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"
18 extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
21 #include "skas_ptrace.h"
22 #include "asm/mmu_context.h"
25 long write_ldt_entry(struct mm_id * mm_idp, int func, struct user_desc * desc,
26 void **addr, int done)
31 /* This is a special handling for the case, that the mm to
32 * modify isn't current->active_mm.
33 * If this is called directly by modify_ldt,
34 * (current->active_mm->context.skas.u == mm_idp)
35 * will be true. So no call to __switch_mm(mm_idp) is done.
36 * If this is called in case of init_new_ldt or PTRACE_LDT,
37 * mm_idp won't belong to current->active_mm, but child->mm.
38 * So we need to switch child's mm into our userspace, then
41 * Note: I'm unsure: should interrupts be disabled here?
43 if(!current->active_mm || current->active_mm == &init_mm ||
44 mm_idp != ¤t->active_mm->context.skas.id)
49 struct ptrace_ldt ldt_op = (struct ptrace_ldt) {
52 .bytecount = sizeof(*desc)};
60 pid = userspace_pid[cpu];
63 res = os_ptrace_ldt(pid, 0, (unsigned long) &ldt_op);
70 res = syscall_stub_data(mm_idp, (unsigned long *)desc,
71 (sizeof(*desc) + sizeof(long) - 1) &
75 unsigned long args[] = { func,
76 (unsigned long)stub_addr,
79 res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
85 /* This is the second part of special handling, that makes
86 * PTRACE_LDT possible to implement.
88 if(current->active_mm && current->active_mm != &init_mm &&
89 mm_idp != ¤t->active_mm->context.skas.id)
90 __switch_mm(¤t->active_mm->context.skas.id);
96 static long read_ldt_from_host(void __user * ptr, unsigned long bytecount)
99 struct ptrace_ldt ptrace_ldt = (struct ptrace_ldt) {
101 .bytecount = bytecount,
102 .ptr = kmalloc(bytecount, GFP_KERNEL)};
105 if(ptrace_ldt.ptr == NULL)
108 /* This is called from sys_modify_ldt only, so userspace_pid gives
109 * us the right number
113 res = os_ptrace_ldt(userspace_pid[cpu], 0, (unsigned long) &ptrace_ldt);
118 n = copy_to_user(ptr, ptrace_ldt.ptr, res);
123 kfree(ptrace_ldt.ptr);
129 * In skas mode, we hold our own ldt data in UML.
130 * Thus, the code implementing sys_modify_ldt_skas
131 * is very similar to (and mostly stolen from) sys_modify_ldt
132 * for arch/i386/kernel/ldt.c
133 * The routines copied and modified in part are:
137 * - sys_modify_ldt_skas
140 static int read_ldt(void __user * ptr, unsigned long bytecount)
144 uml_ldt_t * ldt = ¤t->mm->context.skas.ldt;
146 if(!ldt->entry_count)
148 if(bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
149 bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
153 return read_ldt_from_host(ptr, bytecount);
156 down(&ldt->semaphore);
157 if(ldt->entry_count <= LDT_DIRECT_ENTRIES){
158 size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
161 if(copy_to_user(ptr, ldt->u.entries, size))
167 for(i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
172 if(copy_to_user(ptr, ldt->u.pages[i], size)){
182 if(bytecount == 0 || err == -EFAULT)
185 if(clear_user(ptr, bytecount))
192 static int read_default_ldt(void __user * ptr, unsigned long bytecount)
196 if(bytecount > 5*LDT_ENTRY_SIZE)
197 bytecount = 5*LDT_ENTRY_SIZE;
200 /* UML doesn't support lcall7 and lcall27.
201 * So, we don't really have a default ldt, but emulate
202 * an empty ldt of common host default ldt size.
204 if(clear_user(ptr, bytecount))
210 static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
212 uml_ldt_t * ldt = ¤t->mm->context.skas.ldt;
213 struct mm_id * mm_idp = ¤t->mm->context.skas.id;
215 struct user_desc ldt_info;
216 struct ldt_entry entry0, *ldt_p;
220 if(bytecount != sizeof(ldt_info))
223 if(copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
227 if(ldt_info.entry_number >= LDT_ENTRIES)
229 if(ldt_info.contents == 3){
232 if (ldt_info.seg_not_present == 0)
237 down(&ldt->semaphore);
239 err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
242 else if(ptrace_ldt) {
243 /* With PTRACE_LDT available, this is used as a flag only */
244 ldt->entry_count = 1;
248 if(ldt_info.entry_number >= ldt->entry_count &&
249 ldt_info.entry_number >= LDT_DIRECT_ENTRIES){
250 for(i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
251 i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
254 memcpy(&entry0, ldt->u.entries,
256 ldt->u.pages[i] = (struct ldt_entry *)
257 __get_free_page(GFP_KERNEL|__GFP_ZERO);
258 if(!ldt->u.pages[i]){
260 /* Undo the change in host */
261 memset(&ldt_info, 0, sizeof(ldt_info));
262 write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
266 memcpy(ldt->u.pages[0], &entry0,
268 memcpy(ldt->u.pages[0]+1, ldt->u.entries+1,
269 sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
271 ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
274 if(ldt->entry_count <= ldt_info.entry_number)
275 ldt->entry_count = ldt_info.entry_number + 1;
277 if(ldt->entry_count <= LDT_DIRECT_ENTRIES)
278 ldt_p = ldt->u.entries + ldt_info.entry_number;
280 ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
281 ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;
283 if(ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
284 (func == 1 || LDT_empty(&ldt_info))){
290 ldt_info.useable = 0;
291 ldt_p->a = LDT_entry_a(&ldt_info);
292 ldt_p->b = LDT_entry_b(&ldt_info);
302 static long do_modify_ldt_skas(int func, void __user *ptr,
303 unsigned long bytecount)
309 ret = read_ldt(ptr, bytecount);
313 ret = write_ldt(ptr, bytecount, func);
316 ret = read_default_ldt(ptr, bytecount);
322 static DEFINE_SPINLOCK(host_ldt_lock);
323 static short dummy_list[9] = {0, -1};
324 static short * host_ldt_entries = NULL;
326 static void ldt_get_host_info(void)
329 struct ldt_entry * ldt;
331 int i, size, k, order;
333 spin_lock(&host_ldt_lock);
335 if(host_ldt_entries != NULL){
336 spin_unlock(&host_ldt_lock);
339 host_ldt_entries = dummy_list+1;
341 spin_unlock(&host_ldt_lock);
343 for(i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++);
345 ldt = (struct ldt_entry *)
346 __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
348 printk("ldt_get_host_info: couldn't allocate buffer for host "
353 ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
355 printk("ldt_get_host_info: couldn't read host ldt\n");
359 /* default_ldt is active, simply write an empty entry 0 */
360 host_ldt_entries = dummy_list;
364 for(i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++){
365 if(ldt[i].a != 0 || ldt[i].b != 0)
369 if(size < ARRAY_SIZE(dummy_list))
370 host_ldt_entries = dummy_list;
372 size = (size + 1) * sizeof(dummy_list[0]);
373 tmp = kmalloc(size, GFP_KERNEL);
375 printk("ldt_get_host_info: couldn't allocate host ldt "
379 host_ldt_entries = tmp;
382 for(i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++){
383 if(ldt[i].a != 0 || ldt[i].b != 0) {
384 host_ldt_entries[k++] = i;
387 host_ldt_entries[k] = -1;
390 free_pages((unsigned long)ldt, order);
393 long init_new_ldt(struct mmu_context_skas * new_mm,
394 struct mmu_context_skas * from_mm)
396 struct user_desc desc;
401 struct proc_mm_op copy;
405 init_MUTEX(&new_mm->ldt.semaphore);
408 memset(&desc, 0, sizeof(desc));
410 * We have to initialize a clean ldt.
414 * If the new mm was created using proc_mm, host's
415 * default-ldt currently is assigned, which normally
416 * contains the call-gates for lcall7 and lcall27.
417 * To remove these gates, we simply write an empty
418 * entry as number 0 to the host.
420 err = write_ldt_entry(&new_mm->id, 1, &desc,
425 * Now we try to retrieve info about the ldt, we
426 * inherited from the host. All ldt-entries found
427 * will be reset in the following loop
430 for(num_p=host_ldt_entries; *num_p != -1; num_p++){
431 desc.entry_number = *num_p;
432 err = write_ldt_entry(&new_mm->id, 1, &desc,
433 &addr, *(num_p + 1) == -1);
438 new_mm->ldt.entry_count = 0;
444 /* We have a valid from_mm, so we now have to copy the LDT of
445 * from_mm to new_mm, because using proc_mm an new mm with
446 * an empty/default LDT was created in new_mm()
448 copy = ((struct proc_mm_op) { .op = MM_COPY_SEGMENTS,
451 from_mm->id.u.mm_fd } } );
452 i = os_write_file(new_mm->id.u.mm_fd, ©, sizeof(copy));
453 if(i != sizeof(copy))
454 printk("new_mm : /proc/mm copy_segments failed, "
459 /* Our local LDT is used to supply the data for
460 * modify_ldt(READLDT), if PTRACE_LDT isn't available,
461 * i.e., we have to use the stub for modify_ldt, which
462 * can't handle the big read buffer of up to 64kB.
464 down(&from_mm->ldt.semaphore);
465 if(from_mm->ldt.entry_count <= LDT_DIRECT_ENTRIES){
466 memcpy(new_mm->ldt.u.entries, from_mm->ldt.u.entries,
467 sizeof(new_mm->ldt.u.entries));
470 i = from_mm->ldt.entry_count / LDT_ENTRIES_PER_PAGE;
472 page = __get_free_page(GFP_KERNEL|__GFP_ZERO);
477 new_mm->ldt.u.pages[i] =
478 (struct ldt_entry *) page;
479 memcpy(new_mm->ldt.u.pages[i],
480 from_mm->ldt.u.pages[i], PAGE_SIZE);
483 new_mm->ldt.entry_count = from_mm->ldt.entry_count;
484 up(&from_mm->ldt.semaphore);
492 void free_ldt(struct mmu_context_skas * mm)
496 if(!ptrace_ldt && mm->ldt.entry_count > LDT_DIRECT_ENTRIES){
497 i = mm->ldt.entry_count / LDT_ENTRIES_PER_PAGE;
499 free_page((long )mm->ldt.u.pages[i]);
502 mm->ldt.entry_count = 0;
505 int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
507 return do_modify_ldt_skas(func, ptr, bytecount);