0 ,0};
-
- for (dp = &new_ldt->ldt[0], i = 0; i < first_desc; i++, dp++) {
- if (i < LDTSZ)
- *dp = *(struct real_descriptor *) &ldt[i];
- else
- *dp = template;
+
+ /*
+ * Install new descriptors.
+ */
+ if (descs != 0) {
+ err = copyin(descs, (char *)&new_ldt->ldt[start_sel - begin_sel],
+ num_sels * sizeof(struct real_descriptor));
+ if (err != 0)
+ {
+ task_unlock(task);
+ user_ldt_free(new_ldt);
+ return err;
}
+ } else {
+ bzero(&new_ldt->ldt[start_sel - begin_sel], num_sels * sizeof(struct real_descriptor));
}
- temp = old_ldt;
- old_ldt = new_ldt; /* use new LDT from now on */
- new_ldt = temp; /* discard old LDT */
-
- pcb->ims.ldt = old_ldt; /* new LDT for thread */
+ /*
+ * Validate descriptors.
+ * Only allow descriptors with user priviledges.
+ */
+ for (i = 0, dp = (struct real_descriptor *) &new_ldt->ldt[start_sel - begin_sel];
+ i < num_sels;
+ i++, dp++)
+ {
+ switch (dp->access & ~ACC_A) {
+ case 0:
+ case ACC_P:
+ /* valid empty descriptor */
+ break;
+ case ACC_P | ACC_PL_U | ACC_DATA:
+ case ACC_P | ACC_PL_U | ACC_DATA_W:
+ case ACC_P | ACC_PL_U | ACC_DATA_E:
+ case ACC_P | ACC_PL_U | ACC_DATA_EW:
+ case ACC_P | ACC_PL_U | ACC_CODE:
+ case ACC_P | ACC_PL_U | ACC_CODE_R:
+ case ACC_P | ACC_PL_U | ACC_CODE_C:
+ case ACC_P | ACC_PL_U | ACC_CODE_CR:
+ case ACC_P | ACC_PL_U | ACC_CALL_GATE_16:
+ case ACC_P | ACC_PL_U | ACC_CALL_GATE:
+ break;
+ default:
+ task_unlock(task);
+ user_ldt_free(new_ldt);
+ return EACCES;
+ }
+ }
}
+ task->i386_ldt = new_ldt; /* new LDT for task */
+
/*
- * Install new descriptors.
+ * Switch to new LDT. We need to do this on all CPUs, since
+ * another thread in this same task may be currently running,
+ * and we need to make sure the new LDT is in place
+ * throughout the task before returning to the user.
*/
- bcopy((char *)desc_list,
- (char *)&old_ldt->ldt[first_desc],
- count * sizeof(struct real_descriptor));
+ mp_rendezvous_no_intrs(user_ldt_set_action, task);
- simple_unlock(&pcb->lock);
+ task_unlock(task);
- if (new_ldt)
- kfree((vm_offset_t)new_ldt,
- new_ldt->desc.limit_low+1+sizeof(struct real_descriptor));
-
- /*
- * Free the descriptor list.
+ /* free old LDT. We can't do this until after we've
+ * rendezvoused with all CPUs, in case another thread
+ * in this task was in the process of context switching.
*/
- (void) vm_map_remove(ipc_kernel_map, vm_map_trunc_page(desc_list),
- vm_map_round_page(&desc_list[count]),
- VM_MAP_REMOVE_KUNWIRE);
- return KERN_SUCCESS;
+ if (old_ldt)
+ user_ldt_free(old_ldt);
+
+ *retval = start_sel;
+
+ return 0;
}
-kern_return_t
+int
i386_get_ldt(
- thread_t thr_act,
- int first_selector,
- int selector_count, /* number wanted */
- descriptor_list_t *desc_list, /* in/out */
- mach_msg_type_number_t *count) /* in/out */
+ int *retval,
+ uint32_t start_sel,
+ uint32_t descs, /* out */
+ uint32_t num_sels)
{
- struct user_ldt *user_ldt;
- pcb_t pcb = thr_act->machine.pcb;
- int first_desc = sel_idx(first_selector);
+ user_ldt_t user_ldt;
+ task_t task = current_task();
unsigned int ldt_count;
- vm_size_t ldt_size;
- vm_size_t size, size_needed;
- vm_offset_t addr;
- thread_t thread;
-
- if (thr_act == THREAD_NULL)
- return KERN_INVALID_ARGUMENT;
-
- if (first_desc < 0 || first_desc > 8191)
- return KERN_INVALID_ARGUMENT;
- if (first_desc + selector_count >= 8192)
- return KERN_INVALID_ARGUMENT;
-
- addr = 0;
- size = 0;
-
- for (;;) {
- simple_lock(&pcb->lock);
- user_ldt = pcb->ims.ldt;
- if (user_ldt == 0) {
- simple_unlock(&pcb->lock);
- if (addr)
- kmem_free(ipc_kernel_map, addr, size);
- *count = 0;
- return KERN_SUCCESS;
- }
+ kern_return_t err;
- /*
- * Find how many descriptors we should return.
- */
- ldt_count = (user_ldt->desc.limit_low + 1) /
- sizeof (struct real_descriptor);
- ldt_count -= first_desc;
- if (ldt_count > selector_count)
- ldt_count = selector_count;
+ if (start_sel >= 8192)
+ return EINVAL;
+ if (start_sel + num_sels > 8192)
+ return EINVAL;
+ if (descs == 0)
+ return EINVAL;
- ldt_size = ldt_count * sizeof(struct real_descriptor);
+ task_lock(task);
- /*
- * Do we have the memory we need?
- */
- if (ldt_count <= *count)
- break; /* fits in-line */
+ user_ldt = task->i386_ldt;
+ err = 0;
- size_needed = round_page(ldt_size);
- if (size_needed <= size)
- break;
+ /*
+ * copy out the descriptors
+ */
+
+ if (user_ldt != 0)
+ ldt_count = user_ldt->start + user_ldt->count;
+ else
+ ldt_count = LDTSZ_MIN;
- /*
- * Unlock the pcb and allocate more memory
- */
- simple_unlock(&pcb->lock);
- if (size != 0)
- kmem_free(ipc_kernel_map, addr, size);
+ if (start_sel < ldt_count)
+ {
+ unsigned int copy_sels = num_sels;
- size = size_needed;
+ if (start_sel + num_sels > ldt_count)
+ copy_sels = ldt_count - start_sel;
- if (kmem_alloc(ipc_kernel_map, &addr, size)
- != KERN_SUCCESS)
- return KERN_RESOURCE_SHORTAGE;
+ err = copyout((char *)(current_ldt() + start_sel),
+ descs, copy_sels * sizeof(struct real_descriptor));
}
- /*
- * copy out the descriptors
- */
- bcopy((char *)&user_ldt->ldt[first_desc],
- (char *)addr,
- ldt_size);
- *count = ldt_count;
- simple_unlock(&pcb->lock);
+ task_unlock(task);
- if (addr) {
- vm_size_t size_used, size_left;
- vm_map_copy_t memory;
+ *retval = ldt_count;
- /*
- * Free any unused memory beyond the end of the last page used
- */
- size_used = round_page(ldt_size);
- if (size_used != size)
- kmem_free(ipc_kernel_map,
- addr + size_used, size - size_used);
+ return err;
+}
- /*
- * Zero the remainder of the page being returned.
- */
- size_left = size_used - ldt_size;
- if (size_left > 0)
- bzero((char *)addr + ldt_size, size_left);
+void
+user_ldt_free(
+ user_ldt_t user_ldt)
+{
+ kfree(user_ldt, sizeof(struct user_ldt) + (user_ldt->count * sizeof(struct real_descriptor)));
+}
- /*
- * Unwire the memory and make it into copyin form.
- */
- (void) vm_map_unwire(ipc_kernel_map, vm_map_trunc_page(addr),
- vm_map_round_page(addr + size_used), FALSE);
- (void) vm_map_copyin(ipc_kernel_map, (vm_map_address_t)addr,
- (vm_map_size_t)size_used, TRUE, &memory);
- *desc_list = (descriptor_list_t) memory;
+user_ldt_t
+user_ldt_copy(
+ user_ldt_t user_ldt)
+{
+ if (user_ldt != NULL) {
+ size_t size = sizeof(struct user_ldt) + (user_ldt->count * sizeof(struct real_descriptor));
+ user_ldt_t new_ldt = (user_ldt_t)kalloc(size);
+ if (new_ldt != NULL)
+ bcopy(user_ldt, new_ldt, size);
+ return new_ldt;
}
+
+ return 0;
+}
- return KERN_SUCCESS;
+void
+user_ldt_set_action(
+ void *arg)
+{
+ task_t arg_task = (task_t)arg;
+
+ if (arg_task == current_task()) {
+ user_ldt_set(current_thread());
+ }
}
-#endif
+/*
+ * Set the LDT for the given thread on the current CPU. Should be invoked
+ * with interrupts disabled.
+ */
void
-user_ldt_free(
- user_ldt_t user_ldt)
+user_ldt_set(
+ thread_t thread)
{
- kfree(user_ldt,
- user_ldt->desc.limit_low+1+sizeof(struct real_descriptor));
+ task_t task = thread->task;
+ user_ldt_t user_ldt;
+
+ user_ldt = task->i386_ldt;
+
+ if (user_ldt != 0) {
+ struct real_descriptor *ldtp = (struct real_descriptor *)current_ldt();
+
+ if (user_ldt->start > LDTSZ_MIN) {
+ bzero(&ldtp[LDTSZ_MIN],
+ sizeof(struct real_descriptor) * (user_ldt->start - LDTSZ_MIN));
+ }
+
+ bcopy(user_ldt->ldt, &ldtp[user_ldt->start],
+ sizeof(struct real_descriptor) * (user_ldt->count));
+
+ gdt_desc_p(USER_LDT)->limit_low = (sizeof(struct real_descriptor) * (user_ldt->start + user_ldt->count)) - 1;
+
+ ml_cpu_set_ldt(USER_LDT);
+ } else {
+ ml_cpu_set_ldt(KERNEL_LDT);
+ }
}
projects / apple / xnu.git / blobdiff