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Diffstat (limited to 'gdb/i386-tdep.c')
| -rw-r--r-- | gdb/i386-tdep.c | 494 |
1 files changed, 494 insertions, 0 deletions
diff --git a/gdb/i386-tdep.c b/gdb/i386-tdep.c new file mode 100644 index 0000000..d621fa3 --- /dev/null +++ b/gdb/i386-tdep.c @@ -0,0 +1,494 @@ +/* Intel 386 stuff. + Copyright (C) 1988, 1989 Free Software Foundation, Inc. + +This file is part of GDB. + +GDB 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 1, or (at your option) +any later version. + +GDB 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 GDB; see the file COPYING. If not, write to +the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */ + +#include <stdio.h> +#include "defs.h" +#include "param.h" +#include "frame.h" +#include "inferior.h" +#include "gdbcore.h" + +#ifdef USG +#include <sys/types.h> +#endif + +#include <sys/param.h> +#include <sys/dir.h> +#include <signal.h> +#include <sys/user.h> +#include <sys/ioctl.h> +#include <fcntl.h> + +#ifndef N_SET_MAGIC +#ifdef COFF_FORMAT +#define N_SET_MAGIC(exec, val) ((exec).magic = (val)) +#else +#define N_SET_MAGIC(exec, val) ((exec).a_magic = (val)) +#endif +#endif + +#include <sys/file.h> +#include <sys/stat.h> + +/* I don't know whether this is right for cross-debugging even if you + do somehow manage to get the right include file. */ +#if defined (USE_MACHINE_REG_H) +#include <machine/reg.h> +#else +#include <sys/reg.h> +#endif + +/* helper functions for m-i386.h */ + +/* stdio style buffering to minimize calls to ptrace */ +static CORE_ADDR codestream_next_addr; +static CORE_ADDR codestream_addr; +static unsigned char codestream_buf[sizeof (int)]; +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) +{ + codestream_addr = codestream_next_addr; + codestream_next_addr += sizeof (int); + codestream_off = 0; + codestream_cnt = sizeof (int); + read_memory (codestream_addr, + (unsigned char *)codestream_buf, + sizeof (int)); + + if (peek_flag) + return (codestream_peek()); + else + return (codestream_get()); +} + +static void +codestream_seek (place) +{ + codestream_next_addr = place & -sizeof (int); + codestream_cnt = 0; + codestream_fill (1); + while (codestream_tell() != place) + codestream_get (); +} + +static void +codestream_read (buf, count) + unsigned char *buf; +{ + 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 +i386_follow_jump () +{ + int long_delta; + short short_delta; + char byte_delta; + int data16; + int 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 ((unsigned char *)&short_delta, 2); + pos += short_delta + 3; /* include size of jmp inst */ + } + else + { + codestream_read ((unsigned char *)&long_delta, 4); + pos += long_delta + 5; + } + break; + case 0xeb: + /* relative jump, disp8 (ignore data16) */ + codestream_read ((unsigned char *)&byte_delta, 1); + pos += byte_delta + 2; + break; + } + codestream_seek (pos + data16); +} + +/* + * 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) +{ + 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 (bcmp (buf, proto1, 3) == 0) + pos += 3; + else if (bcmp (buf, proto2, 4) == 0) + pos += 4; + + 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) + { + /* subl with 32 bit immed */ + int locals; + codestream_get(); + if (codestream_get () != 0xec) + /* Some instruction starting with 0x81 other than subl. */ + { + codestream_seek (codestream_tell () - 2); + return 0; + } + /* subl with 32 bit immediate */ + codestream_read ((unsigned char *)&locals, 4); + return (locals); + } + else + { + return (0); + } + } + else if (op == 0xc8) + { + /* enter instruction: arg is 16 bit unsigned immed */ + unsigned short slocals; + codestream_read ((unsigned char *)&slocals, 2); + codestream_get (); /* flush final byte of enter instruction */ + return (slocals); + } + return (-1); +} + +/* Return number of args passed to a frame. + Can return -1, meaning no way to tell. */ + +/* 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 +i386_frame_num_args (fi) + struct frame_info fi; +{ + int retpc; + unsigned char op; + struct frame_info *pfi; + + int frameless; + + FRAMELESS_FUNCTION_INVOCATION (fi, frameless); + 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_info ((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 $<signed imm 8 bits>, %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 $<imm 32>, %esp */ + return read_memory_integer (retpc+2, 4) / 4; + else + return 0; + } + else + { + return 0; + } + } +} + +/* + * 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 $<size>, %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. + */ + +i386_frame_find_saved_regs (fip, fsrp) + struct frame_info *fip; + struct frame_saved_regs *fsrp; +{ + long locals; + unsigned char *p; + unsigned char op; + CORE_ADDR dummy_bottom; + CORE_ADDR adr; + int i; + + bzero (fsrp, sizeof *fsrp); + + /* 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); + fsrp->regs[i] = adr; + } + return; + } + + locals = i386_get_frame_setup (get_pc_function_start (fip->pc)); + + if (locals >= 0) + { + adr = fip->frame - 4 - locals; + for (i = 0; i < 8; i++) + { + op = codestream_get (); + if (op < 0x50 || op > 0x57) + break; + fsrp->regs[op - 0x50] = adr; + adr -= 4; + } + } + + fsrp->regs[PC_REGNUM] = fip->frame + 4; + fsrp->regs[FP_REGNUM] = fip->frame; +} + +/* return pc of first real instruction */ +i386_skip_prologue (pc) +{ + unsigned char op; + int i; + + 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 (); + } + + i386_follow_jump (); + + return (codestream_tell ()); +} + +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); +} + +i386_pop_frame () +{ + FRAME frame = get_current_frame (); + CORE_ADDR fp; + int regnum; + struct frame_saved_regs fsr; + struct frame_info *fi; + char regbuf[MAX_REGISTER_RAW_SIZE]; + + fi = get_frame_info (frame); + fp = fi->frame; + get_frame_saved_regs (fi, &fsr); + for (regnum = 0; regnum < NUM_REGS; regnum++) + { + CORE_ADDR adr; + adr = fsr.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 (); + set_current_frame ( create_new_frame (read_register (FP_REGNUM), + read_pc ())); +} |