kpriv/linux-hardened
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity

uretprobes: Reserve the first slot in xol_vma for trampoline

Browse source 
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>
This commit is contained in:
Anton Arapov 2013-04-03 18:00:32 +02:00 committed by Oleg Nesterov
parent ea024870cf
commit e78aebfd27
1 changed files with 25 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

25
kernel/events/uprobes.c
View file

@ -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)