uprobes: Introduce __create_xol_area()
No functional changes, preparation. Extract the code which actually allocates/installs the new area into the new helper, __create_xol_area(). While at it remove the unnecessary "ret = ENOMEM" and "ret = 0" in xol_add_vma(), they both have no effect. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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@ -1096,16 +1096,14 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
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}
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/* Slot allocation for XOL */
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static int xol_add_vma(struct xol_area *area)
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static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
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{
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struct mm_struct *mm = current->mm;
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int ret = -EALREADY;
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down_write(&mm->mmap_sem);
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if (mm->uprobes_state.xol_area)
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goto fail;
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ret = -ENOMEM;
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/* Try to map as high as possible, this is only a hint. */
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area->vaddr = get_unmapped_area(NULL, TASK_SIZE - PAGE_SIZE, PAGE_SIZE, 0, 0);
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if (area->vaddr & ~PAGE_MASK) {
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@ -1120,28 +1118,17 @@ static int xol_add_vma(struct xol_area *area)
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smp_wmb(); /* pairs with get_xol_area() */
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mm->uprobes_state.xol_area = area;
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ret = 0;
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fail:
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up_write(&mm->mmap_sem);
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return ret;
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}
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/*
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* get_xol_area - Allocate process's xol_area if necessary.
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* This area will be used for storing instructions for execution out of line.
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*
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* Returns the allocated area or NULL.
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*/
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static struct xol_area *get_xol_area(void)
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static struct xol_area *__create_xol_area(void)
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{
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struct mm_struct *mm = current->mm;
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struct xol_area *area;
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uprobe_opcode_t insn = UPROBE_SWBP_INSN;
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area = mm->uprobes_state.xol_area;
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if (area)
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goto ret;
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struct xol_area *area;
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area = kzalloc(sizeof(*area), GFP_KERNEL);
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if (unlikely(!area))
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@ -1155,13 +1142,13 @@ static struct xol_area *get_xol_area(void)
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if (!area->page)
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goto free_bitmap;
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/* allocate first slot of task's xol_area for the return probes */
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set_bit(0, area->bitmap);
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copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE);
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atomic_set(&area->slot_count, 1);
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init_waitqueue_head(&area->wq);
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/* Reserve the 1st slot for get_trampoline_vaddr() */
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set_bit(0, area->bitmap);
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atomic_set(&area->slot_count, 1);
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copy_to_page(area->page, 0, &insn, UPROBE_SWBP_INSN_SIZE);
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if (!xol_add_vma(area))
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if (!xol_add_vma(mm, area))
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return area;
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__free_page(area->page);
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@ -1170,9 +1157,25 @@ static struct xol_area *get_xol_area(void)
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free_area:
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kfree(area);
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out:
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return NULL;
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}
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/*
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* get_xol_area - Allocate process's xol_area if necessary.
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* This area will be used for storing instructions for execution out of line.
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*
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* Returns the allocated area or NULL.
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*/
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static struct xol_area *get_xol_area(void)
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{
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struct mm_struct *mm = current->mm;
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struct xol_area *area;
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if (!mm->uprobes_state.xol_area)
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__create_xol_area();
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area = mm->uprobes_state.xol_area;
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ret:
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smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */
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smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */
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return area;
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}
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