2 * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
3 * Licensed under the GPL
6 #include "linux/sched.h"
7 #include "linux/slab.h"
8 #include "linux/types.h"
9 #include "linux/errno.h"
10 #include "linux/spinlock.h"
11 #include "asm/uaccess.h"
14 #include "asm/unistd.h"
15 #include "choose-mode.h"
17 #include "mode_kern.h"
20 extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
24 static long do_modify_ldt_tt(int func, void __user *ptr,
25 unsigned long bytecount)
27 struct user_desc info;
30 void *p = NULL; /* What we pass to host. */
34 case 0x11: /* write_ldt */
35 /* Do this check now to avoid overflows. */
36 if (bytecount != sizeof(struct user_desc)) {
41 if(copy_from_user(&info, ptr, sizeof(info))) {
49 case 2: /* read_ldt */
51 /* The use of info avoids kmalloc on the write case, not on the
53 buf = kmalloc(bytecount, GFP_KERNEL);
65 res = modify_ldt(func, p, bytecount);
72 /* Modify_ldt was for reading and returned the number of read
74 if(copy_to_user(ptr, p, res))
86 #ifdef CONFIG_MODE_SKAS
89 #include "skas_ptrace.h"
90 #include "asm/mmu_context.h"
93 long write_ldt_entry(struct mm_id * mm_idp, int func, struct user_desc * desc,
94 void **addr, int done)
99 /* This is a special handling for the case, that the mm to
100 * modify isn't current->active_mm.
101 * If this is called directly by modify_ldt,
102 * (current->active_mm->context.skas.u == mm_idp)
103 * will be true. So no call to switch_mm_skas(mm_idp) is done.
104 * If this is called in case of init_new_ldt or PTRACE_LDT,
105 * mm_idp won't belong to current->active_mm, but child->mm.
106 * So we need to switch child's mm into our userspace, then
109 * Note: I'm unsure: should interrupts be disabled here?
111 if(!current->active_mm || current->active_mm == &init_mm ||
112 mm_idp != ¤t->active_mm->context.skas.id)
113 switch_mm_skas(mm_idp);
117 struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
120 .bytecount = sizeof(*desc)};
128 pid = userspace_pid[cpu];
131 res = os_ptrace_ldt(pid, 0, (unsigned long) &ldt_op);
138 res = syscall_stub_data(mm_idp, (unsigned long *)desc,
139 (sizeof(*desc) + sizeof(long) - 1) &
143 unsigned long args[] = { func,
144 (unsigned long)stub_addr,
147 res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
153 /* This is the second part of special handling, that makes
154 * PTRACE_LDT possible to implement.
156 if(current->active_mm && current->active_mm != &init_mm &&
157 mm_idp != ¤t->active_mm->context.skas.id)
158 switch_mm_skas(¤t->active_mm->context.skas.id);
164 static long read_ldt_from_host(void __user * ptr, unsigned long bytecount)
167 struct ptrace_ldt ptrace_ldt = (struct ptrace_ldt) {
169 .bytecount = bytecount,
170 .ptr = kmalloc(bytecount, GFP_KERNEL)};
173 if(ptrace_ldt.ptr == NULL)
176 /* This is called from sys_modify_ldt only, so userspace_pid gives
177 * us the right number
181 res = os_ptrace_ldt(userspace_pid[cpu], 0, (unsigned long) &ptrace_ldt);
186 n = copy_to_user(ptr, ptrace_ldt.ptr, res);
191 kfree(ptrace_ldt.ptr);
197 * In skas mode, we hold our own ldt data in UML.
198 * Thus, the code implementing sys_modify_ldt_skas
199 * is very similar to (and mostly stolen from) sys_modify_ldt
200 * for arch/i386/kernel/ldt.c
201 * The routines copied and modified in part are:
205 * - sys_modify_ldt_skas
208 static int read_ldt(void __user * ptr, unsigned long bytecount)
212 uml_ldt_t * ldt = ¤t->mm->context.skas.ldt;
214 if(!ldt->entry_count)
216 if(bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
217 bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
221 return read_ldt_from_host(ptr, bytecount);
224 down(&ldt->semaphore);
225 if(ldt->entry_count <= LDT_DIRECT_ENTRIES){
226 size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
229 if(copy_to_user(ptr, ldt->u.entries, size))
235 for(i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
240 if(copy_to_user(ptr, ldt->u.pages[i], size)){
250 if(bytecount == 0 || err == -EFAULT)
253 if(clear_user(ptr, bytecount))
260 static int read_default_ldt(void __user * ptr, unsigned long bytecount)
264 if(bytecount > 5*LDT_ENTRY_SIZE)
265 bytecount = 5*LDT_ENTRY_SIZE;
268 /* UML doesn't support lcall7 and lcall27.
269 * So, we don't really have a default ldt, but emulate
270 * an empty ldt of common host default ldt size.
272 if(clear_user(ptr, bytecount))
278 static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
280 uml_ldt_t * ldt = ¤t->mm->context.skas.ldt;
281 struct mm_id * mm_idp = ¤t->mm->context.skas.id;
283 struct user_desc ldt_info;
284 struct ldt_entry entry0, *ldt_p;
288 if(bytecount != sizeof(ldt_info))
291 if(copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
295 if(ldt_info.entry_number >= LDT_ENTRIES)
297 if(ldt_info.contents == 3){
300 if (ldt_info.seg_not_present == 0)
305 down(&ldt->semaphore);
307 err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
310 else if(ptrace_ldt) {
311 /* With PTRACE_LDT available, this is used as a flag only */
312 ldt->entry_count = 1;
316 if(ldt_info.entry_number >= ldt->entry_count &&
317 ldt_info.entry_number >= LDT_DIRECT_ENTRIES){
318 for(i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
319 i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
322 memcpy(&entry0, ldt->u.entries,
324 ldt->u.pages[i] = (struct ldt_entry *)
325 __get_free_page(GFP_KERNEL|__GFP_ZERO);
326 if(!ldt->u.pages[i]){
328 /* Undo the change in host */
329 memset(&ldt_info, 0, sizeof(ldt_info));
330 write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
334 memcpy(ldt->u.pages[0], &entry0,
336 memcpy(ldt->u.pages[0]+1, ldt->u.entries+1,
337 sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
339 ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
342 if(ldt->entry_count <= ldt_info.entry_number)
343 ldt->entry_count = ldt_info.entry_number + 1;
345 if(ldt->entry_count <= LDT_DIRECT_ENTRIES)
346 ldt_p = ldt->u.entries + ldt_info.entry_number;
348 ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
349 ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;
351 if(ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
352 (func == 1 || LDT_empty(&ldt_info))){
358 ldt_info.useable = 0;
359 ldt_p->a = LDT_entry_a(&ldt_info);
360 ldt_p->b = LDT_entry_b(&ldt_info);
370 static long do_modify_ldt_skas(int func, void __user *ptr,
371 unsigned long bytecount)
377 ret = read_ldt(ptr, bytecount);
381 ret = write_ldt(ptr, bytecount, func);
384 ret = read_default_ldt(ptr, bytecount);
390 static DEFINE_SPINLOCK(host_ldt_lock);
391 static short dummy_list[9] = {0, -1};
392 static short * host_ldt_entries = NULL;
394 static void ldt_get_host_info(void)
397 struct ldt_entry * ldt, *tmp;
398 int i, size, k, order;
400 spin_lock(&host_ldt_lock);
402 if(host_ldt_entries != NULL){
403 spin_unlock(&host_ldt_lock);
406 host_ldt_entries = dummy_list+1;
408 spin_unlock(&host_ldt_lock);
410 for(i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++);
412 ldt = (struct ldt_entry *)
413 __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
415 printk("ldt_get_host_info: couldn't allocate buffer for host "
420 ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
422 printk("ldt_get_host_info: couldn't read host ldt\n");
426 /* default_ldt is active, simply write an empty entry 0 */
427 host_ldt_entries = dummy_list;
431 for(i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++){
432 if(ldt[i].a != 0 || ldt[i].b != 0)
436 if(size < ARRAY_SIZE(dummy_list))
437 host_ldt_entries = dummy_list;
439 size = (size + 1) * sizeof(dummy_list[0]);
440 tmp = kmalloc(size, GFP_KERNEL);
442 printk("ldt_get_host_info: couldn't allocate host ldt "
446 host_ldt_entries = tmp;
449 for(i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++){
450 if(ldt[i].a != 0 || ldt[i].b != 0) {
451 host_ldt_entries[k++] = i;
454 host_ldt_entries[k] = -1;
457 free_pages((unsigned long)ldt, order);
460 long init_new_ldt(struct mmu_context_skas * new_mm,
461 struct mmu_context_skas * from_mm)
463 struct user_desc desc;
468 struct proc_mm_op copy;
472 init_MUTEX(&new_mm->ldt.semaphore);
475 memset(&desc, 0, sizeof(desc));
477 * We have to initialize a clean ldt.
481 * If the new mm was created using proc_mm, host's
482 * default-ldt currently is assigned, which normally
483 * contains the call-gates for lcall7 and lcall27.
484 * To remove these gates, we simply write an empty
485 * entry as number 0 to the host.
487 err = write_ldt_entry(&new_mm->id, 1, &desc,
492 * Now we try to retrieve info about the ldt, we
493 * inherited from the host. All ldt-entries found
494 * will be reset in the following loop
497 for(num_p=host_ldt_entries; *num_p != -1; num_p++){
498 desc.entry_number = *num_p;
499 err = write_ldt_entry(&new_mm->id, 1, &desc,
500 &addr, *(num_p + 1) == -1);
505 new_mm->ldt.entry_count = 0;
511 /* We have a valid from_mm, so we now have to copy the LDT of
512 * from_mm to new_mm, because using proc_mm an new mm with
513 * an empty/default LDT was created in new_mm()
515 copy = ((struct proc_mm_op) { .op = MM_COPY_SEGMENTS,
518 from_mm->id.u.mm_fd } } );
519 i = os_write_file(new_mm->id.u.mm_fd, ©, sizeof(copy));
520 if(i != sizeof(copy))
521 printk("new_mm : /proc/mm copy_segments failed, "
526 /* Our local LDT is used to supply the data for
527 * modify_ldt(READLDT), if PTRACE_LDT isn't available,
528 * i.e., we have to use the stub for modify_ldt, which
529 * can't handle the big read buffer of up to 64kB.
531 down(&from_mm->ldt.semaphore);
532 if(from_mm->ldt.entry_count <= LDT_DIRECT_ENTRIES){
533 memcpy(new_mm->ldt.u.entries, from_mm->ldt.u.entries,
534 sizeof(new_mm->ldt.u.entries));
537 i = from_mm->ldt.entry_count / LDT_ENTRIES_PER_PAGE;
539 page = __get_free_page(GFP_KERNEL|__GFP_ZERO);
544 new_mm->ldt.u.pages[i] =
545 (struct ldt_entry *) page;
546 memcpy(new_mm->ldt.u.pages[i],
547 from_mm->ldt.u.pages[i], PAGE_SIZE);
550 new_mm->ldt.entry_count = from_mm->ldt.entry_count;
551 up(&from_mm->ldt.semaphore);
559 void free_ldt(struct mmu_context_skas * mm)
563 if(!ptrace_ldt && mm->ldt.entry_count > LDT_DIRECT_ENTRIES){
564 i = mm->ldt.entry_count / LDT_ENTRIES_PER_PAGE;
566 free_page((long )mm->ldt.u.pages[i]);
569 mm->ldt.entry_count = 0;
573 int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
575 return CHOOSE_MODE_PROC(do_modify_ldt_tt, do_modify_ldt_skas, func,