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uprobes: Teach __create_xol_area() to accept the predefined vaddr

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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>
This commit is contained in:
Oleg Nesterov 2013-10-13 21:18:38 +02:00
parent 6441ec8b7c
commit af0d95af79
1 changed files with 12 additions and 8 deletions
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12
kernel/events/uprobes.c
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@ -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() */