summaryrefslogtreecommitdiff
path: root/arch/x86/um/ldt.c
diff options
context:
space:
mode:
Diffstat (limited to 'arch/x86/um/ldt.c')
-rw-r--r--arch/x86/um/ldt.c371
1 files changed, 371 insertions, 0 deletions
diff --git a/arch/x86/um/ldt.c b/arch/x86/um/ldt.c
new file mode 100644
index 000000000..5c0b711d2
--- /dev/null
+++ b/arch/x86/um/ldt.c
@@ -0,0 +1,371 @@
+/*
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Licensed under the GPL
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <asm/unistd.h>
+#include <os.h>
+#include <skas.h>
+#include <sysdep/tls.h>
+
+extern int modify_ldt(int func, void *ptr, unsigned long bytecount);
+
+static long write_ldt_entry(struct mm_id *mm_idp, int func,
+ struct user_desc *desc, void **addr, int done)
+{
+ long res;
+ void *stub_addr;
+ res = syscall_stub_data(mm_idp, (unsigned long *)desc,
+ (sizeof(*desc) + sizeof(long) - 1) &
+ ~(sizeof(long) - 1),
+ addr, &stub_addr);
+ if (!res) {
+ unsigned long args[] = { func,
+ (unsigned long)stub_addr,
+ sizeof(*desc),
+ 0, 0, 0 };
+ res = run_syscall_stub(mm_idp, __NR_modify_ldt, args,
+ 0, addr, done);
+ }
+
+ return res;
+}
+
+/*
+ * In skas mode, we hold our own ldt data in UML.
+ * Thus, the code implementing sys_modify_ldt_skas
+ * is very similar to (and mostly stolen from) sys_modify_ldt
+ * for arch/i386/kernel/ldt.c
+ * The routines copied and modified in part are:
+ * - read_ldt
+ * - read_default_ldt
+ * - write_ldt
+ * - sys_modify_ldt_skas
+ */
+
+static int read_ldt(void __user * ptr, unsigned long bytecount)
+{
+ int i, err = 0;
+ unsigned long size;
+ uml_ldt_t *ldt = &current->mm->context.arch.ldt;
+
+ if (!ldt->entry_count)
+ goto out;
+ if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
+ bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
+ err = bytecount;
+
+ mutex_lock(&ldt->lock);
+ if (ldt->entry_count <= LDT_DIRECT_ENTRIES) {
+ size = LDT_ENTRY_SIZE*LDT_DIRECT_ENTRIES;
+ if (size > bytecount)
+ size = bytecount;
+ if (copy_to_user(ptr, ldt->u.entries, size))
+ err = -EFAULT;
+ bytecount -= size;
+ ptr += size;
+ }
+ else {
+ for (i=0; i<ldt->entry_count/LDT_ENTRIES_PER_PAGE && bytecount;
+ i++) {
+ size = PAGE_SIZE;
+ if (size > bytecount)
+ size = bytecount;
+ if (copy_to_user(ptr, ldt->u.pages[i], size)) {
+ err = -EFAULT;
+ break;
+ }
+ bytecount -= size;
+ ptr += size;
+ }
+ }
+ mutex_unlock(&ldt->lock);
+
+ if (bytecount == 0 || err == -EFAULT)
+ goto out;
+
+ if (clear_user(ptr, bytecount))
+ err = -EFAULT;
+
+out:
+ return err;
+}
+
+static int read_default_ldt(void __user * ptr, unsigned long bytecount)
+{
+ int err;
+
+ if (bytecount > 5*LDT_ENTRY_SIZE)
+ bytecount = 5*LDT_ENTRY_SIZE;
+
+ err = bytecount;
+ /*
+ * UML doesn't support lcall7 and lcall27.
+ * So, we don't really have a default ldt, but emulate
+ * an empty ldt of common host default ldt size.
+ */
+ if (clear_user(ptr, bytecount))
+ err = -EFAULT;
+
+ return err;
+}
+
+static int write_ldt(void __user * ptr, unsigned long bytecount, int func)
+{
+ uml_ldt_t *ldt = &current->mm->context.arch.ldt;
+ struct mm_id * mm_idp = &current->mm->context.id;
+ int i, err;
+ struct user_desc ldt_info;
+ struct ldt_entry entry0, *ldt_p;
+ void *addr = NULL;
+
+ err = -EINVAL;
+ if (bytecount != sizeof(ldt_info))
+ goto out;
+ err = -EFAULT;
+ if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
+ goto out;
+
+ err = -EINVAL;
+ if (ldt_info.entry_number >= LDT_ENTRIES)
+ goto out;
+ if (ldt_info.contents == 3) {
+ if (func == 1)
+ goto out;
+ if (ldt_info.seg_not_present == 0)
+ goto out;
+ }
+
+ mutex_lock(&ldt->lock);
+
+ err = write_ldt_entry(mm_idp, func, &ldt_info, &addr, 1);
+ if (err)
+ goto out_unlock;
+
+ if (ldt_info.entry_number >= ldt->entry_count &&
+ ldt_info.entry_number >= LDT_DIRECT_ENTRIES) {
+ for (i=ldt->entry_count/LDT_ENTRIES_PER_PAGE;
+ i*LDT_ENTRIES_PER_PAGE <= ldt_info.entry_number;
+ i++) {
+ if (i == 0)
+ memcpy(&entry0, ldt->u.entries,
+ sizeof(entry0));
+ ldt->u.pages[i] = (struct ldt_entry *)
+ __get_free_page(GFP_KERNEL|__GFP_ZERO);
+ if (!ldt->u.pages[i]) {
+ err = -ENOMEM;
+ /* Undo the change in host */
+ memset(&ldt_info, 0, sizeof(ldt_info));
+ write_ldt_entry(mm_idp, 1, &ldt_info, &addr, 1);
+ goto out_unlock;
+ }
+ if (i == 0) {
+ memcpy(ldt->u.pages[0], &entry0,
+ sizeof(entry0));
+ memcpy(ldt->u.pages[0]+1, ldt->u.entries+1,
+ sizeof(entry0)*(LDT_DIRECT_ENTRIES-1));
+ }
+ ldt->entry_count = (i + 1) * LDT_ENTRIES_PER_PAGE;
+ }
+ }
+ if (ldt->entry_count <= ldt_info.entry_number)
+ ldt->entry_count = ldt_info.entry_number + 1;
+
+ if (ldt->entry_count <= LDT_DIRECT_ENTRIES)
+ ldt_p = ldt->u.entries + ldt_info.entry_number;
+ else
+ ldt_p = ldt->u.pages[ldt_info.entry_number/LDT_ENTRIES_PER_PAGE] +
+ ldt_info.entry_number%LDT_ENTRIES_PER_PAGE;
+
+ if (ldt_info.base_addr == 0 && ldt_info.limit == 0 &&
+ (func == 1 || LDT_empty(&ldt_info))) {
+ ldt_p->a = 0;
+ ldt_p->b = 0;
+ }
+ else{
+ if (func == 1)
+ ldt_info.useable = 0;
+ ldt_p->a = LDT_entry_a(&ldt_info);
+ ldt_p->b = LDT_entry_b(&ldt_info);
+ }
+ err = 0;
+
+out_unlock:
+ mutex_unlock(&ldt->lock);
+out:
+ return err;
+}
+
+static long do_modify_ldt_skas(int func, void __user *ptr,
+ unsigned long bytecount)
+{
+ int ret = -ENOSYS;
+
+ switch (func) {
+ case 0:
+ ret = read_ldt(ptr, bytecount);
+ break;
+ case 1:
+ case 0x11:
+ ret = write_ldt(ptr, bytecount, func);
+ break;
+ case 2:
+ ret = read_default_ldt(ptr, bytecount);
+ break;
+ }
+ return ret;
+}
+
+static DEFINE_SPINLOCK(host_ldt_lock);
+static short dummy_list[9] = {0, -1};
+static short * host_ldt_entries = NULL;
+
+static void ldt_get_host_info(void)
+{
+ long ret;
+ struct ldt_entry * ldt;
+ short *tmp;
+ int i, size, k, order;
+
+ spin_lock(&host_ldt_lock);
+
+ if (host_ldt_entries != NULL) {
+ spin_unlock(&host_ldt_lock);
+ return;
+ }
+ host_ldt_entries = dummy_list+1;
+
+ spin_unlock(&host_ldt_lock);
+
+ for (i = LDT_PAGES_MAX-1, order=0; i; i>>=1, order++)
+ ;
+
+ ldt = (struct ldt_entry *)
+ __get_free_pages(GFP_KERNEL|__GFP_ZERO, order);
+ if (ldt == NULL) {
+ printk(KERN_ERR "ldt_get_host_info: couldn't allocate buffer "
+ "for host ldt\n");
+ return;
+ }
+
+ ret = modify_ldt(0, ldt, (1<<order)*PAGE_SIZE);
+ if (ret < 0) {
+ printk(KERN_ERR "ldt_get_host_info: couldn't read host ldt\n");
+ goto out_free;
+ }
+ if (ret == 0) {
+ /* default_ldt is active, simply write an empty entry 0 */
+ host_ldt_entries = dummy_list;
+ goto out_free;
+ }
+
+ for (i=0, size=0; i<ret/LDT_ENTRY_SIZE; i++) {
+ if (ldt[i].a != 0 || ldt[i].b != 0)
+ size++;
+ }
+
+ if (size < ARRAY_SIZE(dummy_list))
+ host_ldt_entries = dummy_list;
+ else {
+ size = (size + 1) * sizeof(dummy_list[0]);
+ tmp = kmalloc(size, GFP_KERNEL);
+ if (tmp == NULL) {
+ printk(KERN_ERR "ldt_get_host_info: couldn't allocate "
+ "host ldt list\n");
+ goto out_free;
+ }
+ host_ldt_entries = tmp;
+ }
+
+ for (i=0, k=0; i<ret/LDT_ENTRY_SIZE; i++) {
+ if (ldt[i].a != 0 || ldt[i].b != 0)
+ host_ldt_entries[k++] = i;
+ }
+ host_ldt_entries[k] = -1;
+
+out_free:
+ free_pages((unsigned long)ldt, order);
+}
+
+long init_new_ldt(struct mm_context *new_mm, struct mm_context *from_mm)
+{
+ struct user_desc desc;
+ short * num_p;
+ int i;
+ long page, err=0;
+ void *addr = NULL;
+
+
+ mutex_init(&new_mm->arch.ldt.lock);
+
+ if (!from_mm) {
+ memset(&desc, 0, sizeof(desc));
+ /*
+ * Now we try to retrieve info about the ldt, we
+ * inherited from the host. All ldt-entries found
+ * will be reset in the following loop
+ */
+ ldt_get_host_info();
+ for (num_p=host_ldt_entries; *num_p != -1; num_p++) {
+ desc.entry_number = *num_p;
+ err = write_ldt_entry(&new_mm->id, 1, &desc,
+ &addr, *(num_p + 1) == -1);
+ if (err)
+ break;
+ }
+ new_mm->arch.ldt.entry_count = 0;
+
+ goto out;
+ }
+
+ /*
+ * Our local LDT is used to supply the data for
+ * modify_ldt(READLDT), if PTRACE_LDT isn't available,
+ * i.e., we have to use the stub for modify_ldt, which
+ * can't handle the big read buffer of up to 64kB.
+ */
+ mutex_lock(&from_mm->arch.ldt.lock);
+ if (from_mm->arch.ldt.entry_count <= LDT_DIRECT_ENTRIES)
+ memcpy(new_mm->arch.ldt.u.entries, from_mm->arch.ldt.u.entries,
+ sizeof(new_mm->arch.ldt.u.entries));
+ else {
+ i = from_mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
+ while (i-->0) {
+ page = __get_free_page(GFP_KERNEL|__GFP_ZERO);
+ if (!page) {
+ err = -ENOMEM;
+ break;
+ }
+ new_mm->arch.ldt.u.pages[i] =
+ (struct ldt_entry *) page;
+ memcpy(new_mm->arch.ldt.u.pages[i],
+ from_mm->arch.ldt.u.pages[i], PAGE_SIZE);
+ }
+ }
+ new_mm->arch.ldt.entry_count = from_mm->arch.ldt.entry_count;
+ mutex_unlock(&from_mm->arch.ldt.lock);
+
+ out:
+ return err;
+}
+
+
+void free_ldt(struct mm_context *mm)
+{
+ int i;
+
+ if (mm->arch.ldt.entry_count > LDT_DIRECT_ENTRIES) {
+ i = mm->arch.ldt.entry_count / LDT_ENTRIES_PER_PAGE;
+ while (i-- > 0)
+ free_page((long) mm->arch.ldt.u.pages[i]);
+ }
+ mm->arch.ldt.entry_count = 0;
+}
+
+int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
+{
+ return do_modify_ldt_skas(func, ptr, bytecount);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-07-01 22:49:37 +0000