vectors.s

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##==========================================================================
##
##      vectors.S
##
##      PowerPC exception vectors
##
##==========================================================================
#####ECOSGPLCOPYRIGHTBEGIN####
## -------------------------------------------
## This file is part of eCos, the Embedded Configurable Operating System.
## Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
## Copyright (C) 2002 Gary Thomas
##
## eCos 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 or (at your option) any later version.
##
## eCos 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 eCos; if not, write to the Free Software Foundation, Inc.,
## 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
##
## As a special exception, if other files instantiate templates or use macros
## or inline functions from this file, or you compile this file and link it
## with other works to produce a work based on this file, this file does not
## by itself cause the resulting work to be covered by the GNU General Public
## License. However the source code for this file must still be made available
## in accordance with section (3) of the GNU General Public License.
##
## This exception does not invalidate any other reasons why a work based on
## this file might be covered by the GNU General Public License.
##
## Alternative licenses for eCos may be arranged by contacting Red Hat, Inc.
## at http://sources.redhat.com/ecos/ecos-license/
## -------------------------------------------
#####ECOSGPLCOPYRIGHTEND####
##==========================================================================
#######DESCRIPTIONBEGIN####
##
## Author(s):    nickg, jskov
## Contributors: nickg, jskov
## Date:         1999-02-20
## Purpose:      PowerPC exception vectors
## Description:  This file defines the code placed into the exception
##               vectors. It also contains the first level default VSRs
##               that save and restore state for both exceptions and
##               interrupts.
##
######DESCRIPTIONEND####
##
##==========================================================================

#===========================================================================
#
#       The PowerPC exception handling has changed as of version 1.3.1.
#       The primary motivation for rewriting the code was to bring it more
#       in line with the other HALs, in particular to allow a RAM application
#       to cleanly take over only a subset of vectors from a running ROM
#	monitor.
#
#       GDB stubs (and CygMon, should it be ported to PPC) copies
#       exception vector entry handler code to address 0. These vector entry
#       handlers (defined by the exception_vector macro below) compute
#       a vector index into the hal_vsr_table, fetch the pointer, and
#       jump to the HAL vector service routine (VSR).
#
#       The hal_vsr_table is located immediately after the vector
#       handlers (at address 0x3000), allowing RAM applications to
#       change VSRs as necessary, while still keeping desired ROM
#       monitor functionality available for debugging.
#
#       ROM applications can still be configured to leave the vector entry
#       handlers at 0xff000000, but there is at the moment no
#       provision for reclaiming the reserved vector space in RAM to
#       application usage.
#
#       RAM applications can also be configured to provide exception
#       handlers which are copied to address 0 on startup, thus taking
#       full control of the target.
#
#
#       Default configuration is for RAM applications to rely on an
#       existing ROM monitor to provide debugging functionality, and
#       for ROM applications to copy vectors to address 0.
#
#
#       Unfortunately the new exception scheme is not compatible with the
#       old scheme. Stubs and applications must be compiled using the same
#       scheme (i.e., old binaries will not run with new stubs, and new
#       binaries will not run with old stubs).
#
#===========================================================================

#include <pkgconf/hal.h>

#ifdef CYGPKG_KERNEL
#include <pkgconf/kernel.h>     // CYGPKG_KERNEL_INSTRUMENT
#endif

#define CYGARC_HAL_COMMON_EXPORT_CPU_MACROS
#include <cyg/hal/ppc_regs.h>

#===========================================================================
                
//        .file   "vectors.S"
        
        .extern hal_interrupt_data
        .extern hal_interrupt_handlers
        .extern hal_interrupt_objects
        .extern hal_vsr_table

        .extern cyg_hal_invoke_constructors
        .extern cyg_instrument
        .extern cyg_start
        .extern hal_IRQ_init
        .extern hal_MMU_init
        .extern hal_enable_caches
        .extern hal_hardware_init
        .extern initialize_stub

        .extern __bss_start
        .extern __bss_end
        .extern __sbss_start
        .extern __sbss_end

#===========================================================================
# MSR initialization value
# zero all bits except:
# FP = floating point available
# ME = machine check enabled
# IP = vectors at 0xFFFxxxxx (ROM startup only)
# IR = instruction address translation
# DR = data address translation
# RI = recoverable interrupt

#define CYG_MSR_COMMON (MSR_FP | MSR_ME | MSR_RI)

#if (CYGHWR_HAL_POWERPC_VECTOR_BASE == 0xfff00000)
# define IP_BIT MSR_IP
#else
# define IP_BIT 0
#endif

#ifdef CYGHWR_HAL_POWERPC_ENABLE_MMU
# define IR_DR_BITS (MSR_IR | MSR_DR)
#else
# define IR_DR_BITS 0
#endif

#define CYG_MSR (CYG_MSR_COMMON | IP_BIT | IR_DR_BITS)

# Include variant macros after MSR definition.        
#include <cyg/hal/arch.inc>
#include <cyg/hal/ppc_offsets.inc>


#===========================================================================
# If the following option is enabled, we only save registers up to R12.
# The PowerPC ABI defines registers 13..31 as callee saved and thus we do
# not need to save them when calling C functions.

#ifdef CYGDBG_HAL_COMMON_INTERRUPTS_SAVE_MINIMUM_CONTEXT
# define MAX_SAVE_REG    12
#else
# define MAX_SAVE_REG    31
#endif                  
        

#if defined(CYGHWR_HAL_POWERPC_NEED_VECTORS)

#===========================================================================
# Start by defining the exceptions vectors that must be placed at
# locations 0xFFF00000 or 0x00000000. The following code will normally
# be located at 0xFFF00000 in the ROM. It may optionally be copied out
# to 0x00000000 if we want to use the RAM vectors. For this reason this code
# MUST BE POSITION INDEPENDENT.
        
        .section ".vectors","ax"

#---------------------------------------------------------------------------
# Macros for generating an exception vector service routine

# Reset vector macro

        .macro  reset_vector name
        .p2align 8
        .globl  __exception_\name
__exception_\name:
#ifdef CYGSEM_HAL_POWERPC_RESET_USES_JUMP        
        bl      _start               
#else
        lwi     r3,_start
        mtlr    r3
        blr
#endif                

        .endm
        
# Generic vector macro
                
        .macro  exception_vector name
        .p2align 8
        .globl  __exception_\name
__exception_\name:
        mtspr   SPRG1,r3                     # stash some work registers away
        mtspr   SPRG2,r4                    
        mtspr   SPRG3,r5                    
        mfcr    r4                           # stash CR
        li      r5,__exception_\name-rom_vectors       # load low half of vector addr
        srwi    r5,r5,6                      # shift right by 6      
        lwi     r3,hal_vsr_table             # table base
        lwzx    r3,r3,r5                     # address of vsr
        mflr    r5                           # save link register
        mtlr    r3                           # put vsr address into it
        li      r3,__exception_\name-rom_vectors       # reload low half of vector addr
        blr                                  # go to common code
        .endm
        
#---------------------------------------------------------------------------
# Define the exception vectors.

// Some platforms won't let us put the vector code just where we want
// This macro introduces some lattitude in vector placement
                        
#ifdef CYG_HAL_FUDGE_VECTOR_ALIGNMENT        
        hal_fudge_vector_alignment
#endif
                
rom_vectors:
        # These are the architecture defined vectors that
        # are always present.
#ifdef CYG_HAL_RESERVED_VECTOR_00000
        hal_reserved_vector_00000                
#else                
        exception_vector        reserved_00000
#endif        
        reset_vector            reset
        exception_vector        machine_check
        exception_vector        data_storage
        exception_vector        instruction_storage
        exception_vector        external
        exception_vector        alignment
        exception_vector        program
        exception_vector        floatingpoint_unavailable
        exception_vector        decrementer
        exception_vector        reserved_00a00
        exception_vector        reserved_00b00
        exception_vector        system_call
        exception_vector        trace
        exception_vector        floatingpoint_assist
        exception_vector        reserved_00f00

        # Variants may define extra vectors.
        hal_extra_vectors

rom_vectors_end:   

#else //  CYGHWR_HAL_POWERPC_NEED_VECTORS

        # When vectors are not included this is the primary entry point.
        .globl  __exception_reset
__exception_reset:
        lwi     r3,_start
        mtlr    r3
        blr
        
#endif //  CYGHWR_HAL_POWERPC_NEED_VECTORS



#===========================================================================
# Real startup code. We jump here from the various reset vectors to set up
# the world.
        
        .text   
        .globl  _start
_start:
        # Initialize CPU to a post-reset state, ensuring the ground doesn''t
        # shift under us while we try to set things up.
        hal_cpu_init

        # Set up global offset table
        lwi     r2,_GLOBAL_OFFSET_TABLE_

        # set up time base register to zero
        xor     r3,r3,r3
        mtspr   TBL_W,r3
        xor     r4,r4,r4
        mtspr   TBU_W,r4

        # Call platform specific hardware initialization
        # This may include memory controller initialization. It is not
        # safe to access RAM until after this point.
        bl      hal_hardware_init	# this is platform dependent
        .globl  _hal_hardware_init_done
_hal_hardware_init_done:

#if !defined(CYG_HAL_STARTUP_ROM) && defined(CYGSEM_HAL_POWERPC_COPY_VECTORS)
        lwi     r3,rom_vectors-4
        lwi     r4,((CYGHWR_HAL_POWERPC_VECTOR_BASE)-4)
        lwi     r5,rom_vectors_end-4
0:      lwzu    r0,4(r3)
        stwu    r0,4(r4)
        cmplw   r3,r5
        bne     0b
#endif