diff options
Diffstat (limited to 'tcg/tcg.c')
| -rw-r--r-- | tcg/tcg.c | 194 |
1 files changed, 194 insertions, 0 deletions
@@ -28,6 +28,9 @@ #include "config.h" +/* Define to jump the ELF file used to communicate with GDB. */ +#undef DEBUG_JIT + #if !defined(CONFIG_DEBUG_TCG) && !defined(NDEBUG) /* define it to suppress various consistency checks (faster) */ #define NDEBUG @@ -45,6 +48,18 @@ #include "cpu.h" #include "tcg-op.h" + +#if TCG_TARGET_REG_BITS == 64 +# define ELF_CLASS ELFCLASS64 +#else +# define ELF_CLASS ELFCLASS32 +#endif +#ifdef HOST_WORDS_BIGENDIAN +# define ELF_DATA ELFDATA2MSB +#else +# define ELF_DATA ELFDATA2LSB +#endif + #include "elf.h" #if defined(CONFIG_USE_GUEST_BASE) && !defined(TCG_TARGET_HAS_GUEST_BASE) @@ -57,6 +72,10 @@ static void tcg_target_qemu_prologue(TCGContext *s); static void patch_reloc(uint8_t *code_ptr, int type, tcg_target_long value, tcg_target_long addend); +static void tcg_register_jit_int(void *buf, size_t size, + void *debug_frame, size_t debug_frame_size) + __attribute__((unused)); + /* Forward declarations for functions declared and used in tcg-target.c. */ static int target_parse_constraint(TCGArgConstraint *ct, const char **pct_str); static void tcg_out_ld(TCGContext *s, TCGType type, TCGReg ret, TCGReg arg1, @@ -2231,3 +2250,178 @@ void tcg_dump_info(FILE *f, fprintf_function cpu_fprintf) cpu_fprintf(f, "[TCG profiler not compiled]\n"); } #endif + +#ifdef ELF_HOST_MACHINE +/* The backend should define ELF_HOST_MACHINE to indicate both what value to + put into the ELF image and to indicate support for the feature. */ + +/* Begin GDB interface. THE FOLLOWING MUST MATCH GDB DOCS. */ +typedef enum { + JIT_NOACTION = 0, + JIT_REGISTER_FN, + JIT_UNREGISTER_FN +} jit_actions_t; + +struct jit_code_entry { + struct jit_code_entry *next_entry; + struct jit_code_entry *prev_entry; + const void *symfile_addr; + uint64_t symfile_size; +}; + +struct jit_descriptor { + uint32_t version; + uint32_t action_flag; + struct jit_code_entry *relevant_entry; + struct jit_code_entry *first_entry; +}; + +void __jit_debug_register_code(void) __attribute__((noinline)); +void __jit_debug_register_code(void) +{ + asm(""); +} + +/* Must statically initialize the version, because GDB may check + the version before we can set it. */ +struct jit_descriptor __jit_debug_descriptor = { 1, 0, 0, 0 }; + +/* End GDB interface. */ + +static int find_string(const char *strtab, const char *str) +{ + const char *p = strtab + 1; + + while (1) { + if (strcmp(p, str) == 0) { + return p - strtab; + } + p += strlen(p) + 1; + } +} + +static void tcg_register_jit_int(void *buf, size_t buf_size, + void *debug_frame, size_t debug_frame_size) +{ + static const char strings[64] = + "\0" + ".text\0" + ".debug_frame\0" + ".symtab\0" + ".strtab\0" + "code_gen_buffer"; + + struct ElfImage { + ElfW(Ehdr) ehdr; + ElfW(Phdr) phdr; + ElfW(Shdr) shdr[5]; + ElfW(Sym) sym[1]; + char str[64]; + }; + + /* We only need a single jit entry; statically allocate it. */ + static struct jit_code_entry one_entry; + + size_t img_size = sizeof(struct ElfImage) + debug_frame_size; + struct ElfImage *img = g_malloc0(img_size); + + img->ehdr.e_ident[EI_MAG0] = ELFMAG0; + img->ehdr.e_ident[EI_MAG1] = ELFMAG1; + img->ehdr.e_ident[EI_MAG2] = ELFMAG2; + img->ehdr.e_ident[EI_MAG3] = ELFMAG3; + img->ehdr.e_ident[EI_CLASS] = ELF_CLASS; + img->ehdr.e_ident[EI_DATA] = ELF_DATA; + img->ehdr.e_ident[EI_VERSION] = EV_CURRENT; + img->ehdr.e_type = ET_EXEC; + img->ehdr.e_machine = ELF_HOST_MACHINE; + img->ehdr.e_version = EV_CURRENT; + img->ehdr.e_phoff = offsetof(struct ElfImage, phdr); + img->ehdr.e_shoff = offsetof(struct ElfImage, shdr); + img->ehdr.e_ehsize = sizeof(ElfW(Shdr)); + img->ehdr.e_phentsize = sizeof(ElfW(Phdr)); + img->ehdr.e_phnum = 1; + img->ehdr.e_shentsize = sizeof(img->shdr[0]); + img->ehdr.e_shnum = ARRAY_SIZE(img->shdr); + img->ehdr.e_shstrndx = ARRAY_SIZE(img->shdr) - 1; + + img->phdr.p_type = PT_LOAD; + img->phdr.p_offset = (char *)buf - (char *)img; + img->phdr.p_vaddr = (ElfW(Addr))buf; + img->phdr.p_paddr = img->phdr.p_vaddr; + img->phdr.p_filesz = 0; + img->phdr.p_memsz = buf_size; + img->phdr.p_flags = PF_X; + + memcpy(img->str, strings, sizeof(img->str)); + + img->shdr[0].sh_type = SHT_NULL; + + /* Trick: The contents of code_gen_buffer are not present in this fake + ELF file; that got allocated elsewhere, discontiguously. Therefore + we mark .text as SHT_NOBITS (similar to .bss) so that readers will + not look for contents. We can record any address at will. */ + img->shdr[1].sh_name = find_string(img->str, ".text"); + img->shdr[1].sh_type = SHT_NOBITS; + img->shdr[1].sh_flags = SHF_EXECINSTR | SHF_ALLOC; + img->shdr[1].sh_addr = (ElfW(Addr))buf; + img->shdr[1].sh_size = buf_size; + + img->shdr[2].sh_name = find_string(img->str, ".debug_frame"); + img->shdr[2].sh_type = SHT_PROGBITS; + img->shdr[2].sh_offset = sizeof(*img); + img->shdr[2].sh_size = debug_frame_size; + memcpy(img + 1, debug_frame, debug_frame_size); + + img->shdr[3].sh_name = find_string(img->str, ".symtab"); + img->shdr[3].sh_type = SHT_SYMTAB; + img->shdr[3].sh_offset = offsetof(struct ElfImage, sym); + img->shdr[3].sh_size = sizeof(img->sym); + img->shdr[3].sh_info = ARRAY_SIZE(img->sym); + img->shdr[3].sh_link = img->ehdr.e_shstrndx; + img->shdr[3].sh_entsize = sizeof(ElfW(Sym)); + + img->shdr[4].sh_name = find_string(img->str, ".strtab"); + img->shdr[4].sh_type = SHT_STRTAB; + img->shdr[4].sh_offset = offsetof(struct ElfImage, str); + img->shdr[4].sh_size = sizeof(img->str); + + img->sym[0].st_name = find_string(img->str, "code_gen_buffer"); + img->sym[0].st_info = ELF_ST_INFO(STB_GLOBAL, STT_FUNC); + img->sym[0].st_shndx = 1; + img->sym[0].st_value = (ElfW(Addr))buf; + img->sym[0].st_size = buf_size; + +#ifdef DEBUG_JIT + /* Enable this block to be able to debug the ELF image file creation. + One can use readelf, objdump, or other inspection utilities. */ + { + FILE *f = fopen("/tmp/qemu.jit", "w+b"); + if (f) { + if (fwrite(img, img_size, 1, f) != buf_size) { + /* Avoid stupid unused return value warning for fwrite. */ + } + fclose(f); + } + } +#endif + + one_entry.symfile_addr = img; + one_entry.symfile_size = img_size; + + __jit_debug_descriptor.action_flag = JIT_REGISTER_FN; + __jit_debug_descriptor.relevant_entry = &one_entry; + __jit_debug_descriptor.first_entry = &one_entry; + __jit_debug_register_code(); +} +#else +/* No support for the feature. Provide the entry point expected by exec.c. */ + +static void tcg_register_jit_int(void *buf, size_t size, + void *debug_frame, size_t debug_frame_size) +{ +} + +void tcg_register_jit(void *buf, size_t buf_size) +{ +} +#endif /* ELF_HOST_MACHINE */ |