From af0d95af79773f7637107cd3871aaabcb425f15a Mon Sep 17 00:00:00 2001 From: Oleg Nesterov Date: Sun, 13 Oct 2013 21:18:38 +0200 Subject: [PATCH] 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 Acked-by: Srikar Dronamraju --- kernel/events/uprobes.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index ad17d813e73e..7d12a45842a7 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1104,11 +1104,14 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area) if (mm->uprobes_state.xol_area) goto fail; - /* 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) { - ret = area->vaddr; - 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); + if (area->vaddr & ~PAGE_MASK) { + ret = area->vaddr; + goto fail; + } } ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE, @@ -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() */ -- 2.20.1