Initial import

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);
+}