#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 *mm)
+{
+ if (current->mm)
+ load_LDT(¤t->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);
+ wmb();
+ pc->ldt = newldt;
+ pc->size = mincount;
+ if (reload) {
+ load_LDT(pc);
+#ifdef CONFIG_SMP
+ if (current->mm->cpu_vm_mask != (1<<smp_processor_id()))
+ smp_call_function(flush_ldt, 0, 1, 1);
+#endif
+ }
+ wmb();
+ 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) {
+ printk(KERN_WARNING "ldt allocation failed\n");
+ new->size = 0;
+ return err;
+ }
+ memcpy(new->ldt, old->ldt, old->size*LDT_ENTRY_SIZE);
+ return 0;
+}
+
/*
- * read_ldt() is not really atomic - this is not a problem since
- * synchronization of reads and writes done to the LDT has to be
- * assured by user-space anyway. Writes are atomic, to protect
- * the security checks done on new descriptors.
+ * 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 release_segments(struct mm_struct *mm)
+{
+ if (mm->context.size) {
+ 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 * ptr, unsigned long bytecount)
{
int err;
unsigned long size;
struct mm_struct * mm = current->mm;
- err = 0;
- if (!mm->context.segments)
- goto out;
+ if (!mm->context.size)
+ return 0;
+ if (bytecount > LDT_ENTRY_SIZE*LDT_ENTRIES)
+ bytecount = LDT_ENTRY_SIZE*LDT_ENTRIES;
- size = LDT_ENTRIES*LDT_ENTRY_SIZE;
+ down(&mm->context.sem);
+ size = mm->context.size*LDT_ENTRY_SIZE;
if (size > bytecount)
size = bytecount;
- err = size;
- if (copy_to_user(ptr, mm->context.segments, size))
+ err = 0;
+ if (copy_to_user(ptr, mm->context.ldt, size))
err = -EFAULT;
-out:
- return err;
+ up(&mm->context.sem);
+ if (err < 0)
+ return err;
+ if (size != bytecount) {
+ /* zero-fill the rest */
+ clear_user(ptr+size, bytecount-size);
+ }
+ return bytecount;
}
static int read_default_ldt(void * ptr, unsigned long bytecount)
err = 0;
address = &default_ldt[0];
- size = sizeof(struct desc_struct);
+ size = 5*sizeof(struct desc_struct);
if (size > bytecount)
size = bytecount;
goto out;
}
- /*
- * the GDT index of the LDT is allocated dynamically, and is
- * limited by MAX_LDT_DESCRIPTORS.
- */
- down_write(&mm->mmap_sem);
- if (!mm->context.segments) {
- void * segments = vmalloc(LDT_ENTRIES*LDT_ENTRY_SIZE);
- error = -ENOMEM;
- if (!segments)
+ down(&mm->context.sem);
+ if (ldt_info.entry_number >= mm->context.size) {
+ error = alloc_ldt(¤t->mm->context, ldt_info.entry_number+1, 1);
+ if (error < 0)
goto out_unlock;
- memset(segments, 0, LDT_ENTRIES*LDT_ENTRY_SIZE);
- wmb();
- mm->context.segments = segments;
- mm->context.cpuvalid = 1UL << smp_processor_id();
- load_LDT(mm);
}
- lp = (__u32 *) ((ldt_info.entry_number << 3) + (char *) mm->context.segments);
+ 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) {
error = 0;
out_unlock:
- up_write(&mm->mmap_sem);
+ up(&mm->context.sem);
out:
return error;
}
show_trace(®s->esp);
}
-/*
- * No need to lock the MM as we are the last user
- */
-void release_segments(struct mm_struct *mm)
-{
- void * ldt = mm->context.segments;
-
- /*
- * free the LDT
- */
- if (ldt) {
- mm->context.segments = NULL;
- clear_LDT();
- vfree(ldt);
- }
-}
-
/*
* Create a kernel thread
*/
void release_thread(struct task_struct *dead_task)
{
if (dead_task->mm) {
- void * ldt = dead_task->mm->context.segments;
-
// temporary debugging check
- if (ldt) {
- printk("WARNING: dead process %8s still has LDT? <%p>\n",
- dead_task->comm, ldt);
+ if (dead_task->mm->context.size) {
+ printk("WARNING: dead process %8s still has LDT? <%p/%d>\n",
+ dead_task->comm,
+ dead_task->mm->context.ldt,
+ dead_task->mm->context.size);
BUG();
}
}
}
-/*
- * we do not have to muck with descriptors here, that is
- * done in switch_mm() as needed.
- */
-void copy_segments(struct task_struct *p, struct mm_struct *new_mm)
-{
- struct mm_struct * old_mm;
- void *old_ldt, *ldt;
-
- ldt = NULL;
- old_mm = current->mm;
- if (old_mm && (old_ldt = old_mm->context.segments) != NULL) {
- /*
- * Completely new LDT, we initialize it from the parent:
- */
- ldt = vmalloc(LDT_ENTRIES*LDT_ENTRY_SIZE);
- if (!ldt)
- printk(KERN_WARNING "ldt allocation failed\n");
- else
- memcpy(ldt, old_ldt, LDT_ENTRIES*LDT_ENTRY_SIZE);
- }
- new_mm->context.segments = ldt;
- new_mm->context.cpuvalid = ~0UL; /* valid on all CPU's - they can't have stale data */
-}
-
/*
* Save a segment.
*/
* possibly do the LDT unload here?
*/
#define destroy_context(mm) do { } while(0)
-#define init_new_context(tsk,mm) 0
+int init_new_context(struct task_struct *tsk, struct mm_struct *mm);
#ifdef CONFIG_SMP
if (likely(prev != next)) {
/* stop flush ipis for the previous mm */
clear_bit(cpu, &prev->cpu_vm_mask);
- /*
- * Re-load LDT if necessary
- */
- if (unlikely(prev->context.segments != next->context.segments))
- load_LDT(next);
#ifdef CONFIG_SMP
cpu_tlbstate[cpu].state = TLBSTATE_OK;
cpu_tlbstate[cpu].active_mm = next;
#endif
set_bit(cpu, &next->cpu_vm_mask);
- set_bit(cpu, &next->context.cpuvalid);
+
/* Re-load page tables */
asm volatile("movl %0,%%cr3": :"r" (__pa(next->pgd)));
+
+ /* load_LDT, if either the previous or next thread
+ * has a non-default LDT.
+ */
+ if (next->context.size+prev->context.size)
+ load_LDT(&next->context);
}
#ifdef CONFIG_SMP
else {
* tlb flush IPI delivery. We must flush our tlb.
*/
local_flush_tlb();
+ load_LDT(&next->context);
}
- if (!test_and_set_bit(cpu, &next->context.cpuvalid))
- load_LDT(next);
}
#endif
}
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