s390: kprobes: Use generic kretprobe trampoline handler

Use the generic kretprobe trampoline handler. Don't use
framepointer verification.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/159870612453.1229682.15950927742606892302.stgit@devnote2

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index d2a71d8..fc30e79 100644 (file)
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -228,6 +228,7 @@ NOKPROBE_SYMBOL(pop_kprobe);
 void arch_prepare_kretprobe(struct kretprobe_instance *ri, struct pt_regs *regs)
 {
        ri->ret_addr = (kprobe_opcode_t *) regs->gprs[14];
+       ri->fp = NULL;
 
        /* Replace the return addr with trampoline addr */
        regs->gprs[14] = (unsigned long) &kretprobe_trampoline;
@@ -331,83 +332,7 @@ static void __used kretprobe_trampoline_holder(void)
  */
 static int trampoline_probe_handler(struct kprobe *p, struct pt_regs *regs)
 {
-       struct kretprobe_instance *ri;
-       struct hlist_head *head, empty_rp;
-       struct hlist_node *tmp;
-       unsigned long flags, orig_ret_address;
-       unsigned long trampoline_address;
-       kprobe_opcode_t *correct_ret_addr;
-
-       INIT_HLIST_HEAD(&empty_rp);
-       kretprobe_hash_lock(current, &head, &flags);
-
-       /*
-        * It is possible to have multiple instances associated with a given
-        * task either because an multiple functions in the call path
-        * have a return probe installed on them, and/or more than one return
-        * return probe was registered for a target function.
-        *
-        * We can handle this because:
-        *     - instances are always inserted at the head of the list
-        *     - when multiple return probes are registered for the same
-        *       function, the first instance's ret_addr will point to the
-        *       real return address, and all the rest will point to
-        *       kretprobe_trampoline
-        */
-       ri = NULL;
-       orig_ret_address = 0;
-       correct_ret_addr = NULL;
-       trampoline_address = (unsigned long) &kretprobe_trampoline;
-       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 (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) {
-                       ri->ret_addr = correct_ret_addr;
-                       ri->rp->handler(ri, regs);
-               }
-
-               recycle_rp_inst(ri, &empty_rp);
-
-               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;
-       }
-
-       regs->psw.addr = orig_ret_address;
-
-       kretprobe_hash_unlock(current, &flags);
-
-       hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
-               hlist_del(&ri->hlist);
-               kfree(ri);
-       }
+       regs->psw.addr = __kretprobe_trampoline_handler(regs, &kretprobe_trampoline, NULL);
        /*
         * By returning a non-zero value, we are telling
         * kprobe_handler() that we don't want the post_handler