381 lines
8.7 KiB
C
381 lines
8.7 KiB
C
/*
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* Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
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* Licensed under the GPL
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*/
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/slab.h>
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#include <linux/syscalls.h>
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#include <linux/uaccess.h>
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#include <asm/unistd.h>
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#include <os.h>
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#include <skas.h>
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#include <sysdep/tls.h>
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static inline int modify_ldt (int func, void *ptr, unsigned long bytecount)
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{
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return syscall(__NR_modify_ldt, func, ptr, bytecount);
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}
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static long write_ldt_entry(struct mm_id *mm_idp, int func,
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struct user_desc *desc, void **addr, int done)
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{
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long res;
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void *stub_addr;
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BUILD_BUG_ON(sizeof(*desc) % sizeof(long));
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res = syscall_stub_data(mm_idp, (unsigned long *)desc,
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sizeof(*desc) / sizeof(long),
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addr, &stub_addr);
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if (!res) {
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unsigned long args[] = { func,
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(unsigned long)stub_addr,
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sizeof(*desc),
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0, 0, 0 };
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res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
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0, addr, done);
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}
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return res;
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}
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/*
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* In skas mode, we hold our own ldt data in UML.
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* Thus, the code implementing sys_modify_ldt_skas
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* is very similar to (and mostly stolen from) sys_modify_ldt
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* for arch/i386/kernel/ldt.c
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* The routines copied and modified in part are:
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* - read_ldt
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* - read_default_ldt
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* - write_ldt
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* - sys_modify_ldt_skas
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*/
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static int read_ldt(void __user * ptr, unsigned long bytecount)
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{
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int i, err = 0;
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unsigned long size;
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uml_ldt_t *ldt = ¤t->mm->context.arch.ldt;
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if (!ldt->entry_count)
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goto out;
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if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
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bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
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err = bytecount;
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mutex_lock(&ldt->lock);
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if (ldt->entry_count <= LDT_DIRECT_ENTRIES) {
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size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
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if (size > bytecount)
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size = bytecount;
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if (copy_to_user(ptr, ldt->u.entries, size))
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err = -EFAULT;
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bytecount -= size;
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ptr += size;
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}
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else {
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for (i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
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i++) {
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size = PAGE_SIZE;
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if (size > bytecount)
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size = bytecount;
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if (copy_to_user(ptr, ldt->u.pages[i], size)) {
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err = -EFAULT;
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break;
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}
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bytecount -= size;
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ptr += size;
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}
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}
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mutex_unlock(&ldt->lock);
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if (bytecount == 0 || err == -EFAULT)
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goto out;
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if (clear_user(ptr, bytecount))
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err = -EFAULT;
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out:
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return err;
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}
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static int read_default_ldt(void __user * ptr, unsigned long bytecount)
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{
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int err;
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if (bytecount > 5*LDT_ENTRY_SIZE)
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bytecount = 5*LDT_ENTRY_SIZE;
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err = bytecount;
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/*
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* UML doesn't support lcall7 and lcall27.
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* So, we don't really have a default ldt, but emulate
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* an empty ldt of common host default ldt size.
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*/
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if (clear_user(ptr, bytecount))
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err = -EFAULT;
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return err;
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}
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static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
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{
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uml_ldt_t *ldt = ¤t->mm->context.arch.ldt;
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struct mm_id * mm_idp = ¤t->mm->context.id;
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int i, err;
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struct user_desc ldt_info;
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struct ldt_entry entry0, *ldt_p;
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void *addr = NULL;
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err = -EINVAL;
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if (bytecount != sizeof(ldt_info))
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goto out;
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err = -EFAULT;
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if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
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goto out;
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err = -EINVAL;
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if (ldt_info.entry_number >= LDT_ENTRIES)
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goto out;
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if (ldt_info.contents == 3) {
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if (func == 1)
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goto out;
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if (ldt_info.seg_not_present == 0)
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goto out;
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}
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mutex_lock(&ldt->lock);
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err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
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if (err)
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goto out_unlock;
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if (ldt_info.entry_number >= ldt->entry_count &&
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ldt_info.entry_number >= LDT_DIRECT_ENTRIES) {
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for (i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
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i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
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i++) {
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if (i == 0)
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memcpy(&entry0, ldt->u.entries,
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sizeof(entry0));
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ldt->u.pages[i] = (struct ldt_entry *)
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__get_free_page(GFP_KERNEL|__GFP_ZERO);
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if (!ldt->u.pages[i]) {
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err = -ENOMEM;
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/* Undo the change in host */
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memset(&ldt_info, 0, sizeof(ldt_info));
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write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
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goto out_unlock;
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}
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if (i == 0) {
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memcpy(ldt->u.pages[0], &entry0,
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sizeof(entry0));
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memcpy(ldt->u.pages[0]+1, ldt->u.entries+1,
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sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
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}
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ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
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}
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}
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if (ldt->entry_count <= ldt_info.entry_number)
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ldt->entry_count = ldt_info.entry_number + 1;
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if (ldt->entry_count <= LDT_DIRECT_ENTRIES)
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ldt_p = ldt->u.entries + ldt_info.entry_number;
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else
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ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
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ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;
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if (ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
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(func == 1 || LDT_empty(&ldt_info))) {
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ldt_p->a = 0;
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ldt_p->b = 0;
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}
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else{
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if (func == 1)
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ldt_info.useable = 0;
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ldt_p->a = LDT_entry_a(&ldt_info);
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ldt_p->b = LDT_entry_b(&ldt_info);
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}
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err = 0;
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out_unlock:
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mutex_unlock(&ldt->lock);
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out:
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return err;
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}
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static long do_modify_ldt_skas(int func, void __user *ptr,
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unsigned long bytecount)
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{
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int ret = -ENOSYS;
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switch (func) {
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case 0:
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ret = read_ldt(ptr, bytecount);
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break;
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case 1:
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case 0x11:
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ret = write_ldt(ptr, bytecount, func);
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break;
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case 2:
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ret = read_default_ldt(ptr, bytecount);
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break;
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}
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return ret;
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}
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static DEFINE_SPINLOCK(host_ldt_lock);
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static short dummy_list[9] = {0, -1};
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static short * host_ldt_entries = NULL;
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static void ldt_get_host_info(void)
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{
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long ret;
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struct ldt_entry * ldt;
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short *tmp;
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int i, size, k, order;
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spin_lock(&host_ldt_lock);
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if (host_ldt_entries != NULL) {
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spin_unlock(&host_ldt_lock);
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return;
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}
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host_ldt_entries = dummy_list+1;
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spin_unlock(&host_ldt_lock);
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for (i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++)
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;
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ldt = (struct ldt_entry *)
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__get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
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if (ldt == NULL) {
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printk(KERN_ERR "ldt_get_host_info: couldn't allocate buffer "
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"for host ldt\n");
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return;
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}
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ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
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if (ret < 0) {
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printk(KERN_ERR "ldt_get_host_info: couldn't read host ldt\n");
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goto out_free;
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}
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if (ret == 0) {
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/* default_ldt is active, simply write an empty entry 0 */
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host_ldt_entries = dummy_list;
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goto out_free;
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}
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for (i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++) {
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if (ldt[i].a != 0 || ldt[i].b != 0)
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size++;
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}
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if (size < ARRAY_SIZE(dummy_list))
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host_ldt_entries = dummy_list;
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else {
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size = (size + 1) * sizeof(dummy_list[0]);
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tmp = kmalloc(size, GFP_KERNEL);
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if (tmp == NULL) {
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printk(KERN_ERR "ldt_get_host_info: couldn't allocate "
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"host ldt list\n");
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goto out_free;
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}
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host_ldt_entries = tmp;
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}
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for (i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++) {
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if (ldt[i].a != 0 || ldt[i].b != 0)
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host_ldt_entries[k++] = i;
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}
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host_ldt_entries[k] = -1;
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out_free:
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free_pages((unsigned long)ldt, order);
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}
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long init_new_ldt(struct mm_context *new_mm, struct mm_context *from_mm)
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{
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struct user_desc desc;
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short * num_p;
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int i;
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long page, err=0;
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void *addr = NULL;
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mutex_init(&new_mm->arch.ldt.lock);
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if (!from_mm) {
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memset(&desc, 0, sizeof(desc));
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/*
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* Now we try to retrieve info about the ldt, we
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* inherited from the host. All ldt-entries found
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* will be reset in the following loop
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*/
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ldt_get_host_info();
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for (num_p=host_ldt_entries; *num_p != -1; num_p++) {
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desc.entry_number = *num_p;
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err = write_ldt_entry(&new_mm->id, 1, &desc,
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&addr, *(num_p + 1) == -1);
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if (err)
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break;
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}
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new_mm->arch.ldt.entry_count = 0;
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goto out;
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}
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/*
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* Our local LDT is used to supply the data for
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* modify_ldt(READLDT), if PTRACE_LDT isn't available,
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* i.e., we have to use the stub for modify_ldt, which
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* can't handle the big read buffer of up to 64kB.
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*/
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mutex_lock(&from_mm->arch.ldt.lock);
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if (from_mm->arch.ldt.entry_count <= LDT_DIRECT_ENTRIES)
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memcpy(new_mm->arch.ldt.u.entries, from_mm->arch.ldt.u.entries,
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sizeof(new_mm->arch.ldt.u.entries));
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else {
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i = from_mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
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while (i-->0) {
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page = __get_free_page(GFP_KERNEL|__GFP_ZERO);
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if (!page) {
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err = -ENOMEM;
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break;
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}
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new_mm->arch.ldt.u.pages[i] =
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(struct ldt_entry *) page;
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memcpy(new_mm->arch.ldt.u.pages[i],
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from_mm->arch.ldt.u.pages[i], PAGE_SIZE);
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}
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}
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new_mm->arch.ldt.entry_count = from_mm->arch.ldt.entry_count;
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mutex_unlock(&from_mm->arch.ldt.lock);
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out:
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return err;
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}
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void free_ldt(struct mm_context *mm)
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{
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int i;
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if (mm->arch.ldt.entry_count > LDT_DIRECT_ENTRIES) {
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i = mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
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while (i-- > 0)
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free_page((long) mm->arch.ldt.u.pages[i]);
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}
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mm->arch.ldt.entry_count = 0;
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}
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SYSCALL_DEFINE3(modify_ldt, int , func , void __user * , ptr ,
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unsigned long , bytecount)
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{
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/* See non-um modify_ldt() for why we do this cast */
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return (unsigned int)do_modify_ldt_skas(func, ptr, bytecount);
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}
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