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.
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
rp_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 4ea3e91..91edd2c 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1623,6 +1623,56 @@ static void handler_chain(struct uprobe *uprobe, struct
pt_regs *regs)
up_read(&uprobe->register_rwsem);
}
+static void handler_uretprobe_chain(struct uprobe *uprobe, struct pt_regs
*regs)
+{
+ struct uprobe_consumer *uc;
+
+ down_read(&uprobe->register_rwsem);
+ for (uc = uprobe->consumers; uc; uc = uc->next) {
+ if (uc->rp_handler)
+ uc->rp_handler(uc, regs);
+ }
+ up_read(&uprobe->register_rwsem);
+}
+
+static void handle_uretprobe(struct xol_area *area, struct pt_regs *regs)
+{
+ struct uprobe_task *utask;
+ struct return_instance *ri, *tmp;
+ unsigned long prev_ret_vaddr;
+
+ utask = get_utask();
+ if (!utask)
+ return;
+
+ ri = utask->return_instances;
+ if (!ri)
+ return;
+
+ instruction_pointer_set(regs, ri->orig_ret_vaddr);
+
+ while (ri) {
+ if (ri->uprobe->consumers)
+ handler_uretprobe_chain(ri->uprobe, regs);
+
+ put_uprobe(ri->uprobe);
+ tmp = ri;
+ prev_ret_vaddr = tmp->orig_ret_vaddr;
+ ri = ri->next;
+ kfree(tmp);
+
+ if (!ri || ri->dirty == false) {
+ /*
+ * This is the first return uprobe (chronologically)
+ * pushed for this particular instance of the probed
+ * function.
+ */
+ utask->return_instances = ri;
+ return;
+ }
+ }
+}
+
/*
* Run handler and ask thread to singlestep.
* Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
@@ -1631,11 +1681,19 @@ static void handle_swbp(struct pt_regs *regs)
{
struct uprobe *uprobe;
unsigned long bp_vaddr;
+ struct xol_area *area;
int uninitialized_var(is_swbp);
bp_vaddr = uprobe_get_swbp_addr(regs);
- uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
+ area = get_xol_area();
+ if (area) {
+ if (bp_vaddr == get_trampoline_vaddr(area)) {
+ handle_uretprobe(area, regs);
+ return;
+ }
+ }
+ 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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