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Commit af0d95af authored by Oleg Nesterov's avatar Oleg Nesterov
Browse files

uprobes: Teach __create_xol_area() to accept the predefined vaddr 



Currently xol_add_vma() uses get_unmapped_area() for area->vaddr,
but the next patches need to use the fixed address. So this patch
adds the new "vaddr" argument to __create_xol_area() which should
be used as area->vaddr if it is nonzero.

xol_add_vma() doesn't bother to verify that the predefined addr is
not used, insert_vm_struct() should fail if find_vma_links() detects
the overlap with the existing vma.

Also, __create_xol_area() doesn't need __GFP_ZERO to allocate area.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
parent 6441ec8b

kernel/events/uprobes.c

+12 −8
Original line number Diff line number Diff line
@@ -1104,12 +1104,15 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) 
	if (mm->uprobes_state.xol_area)

		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);

		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,

				VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, &area->page);
@@ -1124,13 +1127,13 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) 
	return ret;

}



static struct xol_area *__create_xol_area(void)

static struct xol_area *__create_xol_area(unsigned long vaddr)

{

	struct mm_struct *mm = current->mm;

	uprobe_opcode_t insn = UPROBE_SWBP_INSN;

	struct xol_area *area;



	area = kzalloc(sizeof(*area), GFP_KERNEL);

	area = kmalloc(sizeof(*area), GFP_KERNEL);

	if (unlikely(!area))

		goto out;
@@ -1142,6 +1145,7 @@ static struct xol_area *__create_xol_area(void) 
	if (!area->page)

		goto free_bitmap;



	area->vaddr = vaddr;

	init_waitqueue_head(&area->wq);

	/* Reserve the 1st slot for get_trampoline_vaddr() */

	set_bit(0, area->bitmap);
@@ -1172,7 +1176,7 @@ static struct xol_area *get_xol_area(void) 
	struct xol_area *area;



	if (!mm->uprobes_state.xol_area)

		__create_xol_area();

		__create_xol_area(0);



	area = mm->uprobes_state.xol_area;

	smp_read_barrier_depends();	/* pairs with wmb in xol_add_vma() */