Refine the API in the public header

The following should be included in an emulator's simple and clear
public API:
1. create/init core
2. run emulation
3. delete/destroy core

Other components, including as memory, file systems, program data,
etc., should be abstracted from the user, as a result, setting a
configuration value (vm_attr_t) is sufficient. The user should
manage about memory (state_t) and elf stuff before this PR.
The user may just construct a core, run it, and shut it down
after this PR, so they won't need to worry about them anymore.

For stdio remapping, rv_remap_stdstream function is introduced.

The vm_attr_t has multiple fields and they are commented clearly
in the code.

elf is reopened in run_and_trace and dump_test_signature because
elf is allocated inside rv_create and they cannot access them.
It is acceptable to reopen elf since they are only for testing and
debugging. Print inferior exit code to console inside main instead of
syscall_exit because the actual usage of exit code depends on
applications of using riscv public API.

The io interface is not changed in this PR because it could maybe
reused with semu in some way, still need to be investigated. Also,
Logging feature and system emulator integration are not implemented
yet.

related: sysprog21#310

Makefile

@@ -11,11 +11,6 @@ CFLAGS = -std=gnu99 -O2 -Wall -Wextra
 CFLAGS += -Wno-unused-label
 CFLAGS += -include src/common.h
 
-# Set the default stack pointer
-CFLAGS += -D DEFAULT_STACK_ADDR=0xFFFFE000
-# Set the default args starting address
-CFLAGS += -D DEFAULT_ARGS_ADDR=0xFFFFF000
-
 # Enable link-time optimization (LTO)
 ENABLE_LTO ?= 1
 ifeq ($(call has, LTO), 1)
@@ -121,7 +116,7 @@ endif
 ENABLE_JIT ?= 0
 $(call set-feature, JIT)
 ifeq ($(call has, JIT), 1)
-OBJS_EXT += jit.o 
+OBJS_EXT += jit.o
 ifneq ($(processor),$(filter $(processor),x86_64 aarch64 arm64))
 $(error JIT mode only supports for x64 and arm64 target currently.)
 endif

src/elf.c

@@ -259,12 +259,8 @@ bool elf_get_data_section_range(elf_t *e, uint32_t *start, uint32_t *end)
  * Finding data for section headers:
  *   File start + section_header.offset -> section Data
  */
-bool elf_load(elf_t *e, riscv_t *rv, memory_t *mem)
+bool elf_load(elf_t *e, memory_t *mem)
 {
-    /* set the entry point */
-    if (!rv_set_pc(rv, e->hdr->e_entry))
-        return false;
-
     /* loop over all of the program headers */
     for (int p = 0; p < e->hdr->e_phnum; ++p) {
         /* find next program header */

src/elf.h

@@ -145,7 +145,7 @@ const char *elf_find_symbol(elf_t *e, uint32_t addr);
 bool elf_get_data_section_range(elf_t *e, uint32_t *start, uint32_t *end);
 
 /* Load the ELF file into a memory abstraction */
-bool elf_load(elf_t *e, riscv_t *rv, memory_t *mem);
+bool elf_load(elf_t *e, memory_t *mem);
 
 /* get the ELF header */
 struct Elf32_Ehdr *get_elf_header(elf_t *e);

src/emulate.c

@@ -125,7 +125,7 @@ RV_EXCEPTION_LIST
  */
 #define RV_EXC_MISALIGN_HANDLER(mask_or_pc, type, compress, IO)       \
     IIF(IO)                                                           \
-    (if (!rv->io.allow_misalign && unlikely(addr & (mask_or_pc))),    \
+    (if (!PRIV(rv)->allow_misalign && unlikely(addr & (mask_or_pc))), \
      if (unlikely(insn_is_misaligned(PC))))                           \
     {                                                                 \
         rv->compressed = compress;                                    \
@@ -1182,15 +1182,15 @@ void ecall_handler(riscv_t *rv)
 
 void memset_handler(riscv_t *rv)
 {
-    memory_t *m = ((state_t *) rv->userdata)->mem;
+    memory_t *m = PRIV(rv)->mem;
     memset((char *) m->mem_base + rv->X[rv_reg_a0], rv->X[rv_reg_a1],
            rv->X[rv_reg_a2]);
     rv->PC = rv->X[rv_reg_ra] & ~1U;
 }
 
 void memcpy_handler(riscv_t *rv)
 {
-    memory_t *m = ((state_t *) rv->userdata)->mem;
+    memory_t *m = PRIV(rv)->mem;
     memcpy((char *) m->mem_base + rv->X[rv_reg_a0],
            (char *) m->mem_base + rv->X[rv_reg_a1], rv->X[rv_reg_a2]);
     rv->PC = rv->X[rv_reg_ra] & ~1U;

src/io.c

@@ -17,44 +17,36 @@
 
 static uint8_t *data_memory_base;
 
-/*
- * set memory size to 2^32 - 1 bytes
- *
- * The memory size is set to 2^32 - 1 bytes in order to make this emulator
- * portable for both 32-bit and 64-bit platforms. As a result, it can access
- * any segment of the memory on either platform. Furthermore, it is safe
- * because most of the test cases' data memory usage will not exceed this
- * memory size.
- */
-#define MEM_SIZE 0xFFFFFFFFULL
-
-memory_t *memory_new(void)
+memory_t *memory_new(uint32_t size)
 {
+    if (!size)
+        return NULL;
+
     memory_t *mem = malloc(sizeof(memory_t));
     assert(mem);
 #if HAVE_MMAP
-    data_memory_base = mmap(NULL, MEM_SIZE, PROT_READ | PROT_WRITE,
+    data_memory_base = mmap(NULL, size, PROT_READ | PROT_WRITE,
                             MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
     if (data_memory_base == MAP_FAILED) {
         free(mem);
         return NULL;
     }
 #else
-    data_memory_base = malloc(MEM_SIZE);
+    data_memory_base = malloc(size);
     if (!data_memory_base) {
         free(mem);
         return NULL;
     }
 #endif
     mem->mem_base = data_memory_base;
-    mem->mem_size = MEM_SIZE;
+    mem->mem_size = size;
     return mem;
 }
 
 void memory_delete(memory_t *mem)
 {
 #if HAVE_MMAP
-    munmap(mem->mem_base, MEM_SIZE);
+    munmap(mem->mem_base, mem->mem_size);
 #else
     free(mem->mem_base);
 #endif

src/io.h

@@ -17,7 +17,7 @@ typedef struct {
     uint64_t mem_size;
 } memory_t;
 
-memory_t *memory_new(void);
+memory_t *memory_new(uint32_t size);
 void memory_delete(memory_t *m);
 
 /* read a C-style string from memory */

src/jit.c

@@ -1284,7 +1284,7 @@ static void do_fuse2(struct jit_state *state, riscv_t *rv UNUSED, rv_insn_t *ir)
 
 static void do_fuse3(struct jit_state *state, riscv_t *rv, rv_insn_t *ir)
 {
-    memory_t *m = ((state_t *) rv->userdata)->mem;
+    memory_t *m = PRIV(rv)->mem;
     opcode_fuse_t *fuse = ir->fuse;
     for (int i = 0; i < ir->imm2; i++) {
         emit_load(state, S32, parameter_reg[0], temp_reg[0],
@@ -1300,7 +1300,7 @@ static void do_fuse3(struct jit_state *state, riscv_t *rv, rv_insn_t *ir)
 
 static void do_fuse4(struct jit_state *state, riscv_t *rv, rv_insn_t *ir)
 {
-    memory_t *m = ((state_t *) rv->userdata)->mem;
+    memory_t *m = ((vm_attr_t *) rv->userdata)->mem;
     opcode_fuse_t *fuse = ir->fuse;
     for (int i = 0; i < ir->imm2; i++) {
         emit_load(state, S32, parameter_reg[0], temp_reg[0],

src/main.c

@@ -75,8 +75,10 @@ IO_HANDLER_IMPL(byte, write_b, W)
 #undef W
 
 /* run: printing out an instruction trace */
-static void run_and_trace(riscv_t *rv, elf_t *elf)
+static void run_and_trace(riscv_t *rv, const char *prog_name)
 {
+    elf_t *elf = elf_new();
+    assert(elf && elf_open(elf, prog_name));
     const uint32_t cycles_per_step = 1;
 
     for (; !rv_has_halted(rv);) { /* run until the flag is done */
@@ -88,15 +90,8 @@ static void run_and_trace(riscv_t *rv, elf_t *elf)
         /* step instructions */
         rv_step(rv, cycles_per_step);
     }
-}
 
-static void run(riscv_t *rv)
-{
-    const uint32_t cycles_per_step = 100;
-    for (; !rv_has_halted(rv);) { /* run until the flag is done */
-        /* step instructions */
-        rv_step(rv, cycles_per_step);
-    }
+    elf_delete(elf);
 }
 
 static void print_usage(const char *filename)
@@ -188,8 +183,11 @@ static bool parse_args(int argc, char **args)
     return true;
 }
 
-static void dump_test_signature(elf_t *elf)
+static void dump_test_signature(const char *prog_name)
 {
+    elf_t *elf = elf_new();
+    assert(elf && elf_open(elf, prog_name));
+
     uint32_t start = 0, end = 0;
     const struct Elf32_Sym *sym;
     FILE *f = fopen(signature_out_file, "w");
@@ -212,21 +210,33 @@ static void dump_test_signature(elf_t *elf)
         fprintf(f, "%08x\n", memory_read_w(addr));
 
     fclose(f);
+    elf_delete(elf);
 }
 
+#define MEM_SIZE 0xFFFFFFFFULL  /* 2^32 - 1 */
+#define STACK_SIZE 0x1000       /* 4096 */
+#define ARGS_OFFSET_SIZE 0x1000 /* 4096 */
+
 int main(int argc, char **args)
 {
     if (argc == 1 || !parse_args(argc, args)) {
         print_usage(args[0]);
         return 1;
     }
 
-    /* open the ELF file from the file system */
-    elf_t *elf = elf_new();
-    if (!elf_open(elf, opt_prog_name)) {
-        fprintf(stderr, "Unable to open ELF file '%s'\n", opt_prog_name);
-        return 1;
-    }
+    vm_attr_t attr = {
+        .mem_size = MEM_SIZE,
+        .stack_size = STACK_SIZE,
+        .args_offset_size = ARGS_OFFSET_SIZE,
+        .argc = prog_argc,
+        .argv = prog_args,
+        .logging_level = 0,
+        .emu_data.vm_user = malloc(sizeof(vm_user_t)),
+        .cycle_per_step = 100,
+        .allow_misalign = opt_misaligned,
+    };
+    assert(attr.emu_data.vm_user);
+    attr.emu_data.vm_user->elf_program = opt_prog_name;
 
     /* install the I/O handlers for the RISC-V runtime */
     const riscv_io_t io = {
@@ -246,33 +256,18 @@ int main(int argc, char **args)
         .on_ebreak = ebreak_handler,
         .on_memcpy = memcpy_handler,
         .on_memset = memset_handler,
-        .allow_misalign = opt_misaligned,
     };
 
-    state_t *state = state_new();
-
-    /* find the start of the heap */
-    const struct Elf32_Sym *end;
-    if ((end = elf_get_symbol(elf, "_end")))
-        state->break_addr = end->st_value;
-
     /* create the RISC-V runtime */
-    riscv_t *rv =
-        rv_create(&io, state, prog_argc, prog_args, !opt_quiet_outputs);
+    riscv_t *rv = rv_create(&io, &attr);
     if (!rv) {
         fprintf(stderr, "Unable to create riscv emulator\n");
         return 1;
     }
 
-    /* load the ELF file into the memory abstraction */
-    if (!elf_load(elf, rv, state->mem)) {
-        fprintf(stderr, "Unable to load ELF file '%s'\n", args[1]);
-        return 1;
-    }
-
     /* run based on the specified mode */
     if (opt_trace) {
-        run_and_trace(rv, elf);
+        run_and_trace(rv, opt_prog_name);
     }
 #if RV32_HAS(GDBSTUB)
     else if (opt_gdbstub) {
@@ -289,14 +284,13 @@ int main(int argc, char **args)
 
     /* dump test result in test mode */
     if (opt_arch_test)
-        dump_test_signature(elf);
+        dump_test_signature(opt_prog_name);
 
     if (opt_prof_data)
         rv_profile(rv, prof_out_file);
     /* finalize the RISC-V runtime */
-    elf_delete(elf);
     rv_delete(rv);
-    state_delete(state);
 
+    printf("inferior exit code %d\n", attr.exit_code);
     return 0;
 }