uprobes: Introduce __create_xol_area() (6441ec8b) · Commits · 戴 / test

kernel/events/uprobes.c

+25 −22

Original line number	Diff line number	Diff line
		@@ -1096,16 +1096,14 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
		}

		/* 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) {
		@@ -1120,28 +1118,17 @@ static int xol_add_vma(struct xol_area *area)

		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(void)
		{
		struct mm_struct *mm = current->mm;
		struct xol_area *area;
		uprobe_opcode_t insn = UPROBE_SWBP_INSN;

		area = mm->uprobes_state.xol_area;
		if (area)
		goto ret;
		struct xol_area *area;

		area = kzalloc(sizeof(*area), GFP_KERNEL);
		if (unlikely(!area))
		@@ -1155,13 +1142,13 @@ static struct xol_area *get_xol_area(void)
		if (!area->page)
		goto free_bitmap;

		/* allocate first slot of task's xol_area for the return probes */
		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);
		@@ -1170,8 +1157,24 @@ static struct xol_area *get_xol_area(void)
		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();

		area = mm->uprobes_state.xol_area;
		ret:
		smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */
		return area;
		}

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