8321509: False positive in get_trampoline fast path causes crash

[bulasevich]

This change is a backport of JDK-8321509.

Note. This change adds two functions to trampoline_stub_Relocation class. On macos-aarch64 platform it triggers clang to report:

/Users/runner/work/jdk17u-dev/jdk17u-dev/src/hotspot/share/code/relocInfo.hpp:1212:8: error: 'pack_data_to' overrides a member function but is not marked 'override' [-Werror,-Winconsistent-missing-override]
  void pack_data_to(CodeSection * dest);
       ^
   ... (rest of output omitted)

Indeed, trampoline_stub_Relocation::pack_data_to overrides the virtual Relocation::pack_data_to. To fix the issue, I added the override keyword to the declaration of both pack_data_to and unpack_data in the trampoline_stub_Relocation class. To minimize changes, I did not modify other classes.

Also, it required a manual merge due to minor discrepancies between the mainline and jdk17u repositories. The reasons for the manual intervention are as follows:

• Copyright Year
  • The mainline patch updated the copyright from 2023 to 2024
  • In jdk17u the year is still 2021
• NULL -> nullptr conversion
  • mainline deals with nullptr after JDK-8301493: Replace NULL with nullptr in cpu/aarch64
• CodeBlob Lookup Changes
  • on the mainline "JDK-8290025: Remove the Sweeper" changed CodeCache::find_blob_unsafe call to CodeCache::find_blob
  • in jdk17u the old variant is used

See the minor mismatches below. Left: original diff on JDK mainline. Right: diff actually applied

diff --git a/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp b/src/ho    diff --git a/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp b/src/ho
--- a/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp                    --- a/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp
+++ b/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp                    +++ b/src/hotspot/cpu/aarch64/nativeInst_aarch64.cpp
@@ -1,5 +1,5 @@                                                         @@ -1,5 +1,5 @@
 /*                                                                      /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All righ |  - * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All righ
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All righ    + * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All righ
  * Copyright (c) 2014, 2020, Red Hat Inc. All rights reserved.           * Copyright (c) 2014, 2020, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.         * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *                                                                       *
@@ -158,13 +158,18 @@ void NativeGotJump::verify() const {              @@ -158,13 +158,18 @@ void NativeGotJump::verify() const {
 }                                                                       }

 address NativeCall::destination() const {                               address NativeCall::destination() const {
-  address addr = (address)this;                                        -  address addr = (address)this;
-  address destination = instruction_address() + displacement();        -  address destination = instruction_address() + displacement();
+  address addr = instruction_address();                                +  address addr = instruction_address();
+  address destination = addr + displacement();                         +  address destination = addr + displacement();
+                                                                       +
+  // Performance optimization: no need to call find_blob() if it is    +  // Performance optimization: no need to call find_blob() if it is
+  if (destination == addr) {                                           +  if (destination == addr) {
+    return destination;                                                +    return destination;
+  }                                                                    +  }

   // Do we use a trampoline stub for this call?                           // Do we use a trampoline stub for this call?
   CodeBlob* cb = CodeCache::find_blob(addr);                        |     CodeBlob* cb = CodeCache::find_blob_unsafe(addr);   // Else we get assertion if nmethod is zombie.
-  assert(cb && cb->is_nmethod(), "sanity");                            -  assert(cb && cb->is_nmethod(), "sanity");
-  nmethod *nm = (nmethod *)cb;                                         -  nmethod *nm = (nmethod *)cb;
+  assert(cb != nullptr && cb->is_nmethod(), "nmethod expected");       +  assert(cb != nullptr && cb->is_nmethod(), "nmethod expected");
+  nmethod *nm = cb->as_nmethod();                                      +  nmethod *nm = cb->as_nmethod();
   if (nm->stub_contains(destination) && is_NativeCallTrampolineStub       if (nm->stub_contains(destination) && is_NativeCallTrampolineStub
     // Yes we do, so get the destination from the trampoline stub.          // Yes we do, so get the destination from the trampoline stub.
     const address trampoline_stub_addr = destination;                       const address trampoline_stub_addr = destination;
@@ -211,22 +212,18 @@ void NativeCall::set_destination_mt_safe(addre    @@ -211,22 +212,18 @@ void NativeCall::set_destination_mt_safe(addre
 }                                                                       }

 address NativeCall::get_trampoline() {                                  address NativeCall::get_trampoline() {
-  address call_addr = addr_at(0);                                      -  address call_addr = addr_at(0);
+  address call_addr = instruction_address();                           +  address call_addr = instruction_address();

   CodeBlob *code = CodeCache::find_blob(call_addr);                       CodeBlob *code = CodeCache::find_blob(call_addr);
-  assert(code != nullptr, "Could not find the containing code blob" |  -  assert(code != NULL, "Could not find the containing code blob");
+  assert(code != nullptr && code->is_nmethod(), "nmethod expected")    +  assert(code != nullptr && code->is_nmethod(), "nmethod expected")
+  nmethod* nm = code->as_nmethod();                                    +  nmethod* nm = code->as_nmethod();

-  address bl_destination                                               -  address bl_destination
-    = MacroAssembler::pd_call_destination(call_addr);                  -    = MacroAssembler::pd_call_destination(call_addr);
-  if (code->contains(bl_destination) &&                                -  if (code->contains(bl_destination) &&
+  address bl_destination = call_addr + displacement();                 +  address bl_destination = call_addr + displacement();
+  if (nm->stub_contains(bl_destination) &&                             +  if (nm->stub_contains(bl_destination) &&
       is_NativeCallTrampolineStub_at(bl_destination))                         is_NativeCallTrampolineStub_at(bl_destination))
     return bl_destination;                                                  return bl_destination;

-  if (code->is_nmethod()) {                                            -  if (code->is_nmethod()) {
-    return trampoline_stub_Relocation::get_trampoline_for(call_addr    -    return trampoline_stub_Relocation::get_trampoline_for(call_addr
-  }                                                                    -  }
-                                                                       -
-  return nullptr;                                                   |  -  return NULL;
+  return trampoline_stub_Relocation::get_trampoline_for(call_addr,     +  return trampoline_stub_Relocation::get_trampoline_for(call_addr,
 }                                                                       }

 // Inserts a native call instruction at a given pc                      // Inserts a native call instruction at a given pc
diff --git a/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp b/src/ho    diff --git a/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp b/src/ho
--- a/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp                    --- a/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp
+++ b/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp                    +++ b/src/hotspot/cpu/aarch64/nativeInst_aarch64.hpp
@@ -1,5 +1,5 @@                                                         @@ -1,5 +1,5 @@
 /*                                                                      /*
- * Copyright (c) 1997, 2023, Oracle and/or its affiliates. All righ |  - * Copyright (c) 1997, 2021, Oracle and/or its affiliates. All righ
+ * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All righ    + * Copyright (c) 1997, 2024, Oracle and/or its affiliates. All righ
  * Copyright (c) 2014, 2108, Red Hat Inc. All rights reserved.           * Copyright (c) 2014, 2108, Red Hat Inc. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.         * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *                                                                       *
diff --git a/src/hotspot/cpu/aarch64/relocInfo_aarch64.cpp b/src/hot    diff --git a/src/hotspot/cpu/aarch64/relocInfo_aarch64.cpp b/src/hot
--- a/src/hotspot/cpu/aarch64/relocInfo_aarch64.cpp                     --- a/src/hotspot/cpu/aarch64/relocInfo_aarch64.cpp
+++ b/src/hotspot/cpu/aarch64/relocInfo_aarch64.cpp                     +++ b/src/hotspot/cpu/aarch64/relocInfo_aarch64.cpp
@@ -60,13 +60,12 @@ void Relocation::pd_set_data_value(address x, in    @@ -60,13 +60,12 @@ void Relocation::pd_set_data_value(address x, in

 address Relocation::pd_call_destination(address orig_addr) {            address Relocation::pd_call_destination(address orig_addr) {
   assert(is_call(), "should be a call here");                             assert(is_call(), "should be a call here");
-  if (NativeCall::is_call_at(addr())) {                                -  if (NativeCall::is_call_at(addr())) {
-    address trampoline = nativeCall_at(addr())->get_trampoline();      -    address trampoline = nativeCall_at(addr())->get_trampoline();
-    if (trampoline) {                                                  -    if (trampoline) {
-      return nativeCallTrampolineStub_at(trampoline)->destination()    -      return nativeCallTrampolineStub_at(trampoline)->destination()
+  if (orig_addr == nullptr) {                                          +  if (orig_addr == nullptr) {
+    if (NativeCall::is_call_at(addr())) {                              +    if (NativeCall::is_call_at(addr())) {
+      NativeCall* call = nativeCall_at(addr());                        +      NativeCall* call = nativeCall_at(addr());
+      return call->destination();                                      +      return call->destination();
     }                                                                       }
-  }                                                                    -  }
-  if (orig_addr != nullptr) {                                       |  -  if (orig_addr != NULL) {
+  } else {                                                             +  } else {
     address new_addr = MacroAssembler::pd_call_destination(orig_add         address new_addr = MacroAssembler::pd_call_destination(orig_add
     // If call is branch to self, don't try to relocate it, just le         // If call is branch to self, don't try to relocate it, just le
     // as branch to self. This happens during code generation if th         // as branch to self. This happens during code generation if th

---

Progress

• Change must be properly reviewed (1 review required, with at least 1 Reviewer)
• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• JDK-8321509 needs maintainer approval

Issue

• JDK-8321509: False positive in get_trampoline fast path causes crash (Bug - P3)

Reviewing

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https://git.openjdk.org/jdk17u-dev/pull/3441.diff

[bridgekeeper]

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[openjdk]

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[openjdk]

This backport pull request has now been updated with issue from the original commit.