switch_to.S
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###############################################################################
#
# MN10300 Context switch operation
#
# Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
# Written by David Howells (dhowells@redhat.com)
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public Licence
# as published by the Free Software Foundation; either version
# 2 of the Licence, or (at your option) any later version.
#
###############################################################################
#include <linux/sys.h>
#include <linux/linkage.h>
#include <asm/thread_info.h>
#include <asm/cpu-regs.h>
#ifdef CONFIG_SMP
#include <proc/smp-regs.h>
#endif /* CONFIG_SMP */
.text
###############################################################################
#
# struct task_struct *__switch_to(struct thread_struct *prev,
# struct thread_struct *next,
# struct task_struct *prev_task)
#
###############################################################################
ENTRY(__switch_to)
movm [d2,d3,a2,a3,exreg1],(sp)
or EPSW_NMID,epsw
mov (44,sp),d2
mov d0,a0
mov d1,a1
# save prev context
mov __switch_back,d0
mov sp,a2
mov a2,(THREAD_SP,a0)
mov a3,(THREAD_A3,a0)
#ifdef CONFIG_KGDB
btst 0xff,(kgdb_single_step)
bne __switch_to__lift_sstep_bp
__switch_to__continue:
#endif
mov d0,(THREAD_PC,a0)
mov (THREAD_A3,a1),a3
mov (THREAD_SP,a1),a2
# switch
mov a2,sp
# load next context
GET_THREAD_INFO a2
mov a2,(__current_ti)
mov (TI_task,a2),a2
mov a2,(__current)
#ifdef CONFIG_MN10300_CURRENT_IN_E2
mov a2,e2
#endif
mov (THREAD_PC,a1),a2
mov d2,d0 # for ret_from_fork
mov d0,a0 # for __switch_to
jmp (a2)
__switch_back:
and ~EPSW_NMID,epsw
ret [d2,d3,a2,a3,exreg1],32
#ifdef CONFIG_KGDB
###############################################################################
#
# Lift the single-step breakpoints when the task being traced is switched out
# A0 = prev
# A1 = next
#
###############################################################################
__switch_to__lift_sstep_bp:
add -12,sp
mov a0,e4
mov a1,e5
# Clear the single-step flag to prevent us coming this way until we get
# switched back in
bclr 0xff,(kgdb_single_step)
# Remove first breakpoint
mov (kgdb_sstep_bp_addr),a2
cmp 0,a2
beq 1f
movbu (kgdb_sstep_bp),d0
movbu d0,(a2)
#if defined(CONFIG_MN10300_CACHE_FLUSH_ICACHE) || defined(CONFIG_MN10300_CACHE_INV_ICACHE)
mov a2,d0
mov a2,d1
add 1,d1
calls flush_icache_range
#endif
1:
# Remove second breakpoint
mov (kgdb_sstep_bp_addr+4),a2
cmp 0,a2
beq 2f
movbu (kgdb_sstep_bp+1),d0
movbu d0,(a2)
#if defined(CONFIG_MN10300_CACHE_FLUSH_ICACHE) || defined(CONFIG_MN10300_CACHE_INV_ICACHE)
mov a2,d0
mov a2,d1
add 1,d1
calls flush_icache_range
#endif
2:
# Change the resumption address and return
mov __switch_back__reinstall_sstep_bp,d0
mov e4,a0
mov e5,a1
add 12,sp
bra __switch_to__continue
###############################################################################
#
# Reinstall the single-step breakpoints when the task being traced is switched
# back in (A1 points to the new thread_struct).
#
###############################################################################
__switch_back__reinstall_sstep_bp:
add -12,sp
mov a0,e4 # save the return value
mov 0xff,d3
# Reinstall first breakpoint
mov (kgdb_sstep_bp_addr),a2
cmp 0,a2
beq 1f
movbu (a2),d0
movbu d0,(kgdb_sstep_bp)
movbu d3,(a2)
#if defined(CONFIG_MN10300_CACHE_FLUSH_ICACHE) || defined(CONFIG_MN10300_CACHE_INV_ICACHE)
mov a2,d0
mov a2,d1
add 1,d1
calls flush_icache_range
#endif
1:
# Reinstall second breakpoint
mov (kgdb_sstep_bp_addr+4),a2
cmp 0,a2
beq 2f
movbu (a2),d0
movbu d0,(kgdb_sstep_bp+1)
movbu d3,(a2)
#if defined(CONFIG_MN10300_CACHE_FLUSH_ICACHE) || defined(CONFIG_MN10300_CACHE_INV_ICACHE)
mov a2,d0
mov a2,d1
add 1,d1
calls flush_icache_range
#endif
2:
mov d3,(kgdb_single_step)
# Restore the return value (the previous thread_struct pointer)
mov e4,a0
mov a0,d0
add 12,sp
bra __switch_back
#endif /* CONFIG_KGDB */