arm_stub.c

移植到WLIT项目的redboot源代码

//========================================================================
//
//      arm_stub.c
//
//      Helper functions for stub, generic to all ARM processors
//
//========================================================================
//####COPYRIGHTBEGIN####
//                                                                          
// -------------------------------------------                              
// The contents of this file are subject to the Red Hat eCos Public License 
// Version 1.1 (the "License"); you may not use this file except in         
// compliance with the License.  You may obtain a copy of the License at    
// http://www.redhat.com/                                                   
//                                                                          
// Software distributed under the License is distributed on an "AS IS"      
// basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See the 
// License for the specific language governing rights and limitations under 
// the License.                                                             
//                                                                          
// The Original Code is eCos - Embedded Configurable Operating System,      
// released September 30, 1998.                                             
//                                                                          
// The Initial Developer of the Original Code is Red Hat.                   
// Portions created by Red Hat are                                          
// Copyright (C) 1998, 1999, 2000, 2001 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
//####COPYRIGHTEND####
//========================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):     Red Hat, gthomas
// Contributors:  Red Hat, gthomas, jskov
// Date:          1998-11-26
// Purpose:       
// Description:   Helper functions for stub, generic to all ARM processors
// Usage:         
//
//####DESCRIPTIONEND####
//
//========================================================================

#include <stddef.h>

#include <pkgconf/hal.h>

#ifdef CYGPKG_REDBOOT
#include <pkgconf/redboot.h>
#endif

#ifdef CYGDBG_HAL_DEBUG_GDB_INCLUDE_STUBS

#ifdef CYGPKG_HAL_ARM_SIM
#error "GDB Stub support not implemented for ARM SIM"
#endif

#include <cyg/hal/hal_stub.h>
#include <cyg/hal/hal_arch.h>
#include <cyg/hal/hal_intr.h>

#ifndef FALSE
#define FALSE 0
#define TRUE  1
#endif

// Use bit 0 as a thumb-mode flag for next address to be executed.
// Alternative would be to keep track of it using a C variable, but
// since bit 0 is used by the BX instruction, we might as well do the
// same thing and thus avoid checking two different flags.
#define IS_THUMB_ADDR(addr)     ((addr) & 1)
#define MAKE_THUMB_ADDR(addr) ((addr) | 1)
#define UNMAKE_THUMB_ADDR(addr) ((addr) & ~1)

#ifdef CYGDBG_HAL_DEBUG_GDB_THREAD_SUPPORT
#include <cyg/hal/dbg-threads-api.h>    // dbg_currthread_id
#endif

#if defined(CYGNUM_HAL_BREAKPOINT_LIST_SIZE) && (CYGNUM_HAL_BREAKPOINT_LIST_SIZE > 0)
cyg_uint32 __arm_breakinst = HAL_BREAKINST_ARM;
cyg_uint16 __thumb_breakinst = HAL_BREAKINST_THUMB;
#endif

/* Given a trap value TRAP, return the corresponding signal. */

int __computeSignal (unsigned int trap_number)
{
    // Check to see if we stopped because of a hw watchpoint/breakpoint.
#ifdef HAL_STUB_IS_STOPPED_BY_HARDWARE
    {
	void *daddr;
	if (HAL_STUB_IS_STOPPED_BY_HARDWARE(daddr))
	    return SIGTRAP;
    }
#endif
    // should also catch CYGNUM_HAL_VECTOR_UNDEF_INSTRUCTION here but we
    // can't tell the different between a real one and a breakpoint :-(
    switch (trap_number) {
    case CYGNUM_HAL_VECTOR_ABORT_PREFETCH:      // Fall through
    case CYGNUM_HAL_VECTOR_ABORT_DATA:          // Fall through
    case CYGNUM_HAL_VECTOR_reserved:
        return SIGBUS;
    case CYGNUM_HAL_VECTOR_IRQ:
    case CYGNUM_HAL_VECTOR_FIQ:
        return SIGINT;
    default:
        return SIGTRAP;
    }
}


/* Return the trap number corresponding to the last-taken trap. */
int __get_trap_number (void)
{
    // The vector is not not part of the GDB register set so get it
    // directly from the save context.
    return _hal_registers->vector;
}


#if defined(CYGSEM_REDBOOT_BSP_SYSCALLS)
int __is_bsp_syscall(void) 
{
    unsigned long pc = get_register(PC);
    unsigned long cpsr = get_register(PS);  // condition codes

    if (_hal_registers->vector == CYGNUM_HAL_EXCEPTION_INTERRUPT) {
	if (cpsr & CPSR_THUMB_ENABLE)
	    return *(unsigned short *)pc == 0xdf18;
	else
	    return *(unsigned *)pc == 0xef180001;
    }
    return 0;
}
#endif

/* Set the currently-saved pc register value to PC. */

void set_pc (target_register_t pc)
{
    put_register (PC, pc);
}


/*----------------------------------------------------------------------
 * Single-step support
 */

/* Set things up so that the next user resume will execute one instruction.
   This may be done by setting breakpoints or setting a single step flag
   in the saved user registers, for example. */

static unsigned long  ss_saved_pc = 0;
static unsigned long  ss_saved_instr;
static unsigned short ss_saved_thumb_instr;

#define FIXME() {diag_printf("FIXME - %s\n", __FUNCTION__); }

static int
ins_will_execute(unsigned long ins)
{
    unsigned long psr = get_register(PS);  // condition codes
    int res = 0;
    switch ((ins & 0xF0000000) >> 28) {
    case 0x0: // EQ
        res = (psr & PS_Z) != 0;
        break;
    case 0x1: // NE
        res = (psr & PS_Z) == 0;
        break;
    case 0x2: // CS
        res = (psr & PS_C) != 0;
        break;
    case 0x3: // CC
        res = (psr & PS_C) == 0;
        break;
    case 0x4: // MI
        res = (psr & PS_N) != 0;
        break;
    case 0x5: // PL
        res = (psr & PS_N) == 0;
        break;
    case 0x6: // VS
        res = (psr & PS_V) != 0;
        break;
    case 0x7: // VC
        res = (psr & PS_V) == 0;
        break;
    case 0x8: // HI
        res = ((psr & PS_C) != 0) && ((psr & PS_Z) == 0);
        break;
    case 0x9: // LS
        res = ((psr & PS_C) == 0) || ((psr & PS_Z) != 0);
        break;
    case 0xA: // GE
        res = ((psr & (PS_N|PS_V)) == (PS_N|PS_V)) ||
            ((psr & (PS_N|PS_V)) == 0);
        break;
    case 0xB: // LT
        res = ((psr & (PS_N|PS_V)) == PS_N) ||
            ((psr & (PS_N|PS_V)) == PS_V);
        break;
    case 0xC: // GT
        res = ((psr & (PS_N|PS_V)) == (PS_N|PS_V)) ||
            ((psr & (PS_N|PS_V)) == 0);
        res = ((psr & PS_Z) == 0) && res;
        break;
    case 0xD: // LE
        res = ((psr & (PS_N|PS_V)) == PS_N) ||
            ((psr & (PS_N|PS_V)) == PS_V);
        res = ((psr & PS_Z) == PS_Z) || res;
        break;
    case 0xE: // AL
        res = TRUE;
        break;
    case 0xF: // NV
        if (((ins & 0x0E000000) >> 24) == 0xA)
	    res = TRUE;
	else
	    res = FALSE;
        break;
    }
    return res;
}

static unsigned long
RmShifted(int shift)
{
    unsigned long Rm = get_register(shift & 0x00F);
    int shift_count;
    if ((shift & 0x010) == 0) {
        shift_count = (shift & 0xF80) >> 7;
    } else {
        shift_count = get_register((shift & 0xF00) >> 8);
    }
    switch ((shift & 0x060) >> 5) {
    case 0x0: // Logical left
        Rm <<= shift_count;
        break;
    case 0x1: // Logical right
        Rm >>= shift_count;
        break;
    case 0x2: // Arithmetic right
        Rm = (unsigned long)((long)Rm >> shift_count);
        break;
    case 0x3: // Rotate right
        if (shift_count == 0) {
            // Special case, RORx
            Rm >>= 1;
            if (get_register(PS) & PS_C) Rm |= 0x80000000;
        } else {
            Rm = (Rm >> shift_count) | (Rm << (32-shift_count));
        }
        break;
    }
    return Rm;
}

// Decide the next instruction to be executed for a given instruction
static unsigned long *
target_ins(unsigned long *pc, unsigned long ins)
{
    unsigned long new_pc, offset, op2;
    unsigned long Rn;
    int i, reg_count, c;

    switch ((ins & 0x0C000000) >> 26) {
    case 0x0:
        // BX or BLX
        if ((ins & 0x0FFFFFD0) == 0x012FFF10) {
            new_pc = (unsigned long)get_register(ins & 0x0000000F);
            return ((unsigned long *)new_pc);
        }
        // Data processing
        new_pc = (unsigned long)(pc+1);
        if ((ins & 0x0000F000) == 0x0000F000) {
            // Destination register is PC
            if ((ins & 0x0FBF0000) != 0x010F0000) {
                Rn = (unsigned long)get_register((ins & 0x000F0000) >> 16);
                if ((ins & 0x02000000) == 0) {
                    op2 = RmShifted(ins & 0x00000FFF);
                } else {
                    op2 = ins & 0x000000FF;
                    i = (ins & 0x00000F00) >> 8;  // Rotate count                
                    op2 = (op2 >> (i*2)) | (op2 << (32-(i*2)));
                }
                switch ((ins & 0x01E00000) >> 21) {
                case 0x0: // AND
                    new_pc = Rn & op2;
                    break;
                case 0x1: // EOR
                    new_pc = Rn ^ op2;
                    break;
                case 0x2: // SUB
                    new_pc = Rn - op2;
                    break;
                case 0x3: // RSB
                    new_pc = op2 - Rn;
                    break;
                case 0x4: // ADD
                    new_pc = Rn + op2;
                    break;
                case 0x5: // ADC
                    c = (get_register(PS) & PS_C) != 0;
                    new_pc = Rn + op2 + c;
                    break;
                case 0x6: // SBC
                    c = (get_register(PS) & PS_C) != 0;
                    new_pc = Rn - op2 + c - 1;
                    break;
                case 0x7: // RSC
                    c = (get_register(PS) & PS_C) != 0;
                    new_pc = op2 - Rn +c - 1;
                    break;
                case 0x8: // TST
                case 0x9: // TEQ
                case 0xA: // CMP
                case 0xB: // CMN
                    break; // PC doesn't change
                case 0xC: // ORR
                    new_pc = Rn | op2;
                    break;
                case 0xD: // MOV
                    new_pc = op2;
                    break;
                case 0xE: // BIC
                    new_pc = Rn & ~op2;
                    break;
                case 0xF: // MVN
                    new_pc = ~op2;
                    break;
                }
            }
        }
        return ((unsigned long *)new_pc);
    case 0x1:
        if ((ins & 0x02000010) == 0x02000010) {
            // Undefined!
            return (pc+1);
        } else {
            if ((ins & 0x00100000) == 0) {
                // STR
                return (pc+1);
            } else {
                // LDR
                if ((ins & 0x0000F000) != 0x0000F000) {
                    // Rd not PC
                    return (pc+1);
                } else {
                    Rn = (unsigned long)get_register((ins & 0x000F0000) >> 16);
                    if ((ins & 0x000F0000) == 0x000F0000) Rn += 8;  // PC prefetch!
                    if (ins & 0x01000000) {
                        // Add/subtract offset before
                        if ((ins & 0x02000000) == 0) {
                            // Immediate offset
                            if (ins & 0x00800000) {
                                // Add offset
                                Rn += (ins & 0x00000FFF);
                            } else {
                                // Subtract offset
                                Rn -= (ins & 0x00000FFF);
                            }
                        } else {
                            // Offset is in a register
                            if (ins & 0x00800000) {
                                // Add offset
                                Rn += RmShifted(ins & 0x00000FFF);
                            } else {
                                // Subtract offset
                                Rn -= RmShifted(ins & 0x00000FFF);
                            }
                        }
                    }
                    return ((unsigned long *)*(unsigned long *)Rn);
                }
            }
        }
        return (pc+1);
    case 0x2:  // Branch, LDM/STM
        if ((ins & 0x02000000) == 0) {
            // LDM/STM
            if ((ins & 0x00100000) == 0) {
                // STM
                return (pc+1);
            } else {
                // LDM
                if ((ins & 0x00008000) == 0) {
                    // PC not in list
                    return (pc+1);
                } else {
                    Rn = (unsigned long)get_register((ins & 0x000F0000) >> 16);
                    if ((ins & 0x000F0000) == 0x000F0000) Rn += 8;  // PC prefetch!