Sweden-Number/debugger/break.c

351 lines
9.8 KiB
C

/*
* Debugger break-points handling
*
* Copyright 1994 Martin von Loewis
* Copyright 1995 Alexandre Julliard
*/
#include <stdio.h>
#include <stdlib.h>
#include <sys/mman.h>
#include "windows.h"
#include "debugger.h"
#define INT3 0xcc /* int 3 opcode */
#define STEP_FLAG 0x100 /* single-step flag */
#define MAX_BREAKPOINTS 25
typedef struct
{
DBG_ADDR addr;
BYTE addrlen;
BYTE opcode;
BOOL enabled;
BOOL in_use;
} BREAKPOINT;
static BREAKPOINT breakpoints[MAX_BREAKPOINTS];
static int next_bp = 1; /* breakpoint 0 is reserved for step-over */
/***********************************************************************
* DEBUG_ChangeOpcode
*
* Change the opcode at segment:addr.
*/
static void DEBUG_SetOpcode( const DBG_ADDR *addr, BYTE op )
{
if (addr->seg)
{
*(BYTE *)PTR_SEG_OFF_TO_LIN( addr->seg, addr->off ) = op;
}
else /* 32-bit code, so we have to change the protection first */
{
/* There are a couple of problems with this. On Linux prior to
1.1.62, this call fails (ENOACCESS) due to a bug in fs/exec.c.
This code is currently not tested at all on BSD.
How do I determine the page size in a more symbolic manner?
And why does mprotect need that start address of the page
in the first place?
Not that portability matters, this code is i386 only anyways...
How do I get the old protection in order to restore it later on?
*/
if (mprotect((caddr_t)(addr->off & (~4095)), 4096,
PROT_READ | PROT_WRITE | PROT_EXEC) == -1)
{
perror( "Can't set break point" );
return;
}
*(BYTE *)addr->off = op;
mprotect((caddr_t)(addr->off & ~4095), 4096,
PROT_READ | PROT_EXEC );
}
}
/***********************************************************************
* DEBUG_IsStepOverInstr
*
* Determine if the instruction at CS:EIP is an instruction that
* we need to step over (like a call or a repetitive string move).
*/
static BOOL DEBUG_IsStepOverInstr( struct sigcontext_struct *context )
{
BYTE *instr = (BYTE *)PTR_SEG_OFF_TO_LIN(CS_reg(context),EIP_reg(context));
for (;;)
{
switch(*instr)
{
/* Skip all prefixes */
case 0x2e: /* cs: */
case 0x36: /* ss: */
case 0x3e: /* ds: */
case 0x26: /* es: */
case 0x64: /* fs: */
case 0x65: /* gs: */
case 0x66: /* opcode size prefix */
case 0x67: /* addr size prefix */
case 0xf0: /* lock */
case 0xf2: /* repne */
case 0xf3: /* repe */
instr++;
continue;
/* Handle call instructions */
case 0xe8: /* call <offset> */
case 0x9a: /* lcall <seg>:<off> */
return TRUE;
case 0xff: /* call <regmodrm> */
return (((instr[1] & 0x38) == 0x10) ||
((instr[1] & 0x38) == 0x18));
/* Handle string instructions */
case 0x6c: /* insb */
case 0x6d: /* insw */
case 0x6e: /* outsb */
case 0x6f: /* outsw */
case 0xa4: /* movsb */
case 0xa5: /* movsw */
case 0xa6: /* cmpsb */
case 0xa7: /* cmpsw */
case 0xaa: /* stosb */
case 0xab: /* stosw */
case 0xac: /* lodsb */
case 0xad: /* lodsw */
case 0xae: /* scasb */
case 0xaf: /* scasw */
return TRUE;
default:
return FALSE;
}
}
}
/***********************************************************************
* DEBUG_SetBreakpoints
*
* Set or remove all the breakpoints.
*/
void DEBUG_SetBreakpoints( BOOL set )
{
int i;
for (i = 0; i < MAX_BREAKPOINTS; i++)
{
if (breakpoints[i].in_use && breakpoints[i].enabled)
{
if (DEBUG_IsBadWritePtr( &breakpoints[i].addr, 1 ))
{
fprintf( stderr, "Invalid address for breakpoint %d, disabling it\n", i );
breakpoints[i].enabled = FALSE;
}
else DEBUG_SetOpcode( &breakpoints[i].addr,
set ? INT3 : breakpoints[i].opcode );
}
}
}
/***********************************************************************
* DEBUG_FindBreakpoint
*
* Find the breakpoint for a given address. Return the breakpoint
* number or -1 if none.
*/
int DEBUG_FindBreakpoint( const DBG_ADDR *addr )
{
int i;
for (i = 0; i < MAX_BREAKPOINTS; i++)
{
if (breakpoints[i].in_use && breakpoints[i].enabled &&
breakpoints[i].addr.seg == addr->seg &&
breakpoints[i].addr.off == addr->off) return i;
}
return -1;
}
/***********************************************************************
* DEBUG_AddBreakpoint
*
* Add a breakpoint.
*/
void DEBUG_AddBreakpoint( const DBG_ADDR *address )
{
DBG_ADDR addr = *address;
int num;
BYTE *p;
DBG_FIX_ADDR_SEG( &addr, CS_reg(DEBUG_context) );
if (next_bp < MAX_BREAKPOINTS)
num = next_bp++;
else /* try to find an empty slot */
{
for (num = 1; num < MAX_BREAKPOINTS; num++)
if (!breakpoints[num].in_use) break;
if (num >= MAX_BREAKPOINTS)
{
fprintf( stderr, "Too many breakpoints. Please delete some.\n" );
return;
}
}
if (!DBG_CHECK_READ_PTR( &addr, 1 )) return;
p = DBG_ADDR_TO_LIN( &addr );
breakpoints[num].addr = addr;
breakpoints[num].addrlen = !addr.seg ? 32 :
(GET_SEL_FLAGS(addr.seg) & LDT_FLAGS_32BIT) ? 32 : 16;
breakpoints[num].opcode = *p;
breakpoints[num].enabled = TRUE;
breakpoints[num].in_use = TRUE;
fprintf( stderr, "Breakpoint %d at ", num );
DEBUG_PrintAddress( &breakpoints[num].addr, breakpoints[num].addrlen );
fprintf( stderr, "\n" );
}
/***********************************************************************
* DEBUG_DelBreakpoint
*
* Delete a breakpoint.
*/
void DEBUG_DelBreakpoint( int num )
{
if ((num <= 0) || (num >= next_bp) || !breakpoints[num].in_use)
{
fprintf( stderr, "Invalid breakpoint number %d\n", num );
return;
}
breakpoints[num].enabled = FALSE;
breakpoints[num].in_use = FALSE;
}
/***********************************************************************
* DEBUG_EnableBreakpoint
*
* Enable or disable a break point.
*/
void DEBUG_EnableBreakpoint( int num, BOOL enable )
{
if ((num <= 0) || (num >= next_bp) || !breakpoints[num].in_use)
{
fprintf( stderr, "Invalid breakpoint number %d\n", num );
return;
}
breakpoints[num].enabled = enable;
}
/***********************************************************************
* DEBUG_InfoBreakpoints
*
* Display break points information.
*/
void DEBUG_InfoBreakpoints(void)
{
int i;
fprintf( stderr, "Breakpoints:\n" );
for (i = 1; i < next_bp; i++)
{
if (breakpoints[i].in_use)
{
fprintf( stderr, "%d: %c ", i, breakpoints[i].enabled ? 'y' : 'n');
DEBUG_PrintAddress( &breakpoints[i].addr, breakpoints[i].addrlen );
fprintf( stderr, "\n" );
}
}
}
/***********************************************************************
* DEBUG_ShouldContinue
*
* Determine if we should continue execution after a SIGTRAP signal when
* executing in the given mode.
*/
BOOL DEBUG_ShouldContinue( struct sigcontext_struct *context,
enum exec_mode mode )
{
DBG_ADDR addr;
int bpnum;
/* If not single-stepping, back up over the int3 instruction */
if (!(EFL_reg(DEBUG_context) & STEP_FLAG)) EIP_reg(DEBUG_context)--;
addr.seg = (CS_reg(DEBUG_context) == WINE_CODE_SELECTOR) ?
0 : CS_reg(DEBUG_context);
addr.off = EIP_reg(DEBUG_context);
bpnum = DEBUG_FindBreakpoint( &addr );
breakpoints[0].enabled = 0; /* disable the step-over breakpoint */
if ((bpnum != 0) && (bpnum != -1))
{
fprintf( stderr, "Stopped on breakpoint %d at ", bpnum );
DEBUG_PrintAddress( &breakpoints[bpnum].addr,
breakpoints[bpnum].addrlen );
fprintf( stderr, "\n" );
return FALSE;
}
/* no breakpoint, continue if in continuous mode */
return (mode == EXEC_CONT);
}
/***********************************************************************
* DEBUG_RestartExecution
*
* Set the breakpoints to the correct state to restart execution
* in the given mode.
*/
void DEBUG_RestartExecution( struct sigcontext_struct *context,
enum exec_mode mode, int instr_len )
{
DBG_ADDR addr;
addr.seg = (CS_reg(DEBUG_context) == WINE_CODE_SELECTOR) ?
0 : CS_reg(DEBUG_context);
addr.off = EIP_reg(DEBUG_context);
if (DEBUG_FindBreakpoint( &addr ) != -1)
mode = EXEC_STEP_INSTR; /* If there's a breakpoint, skip it */
switch(mode)
{
case EXEC_CONT: /* Continuous execution */
EFL_reg(DEBUG_context) &= ~STEP_FLAG;
DEBUG_SetBreakpoints( TRUE );
break;
case EXEC_STEP_OVER: /* Stepping over a call */
if (DEBUG_IsStepOverInstr(DEBUG_context))
{
EFL_reg(DEBUG_context) &= ~STEP_FLAG;
addr.off += instr_len;
breakpoints[0].addr = addr;
breakpoints[0].enabled = TRUE;
breakpoints[0].in_use = TRUE;
breakpoints[0].opcode = *(BYTE *)DBG_ADDR_TO_LIN( &addr );
DEBUG_SetBreakpoints( TRUE );
break;
}
/* else fall through to single-stepping */
case EXEC_STEP_INSTR: /* Single-stepping an instruction */
EFL_reg(DEBUG_context) |= STEP_FLAG;
break;
}
}