Commit 06553175 authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Jon Medhurst

arm: kprobes: Fix the return address of multiple kretprobes

This is arm port of commit 737480a0 ("kprobes/x86:
Fix the return address of multiple kretprobes").

Fix the return address of subsequent kretprobes when multiple
kretprobes are set on the same function.

For example:

  # cd /sys/kernel/debug/tracing
  # echo "r:event1 sys_symlink" > kprobe_events
  # echo "r:event2 sys_symlink" >> kprobe_events
  # echo 1 > events/kprobes/enable
  # ln -s /tmp/foo /tmp/bar

 (without this patch)

  # cat trace | grep -v ^#
              ln-82    [000] dn.2    68.446525: event1: (kretprobe_trampoline+0x0/0x18 <- SyS_symlink)
              ln-82    [000] dn.2    68.447831: event2: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)

 (with this patch)

  # cat trace | grep -v ^#
              ln-81    [000] dn.1    39.463469: event1: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)
              ln-81    [000] dn.1    39.464701: event2: (ret_fast_syscall+0x0/0x1c <- SyS_symlink)
Signed-off-by: default avatarMasami Hiramatsu <mhiramat@kernel.org>
Cc: KUMANO Syuhei <kumano.prog@gmail.com>
Signed-off-by: default avatarJon Medhurst <tixy@linaro.org>
parent 91fc862c
...@@ -441,6 +441,7 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) ...@@ -441,6 +441,7 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
struct hlist_node *tmp; struct hlist_node *tmp;
unsigned long flags, orig_ret_address = 0; unsigned long flags, orig_ret_address = 0;
unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline; unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
kprobe_opcode_t *correct_ret_addr = NULL;
INIT_HLIST_HEAD(&empty_rp); INIT_HLIST_HEAD(&empty_rp);
kretprobe_hash_lock(current, &head, &flags); kretprobe_hash_lock(current, &head, &flags);
...@@ -463,14 +464,34 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) ...@@ -463,14 +464,34 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
/* another task is sharing our hash bucket */ /* another task is sharing our hash bucket */
continue; continue;
orig_ret_address = (unsigned long)ri->ret_addr;
if (orig_ret_address != trampoline_address)
/*
* This is the real return address. Any other
* instances associated with this task are for
* other calls deeper on the call stack
*/
break;
}
kretprobe_assert(ri, orig_ret_address, trampoline_address);
correct_ret_addr = ri->ret_addr;
hlist_for_each_entry_safe(ri, tmp, head, hlist) {
if (ri->task != current)
/* another task is sharing our hash bucket */
continue;
orig_ret_address = (unsigned long)ri->ret_addr;
if (ri->rp && ri->rp->handler) { if (ri->rp && ri->rp->handler) {
__this_cpu_write(current_kprobe, &ri->rp->kp); __this_cpu_write(current_kprobe, &ri->rp->kp);
get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
ri->ret_addr = correct_ret_addr;
ri->rp->handler(ri, regs); ri->rp->handler(ri, regs);
__this_cpu_write(current_kprobe, NULL); __this_cpu_write(current_kprobe, NULL);
} }
orig_ret_address = (unsigned long)ri->ret_addr;
recycle_rp_inst(ri, &empty_rp); recycle_rp_inst(ri, &empty_rp);
if (orig_ret_address != trampoline_address) if (orig_ret_address != trampoline_address)
...@@ -482,7 +503,6 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs) ...@@ -482,7 +503,6 @@ static __used __kprobes void *trampoline_handler(struct pt_regs *regs)
break; break;
} }
kretprobe_assert(ri, orig_ret_address, trampoline_address);
kretprobe_hash_unlock(current, &flags); kretprobe_hash_unlock(current, &flags);
hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) { hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment