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.
v1 changes:
* pass bp_vaddr to ret_handler()
* simplify handle_uretprobe()
RFCv6 changes:
* rework handle_uretprobe()
RFCv5 changes:
* switch to simply linked list ->return_uprobes
* rework handle_uretprobe()
RFCv4 changes:
* check, whether utask is not NULL in handle_uretprobe()
* get rid of area->rp_trampoline_vaddr
* minor handle_uretprobe() fixups
RFCv3 changes:
* protected uprobe with refcounter. See put_uprobe() in handle_uretprobe()
that reflects increment in prepare_uretprobe()
RFCv2 changes:
* get rid of ->return_consumers member from struct uprobe, introduce
ret_handler() in consumer instead
Signed-off-by: Anton Arapov <an...@redhat.com>
---
kernel/events/uprobes.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 59 insertions(+), 1 deletion(-)
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 08ecfff..d129c1d 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1609,6 +1609,57 @@ static void handler_chain(struct uprobe *uprobe, struct
pt_regs *regs)
up_read(&uprobe->register_rwsem);
}
+static void
+handler_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 handler_uretprobe(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;
+
+ instruction_pointer_set(regs, ri->orig_ret_vaddr);
+
+ for (;;) {
+ handler_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.
@@ -1620,8 +1671,15 @@ 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 (handler_uretprobe(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. */
--
1.8.1.4
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