riscv/
.clang-format
570 B
.gitignore
5 B
.gitsigners
112 B
LICENSE
1.1 KiB
Makefile
1.1 KiB
README
3.3 KiB
color.h
567 B
emulator.c
79.7 KiB
io.c
1.1 KiB
io.h
444 B
jit.c
32.6 KiB
jit.h
5.0 KiB
riscv.c
12.0 KiB
riscv.h
12.0 KiB
types.h
1.0 KiB
jit.h
raw
| 1 | /* |
| 2 | * JIT compiler for RISC-V RV64I -> x86-64. |
| 3 | * |
| 4 | * Translates basic blocks of RISC-V instructions into native x86-64 machine |
| 5 | * code. The generated code operates on the guest CPU state structure directly |
| 6 | * and falls back to the interpreter for ecalls, ebreak, and faults. |
| 7 | * |
| 8 | * Design follows QEMU's TCG approach: translate on first encounter, cache the |
| 9 | * result, and execute the native code on subsequent visits. |
| 10 | */ |
| 11 | #ifndef JIT_H |
| 12 | #define JIT_H |
| 13 | |
| 14 | #include "riscv.h" |
| 15 | #include "types.h" |
| 16 | #include <stdbool.h> |
| 17 | |
| 18 | /* Forward declarations. */ |
| 19 | struct cpu; |
| 20 | |
| 21 | /* --------------------------------------------------------------------------- |
| 22 | * Tuning constants |
| 23 | * ------------------------------------------------------------------------- */ |
| 24 | |
| 25 | /* Size of the JIT code cache (16 MB). */ |
| 26 | #define JIT_CODE_CACHE_SIZE (16 * 1024 * 1024) |
| 27 | |
| 28 | /* Maximum number of x86-64 bytes emitted per guest instruction. |
| 29 | * Conservative upper bound -- most instructions compile to <30 bytes. */ |
| 30 | #define JIT_MAX_INSN_BYTES 128 |
| 31 | |
| 32 | /* Maximum guest instructions in a single translated block. */ |
| 33 | #define JIT_MAX_BLOCK_INSNS 256 |
| 34 | |
| 35 | /* Number of hash-table buckets for block lookup (must be power of 2). */ |
| 36 | #define JIT_BLOCK_HASH_SIZE (64 * 1024) |
| 37 | |
| 38 | /* Maximum number of translated blocks. */ |
| 39 | #define JIT_MAX_BLOCKS (256 * 1024) |
| 40 | |
| 41 | /* Exit reasons returned by generated code. */ |
| 42 | enum jit_exit { |
| 43 | JIT_EXIT_BRANCH = 0, /* End of block -- branch/jump, update PC. */ |
| 44 | JIT_EXIT_ECALL = 1, /* ECALL -- needs interpreter handling. */ |
| 45 | JIT_EXIT_EBREAK = 2, /* EBREAK -- needs interpreter handling. */ |
| 46 | JIT_EXIT_FAULT = 3, /* Memory fault -- needs interpreter handling. */ |
| 47 | JIT_EXIT_CHAIN = 4, /* Chain to next block (PC already set). */ |
| 48 | JIT_EXIT_RET = 5, /* Program returned (jalr x0, ra, 0 with ra==0). */ |
| 49 | }; |
| 50 | |
| 51 | /* A translated block of native code. */ |
| 52 | struct jit_block { |
| 53 | u32 guest_pc; /* Guest PC this block starts at. */ |
| 54 | u32 guest_end_pc; /* Guest PC *after* last instruction. */ |
| 55 | u32 insn_count; /* Number of guest instructions translated.*/ |
| 56 | u8 *code; /* Pointer into code cache. */ |
| 57 | u32 code_size; /* Size of generated x86-64 code. */ |
| 58 | struct jit_block *hash_next; /* Hash chain. */ |
| 59 | }; |
| 60 | |
| 61 | /* Complete JIT state. */ |
| 62 | struct jit_state { |
| 63 | /* Executable code cache (mmap'd RWX). */ |
| 64 | u8 *code_cache; |
| 65 | u32 code_cache_used; |
| 66 | |
| 67 | /* Block hash table (open-chaining). */ |
| 68 | struct jit_block *block_hash[JIT_BLOCK_HASH_SIZE]; |
| 69 | |
| 70 | /* Block storage (static pool). */ |
| 71 | struct jit_block blocks[JIT_MAX_BLOCKS]; |
| 72 | u32 block_count; |
| 73 | |
| 74 | /* Statistics. */ |
| 75 | u64 blocks_compiled; |
| 76 | u64 blocks_executed; |
| 77 | u64 insns_executed; |
| 78 | |
| 79 | /* Whether JIT is available (mmap succeeded, x86-64 host). */ |
| 80 | bool available; |
| 81 | }; |
| 82 | |
| 83 | /* --------------------------------------------------------------------------- |
| 84 | * API |
| 85 | * ------------------------------------------------------------------------- */ |
| 86 | |
| 87 | /* Initialise the JIT. Returns true on success. |
| 88 | * On non-x86-64 hosts or if mmap fails, returns false and the emulator |
| 89 | * should fall back to the interpreter. */ |
| 90 | bool jit_init(struct jit_state *jit); |
| 91 | |
| 92 | /* Release JIT resources. */ |
| 93 | void jit_destroy(struct jit_state *jit); |
| 94 | |
| 95 | /* Flush the entire translation cache (e.g. after self-modifying code). */ |
| 96 | void jit_flush(struct jit_state *jit); |
| 97 | |
| 98 | /* Compile (but don't look up) a block starting at `guest_pc`. |
| 99 | * Returns NULL if the code cache is full or compilation fails. */ |
| 100 | struct jit_block *jit_compile_block( |
| 101 | struct jit_state *jit, |
| 102 | u32 guest_pc, |
| 103 | u8 *memory, |
| 104 | u32 program_base, |
| 105 | u32 program_bytes |
| 106 | ); |
| 107 | |
| 108 | /* Inline fast-path block lookup (hash table probe). */ |
| 109 | static inline struct jit_block *jit_lookup_block( |
| 110 | struct jit_state *jit, u32 guest_pc |
| 111 | ) { |
| 112 | u32 h = (guest_pc >> 2) & (JIT_BLOCK_HASH_SIZE - 1); |
| 113 | struct jit_block *b = jit->block_hash[h]; |
| 114 | while (b) { |
| 115 | if (b->guest_pc == guest_pc) |
| 116 | return b; |
| 117 | b = b->hash_next; |
| 118 | } |
| 119 | return NULL; |
| 120 | } |
| 121 | |
| 122 | /* Look up or compile a block. Calls the inline lookup first, falls |
| 123 | * back to the compiler on a miss. */ |
| 124 | static inline struct jit_block *jit_get_block( |
| 125 | struct jit_state *jit, |
| 126 | u32 guest_pc, |
| 127 | u8 *memory, |
| 128 | u32 program_base, |
| 129 | u32 program_bytes |
| 130 | ) { |
| 131 | struct jit_block *b = jit_lookup_block(jit, guest_pc); |
| 132 | if (b) |
| 133 | return b; |
| 134 | return jit_compile_block( |
| 135 | jit, guest_pc, memory, program_base, program_bytes |
| 136 | ); |
| 137 | } |
| 138 | |
| 139 | /* Signature of generated block entry points. |
| 140 | * Args: pointer to cpu->regs[], pointer to memory[]. |
| 141 | * Returns: exit reason (enum jit_exit). */ |
| 142 | typedef int (*jit_block_fn)(u64 *regs, u8 *memory, u32 *pc_out); |
| 143 | |
| 144 | /* Execute a translated block. Returns the exit reason. */ |
| 145 | static inline int jit_exec_block( |
| 146 | struct jit_block *block, u64 *regs, u8 *memory, u32 *pc_out |
| 147 | ) { |
| 148 | jit_block_fn fn = (jit_block_fn)(void *)block->code; |
| 149 | return fn(regs, memory, pc_out); |
| 150 | } |
| 151 | |
| 152 | #endif /* JIT_H */ |