[S390] kprobes: Fix the return address of multiple kretprobes

Analog to git commit 737480a0d525dae13306296da08029dff545bc72
fix the return address of subsequent kretprobes when multiple
kretprobes are set on the same function.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 26 insertions, 3 deletions

diff --git a/arch/s390/kernel/kprobes.c b/arch/s390/kernel/kprobes.c
index 70cf73bdba25..2564793ec2b6 100644
--- a/arch/s390/kernel/kprobes.c
+++ b/arch/s390/kernel/kprobes.c
@@ -349,6 +349,7 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
         struct hlist_node *node, *tmp;
         unsigned long flags, orig_ret_address = 0;
         unsigned long trampoline_address = (unsigned long)&kretprobe_trampoline;
+        kprobe_opcode_t *correct_ret_addr = NULL;
 
         INIT_HLIST_HEAD(&empty_rp);
         kretprobe_hash_lock(current, &head, &flags);
@@ -371,10 +372,32 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
                         /* another task is sharing our hash bucket */
                         continue;
 
-                if (ri->rp && ri->rp->handler)
-                        ri->rp->handler(ri, regs);
+                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, node, 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) {
@@ -386,7 +409,7 @@ static int __kprobes trampoline_probe_handler(struct kprobe *p,
                         break;
                 }
         }
-        kretprobe_assert(ri, orig_ret_address, trampoline_address);
+
         regs->psw.addr = orig_ret_address | PSW_ADDR_AMODE;
 
         reset_current_kprobe();