Implement loading of test signatures

src/elf.cpp

@@ -57,29 +57,38 @@ struct Elf32Section {
   uint32_t sh_entsize;    // Entry size if section holds table
 };
 
-bool should_load_section(const Elf32Section& section_header) {
-    // Check if the section has the SHF_ALLOC flag, which indicates
-    // the section should be loaded into memory
-    if (section_header.sh_flags & SHF_ALLOC) {
-        // Further filter out sections that shouldn't be loaded
-        switch (section_header.sh_type) {
-            case SHT_PROGBITS:   // Typically contains code or data
-            case SHT_INIT_ARRAY: // Initialization function pointers
-            case SHT_FINI_ARRAY: // Termination function pointers
-            case SHT_NOBITS:     // .bss section (uninitialized data)
-                return true;
+struct Elf32Sym {
+  uint32_t st_name;   // Symbol name (index into string table)
+  uint32_t st_value;  // Symbol value (address or offset)
+  uint32_t st_size;   // Size of the symbol
+  uint8_t st_info;    // Symbol type and binding attributes
+  uint8_t st_other;   // Symbol visibility
+  uint16_t st_shndx;  // Section header index related to this symbol
+};
 
-            // Exclude debug and other non-loadable sections
-            case SHT_SYMTAB:     // Symbol table
-            case SHT_STRTAB:     // String table
-            case SHT_RELA:       // Relocation entries
-            case SHT_DYNAMIC:    // Dynamic linking information
-            case SHT_NOTE:       // Note section
-            default:
-                return false;
-        }
+bool should_load_section(const Elf32Section& section_header) {
+  // Check if the section has the SHF_ALLOC flag, which indicates
+  // the section should be loaded into memory
+  if (section_header.sh_flags & SHF_ALLOC) {
+    // Further filter out sections that shouldn't be loaded
+    switch (section_header.sh_type) {
+      case SHT_PROGBITS:    // Typically contains code or data
+      case SHT_INIT_ARRAY:  // Initialization function pointers
+      case SHT_FINI_ARRAY:  // Termination function pointers
+      case SHT_NOBITS:      // .bss section (uninitialized data)
+        return true;
+
+      // Exclude debug and other non-loadable sections
+      case SHT_SYMTAB:   // Symbol table
+      case SHT_STRTAB:   // String table
+      case SHT_RELA:     // Relocation entries
+      case SHT_DYNAMIC:  // Dynamic linking information
+      case SHT_NOTE:     // Note section
+      default:
+        return false;
     }
-    return false;
+  }
+  return false;
 }
 
 std::vector<uint8_t> load_elf(const std::string& filename, size_t memory_size) {
@@ -143,7 +152,7 @@ std::vector<uint8_t> load_elf(const std::string& filename, size_t memory_size) {
     throw std::runtime_error("No loadable sections found");
   }
 
-  std::vector<uint8_t> loadedData(memoryEnd-memoryStart, 0);
+  std::vector<uint8_t> loadedData(memoryEnd - memoryStart, 0);
 
   // Load .text and .sdata sections
   for (const Elf32Section& shdr : sectionHeaders) {
@@ -153,8 +162,9 @@ std::vector<uint8_t> load_elf(const std::string& filename, size_t memory_size) {
       }
 
       file.seekg(shdr.sh_offset);
-      file.read(reinterpret_cast<char*>(&loadedData[shdr.sh_addr-memoryStart]),
-                shdr.sh_size);
+      file.read(
+          reinterpret_cast<char*>(&loadedData[shdr.sh_addr - memoryStart]),
+          shdr.sh_size);
       if (!file) {
         throw std::runtime_error("Failed to read section data");
       }
@@ -163,3 +173,86 @@ std::vector<uint8_t> load_elf(const std::string& filename, size_t memory_size) {
 
   return loadedData;
 }
+
+std::tuple<uint32_t, uint32_t> elf_get_signature(const std::string& filename) {
+  std::ifstream file(filename, std::ios::binary);
+  if (!file.is_open()) {
+    throw std::runtime_error("Failed to open ELF file");
+  }
+
+  // Read the ELF header
+  Elf32Header ehdr;
+  file.read(reinterpret_cast<char*>(&ehdr), sizeof(ehdr));
+  if (!file) {
+    throw std::runtime_error("Failed to read ELF header");
+  }
+
+  // Validate ELF magic and basic properties
+  if (std::memcmp(ehdr.e_ident, ELF_MAGIC, sizeof(ELF_MAGIC)) != 0) {
+    throw std::runtime_error("Invalid ELF magic number");
+  }
+  if (ehdr.e_ident[4] != ELF_CLASS_32 || ehdr.e_ident[5] != ELF_LITTLE_ENDIAN) {
+    throw std::runtime_error("Unsupported ELF class or endianness");
+  }
+  if (ehdr.e_type != ELF_TYPE_EXECUTABLE ||
+      ehdr.e_machine != ELF_MACHINE_RISCV) {
+    throw std::runtime_error("Unsupported ELF type or machine");
+  }
+
+  // Read section headers
+  file.seekg(ehdr.e_shoff);
+  std::vector<Elf32Section> sectionHeaders(ehdr.e_shnum);
+  for (size_t i = 0; i < ehdr.e_shnum; ++i) {
+    file.read(reinterpret_cast<char*>(&sectionHeaders[i]),
+              sizeof(Elf32Section));
+    if (!file) {
+      throw std::runtime_error("Failed to read section headers");
+    }
+  }
+
+  // Load symbols
+  std::vector<Elf32Sym> sectionSymTable;
+  std::vector<char> sectionStrTable;
+
+  for (const Elf32Section& shdr : sectionHeaders) {
+    if (shdr.sh_type == SHT_SYMTAB) {
+      size_t symbol_count = shdr.sh_size / shdr.sh_entsize;
+      sectionSymTable = std::vector<Elf32Sym>(symbol_count);
+
+      file.seekg(shdr.sh_offset);
+      file.read(reinterpret_cast<char*>(sectionSymTable.data()), shdr.sh_size);
+      if (!file) {
+        throw std::runtime_error("Failed to read section symbol table");
+      }
+
+      const Elf32Section& strtab_shdr = sectionHeaders[shdr.sh_link];
+
+      sectionStrTable = std::vector<char>(strtab_shdr.sh_size);
+      file.seekg(strtab_shdr.sh_offset);
+      file.read(sectionStrTable.data(), strtab_shdr.sh_size);
+      if (!file) {
+        throw std::runtime_error("Failed to read section symbol string table");
+      }
+    }
+  }
+
+  uint32_t begin_signature = 0;
+  uint32_t end_signature = 0;
+
+  for (const Elf32Sym sym : sectionSymTable) {
+    const char* name = &sectionStrTable[sym.st_name];
+
+    if (std::strcmp(name, "begin_signature") == 0) {
+      begin_signature = sym.st_value;
+    }
+    if (std::strcmp(name, "end_signature") == 0) {
+      end_signature = sym.st_value;
+    }
+  }
+
+  if (end_signature == 0 || begin_signature >= end_signature) {
+    return std::make_tuple<uint32_t, uint32_t>(0, 0);
+  }
+
+  return std::make_tuple(begin_signature, end_signature);
+}

src/elf.hpp

@@ -5,3 +5,5 @@
 #include <vector>
 
 std::vector<uint8_t> load_elf(const std::string& filename, size_t memory_size);
+
+std::tuple<uint32_t, uint32_t> elf_get_signature(const std::string& filename);

src/rve.cpp

@@ -14,12 +14,19 @@ int main(int argc, char *argv[]) {
 
   bool debug = false;
   std::string program_filename = "";
+  std::string signature_filename = "";
 
   for (int i = 1; i < argc; ++i) {
-    if (std::string(argv[i]) == "--debug")
+    if (std::string(argv[i]) == "--debug") {
       debug = true;
-    else
+    } else if (std::string(argv[i]) == "--signature") {
+      if (i + 1 < argc) {
+        signature_filename = argv[i + 1];
+        ++i;
+      }
+    } else {
       program_filename = std::filesystem::absolute(argv[i]);
+    }
   }
   if (program_filename == "") {
     std::cerr << "Expected filename of program to execute" << std::endl;
@@ -27,14 +34,17 @@ int main(int argc, char *argv[]) {
   }
 
   std::vector<uint8_t> memory;
+  std::tuple<uint32_t, uint32_t> signature;
   try {
     memory = load_elf(program_filename, MEMORY_SIZE);
+
+    signature = elf_get_signature(program_filename);
   } catch (const std::exception &e) {
     std::cerr << e.what() << std::endl;
     return 1;
   }
 
-  memory.resize(MEMORY_SIZE, 0);
+  memory.resize(std::max(memory.size(), MEMORY_SIZE), 0);
 
   VM vm(memory, program_filename);
 
@@ -46,6 +56,30 @@ int main(int argc, char *argv[]) {
       std::cerr << "Emulator error: " << e.what() << std::endl;
       return 1;
     }
+
+    if (signature_filename.size() > 0) {
+      uint32_t signature_begin = std::get<0>(signature) + 4;
+      uint32_t signature_end = std::get<1>(signature);
+
+      std::vector<uint8_t> mem =
+          vm.read_memory(signature_begin, signature_end - signature_begin);
+
+      std::ofstream file(signature_filename);
+      if (!file) {
+        throw std::runtime_error("Failed to open signature file for writing");
+      }
+
+      for (size_t i = 0; i < mem.size() / 4; i++) {
+        uint32_t val = *reinterpret_cast<uint32_t *>(&mem[i * 4]);
+        file << std::hex << std::setfill('0') << std::setw(8) << val << std::dec
+             << "\n";
+      }
+
+      file.close();
+      if (!file) {
+        throw std::runtime_error("Error occurred while writing to file");
+      }
+    }
   } else {
     // to debug, do: "set debug remote 1" in gdb
     // and then "target remote :1234"

src/vm.cpp

@@ -47,6 +47,7 @@ void VM::setreg(int regnum, uint32_t value) {
 
 std::vector<uint8_t> VM::read_memory(size_t start, size_t size) {
   if (start >= PROGRAM_ADDR) {
+    start -= PROGRAM_ADDR;
     if (start + size > memory_.size()) {
       return std::vector<uint8_t>(size, 0);
     }
@@ -172,6 +173,13 @@ void VM::step() {
   int32_t imm;
 
   switch (opcode) {
+    case 0x0F: {
+      if (instr == 0xff0000f) {  // fence iorw, iorw
+      } else {
+        throw std::runtime_error("Unknown fence instruction");
+      }
+      break;
+    }
     case 0x33: {  // R-type
       if (funct7 == 0x00) {
         if (funct3 == 0x0) {  // ADD

test/rve/env/model_test.h

@@ -15,6 +15,7 @@
   li x1, 1;                                                                   \
   write_tohost:                                                               \
     sw x1, tohost, t5;                                                        \
+    ebreak
     j write_tohost;
 
 #define RVMODEL_BOOT

test/rve/riscof_rve.py

@@ -145,7 +145,7 @@ class rve(pluginTemplate):
           # echo statement.
           if self.target_run:
             # set up the simulation command. Template is for spike. Please change.
-            simcmd = self.dut_exe + ' {0}'.format(elf)
+            simcmd = self.dut_exe + ' --signature {0} {1}'.format(sig_file, elf)
           else:
             simcmd = 'echo "NO RUN"'