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: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
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@ -1104,11 +1104,14 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
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if (mm->uprobes_state.xol_area)
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goto fail;
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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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ret = area->vaddr;
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goto fail;
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if (!area->vaddr) {
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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,
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PAGE_SIZE, 0, 0);
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if (area->vaddr & ~PAGE_MASK) {
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ret = area->vaddr;
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goto fail;
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}
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}
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ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE,
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@ -1124,13 +1127,13 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
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return ret;
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}
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static struct xol_area *__create_xol_area(void)
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static struct xol_area *__create_xol_area(unsigned long vaddr)
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{
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struct mm_struct *mm = current->mm;
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uprobe_opcode_t insn = UPROBE_SWBP_INSN;
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struct xol_area *area;
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area = kzalloc(sizeof(*area), GFP_KERNEL);
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area = kmalloc(sizeof(*area), GFP_KERNEL);
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if (unlikely(!area))
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goto out;
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@ -1142,6 +1145,7 @@ static struct xol_area *__create_xol_area(void)
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if (!area->page)
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goto free_bitmap;
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area->vaddr = vaddr;
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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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@ -1172,7 +1176,7 @@ static struct xol_area *get_xol_area(void)
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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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__create_xol_area(0);
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area = mm->uprobes_state.xol_area;
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smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */
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