hal_stub.c

eCos1.31版

//=============================================================================
//
//      hal_stub.c
//
//      Helper functions for stub, specific to eCos HAL
//
//=============================================================================
//####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 Red Hat, Inc.                             
// All Rights Reserved.                                                     
// -------------------------------------------                              
//                                                                          
//####COPYRIGHTEND####
//=============================================================================
//#####DESCRIPTIONBEGIN####
//
// Author(s):   jskov (based on powerpc/cogent hal_stub.c)
// Contributors:jskov
// Date:        1999-02-12
// Purpose:     Helper functions for stub, specific to eCos HAL
// Description: Parts of the GDB stub requirements are provided by
//              the eCos HAL, rather than target and/or board specific
//              code. 
//
//####DESCRIPTIONEND####
//
//=============================================================================

#include <pkgconf/hal.h>
#ifdef CYGPKG_CYGMON
#include <pkgconf/cygmon.h>
#endif

#ifdef CYGDBG_HAL_DEBUG_GDB_INCLUDE_STUBS

#include <cyg/hal/hal_stub.h>           // Our header

#include <cyg/hal/hal_arch.h>           // HAL_BREAKINST
#include <cyg/hal/hal_cache.h>          // HAL_xCACHE_x
#include <cyg/hal/hal_intr.h>           // interrupt disable/restore

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


//-----------------------------------------------------------------------------
// Extra eCos data.

// Saved registers.
HAL_SavedRegisters *_hal_registers;
target_register_t registers[NUMREGS];
target_register_t alt_registers[NUMREGS] ;  // Thread or saved process state
target_register_t * _registers = registers; // Pointer to current set of registers

// Interrupt control.
static volatile __PFI __interruptible_control;

//-----------------------------------------------------------------------------
// Register access

// Return the currently-saved value corresponding to register REG of
// the exception context.
target_register_t 
get_register (regnames_t reg)
{
    return _registers[reg];
}

// Store VALUE in the register corresponding to WHICH in the exception
// context.
void 
put_register (regnames_t which, target_register_t value)
{
    _registers[which] = value;
}

//-----------------------------------------------------------------------------
// Serial stuff
#ifdef CYGPKG_CYGMON
extern void ecos_bsp_console_putc(char);
extern char ecos_bsp_console_getc(void);
#endif

// Write C to the current serial port.
void 
putDebugChar (int c)
{
#ifdef CYGPKG_CYGMON
    ecos_bsp_console_putc(c);
#else
    HAL_STUB_PLATFORM_PUT_CHAR(c);
#endif
}

// Read one character from the current serial port.
int 
getDebugChar (void)
{
#ifdef CYGPKG_CYGMON
    return ecos_bsp_console_getc();
#else
    return HAL_STUB_PLATFORM_GET_CHAR();
#endif
}

// Set the baud rate for the current serial port.
void 
__set_baud_rate (int baud) 
{
#ifdef CYGPKG_CYGMON
    // FIXME!
#else
    HAL_STUB_PLATFORM_SET_BAUD_RATE(baud);
#endif
}

//-----------------------------------------------------------------------------
// GDB interrupt (BREAK) support.

#ifdef CYGDBG_HAL_DEBUG_GDB_BREAK_SUPPORT

#ifndef CYGPKG_HAL_ARM

#if (HAL_BREAKINST_SIZE == 1)
typedef cyg_uint8 t_inst;
#elif (HAL_BREAKINST_SIZE == 2)
typedef cyg_uint16 t_inst;
#elif (HAL_BREAKINST_SIZE == 4)
typedef cyg_uint32 t_inst;
#else
#error "Don't know how to handle that size"
#endif

typedef struct
{
  t_inst *targetAddr;
  t_inst savedInstr;
} instrBuffer;

static instrBuffer break_buffer;

volatile int cyg_hal_gdb_running_step = 0;

void 
cyg_hal_gdb_place_break (target_register_t pc)
{
    cyg_hal_gdb_interrupt( pc ); // Let's hope this becomes a drop-through:
}

void 
cyg_hal_gdb_interrupt (target_register_t pc)
{
    // Clear flag that we Continued instead of Stepping
    cyg_hal_gdb_running_step = 0;
    // and override existing break? So that a ^C takes effect...
    if (NULL != break_buffer.targetAddr)
        cyg_hal_gdb_remove_break( (target_register_t)break_buffer.targetAddr );

    if (NULL == break_buffer.targetAddr) {
        break_buffer.targetAddr = (t_inst*) pc;
        break_buffer.savedInstr = *(t_inst*)pc;
        *(t_inst*)pc = (t_inst)HAL_BREAKINST;

        __data_cache(CACHE_FLUSH);
        __instruction_cache(CACHE_FLUSH);
    }
}

int 
cyg_hal_gdb_remove_break (target_register_t pc)
{
    if ( cyg_hal_gdb_running_step )
        return 0;

    if ((t_inst*)pc == break_buffer.targetAddr) {
        *(t_inst*)pc = break_buffer.savedInstr;
        break_buffer.targetAddr = NULL;

        __data_cache(CACHE_FLUSH);
        __instruction_cache(CACHE_FLUSH);
        return 1;
    }
    return 0;
}

int 
cyg_hal_gdb_break_is_set (void)
{
    if (NULL != break_buffer.targetAddr) {
        return 1;
    }
    return 0;
}

#endif // CYGPKG_HAL_ARM

#endif // CYGDBG_HAL_DEBUG_GDB_BREAK_SUPPORT

// Use this function to disable serial interrupts whenever reply
// characters are expected from GDB.  The reason we want to control
// whether the target can be interrupted or not is simply that GDB on
// the host will be sending acknowledge characters/commands while the
// stub is running - if serial interrupts were still active, the
// characters would never reach the (polling) getDebugChar.
static void
interruptible(int state)
{
    static int __interrupts_suspended = 0;

    if (__interruptible_control) {
        if (state) {
            __interrupts_suspended--;
            if (0 >= __interrupts_suspended) {
                __interrupts_suspended = 0;
                __interruptible_control(1);
            }
        } else {
            __interrupts_suspended++;
            if (1 == __interrupts_suspended)
                __interruptible_control(0);
        }
    }
}

//-----------------------------------------------------------------------------
// eCos stub entry and exit magic.

#ifdef CYGDBG_HAL_DEBUG_GDB_BREAK_SUPPORT
int cyg_hal_gdb_break;
#endif

// Called at stub *entry*
static void 
handle_exception_cleanup( void )
{
    interruptible(0);

    // Expand the HAL_SavedRegisters structure into the GDB register
    // array format.
    HAL_GET_GDB_REGISTERS(&registers[0], _hal_registers);
    _registers = &registers[0];

#ifdef HAL_STUB_PLATFORM_STUBS_FIXUP
    // Some architectures may need to fix the PC in case of a partial
    // or fully executed trap instruction. GDB only takes correct action
    // when the PC is pointing to the breakpoint instruction it set.
    // 
    // Most architectures would leave PC pointing at the trap
    // instruction itself though, and so do not need to do anything
    // special.
    HAL_STUB_PLATFORM_STUBS_FIXUP();
#endif

#ifdef CYGDBG_HAL_DEBUG_GDB_BREAK_SUPPORT
    // If we continued instead of stepping, when there was a break set
    // ie. we were stepping within a critical region, clear the break, and
    // that flag.  If we stopped for some other reason, this has no effect.
    if ( cyg_hal_gdb_running_step ) {
        cyg_hal_gdb_running_step = 0;
        cyg_hal_gdb_remove_break(get_register (PC));
    }

    // FIXME: (there may be a better way to do this)
    // If we hit a breakpoint set by the gdb interrupt stub, make it
    // seem like an interrupt rather than having hit a breakpoint.
    if (cyg_hal_gdb_remove_break(get_register (PC)))
        cyg_hal_gdb_break = 1;
    else
        cyg_hal_gdb_break = 0;
#endif
}

// Called at stub *exit*
static void 
handle_exception_init( void )
{
    // Compact register array again.
    HAL_SET_GDB_REGISTERS(_hal_registers, &registers[0]);

    interruptible(1);
}


//-----------------------------------------------------------------------------
// Initialization.

// Signal handler.
int 
cyg_hal_process_signal (int signal)
{
    // We don't care about the signal (atm).
    return 0;
}

// Install the standard set of trap handlers for the stub.
void 
__install_traps (void)
{
    // Set signal handling vector so we can treat 'C<signum>' as 'c'.
    __process_signal_vec = &cyg_hal_process_signal;
    // Set exit vector to reset vector. This will allow automatic reset on