Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 255 insertions, 0 deletions

diff --git a/arch/i386/kernel/ldt.c b/arch/i386/kernel/ldt.c
new file mode 100644
index 00000000000..bb50afbee92
--- /dev/null
+++ b/arch/i386/kernel/ldt.c
@@ -0,0 +1,255 @@
+/*
+ * linux/kernel/ldt.c
+ *
+ * Copyright (C) 1992 Krishna Balasubramanian and Linus Torvalds
+ * Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
+ */
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/smp.h>
+#include <linux/smp_lock.h>
+#include <linux/vmalloc.h>
+#include <linux/slab.h>
+
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <asm/ldt.h>
+#include <asm/desc.h>
+
+#ifdef CONFIG_SMP /* avoids "defined but not used" warnig */
+static void flush_ldt(void *null)
+{
+	if (current->active_mm)
+		load_LDT(&current->active_mm->context);
+}
+#endif
+
+static int alloc_ldt(mm_context_t *pc, int mincount, int reload)
+{
+	void *oldldt;
+	void *newldt;
+	int oldsize;
+
+	if (mincount <= pc->size)
+		return 0;
+	oldsize = pc->size;
+	mincount = (mincount+511)&(~511);
+	if (mincount*LDT_ENTRY_SIZE > PAGE_SIZE)
+		newldt = vmalloc(mincount*LDT_ENTRY_SIZE);
+	else
+		newldt = kmalloc(mincount*LDT_ENTRY_SIZE, GFP_KERNEL);
+
+	if (!newldt)
+		return -ENOMEM;
+
+	if (oldsize)
+		memcpy(newldt, pc->ldt, oldsize*LDT_ENTRY_SIZE);
+	oldldt = pc->ldt;
+	memset(newldt+oldsize*LDT_ENTRY_SIZE, 0, (mincount-oldsize)*LDT_ENTRY_SIZE);
+	pc->ldt = newldt;
+	wmb();
+	pc->size = mincount;
+	wmb();
+
+	if (reload) {
+#ifdef CONFIG_SMP
+		cpumask_t mask;
+		preempt_disable();
+		load_LDT(pc);
+		mask = cpumask_of_cpu(smp_processor_id());
+		if (!cpus_equal(current->mm->cpu_vm_mask, mask))
+			smp_call_function(flush_ldt, NULL, 1, 1);
+		preempt_enable();
+#else
+		load_LDT(pc);
+#endif
+	}
+	if (oldsize) {
+		if (oldsize*LDT_ENTRY_SIZE > PAGE_SIZE)
+			vfree(oldldt);
+		else
+			kfree(oldldt);
+	}
+	return 0;
+}
+
+static inline int copy_ldt(mm_context_t *new, mm_context_t *old)
+{
+	int err = alloc_ldt(new, old->size, 0);
+	if (err < 0)
+		return err;
+	memcpy(new->ldt, old->ldt, old->size*LDT_ENTRY_SIZE);
+	return 0;
+}
+
+/*
+ * we do not have to muck with descriptors here, that is
+ * done in switch_mm() as needed.
+ */
+int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
+{
+	struct mm_struct * old_mm;
+	int retval = 0;
+
+	init_MUTEX(&mm->context.sem);
+	mm->context.size = 0;
+	old_mm = current->mm;
+	if (old_mm && old_mm->context.size > 0) {
+		down(&old_mm->context.sem);
+		retval = copy_ldt(&mm->context, &old_mm->context);
+		up(&old_mm->context.sem);
+	}
+	return retval;
+}
+
+/*
+ * No need to lock the MM as we are the last user
+ */
+void destroy_context(struct mm_struct *mm)
+{
+	if (mm->context.size) {
+		if (mm == current->active_mm)
+			clear_LDT();
+		if (mm->context.size*LDT_ENTRY_SIZE > PAGE_SIZE)
+			vfree(mm->context.ldt);
+		else
+			kfree(mm->context.ldt);
+		mm->context.size = 0;
+	}
+}
+
+static int read_ldt(void __user * ptr, unsigned long bytecount)
+{
+	int err;
+	unsigned long size;
+	struct mm_struct * mm = current->mm;
+
+	if (!mm->context.size)
+		return 0;
+	if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
+		bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
+
+	down(&mm->context.sem);
+	size = mm->context.size*LDT_ENTRY_SIZE;
+	if (size > bytecount)
+		size = bytecount;
+
+	err = 0;
+	if (copy_to_user(ptr, mm->context.ldt, size))
+		err = -EFAULT;
+	up(&mm->context.sem);
+	if (err < 0)
+		goto error_return;
+	if (size != bytecount) {
+		/* zero-fill the rest */
+		if (clear_user(ptr+size, bytecount-size) != 0) {
+			err = -EFAULT;
+			goto error_return;
+		}
+	}
+	return bytecount;
+error_return:
+	return err;
+}
+
+static int read_default_ldt(void __user * ptr, unsigned long bytecount)
+{
+	int err;
+	unsigned long size;
+	void *address;
+
+	err = 0;
+	address = &default_ldt[0];
+	size = 5*sizeof(struct desc_struct);
+	if (size > bytecount)
+		size = bytecount;
+
+	err = size;
+	if (copy_to_user(ptr, address, size))
+		err = -EFAULT;
+
+	return err;
+}
+
+static int write_ldt(void __user * ptr, unsigned long bytecount, int oldmode)
+{
+	struct mm_struct * mm = current->mm;
+	__u32 entry_1, entry_2, *lp;
+	int error;
+	struct user_desc ldt_info;
+
+	error = -EINVAL;
+	if (bytecount != sizeof(ldt_info))
+		goto out;
+	error = -EFAULT; 	
+	if (copy_from_user(&ldt_info, ptr, sizeof(ldt_info)))
+		goto out;
+
+	error = -EINVAL;
+	if (ldt_info.entry_number >= LDT_ENTRIES)
+		goto out;
+	if (ldt_info.contents == 3) {
+		if (oldmode)
+			goto out;
+		if (ldt_info.seg_not_present == 0)
+			goto out;
+	}
+
+	down(&mm->context.sem);
+	if (ldt_info.entry_number >= mm->context.size) {
+		error = alloc_ldt(&current->mm->context, ldt_info.entry_number+1, 1);
+		if (error < 0)
+			goto out_unlock;
+	}
+
+	lp = (__u32 *) ((ldt_info.entry_number << 3) + (char *) mm->context.ldt);
+
+   	/* Allow LDTs to be cleared by the user. */
+   	if (ldt_info.base_addr == 0 && ldt_info.limit == 0) {
+		if (oldmode || LDT_empty(&ldt_info)) {
+			entry_1 = 0;
+			entry_2 = 0;
+			goto install;
+		}
+	}
+
+	entry_1 = LDT_entry_a(&ldt_info);
+	entry_2 = LDT_entry_b(&ldt_info);
+	if (oldmode)
+		entry_2 &= ~(1 << 20);
+
+	/* Install the new entry ...  */
+install:
+	*lp	= entry_1;
+	*(lp+1)	= entry_2;
+	error = 0;
+
+out_unlock:
+	up(&mm->context.sem);
+out:
+	return error;
+}
+
+asmlinkage int sys_modify_ldt(int func, void __user *ptr, unsigned long bytecount)
+{
+	int ret = -ENOSYS;
+
+	switch (func) {
+	case 0:
+		ret = read_ldt(ptr, bytecount);
+		break;
+	case 1:
+		ret = write_ldt(ptr, bytecount, 1);
+		break;
+	case 2:
+		ret = read_default_ldt(ptr, bytecount);
+		break;
+	case 0x11:
+		ret = write_ldt(ptr, bytecount, 0);
+		break;
+	}
+	return ret;
+}