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uretprobes: Return probe exit, invoke handlers

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Uretprobe handlers are invoked when the trampoline is hit, on completion
the trampoline is replaced with the saved return address and the uretprobe
instance deleted.

TODO: handle_trampoline() assumes that ->return_instances is always valid.
We should teach it to handle longjmp() which can invalidate the pending
return_instance's. This is nontrivial, we will try to do this in a separate
series.

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 18:00:36 +02:00 committed by Oleg Nesterov
parent 0dfd0eb8e4
commit fec8898d86
1 changed files with 64 additions and 1 deletions
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65
kernel/events/uprobes.c
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@ -1633,6 +1633,62 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
up_read(&uprobe->register_rwsem);
}
static void
handle_uretprobe_chain(struct return_instance *ri, struct pt_regs *regs)
{
struct uprobe *uprobe = ri->uprobe;
struct uprobe_consumer *uc;
down_read(&uprobe->register_rwsem);
for (uc = uprobe->consumers; uc; uc = uc->next) {
if (uc->ret_handler)
uc->ret_handler(uc, ri->func, regs);
}
up_read(&uprobe->register_rwsem);
}
static bool handle_trampoline(struct pt_regs *regs)
{
struct uprobe_task *utask;
struct return_instance *ri, *tmp;
bool chained;
utask = current->utask;
if (!utask)
return false;
ri = utask->return_instances;
if (!ri)
return false;
/*
* TODO: we should throw out return_instance's invalidated by
* longjmp(), currently we assume that the probed function always
* returns.
*/
instruction_pointer_set(regs, ri->orig_ret_vaddr);
for (;;) {
handle_uretprobe_chain(ri, regs);
chained = ri->chained;
put_uprobe(ri->uprobe);
tmp = ri;
ri = ri->next;
kfree(tmp);
if (!chained)
break;
BUG_ON(!ri);
}
utask->return_instances = ri;
return true;
}
/*
* Run handler and ask thread to singlestep.
* Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
@ -1644,8 +1700,15 @@ static void handle_swbp(struct pt_regs *regs)
int uninitialized_var(is_swbp);
bp_vaddr = uprobe_get_swbp_addr(regs);
uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
if (bp_vaddr == get_trampoline_vaddr()) {
if (handle_trampoline(regs))
return;
pr_warn("uprobe: unable to handle uretprobe pid/tgid=%d/%d\n",
current->pid, current->tgid);
}
uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
if (!uprobe) {
if (is_swbp > 0) {
/* No matching uprobe; signal SIGTRAP. */