[lldb] Support disassembling RISC-V proprietary instructions

lldb/examples/python/filter_disasm.py

@@ -0,0 +1,87 @@
+"""
+Defines a command, fdis, that does filtered disassembly. The command does the
+lldb disassemble command with -b and any other arguments passed in, and
+pipes that through a provided filter program.
+
+The intention is to support disassembly of RISC-V proprietary instructions.
+This is handled with llvm-objdump by piping the output of llvm-objdump through
+a filter program. This script is intended to mimic that workflow.
+"""
+
+import lldb
+import subprocess
+
+filter_program = "crustfilt"
+
+def __lldb_init_module(debugger, dict):
+    debugger.HandleCommand(
+        'command script add -f filter_disasm.fdis fdis')
+    print("Disassembly filter command (fdis) loaded")
+    print("Filter program set to %s" % filter_program)
+
+
+def fdis(debugger, args, result, dict):
+    """
+  Call the built in disassembler, then pass its output to a filter program
+  to add in disassembly for hidden opcodes.
+  Except for get and set, use the fdis command like the disassemble command.
+  By default, the filter program is crustfilt, from
+  https://github.com/quic/crustfilt . This can be changed by changing
+  the global variable filter_program.
+
+  Usage:
+    fdis [[get] [set <program>] [<disassembly options>]]
+
+    Choose one of the following:
+        get
+            Gets the current filter program
+
+        set <program>
+            Sets the current filter program. This can be an executable, which
+            will be found on PATH, or an absolute path.
+
+        <disassembly options>
+            If the first argument is not get or set, the args will be passed
+            to the disassemble command as is.
+
+    """
+
+    global filter_program
+    args_list = args.split(' ')
+    result.Clear()
+
+    if len(args_list) == 1 and args_list[0] == 'get':
+        result.PutCString(filter_program)
+        result.SetStatus(lldb.eReturnStatusSuccessFinishResult)
+        return
+
+    if len(args_list) == 2 and args_list[0] == 'set':
+        filter_program = args_list[1]
+        result.PutCString("Filter program set to %s" % filter_program)
+        result.SetStatus(lldb.eReturnStatusSuccessFinishResult)
+        return
+
+    res = lldb.SBCommandReturnObject()
+    debugger.GetCommandInterpreter().HandleCommand('disassemble -b ' + args, res)
+    if (len(res.GetError()) > 0):
+        result.SetError(res.GetError())
+        result.SetStatus(lldb.eReturnStatusFailed)
+        return
+    output = res.GetOutput()
+
+    try:
+        proc = subprocess.run([filter_program], capture_output=True, text=True, input=output)
+    except (subprocess.SubprocessError, OSError) as e:
+        result.PutCString("Error occurred. Original disassembly:\n\n" + output)
+        result.SetError(str(e))
+        result.SetStatus(lldb.eReturnStatusFailed)
+        return
+
+    print(proc.stderr)
+    if proc.stderr:
+        pass
+        #result.SetError(proc.stderr)
+        #result.SetStatus(lldb.eReturnStatusFailed)
+    else:
+        result.PutCString(proc.stdout)
+        result.SetStatus(lldb.eReturnStatusSuccessFinishResult)

lldb/include/lldb/Core/Opcode.h

@@ -200,6 +200,7 @@ class Opcode {
   }
 
   int Dump(Stream *s, uint32_t min_byte_width);
+  int DumpRISCV(Stream *s, uint32_t min_byte_width);
 
   const void *GetOpcodeBytes() const {
     return ((m_type == Opcode::eTypeBytes) ? m_data.inst.bytes : nullptr);

lldb/source/Core/Disassembler.cpp

@@ -658,8 +658,13 @@ void Instruction::Dump(lldb_private::Stream *s, uint32_t max_opcode_byte_size,
       // the byte dump to be able to always show 15 bytes (3 chars each) plus a
       // space
       if (max_opcode_byte_size > 0)
-        m_opcode.Dump(&ss, max_opcode_byte_size * 3 + 1);
-      else
+        // make RISC-V opcode dump look like llvm-objdump
+        if (exe_ctx &&
+            exe_ctx->GetTargetSP()->GetArchitecture().GetTriple().isRISCV())
+          m_opcode.DumpRISCV(&ss, max_opcode_byte_size * 3 + 1);
+        else
+          m_opcode.Dump(&ss, max_opcode_byte_size * 3 + 1);
+       else
         m_opcode.Dump(&ss, 15 * 3 + 1);
     } else {
       // Else, we have ARM or MIPS which can show up to a uint32_t 0x00000000
@@ -685,10 +690,13 @@ void Instruction::Dump(lldb_private::Stream *s, uint32_t max_opcode_byte_size,
     }
   }
   const size_t opcode_pos = ss.GetSizeOfLastLine();
-  const std::string &opcode_name =
+  std::string &opcode_name =
       show_color ? m_markup_opcode_name : m_opcode_name;
   const std::string &mnemonics = show_color ? m_markup_mnemonics : m_mnemonics;
 
+  if (opcode_name.empty())
+    opcode_name = "<unknown>";
+
   // The default opcode size of 7 characters is plenty for most architectures
   // but some like arm can pull out the occasional vqrshrun.s16.  We won't get
   // consistent column spacing in these cases, unfortunately. Also note that we

lldb/source/Core/Opcode.cpp

@@ -78,6 +78,44 @@ lldb::ByteOrder Opcode::GetDataByteOrder() const {
   return eByteOrderInvalid;
 }
 
+// make RISC-V byte dumps look like llvm-objdump, instead of just dumping bytes
+int Opcode::DumpRISCV(Stream *s, uint32_t min_byte_width) {
+  const uint32_t previous_bytes = s->GetWrittenBytes();
+  // if m_type is not bytes, call Dump
+  if (m_type != Opcode::eTypeBytes)
+    return Dump(s, min_byte_width);
+
+  // from RISCVPrettyPrinter in llvm-objdump.cpp
+  // if size % 4 == 0, print as 1 or 2 32 bit values (32 or 64 bit inst)
+  // else if size % 2 == 0, print as 1 or 3 16 bit values (16 or 48 bit inst)
+  // else fall back and print bytes
+  for (uint32_t i = 0; i < m_data.inst.length;) {
+    if (i > 0)
+      s->PutChar(' ');
+    if (!(m_data.inst.length % 4)) {
+      s->Printf("%2.2x%2.2x%2.2x%2.2x", m_data.inst.bytes[i + 3],
+                                        m_data.inst.bytes[i + 2],
+                                        m_data.inst.bytes[i + 1],
+                                        m_data.inst.bytes[i + 0]);
+      i += 4;
+    } else if (!(m_data.inst.length % 2)) {
+      s->Printf("%2.2x%2.2x", m_data.inst.bytes[i + 1],
+                              m_data.inst.bytes[i + 0]);
+      i += 2;
+    } else {
+      s->Printf("%2.2x", m_data.inst.bytes[i]);
+      ++i;
+    }
+  }
+
+  uint32_t bytes_written_so_far = s->GetWrittenBytes() - previous_bytes;
+  // Add spaces to make sure bytes display comes out even in case opcodes aren't
+  // all the same size.
+  if (bytes_written_so_far < min_byte_width)
+    s->Printf("%*s", min_byte_width - bytes_written_so_far, "");
+  return s->GetWrittenBytes() - previous_bytes;
+}
+
 uint32_t Opcode::GetData(DataExtractor &data) const {
   uint32_t byte_size = GetByteSize();
   uint8_t swap_buf[8];

lldb/source/Plugins/Disassembler/LLVMC/DisassemblerLLVMC.cpp

@@ -61,6 +61,8 @@ class DisassemblerLLVMC::MCDisasmInstance {
 
   uint64_t GetMCInst(const uint8_t *opcode_data, size_t opcode_data_len,
                      lldb::addr_t pc, llvm::MCInst &mc_inst) const;
+  bool GetMCInst(const uint8_t *opcode_data, size_t opcode_data_len,
+                 lldb::addr_t pc, llvm::MCInst &mc_inst, size_t &size) const;
   void PrintMCInst(llvm::MCInst &mc_inst, lldb::addr_t pc,
                    std::string &inst_string, std::string &comments_string);
   void SetStyle(bool use_hex_immed, HexImmediateStyle hex_style);
@@ -524,11 +526,11 @@ class InstructionLLVMC : public lldb_private::Instruction {
           const addr_t pc = m_address.GetFileAddress();
           llvm::MCInst inst;
 
-          const size_t inst_size =
-              mc_disasm_ptr->GetMCInst(opcode_data, opcode_data_len, pc, inst);
-          if (inst_size == 0)
-            m_opcode.Clear();
-          else {
+          size_t inst_size = 0;
+          m_is_valid = mc_disasm_ptr->GetMCInst(opcode_data, opcode_data_len,
+                                                pc, inst, inst_size);
+          m_opcode.Clear();
+          if (inst_size != 0) {
             m_opcode.SetOpcodeBytes(opcode_data, inst_size);
             m_is_valid = true;
           }
@@ -604,10 +606,11 @@ class InstructionLLVMC : public lldb_private::Instruction {
         const uint8_t *opcode_data = data.GetDataStart();
         const size_t opcode_data_len = data.GetByteSize();
         llvm::MCInst inst;
-        size_t inst_size =
-            mc_disasm_ptr->GetMCInst(opcode_data, opcode_data_len, pc, inst);
-
-        if (inst_size > 0) {
+        size_t inst_size = 0;
+        bool valid = mc_disasm_ptr->GetMCInst(opcode_data, opcode_data_len, pc,
+                                             inst, inst_size);
+
+        if (valid && inst_size > 0) {
           mc_disasm_ptr->SetStyle(use_hex_immediates, hex_style);
 
           const bool saved_use_color = mc_disasm_ptr->GetUseColor();
@@ -1206,9 +1209,10 @@ class InstructionLLVMC : public lldb_private::Instruction {
     const uint8_t *opcode_data = data.GetDataStart();
     const size_t opcode_data_len = data.GetByteSize();
     llvm::MCInst inst;
-    const size_t inst_size =
-        mc_disasm_ptr->GetMCInst(opcode_data, opcode_data_len, pc, inst);
-    if (inst_size == 0)
+    size_t inst_size = 0;
+    const bool valid = mc_disasm_ptr->GetMCInst(opcode_data, opcode_data_len,
+                                                pc, inst, inst_size);
+    if (!valid)
       return;
 
     m_has_visited_instruction = true;
@@ -1337,19 +1341,18 @@ DisassemblerLLVMC::MCDisasmInstance::MCDisasmInstance(
          m_asm_info_up && m_context_up && m_disasm_up && m_instr_printer_up);
 }
 
-uint64_t DisassemblerLLVMC::MCDisasmInstance::GetMCInst(
+bool DisassemblerLLVMC::MCDisasmInstance::GetMCInst(
     const uint8_t *opcode_data, size_t opcode_data_len, lldb::addr_t pc,
-    llvm::MCInst &mc_inst) const {
+    llvm::MCInst &mc_inst, size_t &size) const {
   llvm::ArrayRef<uint8_t> data(opcode_data, opcode_data_len);
   llvm::MCDisassembler::DecodeStatus status;
 
-  uint64_t new_inst_size;
-  status = m_disasm_up->getInstruction(mc_inst, new_inst_size, data, pc,
+  status = m_disasm_up->getInstruction(mc_inst, size, data, pc,
                                        llvm::nulls());
   if (status == llvm::MCDisassembler::Success)
-    return new_inst_size;
+    return true;
   else
-    return 0;
+    return false;
 }
 
 void DisassemblerLLVMC::MCDisasmInstance::PrintMCInst(

lldb/source/Utility/ArchSpec.cpp

@@ -228,9 +228,9 @@ static const CoreDefinition g_core_definitions[] = {
     {eByteOrderLittle, 4, 4, 4, llvm::Triple::hexagon,
      ArchSpec::eCore_hexagon_hexagonv5, "hexagonv5"},
 
-    {eByteOrderLittle, 4, 2, 4, llvm::Triple::riscv32, ArchSpec::eCore_riscv32,
+    {eByteOrderLittle, 4, 2, 8, llvm::Triple::riscv32, ArchSpec::eCore_riscv32,
      "riscv32"},
-    {eByteOrderLittle, 8, 2, 4, llvm::Triple::riscv64, ArchSpec::eCore_riscv64,
+    {eByteOrderLittle, 8, 2, 8, llvm::Triple::riscv64, ArchSpec::eCore_riscv64,
      "riscv64"},
 
     {eByteOrderLittle, 4, 4, 4, llvm::Triple::loongarch32,