}
/* Slot allocation for XOL */
-static int xol_add_vma(struct xol_area *area)
+static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
{
- struct mm_struct *mm = current->mm;
int ret = -EALREADY;
down_write(&mm->mmap_sem);
if (mm->uprobes_state.xol_area)
goto fail;
- ret = -ENOMEM;
- /* Try to map as high as possible, this is only a hint. */
- area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0);
- if (area->vaddr & ~PAGE_MASK) {
- ret = area->vaddr;
- goto fail;
+ if (!area->vaddr) {
+ /* Try to map as high as possible, this is only a hint. */
+ area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE,
+ PAGE_SIZE, 0, 0);
+ if (area->vaddr & ~PAGE_MASK) {
+ ret = area->vaddr;
+ goto fail;
+ }
}
ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE,
smp_wmb(); /* pairs with get_xol_area() */
mm->uprobes_state.xol_area = area;
- ret = 0;
fail:
up_write(&mm->mmap_sem);
return ret;
}
-/*
- * get_xol_area - Allocate process's xol_area if necessary.
- * This area will be used for storing instructions for execution out of line.
- *
- * Returns the allocated area or NULL.
- */
-static struct xol_area *get_xol_area(void)
+static struct xol_area *__create_xol_area(unsigned long vaddr)
{
struct mm_struct *mm = current->mm;
- struct xol_area *area;
uprobe_opcode_t insn = UPROBE_SWBP_INSN;
+ struct xol_area *area;
- area = mm->uprobes_state.xol_area;
- if (area)
- goto ret;
-
- area = kzalloc(sizeof(*area), GFP_KERNEL);
+ area = kmalloc(sizeof(*area), GFP_KERNEL);
if (unlikely(!area))
goto out;
if (!area->page)
goto free_bitmap;
- /* allocate first slot of task's xol_area for the return probes */
+ area->vaddr = vaddr;
+ init_waitqueue_head(&area->wq);
+ /* Reserve the 1st slot for get_trampoline_vaddr() */
set_bit(0, area->bitmap);
- copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE);
atomic_set(&area->slot_count, 1);
- init_waitqueue_head(&area->wq);
+ copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE);
- if (!xol_add_vma(area))
+ if (!xol_add_vma(mm, area))
return area;
__free_page(area->page);
free_area:
kfree(area);
out:
+ return NULL;
+}
+
+/*
+ * get_xol_area - Allocate process's xol_area if necessary.
+ * This area will be used for storing instructions for execution out of line.
+ *
+ * Returns the allocated area or NULL.
+ */
+static struct xol_area *get_xol_area(void)
+{
+ struct mm_struct *mm = current->mm;
+ struct xol_area *area;
+
+ if (!mm->uprobes_state.xol_area)
+ __create_xol_area(0);
+
area = mm->uprobes_state.xol_area;
- ret:
- smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */
+ smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */
return area;
}
}
/*
- * Called in context of a new clone/fork from copy_process.
- */
-void uprobe_copy_process(struct task_struct *t)
-{
- t->utask = NULL;
-}
-
-/*
* Allocate a uprobe_task object for the task if if necessary.
* Called when the thread hits a breakpoint.
*
return current->utask;
}
+static int dup_utask(struct task_struct *t, struct uprobe_task *o_utask)
+{
+ struct uprobe_task *n_utask;
+ struct return_instance **p, *o, *n;
+
+ n_utask = kzalloc(sizeof(struct uprobe_task), GFP_KERNEL);
+ if (!n_utask)
+ return -ENOMEM;
+ t->utask = n_utask;
+
+ p = &n_utask->return_instances;
+ for (o = o_utask->return_instances; o; o = o->next) {
+ n = kmalloc(sizeof(struct return_instance), GFP_KERNEL);
+ if (!n)
+ return -ENOMEM;
+
+ *n = *o;
+ atomic_inc(&n->uprobe->ref);
+ n->next = NULL;
+
+ *p = n;
+ p = &n->next;
+ n_utask->depth++;
+ }
+
+ return 0;
+}
+
+static void uprobe_warn(struct task_struct *t, const char *msg)
+{
+ pr_warn("uprobe: %s:%d failed to %s\n",
+ current->comm, current->pid, msg);
+}
+
+/*
+ * Called in context of a new clone/fork from copy_process.
+ */
+void uprobe_copy_process(struct task_struct *t)
+{
+ struct uprobe_task *utask = current->utask;
+ struct mm_struct *mm = current->mm;
+
+ t->utask = NULL;
+
+ if (mm == t->mm || !utask || !utask->return_instances)
+ return;
+
+ if (dup_utask(t, utask))
+ return uprobe_warn(t, "dup ret instances");
+}
+
/*
* Current area->vaddr notion assume the trampoline address is always
* equal area->vaddr.