diff options
author | Oleg Nesterov <oleg@redhat.com> | 2013-10-13 21:18:35 +0200 |
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committer | Oleg Nesterov <oleg@redhat.com> | 2013-10-29 18:02:50 +0100 |
commit | 6441ec8b7c108b72789d120562b9f1d976e4aaaf (patch) | |
tree | 3b8e813084698de0470713487e16941a08e5cace /kernel/events/uprobes.c | |
parent | b68e0749100e1b901bf11330f149b321c082178e (diff) | |
download | op-kernel-dev-6441ec8b7c108b72789d120562b9f1d976e4aaaf.zip op-kernel-dev-6441ec8b7c108b72789d120562b9f1d976e4aaaf.tar.gz |
uprobes: Introduce __create_xol_area()
No functional changes, preparation.
Extract the code which actually allocates/installs the new area
into the new helper, __create_xol_area().
While at it remove the unnecessary "ret = ENOMEM" and "ret = 0"
in xol_add_vma(), they both have no effect.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/events/uprobes.c')
-rw-r--r-- | kernel/events/uprobes.c | 47 |
1 files changed, 25 insertions, 22 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index db7a1dc..ad17d81 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -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); @@ -1170,9 +1157,25 @@ 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() */ + smp_read_barrier_depends(); /* pairs with wmb in xol_add_vma() */ return area; } |