8369946: Bytecode rewriting causes Java heap corruption on PPC

Reviewed-by: rrich
Backport-of: 6bf3581bbacc2ed8f6411d23a5ab332376c53c87

Author: TheRealMDoerr

src/hotspot/cpu/ppc/interp_masm_ppc.hpp

@@ -126,7 +126,8 @@ class InterpreterMacroAssembler: public MacroAssembler {
 
   void get_cache_index_at_bcp(Register Rdst, int bcp_offset, size_t index_size);
 
-  void get_cache_and_index_at_bcp(Register cache, int bcp_offset, size_t index_size = sizeof(u2));
+  void get_cache_and_index_at_bcp(Register cache, int bcp_offset, size_t index_size = sizeof(u2),
+                                  bool for_fast_bytecode = false);
   void load_resolved_indy_entry(Register cache, Register index);
 
   void get_u4(Register Rdst, Register Rsrc, int offset, signedOrNot is_signed);

src/hotspot/cpu/ppc/interp_masm_ppc_64.cpp

@@ -451,10 +451,18 @@ void InterpreterMacroAssembler::get_cache_index_at_bcp(Register Rdst, int bcp_of
 }
 
 void InterpreterMacroAssembler::get_cache_and_index_at_bcp(Register cache, int bcp_offset,
-                                                           size_t index_size) {
+                                                           size_t index_size, bool for_fast_bytecode) {
   get_cache_index_at_bcp(cache, bcp_offset, index_size);
   sldi(cache, cache, exact_log2(in_words(ConstantPoolCacheEntry::size()) * BytesPerWord));
   add(cache, R27_constPoolCache, cache);
+
+  if (for_fast_bytecode) {
+    // Prevent speculative loading from ConstantPoolCacheEntry as it can miss the info written by another thread.
+    // TemplateTable::patch_bytecode uses release-store.
+    // We reached here via control dependency (Bytecode dispatch has used the rewritten Bytecode).
+    // So, we can use control-isync based ordering.
+    isync();
+  }
 }
 
 // Load 4-byte signed or unsigned integer in Java format (that is, big-endian format)

src/hotspot/cpu/ppc/templateTable_ppc_64.cpp

@@ -147,7 +147,9 @@ void TemplateTable::patch_bytecode(Bytecodes::Code new_bc, Register Rnew_bc, Reg
     __ bind(L_fast_patch);
   }
 
-  // Patch bytecode.
+  // Patch bytecode with release store to coordinate with ConstantPoolCacheEntry
+  // loads in fast bytecode codelets.
+  __ release();
   __ stb(Rnew_bc, 0, R14_bcp);
 
   __ bind(L_patch_done);
@@ -311,6 +313,7 @@ void TemplateTable::fast_aldc(LdcType type) {
   // We are resolved if the resolved reference cache entry contains a
   // non-null object (CallSite, etc.)
   __ get_cache_index_at_bcp(R31, 1, index_size);  // Load index.
+  // Only rewritten during link time. So, no need for memory barriers for accessing resolved info.
   __ load_resolved_reference_at_index(R17_tos, R31, R11_scratch1, R12_scratch2, &is_null);
 
   // Convert null sentinel to null
@@ -2377,7 +2380,7 @@ void TemplateTable::load_invoke_cp_cache_entry(int byte_no,
   if (is_invokevfinal) {
     assert(Ritable_index == noreg, "register not used");
     // Already resolved.
-    __ get_cache_and_index_at_bcp(Rcache, 1);
+    __ get_cache_and_index_at_bcp(Rcache, 1, sizeof(u2), /* for_fast_bytecode */ true);
   } else {
     resolve_cache_and_index(byte_no, Rcache, /* temp */ Rmethod, sizeof(u2));
   }
@@ -3084,7 +3087,7 @@ void TemplateTable::fast_storefield(TosState state) {
   const ConditionRegister CR_is_vol = CCR2; // Non-volatile condition register (survives runtime call in do_oop_store).
 
   // Constant pool already resolved => Load flags and offset of field.
-  __ get_cache_and_index_at_bcp(Rcache, 1);
+  __ get_cache_and_index_at_bcp(Rcache, 1, sizeof(u2), /* for_fast_bytecode */ true);
   jvmti_post_field_mod(Rcache, Rscratch, false /* not static */);
   load_field_cp_cache_entry(noreg, Rcache, noreg, Roffset, Rflags, false); // Uses R11, R12
 
@@ -3165,7 +3168,7 @@ void TemplateTable::fast_accessfield(TosState state) {
                  // R12_scratch2 used by load_field_cp_cache_entry
 
   // Constant pool already resolved. Get the field offset.
-  __ get_cache_and_index_at_bcp(Rcache, 1);
+  __ get_cache_and_index_at_bcp(Rcache, 1, sizeof(u2), /* for_fast_bytecode */ true);
   load_field_cp_cache_entry(noreg, Rcache, noreg, Roffset, Rflags, false); // Uses R11, R12
 
   // JVMTI support
@@ -3304,7 +3307,7 @@ void TemplateTable::fast_xaccess(TosState state) {
   __ ld(Rclass_or_obj, 0, R18_locals);
 
   // Constant pool already resolved. Get the field offset.
-  __ get_cache_and_index_at_bcp(Rcache, 2);
+  __ get_cache_and_index_at_bcp(Rcache, 2, sizeof(u2), /* for_fast_bytecode */ true);
   load_field_cp_cache_entry(noreg, Rcache, noreg, Roffset, Rflags, false); // Uses R11, R12
 
   // JVMTI support not needed, since we switch back to single bytecode as soon as debugger attaches.