/* Intel 386 target-dependent stuff. Copyright (C) 1988, 1989, 1991, 1994, 1995, 1996, 1998 Free Software Foundation, Inc. This file is part of GDB. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include "defs.h" #include "gdb_string.h" #include "frame.h" #include "inferior.h" #include "gdbcore.h" #include "target.h" #include "floatformat.h" #include "symtab.h" #include "gdbcmd.h" #include "command.h" static long i386_get_frame_setup PARAMS ((CORE_ADDR)); static void i386_follow_jump PARAMS ((void)); static void codestream_read PARAMS ((unsigned char *, int)); static void codestream_seek PARAMS ((CORE_ADDR)); static unsigned char codestream_fill PARAMS ((int)); CORE_ADDR skip_trampoline_code PARAMS ((CORE_ADDR, char *)); static int gdb_print_insn_i386 (bfd_vma, disassemble_info *); void _initialize_i386_tdep PARAMS ((void)); /* i386_register_byte[i] is the offset into the register file of the start of register number i. We initialize this from i386_register_raw_size. */ int i386_register_byte[MAX_NUM_REGS]; /* i386_register_raw_size[i] is the number of bytes of storage in GDB's register array occupied by register i. */ int i386_register_raw_size[MAX_NUM_REGS] = { 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 10, 10, 10, 10, 10, 10, 10, 10, 4, 4, 4, 4, 4, 4, 4, 4, 16, 16, 16, 16, 16, 16, 16, 16, 4 }; /* i386_register_virtual_size[i] is the size in bytes of the virtual type of register i. */ int i386_register_virtual_size[MAX_NUM_REGS]; /* This is the variable the is set with "set disassembly-flavor", and its legitimate values. */ static char att_flavor[] = "att"; static char intel_flavor[] = "intel"; static char *valid_flavors[] = { att_flavor, intel_flavor, NULL }; static char *disassembly_flavor = att_flavor; static void i386_print_register PARAMS ((char *, int, int)); /* This is used to keep the bfd arch_info in sync with the disassembly flavor. */ static void set_disassembly_flavor_sfunc PARAMS ((char *, int, struct cmd_list_element *)); static void set_disassembly_flavor PARAMS ((void)); /* Stdio style buffering was used to minimize calls to ptrace, but this buffering did not take into account that the code section being accessed may not be an even number of buffers long (even if the buffer is only sizeof(int) long). In cases where the code section size happened to be a non-integral number of buffers long, attempting to read the last buffer would fail. Simply using target_read_memory and ignoring errors, rather than read_memory, is not the correct solution, since legitimate access errors would then be totally ignored. To properly handle this situation and continue to use buffering would require that this code be able to determine the minimum code section size granularity (not the alignment of the section itself, since the actual failing case that pointed out this problem had a section alignment of 4 but was not a multiple of 4 bytes long), on a target by target basis, and then adjust it's buffer size accordingly. This is messy, but potentially feasible. It probably needs the bfd library's help and support. For now, the buffer size is set to 1. (FIXME -fnf) */ #define CODESTREAM_BUFSIZ 1 /* Was sizeof(int), see note above. */ static CORE_ADDR codestream_next_addr; static CORE_ADDR codestream_addr; static unsigned char codestream_buf[CODESTREAM_BUFSIZ]; static int codestream_off; static int codestream_cnt; #define codestream_tell() (codestream_addr + codestream_off) #define codestream_peek() (codestream_cnt == 0 ? \ codestream_fill(1): codestream_buf[codestream_off]) #define codestream_get() (codestream_cnt-- == 0 ? \ codestream_fill(0) : codestream_buf[codestream_off++]) static unsigned char codestream_fill (peek_flag) int peek_flag; { codestream_addr = codestream_next_addr; codestream_next_addr += CODESTREAM_BUFSIZ; codestream_off = 0; codestream_cnt = CODESTREAM_BUFSIZ; read_memory (codestream_addr, (char *) codestream_buf, CODESTREAM_BUFSIZ); if (peek_flag) return (codestream_peek ()); else return (codestream_get ()); } static void codestream_seek (place) CORE_ADDR place; { codestream_next_addr = place / CODESTREAM_BUFSIZ; codestream_next_addr *= CODESTREAM_BUFSIZ; codestream_cnt = 0; codestream_fill (1); while (codestream_tell () != place) codestream_get (); } static void codestream_read (buf, count) unsigned char *buf; int count; { unsigned char *p; int i; p = buf; for (i = 0; i < count; i++) *p++ = codestream_get (); } /* next instruction is a jump, move to target */ static void i386_follow_jump () { unsigned char buf[4]; long delta; int data16; CORE_ADDR pos; pos = codestream_tell (); data16 = 0; if (codestream_peek () == 0x66) { codestream_get (); data16 = 1; } switch (codestream_get ()) { case 0xe9: /* relative jump: if data16 == 0, disp32, else disp16 */ if (data16) { codestream_read (buf, 2); delta = extract_signed_integer (buf, 2); /* include size of jmp inst (including the 0x66 prefix). */ pos += delta + 4; } else { codestream_read (buf, 4); delta = extract_signed_integer (buf, 4); pos += delta + 5; } break; case 0xeb: /* relative jump, disp8 (ignore data16) */ codestream_read (buf, 1); /* Sign-extend it. */ delta = extract_signed_integer (buf, 1); pos += delta + 2; break; } codestream_seek (pos); } /* * find & return amound a local space allocated, and advance codestream to * first register push (if any) * * if entry sequence doesn't make sense, return -1, and leave * codestream pointer random */ static long i386_get_frame_setup (pc) CORE_ADDR pc; { unsigned char op; codestream_seek (pc); i386_follow_jump (); op = codestream_get (); if (op == 0x58) /* popl %eax */ { /* * this function must start with * * popl %eax 0x58 * xchgl %eax, (%esp) 0x87 0x04 0x24 * or xchgl %eax, 0(%esp) 0x87 0x44 0x24 0x00 * * (the system 5 compiler puts out the second xchg * inst, and the assembler doesn't try to optimize it, * so the 'sib' form gets generated) * * this sequence is used to get the address of the return * buffer for a function that returns a structure */ int pos; unsigned char buf[4]; static unsigned char proto1[3] = {0x87, 0x04, 0x24}; static unsigned char proto2[4] = {0x87, 0x44, 0x24, 0x00}; pos = codestream_tell (); codestream_read (buf, 4); if (memcmp (buf, proto1, 3) == 0) pos += 3; else if (memcmp (buf, proto2, 4) == 0) pos += 4; codestream_seek (pos); op = codestream_get (); /* update next opcode */ } if (op == 0x68 || op == 0x6a) { /* * this function may start with * * pushl constant * call _probe * addl $4, %esp * followed by * pushl %ebp * etc. */ int pos; unsigned char buf[8]; /* Skip past the pushl instruction; it has either a one-byte or a four-byte operand, depending on the opcode. */ pos = codestream_tell (); if (op == 0x68) pos += 4; else pos += 1; codestream_seek (pos); /* Read the following 8 bytes, which should be "call _probe" (6 bytes) followed by "addl $4,%esp" (2 bytes). */ codestream_read (buf, sizeof (buf)); if (buf[0] == 0xe8 && buf[6] == 0xc4 && buf[7] == 0x4) pos += sizeof (buf); codestream_seek (pos); op = codestream_get (); /* update next opcode */ } if (op == 0x55) /* pushl %ebp */ { /* check for movl %esp, %ebp - can be written two ways */ switch (codestream_get ()) { case 0x8b: if (codestream_get () != 0xec) return (-1); break; case 0x89: if (codestream_get () != 0xe5) return (-1); break; default: return (-1); } /* check for stack adjustment * subl $XXX, %esp * * note: you can't subtract a 16 bit immediate * from a 32 bit reg, so we don't have to worry * about a data16 prefix */ op = codestream_peek (); if (op == 0x83) { /* subl with 8 bit immed */ codestream_get (); if (codestream_get () != 0xec) /* Some instruction starting with 0x83 other than subl. */ { codestream_seek (codestream_tell () - 2); return 0; } /* subl with signed byte immediate * (though it wouldn't make sense to be negative) */ return (codestream_get ()); } else if (op == 0x81) { char buf[4]; /* Maybe it is subl with 32 bit immedediate. */ codestream_get (); if (codestream_get () != 0xec) /* Some instruction starting with 0x81 other than subl. */ { codestream_seek (codestream_tell () - 2); return 0; } /* It is subl with 32 bit immediate. */ codestream_read ((unsigned char *) buf, 4); return extract_signed_integer (buf, 4); } else { return (0); } } else if (op == 0xc8) { char buf[2]; /* enter instruction: arg is 16 bit unsigned immed */ codestream_read ((unsigned char *) buf, 2); codestream_get (); /* flush final byte of enter instruction */ return extract_unsigned_integer (buf, 2); } return (-1); } /* Return number of args passed to a frame. Can return -1, meaning no way to tell. */ int i386_frame_num_args (fi) struct frame_info *fi; { #if 1 return -1; #else /* This loses because not only might the compiler not be popping the args right after the function call, it might be popping args from both this call and a previous one, and we would say there are more args than there really are. */ int retpc; unsigned char op; struct frame_info *pfi; /* on the 386, the instruction following the call could be: popl %ecx - one arg addl $imm, %esp - imm/4 args; imm may be 8 or 32 bits anything else - zero args */ int frameless; frameless = FRAMELESS_FUNCTION_INVOCATION (fi); if (frameless) /* In the absence of a frame pointer, GDB doesn't get correct values for nameless arguments. Return -1, so it doesn't print any nameless arguments. */ return -1; pfi = get_prev_frame (fi); if (pfi == 0) { /* Note: this can happen if we are looking at the frame for main, because FRAME_CHAIN_VALID won't let us go into start. If we have debugging symbols, that's not really a big deal; it just means it will only show as many arguments to main as are declared. */ return -1; } else { retpc = pfi->pc; op = read_memory_integer (retpc, 1); if (op == 0x59) /* pop %ecx */ return 1; else if (op == 0x83) { op = read_memory_integer (retpc + 1, 1); if (op == 0xc4) /* addl $, %esp */ return (read_memory_integer (retpc + 2, 1) & 0xff) / 4; else return 0; } else if (op == 0x81) { /* add with 32 bit immediate */ op = read_memory_integer (retpc + 1, 1); if (op == 0xc4) /* addl $, %esp */ return read_memory_integer (retpc + 2, 4) / 4; else return 0; } else { return 0; } } #endif } /* * parse the first few instructions of the function to see * what registers were stored. * * We handle these cases: * * The startup sequence can be at the start of the function, * or the function can start with a branch to startup code at the end. * * %ebp can be set up with either the 'enter' instruction, or * 'pushl %ebp, movl %esp, %ebp' (enter is too slow to be useful, * but was once used in the sys5 compiler) * * Local space is allocated just below the saved %ebp by either the * 'enter' instruction, or by 'subl $, %esp'. 'enter' has * a 16 bit unsigned argument for space to allocate, and the * 'addl' instruction could have either a signed byte, or * 32 bit immediate. * * Next, the registers used by this function are pushed. In * the sys5 compiler they will always be in the order: %edi, %esi, %ebx * (and sometimes a harmless bug causes it to also save but not restore %eax); * however, the code below is willing to see the pushes in any order, * and will handle up to 8 of them. * * If the setup sequence is at the end of the function, then the * next instruction will be a branch back to the start. */ void i386_frame_init_saved_regs (fip) struct frame_info *fip; { long locals = -1; unsigned char op; CORE_ADDR dummy_bottom; CORE_ADDR adr; CORE_ADDR pc; int i; if (fip->saved_regs) return; frame_saved_regs_zalloc (fip); /* if frame is the end of a dummy, compute where the * beginning would be */ dummy_bottom = fip->frame - 4 - REGISTER_BYTES - CALL_DUMMY_LENGTH; /* check if the PC is in the stack, in a dummy frame */ if (dummy_bottom <= fip->pc && fip->pc <= fip->frame) { /* all regs were saved by push_call_dummy () */ adr = fip->frame; for (i = 0; i < NUM_REGS; i++) { adr -= REGISTER_RAW_SIZE (i); fip->saved_regs[i] = adr; } return; } pc = get_pc_function_start (fip->pc); if (pc != 0) locals = i386_get_frame_setup (pc); if (locals >= 0) { adr = fip->frame - 4 - locals; for (i = 0; i < 8; i++) { op = codestream_get (); if (op < 0x50 || op > 0x57) break; #ifdef I386_REGNO_TO_SYMMETRY /* Dynix uses different internal numbering. Ick. */ fip->saved_regs[I386_REGNO_TO_SYMMETRY (op - 0x50)] = adr; #else fip->saved_regs[op - 0x50] = adr; #endif adr -= 4; } } fip->saved_regs[PC_REGNUM] = fip->frame + 4; fip->saved_regs[FP_REGNUM] = fip->frame; } /* return pc of first real instruction */ int i386_skip_prologue (pc) int pc; { unsigned char op; int i; static unsigned char pic_pat[6] = {0xe8, 0, 0, 0, 0, /* call 0x0 */ 0x5b, /* popl %ebx */ }; CORE_ADDR pos; if (i386_get_frame_setup (pc) < 0) return (pc); /* found valid frame setup - codestream now points to * start of push instructions for saving registers */ /* skip over register saves */ for (i = 0; i < 8; i++) { op = codestream_peek (); /* break if not pushl inst */ if (op < 0x50 || op > 0x57) break; codestream_get (); } /* The native cc on SVR4 in -K PIC mode inserts the following code to get the address of the global offset table (GOT) into register %ebx. call 0x0 popl %ebx movl %ebx,x(%ebp) (optional) addl y,%ebx This code is with the rest of the prologue (at the end of the function), so we have to skip it to get to the first real instruction at the start of the function. */ pos = codestream_tell (); for (i = 0; i < 6; i++) { op = codestream_get (); if (pic_pat[i] != op) break; } if (i == 6) { unsigned char buf[4]; long delta = 6; op = codestream_get (); if (op == 0x89) /* movl %ebx, x(%ebp) */ { op = codestream_get (); if (op == 0x5d) /* one byte offset from %ebp */ { delta += 3; codestream_read (buf, 1); } else if (op == 0x9d) /* four byte offset from %ebp */ { delta += 6; codestream_read (buf, 4); } else /* unexpected instruction */ delta = -1; op = codestream_get (); } /* addl y,%ebx */ if (delta > 0 && op == 0x81 && codestream_get () == 0xc3) { pos += delta + 6; } } codestream_seek (pos); i386_follow_jump (); return (codestream_tell ()); } void i386_push_dummy_frame () { CORE_ADDR sp = read_register (SP_REGNUM); int regnum; char regbuf[MAX_REGISTER_RAW_SIZE]; sp = push_word (sp, read_register (PC_REGNUM)); sp = push_word (sp, read_register (FP_REGNUM)); write_register (FP_REGNUM, sp); for (regnum = 0; regnum < NUM_REGS; regnum++) { read_register_gen (regnum, regbuf); sp = push_bytes (sp, regbuf, REGISTER_RAW_SIZE (regnum)); } write_register (SP_REGNUM, sp); } void i386_pop_frame () { struct frame_info *frame = get_current_frame (); CORE_ADDR fp; int regnum; char regbuf[MAX_REGISTER_RAW_SIZE]; fp = FRAME_FP (frame); i386_frame_init_saved_regs (frame); for (regnum = 0; regnum < NUM_REGS; regnum++) { CORE_ADDR adr; adr = frame->saved_regs[regnum]; if (adr) { read_memory (adr, regbuf, REGISTER_RAW_SIZE (regnum)); write_register_bytes (REGISTER_BYTE (regnum), regbuf, REGISTER_RAW_SIZE (regnum)); } } write_register (FP_REGNUM, read_memory_integer (fp, 4)); write_register (PC_REGNUM, read_memory_integer (fp + 4, 4)); write_register (SP_REGNUM, fp + 8); flush_cached_frames (); } #ifdef GET_LONGJMP_TARGET /* Figure out where the longjmp will land. Slurp the args out of the stack. We expect the first arg to be a pointer to the jmp_buf structure from which we extract the pc (JB_PC) that we will land at. The pc is copied into PC. This routine returns true on success. */ int get_longjmp_target (pc) CORE_ADDR *pc; { char buf[TARGET_PTR_BIT / TARGET_CHAR_BIT]; CORE_ADDR sp, jb_addr; sp = read_register (SP_REGNUM); if (target_read_memory (sp + SP_ARG0, /* Offset of first arg on stack */ buf, TARGET_PTR_BIT / TARGET_CHAR_BIT)) return 0; jb_addr = extract_address (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT); if (target_read_memory (jb_addr + JB_PC * JB_ELEMENT_SIZE, buf, TARGET_PTR_BIT / TARGET_CHAR_BIT)) return 0; *pc = extract_address (buf, TARGET_PTR_BIT / TARGET_CHAR_BIT); return 1; } #endif /* GET_LONGJMP_TARGET */ void i386_extract_return_value (type, regbuf, valbuf) struct type *type; char regbuf[REGISTER_BYTES]; char *valbuf; { /* On AIX, i386 GNU/Linux and DJGPP, floating point values are returned in floating point registers. */ /* FIXME: cagney/2000-02-29: This function needs to be rewritten using multi-arch. Please don't keep adding to this #ifdef spaghetti. */ #if defined(I386_AIX_TARGET) || defined(I386_GNULINUX_TARGET) || defined(I386_DJGPP_TARGET) if (TYPE_CODE_FLT == TYPE_CODE (type)) { double d; /* 387 %st(0), gcc uses this */ floatformat_to_double (&floatformat_i387_ext, #if defined(FPDATA_REGNUM) ®buf[REGISTER_BYTE (FPDATA_REGNUM)], #else /* !FPDATA_REGNUM */ ®buf[REGISTER_BYTE (FP0_REGNUM)], #endif /* FPDATA_REGNUM */ &d); store_floating (valbuf, TYPE_LENGTH (type), d); } else #endif /* I386_AIX_TARGET || I386_GNULINUX_TARGET || I386_DJGPP_TARGET */ { #if defined(LOW_RETURN_REGNUM) int len = TYPE_LENGTH (type); int low_size = REGISTER_RAW_SIZE (LOW_RETURN_REGNUM); int high_size = REGISTER_RAW_SIZE (HIGH_RETURN_REGNUM); if (len <= low_size) memcpy (valbuf, regbuf + REGISTER_BYTE (LOW_RETURN_REGNUM), len); else if (len <= (low_size + high_size)) { memcpy (valbuf, regbuf + REGISTER_BYTE (LOW_RETURN_REGNUM), low_size); memcpy (valbuf + low_size, regbuf + REGISTER_BYTE (HIGH_RETURN_REGNUM), len - low_size); } else error ("GDB bug: i386-tdep.c (i386_extract_return_value): Don't know how to find a return value %d bytes long", len); #else /* !LOW_RETURN_REGNUM */ memcpy (valbuf, regbuf, TYPE_LENGTH (type)); #endif /* LOW_RETURN_REGNUM */ } } #ifdef I386V4_SIGTRAMP_SAVED_PC /* Get saved user PC for sigtramp from the pushed ucontext on the stack for all three variants of SVR4 sigtramps. */ CORE_ADDR i386v4_sigtramp_saved_pc (frame) struct frame_info *frame; { CORE_ADDR saved_pc_offset = 4; char *name = NULL; find_pc_partial_function (frame->pc, &name, NULL, NULL); if (name) { if (STREQ (name, "_sigreturn")) saved_pc_offset = 132 + 14 * 4; else if (STREQ (name, "_sigacthandler")) saved_pc_offset = 80 + 14 * 4; else if (STREQ (name, "sigvechandler")) saved_pc_offset = 120 + 14 * 4; } if (frame->next) return read_memory_integer (frame->next->frame + saved_pc_offset, 4); return read_memory_integer (read_register (SP_REGNUM) + saved_pc_offset, 4); } #endif /* I386V4_SIGTRAMP_SAVED_PC */ #ifdef STATIC_TRANSFORM_NAME /* SunPRO encodes the static variables. This is not related to C++ mangling, it is done for C too. */ char * sunpro_static_transform_name (name) char *name; { char *p; if (IS_STATIC_TRANSFORM_NAME (name)) { /* For file-local statics there will be a period, a bunch of junk (the contents of which match a string given in the N_OPT), a period and the name. For function-local statics there will be a bunch of junk (which seems to change the second character from 'A' to 'B'), a period, the name of the function, and the name. So just skip everything before the last period. */ p = strrchr (name, '.'); if (p != NULL) name = p + 1; } return name; } #endif /* STATIC_TRANSFORM_NAME */ /* Stuff for WIN32 PE style DLL's but is pretty generic really. */ CORE_ADDR skip_trampoline_code (pc, name) CORE_ADDR pc; char *name; { if (pc && read_memory_unsigned_integer (pc, 2) == 0x25ff) /* jmp *(dest) */ { unsigned long indirect = read_memory_unsigned_integer (pc + 2, 4); struct minimal_symbol *indsym = indirect ? lookup_minimal_symbol_by_pc (indirect) : 0; char *symname = indsym ? SYMBOL_NAME (indsym) : 0; if (symname) { if (strncmp (symname, "__imp_", 6) == 0 || strncmp (symname, "_imp_", 5) == 0) return name ? 1 : read_memory_unsigned_integer (indirect, 4); } } return 0; /* not a trampoline */ } static int gdb_print_insn_i386 (memaddr, info) bfd_vma memaddr; disassemble_info *info; { if (disassembly_flavor == att_flavor) return print_insn_i386_att (memaddr, info); else if (disassembly_flavor == intel_flavor) return print_insn_i386_intel (memaddr, info); /* Never reached - disassembly_flavour is always either att_flavor or intel_flavor */ abort (); } /* If the disassembly mode is intel, we have to also switch the bfd mach_type. This function is run in the set disassembly_flavor command, and does that. */ static void set_disassembly_flavor_sfunc (args, from_tty, c) char *args; int from_tty; struct cmd_list_element *c; { set_disassembly_flavor (); } static void set_disassembly_flavor () { if (disassembly_flavor == att_flavor) set_architecture_from_arch_mach (bfd_arch_i386, bfd_mach_i386_i386); else if (disassembly_flavor == intel_flavor) set_architecture_from_arch_mach (bfd_arch_i386, bfd_mach_i386_i386_intel_syntax); } void _initialize_i386_tdep () { /* Initialize the table saying where each register starts in the register file. */ { int i, offset; offset = 0; for (i = 0; i < MAX_NUM_REGS; i++) { i386_register_byte[i] = offset; offset += i386_register_raw_size[i]; } } /* Initialize the table of virtual register sizes. */ { int i; for (i = 0; i < MAX_NUM_REGS; i++) i386_register_virtual_size[i] = TYPE_LENGTH (REGISTER_VIRTUAL_TYPE (i)); } tm_print_insn = gdb_print_insn_i386; tm_print_insn_info.mach = bfd_lookup_arch (bfd_arch_i386, 0)->mach; /* Add the variable that controls the disassembly flavor */ { struct cmd_list_element *new_cmd; new_cmd = add_set_enum_cmd ("disassembly-flavor", no_class, valid_flavors, (char *) &disassembly_flavor, "Set the disassembly flavor, the valid values are \"att\" and \"intel\", \ and the default value is \"att\".", &setlist); new_cmd->function.sfunc = set_disassembly_flavor_sfunc; add_show_from_set (new_cmd, &showlist); } /* Finally, initialize the disassembly flavor to the default given in the disassembly_flavor variable */ set_disassembly_flavor (); }