6537506: Provide a mechanism for specifying Java-level USDT-like dtrace probes

Initial checkin of JSDT code

Reviewed-by: acorn, sbohne

hotspot/src/cpu/x86/vm/sharedRuntime_x86_32.cpp

@@ -1880,6 +1880,379 @@ nmethod *SharedRuntime::generate_native_wrapper(MacroAssembler *masm,
 
 }
 
+#ifdef HAVE_DTRACE_H
+// ---------------------------------------------------------------------------
+// Generate a dtrace nmethod for a given signature.  The method takes arguments
+// in the Java compiled code convention, marshals them to the native
+// abi and then leaves nops at the position you would expect to call a native
+// function. When the probe is enabled the nops are replaced with a trap
+// instruction that dtrace inserts and the trace will cause a notification
+// to dtrace.
+//
+// The probes are only able to take primitive types and java/lang/String as
+// arguments.  No other java types are allowed. Strings are converted to utf8
+// strings so that from dtrace point of view java strings are converted to C
+// strings. There is an arbitrary fixed limit on the total space that a method
+// can use for converting the strings. (256 chars per string in the signature).
+// So any java string larger then this is truncated.
+
+nmethod *SharedRuntime::generate_dtrace_nmethod(
+    MacroAssembler *masm, methodHandle method) {
+
+  // generate_dtrace_nmethod is guarded by a mutex so we are sure to
+  // be single threaded in this method.
+  assert(AdapterHandlerLibrary_lock->owned_by_self(), "must be");
+
+  // Fill in the signature array, for the calling-convention call.
+  int total_args_passed = method->size_of_parameters();
+
+  BasicType* in_sig_bt  = NEW_RESOURCE_ARRAY(BasicType, total_args_passed);
+  VMRegPair  *in_regs   = NEW_RESOURCE_ARRAY(VMRegPair, total_args_passed);
+
+  // The signature we are going to use for the trap that dtrace will see
+  // java/lang/String is converted. We drop "this" and any other object
+  // is converted to NULL.  (A one-slot java/lang/Long object reference
+  // is converted to a two-slot long, which is why we double the allocation).
+  BasicType* out_sig_bt = NEW_RESOURCE_ARRAY(BasicType, total_args_passed * 2);
+  VMRegPair* out_regs   = NEW_RESOURCE_ARRAY(VMRegPair, total_args_passed * 2);
+
+  int i=0;
+  int total_strings = 0;
+  int first_arg_to_pass = 0;
+  int total_c_args = 0;
+  int box_offset = java_lang_boxing_object::value_offset_in_bytes();
+
+  if( !method->is_static() ) {  // Pass in receiver first
+    in_sig_bt[i++] = T_OBJECT;
+    first_arg_to_pass = 1;
+  }
+
+  // We need to convert the java args to where a native (non-jni) function
+  // would expect them. To figure out where they go we convert the java
+  // signature to a C signature.
+
+  SignatureStream ss(method->signature());
+  for ( ; !ss.at_return_type(); ss.next()) {
+    BasicType bt = ss.type();
+    in_sig_bt[i++] = bt;  // Collect remaining bits of signature
+    out_sig_bt[total_c_args++] = bt;
+    if( bt == T_OBJECT) {
+      symbolOop s = ss.as_symbol_or_null();
+      if (s == vmSymbols::java_lang_String()) {
+        total_strings++;
+        out_sig_bt[total_c_args-1] = T_ADDRESS;
+      } else if (s == vmSymbols::java_lang_Boolean() ||
+                 s == vmSymbols::java_lang_Character() ||
+                 s == vmSymbols::java_lang_Byte() ||
+                 s == vmSymbols::java_lang_Short() ||
+                 s == vmSymbols::java_lang_Integer() ||
+                 s == vmSymbols::java_lang_Float()) {
+        out_sig_bt[total_c_args-1] = T_INT;
+      } else if (s == vmSymbols::java_lang_Long() ||
+                 s == vmSymbols::java_lang_Double()) {
+        out_sig_bt[total_c_args-1] = T_LONG;
+        out_sig_bt[total_c_args++] = T_VOID;
+      }
+    } else if ( bt == T_LONG || bt == T_DOUBLE ) {
+      in_sig_bt[i++] = T_VOID;   // Longs & doubles take 2 Java slots
+      out_sig_bt[total_c_args++] = T_VOID;
+    }
+  }
+
+  assert(i==total_args_passed, "validly parsed signature");
+
+  // Now get the compiled-Java layout as input arguments
+  int comp_args_on_stack;
+  comp_args_on_stack = SharedRuntime::java_calling_convention(
+      in_sig_bt, in_regs, total_args_passed, false);
+
+  // Now figure out where the args must be stored and how much stack space
+  // they require (neglecting out_preserve_stack_slots).
+
+  int out_arg_slots;
+  out_arg_slots = c_calling_convention(out_sig_bt, out_regs, total_c_args);
+
+  // Calculate the total number of stack slots we will need.
+
+  // First count the abi requirement plus all of the outgoing args
+  int stack_slots = SharedRuntime::out_preserve_stack_slots() + out_arg_slots;
+
+  // Now space for the string(s) we must convert
+
+  int* string_locs   = NEW_RESOURCE_ARRAY(int, total_strings + 1);
+  for (i = 0; i < total_strings ; i++) {
+    string_locs[i] = stack_slots;
+    stack_slots += max_dtrace_string_size / VMRegImpl::stack_slot_size;
+  }
+
+  // + 2 for return address (which we own) and saved rbp,
+
+  stack_slots += 2;
+
+  // Ok The space we have allocated will look like:
+  //
+  //
+  // FP-> |                     |
+  //      |---------------------|
+  //      | string[n]           |
+  //      |---------------------| <- string_locs[n]
+  //      | string[n-1]         |
+  //      |---------------------| <- string_locs[n-1]
+  //      | ...                 |
+  //      | ...                 |
+  //      |---------------------| <- string_locs[1]
+  //      | string[0]           |
+  //      |---------------------| <- string_locs[0]
+  //      | outbound memory     |
+  //      | based arguments     |
+  //      |                     |
+  //      |---------------------|
+  //      |                     |
+  // SP-> | out_preserved_slots |
+  //
+  //
+
+  // Now compute actual number of stack words we need rounding to make
+  // stack properly aligned.
+  stack_slots = round_to(stack_slots, 2 * VMRegImpl::slots_per_word);
+
+  int stack_size = stack_slots * VMRegImpl::stack_slot_size;
+
+  intptr_t start = (intptr_t)__ pc();
+
+  // First thing make an ic check to see if we should even be here
+
+  // We are free to use all registers as temps without saving them and
+  // restoring them except rbp. rbp, is the only callee save register
+  // as far as the interpreter and the compiler(s) are concerned.
+
+  const Register ic_reg = rax;
+  const Register receiver = rcx;
+  Label hit;
+  Label exception_pending;
+
+
+  __ verify_oop(receiver);
+  __ cmpl(ic_reg, Address(receiver, oopDesc::klass_offset_in_bytes()));
+  __ jcc(Assembler::equal, hit);
+
+  __ jump(RuntimeAddress(SharedRuntime::get_ic_miss_stub()));
+
+  // verified entry must be aligned for code patching.
+  // and the first 5 bytes must be in the same cache line
+  // if we align at 8 then we will be sure 5 bytes are in the same line
+  __ align(8);
+
+  __ bind(hit);
+
+  int vep_offset = ((intptr_t)__ pc()) - start;
+
+
+  // The instruction at the verified entry point must be 5 bytes or longer
+  // because it can be patched on the fly by make_non_entrant. The stack bang
+  // instruction fits that requirement.
+
+  // Generate stack overflow check
+
+
+  if (UseStackBanging) {
+    if (stack_size <= StackShadowPages*os::vm_page_size()) {
+      __ bang_stack_with_offset(StackShadowPages*os::vm_page_size());
+    } else {
+      __ movl(rax, stack_size);
+      __ bang_stack_size(rax, rbx);
+    }
+  } else {
+    // need a 5 byte instruction to allow MT safe patching to non-entrant
+    __ fat_nop();
+  }
+
+  assert(((int)__ pc() - start - vep_offset) >= 5,
+         "valid size for make_non_entrant");
+
+  // Generate a new frame for the wrapper.
+  __ enter();
+
+  // -2 because return address is already present and so is saved rbp,
+  if (stack_size - 2*wordSize != 0) {
+    __ subl(rsp, stack_size - 2*wordSize);
+  }
+
+  // Frame is now completed as far a size and linkage.
+
+  int frame_complete = ((intptr_t)__ pc()) - start;
+
+  // First thing we do store all the args as if we are doing the call.
+  // Since the C calling convention is stack based that ensures that
+  // all the Java register args are stored before we need to convert any
+  // string we might have.
+
+  int sid = 0;
+  int c_arg, j_arg;
+  int string_reg = 0;
+
+  for (j_arg = first_arg_to_pass, c_arg = 0 ;
+       j_arg < total_args_passed ; j_arg++, c_arg++ ) {
+
+    VMRegPair src = in_regs[j_arg];
+    VMRegPair dst = out_regs[c_arg];
+    assert(dst.first()->is_stack() || in_sig_bt[j_arg] == T_VOID,
+           "stack based abi assumed");
+
+    switch (in_sig_bt[j_arg]) {
+
+      case T_ARRAY:
+      case T_OBJECT:
+        if (out_sig_bt[c_arg] == T_ADDRESS) {
+          // Any register based arg for a java string after the first
+          // will be destroyed by the call to get_utf so we store
+          // the original value in the location the utf string address
+          // will eventually be stored.
+          if (src.first()->is_reg()) {
+            if (string_reg++ != 0) {
+              simple_move32(masm, src, dst);
+            }
+          }
+        } else if (out_sig_bt[c_arg] == T_INT || out_sig_bt[c_arg] == T_LONG) {
+          // need to unbox a one-word value
+          Register in_reg = rax;
+          if ( src.first()->is_reg() ) {
+            in_reg = src.first()->as_Register();
+          } else {
+            simple_move32(masm, src, in_reg->as_VMReg());
+          }
+          Label skipUnbox;
+          __ movl(Address(rsp, reg2offset_out(dst.first())), NULL_WORD);
+          if ( out_sig_bt[c_arg] == T_LONG ) {
+            __ movl(Address(rsp, reg2offset_out(dst.second())), NULL_WORD);
+          }
+          __ testl(in_reg, in_reg);
+          __ jcc(Assembler::zero, skipUnbox);
+          assert(dst.first()->is_stack() &&
+                 (!dst.second()->is_valid() || dst.second()->is_stack()),
+                 "value(s) must go into stack slots");
+          if ( out_sig_bt[c_arg] == T_LONG ) {
+            __ movl(rbx, Address(in_reg,
+                                 box_offset + VMRegImpl::stack_slot_size));
+            __ movl(Address(rsp, reg2offset_out(dst.second())), rbx);
+          }
+          __ movl(in_reg,  Address(in_reg, box_offset));
+          __ movl(Address(rsp, reg2offset_out(dst.first())), in_reg);
+          __ bind(skipUnbox);
+        } else {
+          // Convert the arg to NULL
+          __ movl(Address(rsp, reg2offset_out(dst.first())), NULL_WORD);
+        }
+        if (out_sig_bt[c_arg] == T_LONG) {
+          assert(out_sig_bt[c_arg+1] == T_VOID, "must be");
+          ++c_arg; // Move over the T_VOID To keep the loop indices in sync
+        }
+        break;
+
+      case T_VOID:
+        break;
+
+      case T_FLOAT:
+        float_move(masm, src, dst);
+        break;
+
+      case T_DOUBLE:
+        assert( j_arg + 1 < total_args_passed &&
+                in_sig_bt[j_arg + 1] == T_VOID, "bad arg list");
+        double_move(masm, src, dst);
+        break;
+
+      case T_LONG :
+        long_move(masm, src, dst);
+        break;
+
+      case T_ADDRESS: assert(false, "found T_ADDRESS in java args");
+
+      default:
+        simple_move32(masm, src, dst);
+    }
+  }
+
+  // Now we must convert any string we have to utf8
+  //
+
+  for (sid = 0, j_arg = first_arg_to_pass, c_arg = 0 ;
+       sid < total_strings ; j_arg++, c_arg++ ) {
+
+    if (out_sig_bt[c_arg] == T_ADDRESS) {
+
+      Address utf8_addr = Address(
+          rsp, string_locs[sid++] * VMRegImpl::stack_slot_size);
+      __ leal(rax, utf8_addr);
+
+      // The first string we find might still be in the original java arg
+      // register
+      VMReg orig_loc = in_regs[j_arg].first();
+      Register string_oop;
+
+      // This is where the argument will eventually reside
+      Address dest = Address(rsp, reg2offset_out(out_regs[c_arg].first()));
+
+      if (sid == 1 && orig_loc->is_reg()) {
+        string_oop = orig_loc->as_Register();
+        assert(string_oop != rax, "smashed arg");
+      } else {
+
+        if (orig_loc->is_reg()) {
+          // Get the copy of the jls object
+          __ movl(rcx, dest);
+        } else {
+          // arg is still in the original location
+          __ movl(rcx, Address(rbp, reg2offset_in(orig_loc)));
+        }
+        string_oop = rcx;
+
+      }
+      Label nullString;
+      __ movl(dest, NULL_WORD);
+      __ testl(string_oop, string_oop);
+      __ jcc(Assembler::zero, nullString);
+
+      // Now we can store the address of the utf string as the argument
+      __ movl(dest, rax);
+
+      // And do the conversion
+      __ call_VM_leaf(CAST_FROM_FN_PTR(
+             address, SharedRuntime::get_utf), string_oop, rax);
+      __ bind(nullString);
+    }
+
+    if (in_sig_bt[j_arg] == T_OBJECT && out_sig_bt[c_arg] == T_LONG) {
+      assert(out_sig_bt[c_arg+1] == T_VOID, "must be");
+      ++c_arg; // Move over the T_VOID To keep the loop indices in sync
+    }
+  }
+
+
+  // Ok now we are done. Need to place the nop that dtrace wants in order to
+  // patch in the trap
+
+  int patch_offset = ((intptr_t)__ pc()) - start;
+
+  __ nop();
+
+
+  // Return
+
+  __ leave();
+  __ ret(0);
+
+  __ flush();
+
+  nmethod *nm = nmethod::new_dtrace_nmethod(
+      method, masm->code(), vep_offset, patch_offset, frame_complete,
+      stack_slots / VMRegImpl::slots_per_word);
+  return nm;
+
+}
+
+#endif // HAVE_DTRACE_H
+
 // this function returns the adjust size (in number of words) to a c2i adapter
 // activation for use during deoptimization
 int Deoptimization::last_frame_adjust(int callee_parameters, int callee_locals ) {