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.
v2:
get rid of ->return_consumers
use rp_handler()
Signed-off-by: Anton Arapov <an...@redhat.com>
---
arch/x86/include/asm/uprobes.h | 5 ++++
include/linux/uprobes.h | 4 +++
kernel/events/uprobes.c | 61 +++++++++++++++++++++++++++++++++++++++++-
3 files changed, 69 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
index c353555..9a605b8 100644
--- a/arch/x86/include/asm/uprobes.h
+++ b/arch/x86/include/asm/uprobes.h
@@ -56,4 +56,9 @@ extern bool arch_uprobe_xol_was_trapped(struct task_struct
*tsk);
extern int arch_uprobe_exception_notify(struct notifier_block *self, unsigned
long val, void *data);
extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs
*regs);
extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long
rp_trampoline_vaddr, struct pt_regs *regs);
+
+static inline unsigned long arch_uretprobe_get_sp(struct pt_regs *regs)
+{
+ return (unsigned long)regs->sp;
+}
#endif /* _ASM_UPROBES_H */
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h
index cdc4d53..1a229db 100644
--- a/include/linux/uprobes.h
+++ b/include/linux/uprobes.h
@@ -45,7 +45,11 @@ enum uprobe_filter_ctx {
};
struct uprobe_consumer {
+ /* probe handler */
int (*handler)(struct uprobe_consumer *self, struct pt_regs *regs);
+ /* return probe handler */
+ int (*rp_handler)(struct uprobe_consumer *self, struct pt_regs *regs);
+
bool (*filter)(struct uprobe_consumer *self,
enum uprobe_filter_ctx ctx,
struct mm_struct *mm);
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index d6fa497..8232c29 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1548,6 +1548,57 @@ static void handler_chain(struct uprobe *uprobe, struct
pt_regs *regs)
up_read(&uprobe->register_rwsem);
}
+static void handler_rp_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_rp_swbp(struct pt_regs *regs)
+{
+ struct hlist_head *head;
+ struct hlist_node *r1, *r2;
+
+ struct return_uprobe_i *ri;
+ struct uprobe_task *utask;
+
+ struct xol_area *area;
+ unsigned long rp_trampoline_vaddr;
+ unsigned long orig_ret_vaddr, cur_sp;
+
+ cur_sp = arch_uretprobe_get_sp(regs);
+ utask = current->utask;
+ head = &utask->return_uprobes;
+
+ area = get_xol_area();
+ rp_trampoline_vaddr = area->vaddr;
+
+ hlist_for_each_entry_safe(ri, r1, r2, head, hlist) {
+ orig_ret_vaddr = ri->orig_ret_vaddr;
+
+ if (ri->uprobe->consumers) {
+ instruction_pointer_set(regs, orig_ret_vaddr);
+ handler_rp_chain(ri->uprobe, regs);
+ }
+
+ hlist_del(&ri->hlist);
+ kfree(ri);
+
+ if (orig_ret_vaddr != rp_trampoline_vaddr)
+ return;
+ }
+
+ printk(KERN_ERR "uretprobe: no instance with original return address!"
+ " pid/tgid=%d/%d", current->pid, current->tgid);
+ send_sig(SIGSEGV, current, 0);
+}
+
/*
* Run handler and ask thread to singlestep.
* Ensure all non-fatal signals cannot interrupt thread while it singlesteps.
@@ -1555,12 +1606,20 @@ static void handler_chain(struct uprobe *uprobe, struct
pt_regs *regs)
static void handle_swbp(struct pt_regs *regs)
{
struct uprobe *uprobe;
+ struct xol_area *area;
unsigned long bp_vaddr;
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 == area->vaddr) {
+ handle_rp_swbp(regs);
+ return;
+ }
+ }
+ uprobe = find_active_uprobe(bp_vaddr, &is_swbp);
if (!uprobe) {
if (is_swbp > 0) {
/* No matching uprobe; signal SIGTRAP. */
--
1.8.0.2
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