From aaf11effb2d3125072813a0c4ef15098ea556d7f Mon Sep 17 00:00:00 2001
From: TheRealMDoerr <martin.doerr@sap.com>
Date: Tue, 27 Sep 2022 11:16:27 +0200
Subject: [PATCH] Backport 14c6ac457d319a2e7f9cc9e7355c81c421a065dd

---
 src/hotspot/os_cpu/aix_ppc/thread_aix_ppc.cpp | 82 ++++++++++++++++---
 .../os_cpu/linux_ppc/thread_linux_ppc.cpp     |  4 +-
 2 files changed, 75 insertions(+), 11 deletions(-)

diff --git a/src/hotspot/os_cpu/aix_ppc/thread_aix_ppc.cpp b/src/hotspot/os_cpu/aix_ppc/thread_aix_ppc.cpp
index f8953c00554..17136141311 100644
--- a/src/hotspot/os_cpu/aix_ppc/thread_aix_ppc.cpp
+++ b/src/hotspot/os_cpu/aix_ppc/thread_aix_ppc.cpp
@@ -1,6 +1,7 @@
 /*
- * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012, 2014 SAP SE. All rights reserved.
+ * Copyright (c) 2022, IBM Corp.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -24,6 +25,7 @@
  */
 
 #include "precompiled.hpp"
+#include "memory/metaspace.hpp"
 #include "runtime/frame.inline.hpp"
 #include "runtime/thread.hpp"
 
@@ -34,23 +36,83 @@ frame JavaThread::pd_last_frame() {
   address pc = _anchor.last_Java_pc();
 
   // Last_Java_pc ist not set, if we come here from compiled code.
-  if (pc == NULL)
-    pc =  (address) *(sp + 2);
+  // Assume spill slot for link register contains a suitable pc.
+  // Should have been filled by method entry code.
+  if (pc == NULL) {
+    pc = (address) *(sp + 2);
+  }
 
   return frame(sp, pc);
 }
 
 bool JavaThread::pd_get_top_frame_for_profiling(frame* fr_addr, void* ucontext, bool isInJava) {
-  ucontext_t* uc = (ucontext_t*) ucontext;
-  *fr_addr = frame((intptr_t*)uc->uc_mcontext.jmp_context.gpr[1/*REG_SP*/],
-                   (address)uc->uc_mcontext.jmp_context.iar);
-  return true;
+
+  // If we have a last_Java_frame, then we should use it even if
+  // isInJava == true.  It should be more reliable than ucontext info.
+  if (has_last_Java_frame() && frame_anchor()->walkable()) {
+    frame last_frame = pd_last_frame();
+    if (last_frame.pc() == nullptr) return false;
+    *fr_addr = last_frame;
+    return true;
+  }
+
+  // At this point, we don't have a last_Java_frame, so
+  // we try to glean some information out of the ucontext
+  // if we were running Java code when SIGPROF came in.
+  if (isInJava) {
+    ucontext_t* uc = (ucontext_t*) ucontext;
+    address pc = (address)uc->uc_mcontext.jmp_context.iar;
+
+    if (pc == NULL) {
+      // ucontext wasn't useful
+      return false;
+    }
+
+    frame ret_frame((intptr_t*)uc->uc_mcontext.jmp_context.gpr[1/*REG_SP*/], pc);
+
+    if (ret_frame.fp() == NULL) {
+      // The found frame does not have a valid frame pointer.
+      // Bail out because this will create big trouble later on, either
+      //  - when using istate, calculated as (NULL - ijava_state_size) or
+      //  - when using fp() directly in safe_for_sender()
+      //
+      // There is no conclusive description (yet) how this could happen, but it does.
+      // For more details on what was observed, see thread_linux_s390.cpp
+      return false;
+    }
+
+    if (ret_frame.is_interpreted_frame()) {
+      frame::ijava_state *istate = ret_frame.get_ijava_state();
+      const Method *m = (const Method*)(istate->method);
+      if (!Method::is_valid_method(m)) return false;
+      if (!Metaspace::contains(m->constMethod())) return false;
+
+      uint64_t reg_bcp = uc->uc_mcontext.jmp_context.gpr[14/*R14_bcp*/];
+      uint64_t istate_bcp = istate->bcp;
+      uint64_t code_start = (uint64_t)(m->code_base());
+      uint64_t code_end = (uint64_t)(m->code_base() + m->code_size());
+      if (istate_bcp >= code_start && istate_bcp < code_end) {
+        // we have a valid bcp, don't touch it, do nothing
+      } else if (reg_bcp >= code_start && reg_bcp < code_end) {
+        istate->bcp = reg_bcp;
+      } else {
+        return false;
+      }
+    }
+    if (!ret_frame.safe_for_sender(this)) {
+      // nothing else to try if the frame isn't good
+      return false;
+    }
+    *fr_addr = ret_frame;
+    return true;
+  }
+  // nothing else to try
+  return false;
 }
 
-// Forte Analyzer AsyncGetCallTrace profiling support is not implemented on Aix/PPC.
+// Forte Analyzer AsyncGetCallTrace profiling support.
 bool JavaThread::pd_get_top_frame_for_signal_handler(frame* fr_addr, void* ucontext, bool isInJava) {
-  Unimplemented();
-  return false;
+  return pd_get_top_frame_for_profiling(fr_addr, ucontext, isInJava);
 }
 
 void JavaThread::cache_global_variables() { }
diff --git a/src/hotspot/os_cpu/linux_ppc/thread_linux_ppc.cpp b/src/hotspot/os_cpu/linux_ppc/thread_linux_ppc.cpp
index d7546a79048..fb229b505c1 100644
--- a/src/hotspot/os_cpu/linux_ppc/thread_linux_ppc.cpp
+++ b/src/hotspot/os_cpu/linux_ppc/thread_linux_ppc.cpp
@@ -49,7 +49,9 @@ bool JavaThread::pd_get_top_frame_for_profiling(frame* fr_addr, void* ucontext,
   // If we have a last_Java_frame, then we should use it even if
   // isInJava == true.  It should be more reliable than ucontext info.
   if (has_last_Java_frame() && frame_anchor()->walkable()) {
-    *fr_addr = pd_last_frame();
+    frame last_frame = pd_last_frame();
+    if (last_frame.pc() == nullptr) return false;
+    *fr_addr = last_frame;
     return true;
   }