arm64: kprobes: Use generic kretprobe trampoline handler

Use the generic kretprobe trampoline handler, and use
kernel_stack_pointer(regs) for framepointer verification.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/159870603544.1229682.10309733593594205725.stgit@devnote2

diff --git a/arch/arm64/kernel/probes/kprobes.c b/arch/arm64/kernel/probes/kprobes.c
index 5290f17..deba738 100644 (file)
--- a/arch/arm64/kernel/probes/kprobes.c
+++ b/arch/arm64/kernel/probes/kprobes.c
@@ -464,87 +464,15 @@ int __init arch_populate_kprobe_blacklist(void)
 
 void __kprobes __used *trampoline_probe_handler(struct pt_regs *regs)
 {
-       struct kretprobe_instance *ri = NULL;
-       struct hlist_head *head, empty_rp;
-       struct hlist_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);
-
-       /*
-        * It is possible to have multiple instances associated with a given
-        * task either because multiple functions in the call path have
-        * return probes installed on them, and/or more than one
-        * return probe was registered for a target function.
-        *
-        * We can handle this because:
-        *     - instances are always pushed into the head of the list
-        *     - when multiple return probes are registered for the same
-        *       function, the (chronologically) first instance's ret_addr
-        *       will be the real return address, and all the rest will
-        *       point to 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) {
-                       __this_cpu_write(current_kprobe, &ri->rp->kp);
-                       get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE;
-                       ri->ret_addr = correct_ret_addr;
-                       ri->rp->handler(ri, regs);
-                       __this_cpu_write(current_kprobe, NULL);
-               }
-
-               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;
-       }
-
-       kretprobe_hash_unlock(current, &flags);
-
-       hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
-               hlist_del(&ri->hlist);
-               kfree(ri);
-       }
-       return (void *)orig_ret_address;
+       return (void *)kretprobe_trampoline_handler(regs, &kretprobe_trampoline,
+                                       (void *)kernel_stack_pointer(regs));
 }
 
 void __kprobes arch_prepare_kretprobe(struct kretprobe_instance *ri,
                                      struct pt_regs *regs)
 {
        ri->ret_addr = (kprobe_opcode_t *)regs->regs[30];
+       ri->fp = (void *)kernel_stack_pointer(regs);
 
        /* replace return addr (x30) with trampoline */
        regs->regs[30] = (long)&kretprobe_trampoline;