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 000000000000..bb50afbee921
--- /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;
+}