diff options
| author | Anton Arapov <anton@redhat.com> | 2013-04-03 18:00:32 +0200 |
|---|---|---|
| committer | Oleg Nesterov <oleg@redhat.com> | 2013-04-13 15:31:54 +0200 |
| commit | e78aebfd27256ca59ccd3e6cf62cfad2a80e02d3 (patch) | |
| tree | 6655e753d20bf964fbdcb6eefb3087dd954e2a1f /kernel/events | |
| parent | ea024870cf10687b3fded66a9deb6253888f30b7 (diff) | |
uretprobes: Reserve the first slot in xol_vma for trampoline
Allocate trampoline page, as the very first one in uprobed
task xol area, and fill it with breakpoint opcode.
Also introduce get_trampoline_vaddr() helper, to wrap the
trampoline address extraction from area->vaddr. That removes
confusion and eases the debug experience in case ->vaddr
notion will be changed.
Signed-off-by: Anton Arapov <anton@redhat.com>
Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Diffstat (limited to 'kernel/events')
| -rw-r--r-- | kernel/events/uprobes.c | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index eb384e90ac92..d345b7c6cb2d 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -1132,6 +1132,7 @@ static struct xol_area *get_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) @@ -1149,7 +1150,12 @@ 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 */ + 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); + if (!xol_add_vma(area)) return area; @@ -1346,6 +1352,25 @@ static struct uprobe_task *get_utask(void) return current->utask; } +/* + * Current area->vaddr notion assume the trampoline address is always + * equal area->vaddr. + * + * Returns -1 in case the xol_area is not allocated. + */ +static unsigned long get_trampoline_vaddr(void) +{ + struct xol_area *area; + unsigned long trampoline_vaddr = -1; + + area = current->mm->uprobes_state.xol_area; + smp_read_barrier_depends(); + if (area) + trampoline_vaddr = area->vaddr; + + return trampoline_vaddr; +} + /* Prepare to single-step probed instruction out of line. */ static int pre_ssout(struct uprobe *uprobe, struct pt_regs *regs, unsigned long bp_vaddr) |