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kernel-ark/arch/frv/kernel/break.S
David Howells 28baebae73 [PATCH] FRV: Use virtual interrupt disablement 
Make the FRV arch use virtual interrupt disablement because accesses to the
processor status register (PSR) are relatively slow and because we will
soon have the need to deal with multiple interrupt controls at the same
time (separate h/w and inter-core interrupts).

The way this is done is to dedicate one of the four integer condition code
registers (ICC2) to maintaining a virtual interrupt disablement state
whilst inside the kernel.  This uses the ICC2.Z flag (Zero) to indicate
whether the interrupts are virtually disabled and the ICC2.C flag (Carry)
to indicate whether the interrupts are physically disabled.

ICC2.Z is set to indicate interrupts are virtually disabled.  ICC2.C is set
to indicate interrupts are physically enabled.  Under normal running
conditions Z==0 and C==1.

Disabling interrupts with local_irq_disable() doesn't then actually
physically disable interrupts - it merely sets ICC2.Z to 1.  Should an
interrupt then happen, the exception prologue will note ICC2.Z is set and
branch out of line using one instruction (an unlikely BEQ).  Here it will
physically disable interrupts and clear ICC2.C.

When it comes time to enable interrupts (local_irq_enable()), this simply
clears the ICC2.Z flag and invokes a trap #2 if both Z and C flags are
clear (the HI integer condition).  This can be done with the TIHI
conditional trap instruction.

The trap then physically reenables interrupts and sets ICC2.C again.  Upon
returning the interrupt will be taken as interrupts will then be enabled.
Note that whilst processing the trap, the whole exceptions system is
disabled, and so an interrupt can't happen till it returns.

If no pending interrupt had happened, ICC2.C would still be set, the HI
condition would not be fulfilled, and no trap will happen.

Saving interrupts (local_irq_save) is simply a matter of pulling the ICC2.Z
flag out of the CCR register, shifting it down and masking it off.  This
gives a result of 0 if interrupts were enabled and 1 if they weren't.

Restoring interrupts (local_irq_restore) is then a matter of taking the
saved value mentioned previously and XOR'ing it against 1.  If it was one,
the result will be zero, and if it was zero the result will be non-zero.
This result is then used to affect the ICC2.Z flag directly (it is a
condition code flag after all).  An XOR instruction does not affect the
Carry flag, and so that bit of state is unchanged.  The two flags can then
be sampled to see if they're both zero using the trap (TIHI) as for the
unconditional reenablement (local_irq_enable).

This patch also:

 (1) Modifies the debugging stub (break.S) to handle single-stepping crossing
     into the trap #2 handler and into virtually disabled interrupts.

 (2) Removes superseded fixup pointers from the second instructions in the trap
     tables (there's no a separate fixup table for this).

 (3) Declares the trap #3 vector for use in .org directives in the trap table.

 (4) Moves irq_enter() and irq_exit() in do_IRQ() to avoid problems with
     virtual interrupt handling, and removes the duplicate code that has now
     been folded into irq_exit() (softirq and preemption handling).

 (5) Tells the compiler in the arch Makefile that ICC2 is now reserved.

 (6) Documents the in-kernel ABI, including the virtual interrupts.

 (7) Renames the old irq management functions to different names.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-14 16:09:35 -08:00

790 lines
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/* break.S: Break interrupt handling (kept separate from entry.S)
*
* Copyright (C) 2003 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 License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/sys.h>
#include <linux/config.h>
#include <linux/linkage.h>
#include <asm/setup.h>
#include <asm/segment.h>
#include <asm/ptrace.h>
#include <asm/spr-regs.h>
#include <asm/errno.h>
#
# the break handler has its own stack
#
.section .bss.stack
.globl __break_user_context
.balign 8192
__break_stack:
.space (8192 - (USER_CONTEXT_SIZE + REG__DEBUG_XTRA)) & ~7
__break_stack_tos:
.space REG__DEBUG_XTRA
__break_user_context:
.space USER_CONTEXT_SIZE
#
# miscellaneous variables
#
.section .bss
#ifdef CONFIG_MMU
.globl __break_tlb_miss_real_return_info
__break_tlb_miss_real_return_info:
.balign 8
.space 2*4 /* saved PCSR, PSR for TLB-miss handler fixup */
#endif
__break_trace_through_exceptions:
.space 4
#define CS2_ECS1 0xe1200000
#define CS2_USERLED 0x4
.macro LEDS val,reg
# sethi.p %hi(CS2_ECS1+CS2_USERLED),gr30
# setlo %lo(CS2_ECS1+CS2_USERLED),gr30
# setlos #~\val,\reg
# st \reg,@(gr30,gr0)
# setlos #0x5555,\reg
# sethi.p %hi(0xffc00100),gr30
# setlo %lo(0xffc00100),gr30
# sth \reg,@(gr30,gr0)
# membar
.endm
###############################################################################
#
# entry point for Break Exceptions/Interrupts
#
###############################################################################
.text
.balign 4
.globl __entry_break
__entry_break:
#ifdef CONFIG_MMU
movgs gr31,scr3
#endif
LEDS 0x1001,gr31
sethi.p %hi(__break_user_context),gr31
setlo %lo(__break_user_context),gr31
stdi gr2,@(gr31,#REG_GR(2))
movsg ccr,gr3
sti gr3,@(gr31,#REG_CCR)
# catch the return from a TLB-miss handler that had single-step disabled
# traps will be enabled, so we have to do this now
#ifdef CONFIG_MMU
movsg bpcsr,gr3
sethi.p %hi(__break_tlb_miss_return_breaks_here),gr2
setlo %lo(__break_tlb_miss_return_breaks_here),gr2
subcc gr2,gr3,gr0,icc0
beq icc0,#2,__break_return_singlestep_tlbmiss
#endif
# determine whether we have stepped through into an exception
# - we need to take special action to suspend h/w single stepping if we've done
# that, so that the gdbstub doesn't get bogged down endlessly stepping through
# external interrupt handling
movsg bpsr,gr3
andicc gr3,#BPSR_BET,gr0,icc0
bne icc0,#2,__break_maybe_userspace /* jump if PSR.ET was 1 */
LEDS 0x1003,gr2
movsg brr,gr3
andicc gr3,#BRR_ST,gr0,icc0
andicc.p gr3,#BRR_SB,gr0,icc1
bne icc0,#2,__break_step /* jump if single-step caused break */
beq icc1,#2,__break_continue /* jump if BREAK didn't cause break */
LEDS 0x1007,gr2
# handle special breaks
movsg bpcsr,gr3
sethi.p %hi(__entry_return_singlestep_breaks_here),gr2
setlo %lo(__entry_return_singlestep_breaks_here),gr2
subcc gr2,gr3,gr0,icc0
beq icc0,#2,__break_return_singlestep
bra __break_continue
###############################################################################
#
# handle BREAK instruction in kernel-mode exception epilogue
#
###############################################################################
__break_return_singlestep:
LEDS 0x100f,gr2
# special break insn requests single-stepping to be turned back on
# HERE RETT
# PSR.ET 0 0
# PSR.PS old PSR.S ?
# PSR.S 1 1
# BPSR.ET 0 1 (can't have caused orig excep otherwise)
# BPSR.BS 1 old PSR.S
movsg dcr,gr2
sethi.p %hi(DCR_SE),gr3
setlo %lo(DCR_SE),gr3
or gr2,gr3,gr2
movgs gr2,dcr
movsg psr,gr2
andi gr2,#PSR_PS,gr2
slli gr2,#11,gr2 /* PSR.PS -> BPSR.BS */
ori gr2,#BPSR_BET,gr2 /* 1 -> BPSR.BET */
movgs gr2,bpsr
# return to the invoker of the original kernel exception
movsg pcsr,gr2
movgs gr2,bpcsr
LEDS 0x101f,gr2
ldi @(gr31,#REG_CCR),gr3
movgs gr3,ccr
lddi.p @(gr31,#REG_GR(2)),gr2
xor gr31,gr31,gr31
movgs gr0,brr
#ifdef CONFIG_MMU
movsg scr3,gr31
#endif
rett #1
###############################################################################
#
# handle BREAK instruction in TLB-miss handler return path
#
###############################################################################
#ifdef CONFIG_MMU
__break_return_singlestep_tlbmiss:
LEDS 0x1100,gr2
sethi.p %hi(__break_tlb_miss_real_return_info),gr3
setlo %lo(__break_tlb_miss_real_return_info),gr3
lddi @(gr3,#0),gr2
movgs gr2,pcsr
movgs gr3,psr
bra __break_return_singlestep
#endif
###############################################################################
#
# handle single stepping into an exception prologue from kernel mode
# - we try and catch it whilst it is still in the main vector table
# - if we catch it there, we have to jump to the fixup handler
# - there is a fixup table that has a pointer for every 16b slot in the trap
# table
#
###############################################################################
__break_step:
LEDS 0x2003,gr2
# external interrupts seem to escape from the trap table before single
# step catches up with them
movsg bpcsr,gr2
sethi.p %hi(__entry_kernel_external_interrupt),gr3
setlo %lo(__entry_kernel_external_interrupt),gr3
subcc.p gr2,gr3,gr0,icc0
sethi %hi(__entry_uspace_external_interrupt),gr3
setlo.p %lo(__entry_uspace_external_interrupt),gr3
beq icc0,#2,__break_step_kernel_external_interrupt
subcc.p gr2,gr3,gr0,icc0
sethi %hi(__entry_kernel_external_interrupt_virtually_disabled),gr3
setlo.p %lo(__entry_kernel_external_interrupt_virtually_disabled),gr3
beq icc0,#2,__break_step_uspace_external_interrupt
subcc.p gr2,gr3,gr0,icc0
sethi %hi(__entry_kernel_external_interrupt_virtual_reenable),gr3
setlo.p %lo(__entry_kernel_external_interrupt_virtual_reenable),gr3
beq icc0,#2,__break_step_kernel_external_interrupt_virtually_disabled
subcc gr2,gr3,gr0,icc0
beq icc0,#2,__break_step_kernel_external_interrupt_virtual_reenable
LEDS 0x2007,gr2
# the two main vector tables are adjacent on one 8Kb slab
movsg bpcsr,gr2
setlos #0xffffe000,gr3
and gr2,gr3,gr2
sethi.p %hi(__trap_tables),gr3
setlo %lo(__trap_tables),gr3
subcc gr2,gr3,gr0,icc0
bne icc0,#2,__break_continue
LEDS 0x200f,gr2
# skip workaround if so requested by GDB
sethi.p %hi(__break_trace_through_exceptions),gr3
setlo %lo(__break_trace_through_exceptions),gr3
ld @(gr3,gr0),gr3
subcc gr3,gr0,gr0,icc0
bne icc0,#0,__break_continue
LEDS 0x201f,gr2
# access the fixup table - there's a 1:1 mapping between the slots in the trap tables and
# the slots in the trap fixup tables allowing us to simply divide the offset into the
# former by 4 to access the latter
sethi.p %hi(__trap_tables),gr3
setlo %lo(__trap_tables),gr3
movsg bpcsr,gr2
sub gr2,gr3,gr2
srli.p gr2,#2,gr2
sethi %hi(__trap_fixup_tables),gr3
setlo.p %lo(__trap_fixup_tables),gr3
andi gr2,#~3,gr2
ld @(gr2,gr3),gr2
jmpil @(gr2,#0)
# step through an internal exception from kernel mode
.globl __break_step_kernel_softprog_interrupt
__break_step_kernel_softprog_interrupt:
sethi.p %hi(__entry_kernel_softprog_interrupt_reentry),gr3
setlo %lo(__entry_kernel_softprog_interrupt_reentry),gr3
bra __break_return_as_kernel_prologue
# step through an external interrupt from kernel mode
.globl __break_step_kernel_external_interrupt
__break_step_kernel_external_interrupt:
# deal with virtual interrupt disablement
beq icc2,#0,__break_step_kernel_external_interrupt_virtually_disabled
sethi.p %hi(__entry_kernel_external_interrupt_reentry),gr3
setlo %lo(__entry_kernel_external_interrupt_reentry),gr3
__break_return_as_kernel_prologue:
LEDS 0x203f,gr2
movgs gr3,bpcsr
# do the bit we had to skip
#ifdef CONFIG_MMU
movsg ear0,gr2 /* EAR0 can get clobbered by gdb-stub (ICI/ICEI) */
movgs gr2,scr2
#endif
or.p sp,gr0,gr2 /* set up the stack pointer */
subi sp,#REG__END,sp
sti.p gr2,@(sp,#REG_SP)
setlos #REG__STATUS_STEP,gr2
sti gr2,@(sp,#REG__STATUS) /* record single step status */
# cancel single-stepping mode
movsg dcr,gr2
sethi.p %hi(~DCR_SE),gr3
setlo %lo(~DCR_SE),gr3
and gr2,gr3,gr2
movgs gr2,dcr
LEDS 0x207f,gr2
ldi @(gr31,#REG_CCR),gr3
movgs gr3,ccr
lddi.p @(gr31,#REG_GR(2)),gr2
xor gr31,gr31,gr31
movgs gr0,brr
#ifdef CONFIG_MMU
movsg scr3,gr31
#endif
rett #1
# we single-stepped into an interrupt handler whilst interrupts were merely virtually disabled
# need to really disable interrupts, set flag, fix up and return
__break_step_kernel_external_interrupt_virtually_disabled:
movsg psr,gr2
andi gr2,#~PSR_PIL,gr2
ori gr2,#PSR_PIL_14,gr2 /* debugging interrupts only */
movgs gr2,psr
ldi @(gr31,#REG_CCR),gr3
movgs gr3,ccr
subcc.p gr0,gr0,gr0,icc2 /* leave Z set, clear C */
# exceptions must've been enabled and we must've been in supervisor mode
setlos BPSR_BET|BPSR_BS,gr3
movgs gr3,bpsr
# return to where the interrupt happened
movsg pcsr,gr2
movgs gr2,bpcsr
lddi.p @(gr31,#REG_GR(2)),gr2
xor gr31,gr31,gr31
movgs gr0,brr
#ifdef CONFIG_MMU
movsg scr3,gr31
#endif
rett #1
# we stepped through into the virtual interrupt reenablement trap
#
# we also want to single step anyway, but after fixing up so that we get an event on the
# instruction after the broken-into exception returns
.globl __break_step_kernel_external_interrupt_virtual_reenable
__break_step_kernel_external_interrupt_virtual_reenable:
movsg psr,gr2
andi gr2,#~PSR_PIL,gr2
movgs gr2,psr
ldi @(gr31,#REG_CCR),gr3
movgs gr3,ccr
subicc gr0,#1,gr0,icc2 /* clear Z, set C */
# save the adjusted ICC2
movsg ccr,gr3
sti gr3,@(gr31,#REG_CCR)
# exceptions must've been enabled and we must've been in supervisor mode
setlos BPSR_BET|BPSR_BS,gr3
movgs gr3,bpsr
# return to where the trap happened
movsg pcsr,gr2
movgs gr2,bpcsr
# and then process the single step
bra __break_continue
# step through an internal exception from uspace mode
.globl __break_step_uspace_softprog_interrupt
__break_step_uspace_softprog_interrupt:
sethi.p %hi(__entry_uspace_softprog_interrupt_reentry),gr3
setlo %lo(__entry_uspace_softprog_interrupt_reentry),gr3
bra __break_return_as_uspace_prologue
# step through an external interrupt from kernel mode
.globl __break_step_uspace_external_interrupt
__break_step_uspace_external_interrupt:
sethi.p %hi(__entry_uspace_external_interrupt_reentry),gr3
setlo %lo(__entry_uspace_external_interrupt_reentry),gr3
__break_return_as_uspace_prologue:
LEDS 0x20ff,gr2
movgs gr3,bpcsr
# do the bit we had to skip
sethi.p %hi(__kernel_frame0_ptr),gr28
setlo %lo(__kernel_frame0_ptr),gr28
ldi.p @(gr28,#0),gr28
setlos #REG__STATUS_STEP,gr2
sti gr2,@(gr28,#REG__STATUS) /* record single step status */
# cancel single-stepping mode
movsg dcr,gr2
sethi.p %hi(~DCR_SE),gr3
setlo %lo(~DCR_SE),gr3
and gr2,gr3,gr2
movgs gr2,dcr
LEDS 0x20fe,gr2
ldi @(gr31,#REG_CCR),gr3
movgs gr3,ccr
lddi.p @(gr31,#REG_GR(2)),gr2
xor gr31,gr31,gr31
movgs gr0,brr
#ifdef CONFIG_MMU
movsg scr3,gr31
#endif
rett #1
#ifdef CONFIG_MMU
# step through an ITLB-miss handler from user mode
.globl __break_user_insn_tlb_miss
__break_user_insn_tlb_miss:
# we'll want to try the trap stub again
sethi.p %hi(__trap_user_insn_tlb_miss),gr2
setlo %lo(__trap_user_insn_tlb_miss),gr2
movgs gr2,bpcsr
__break_tlb_miss_common:
LEDS 0x2101,gr2
# cancel single-stepping mode
movsg dcr,gr2
sethi.p %hi(~DCR_SE),gr3
setlo %lo(~DCR_SE),gr3
and gr2,gr3,gr2
movgs gr2,dcr
# we'll swap the real return address for one with a BREAK insn so that we can re-enable
# single stepping on return
movsg pcsr,gr2
sethi.p %hi(__break_tlb_miss_real_return_info),gr3
setlo %lo(__break_tlb_miss_real_return_info),gr3
sti gr2,@(gr3,#0)
sethi.p %hi(__break_tlb_miss_return_break),gr2
setlo %lo(__break_tlb_miss_return_break),gr2
movgs gr2,pcsr
# we also have to fudge PSR because the return BREAK is in kernel space and we want
# to get a BREAK fault not an access violation should the return be to userspace
movsg psr,gr2
sti.p gr2,@(gr3,#4)
ori gr2,#PSR_PS,gr2
movgs gr2,psr
LEDS 0x2102,gr2
ldi @(gr31,#REG_CCR),gr3
movgs gr3,ccr
lddi @(gr31,#REG_GR(2)),gr2
movsg scr3,gr31
movgs gr0,brr
rett #1
# step through a DTLB-miss handler from user mode
.globl __break_user_data_tlb_miss
__break_user_data_tlb_miss:
# we'll want to try the trap stub again
sethi.p %hi(__trap_user_data_tlb_miss),gr2
setlo %lo(__trap_user_data_tlb_miss),gr2
movgs gr2,bpcsr
bra __break_tlb_miss_common
# step through an ITLB-miss handler from kernel mode
.globl __break_kernel_insn_tlb_miss
__break_kernel_insn_tlb_miss:
# we'll want to try the trap stub again
sethi.p %hi(__trap_kernel_insn_tlb_miss),gr2
setlo %lo(__trap_kernel_insn_tlb_miss),gr2
movgs gr2,bpcsr
bra __break_tlb_miss_common
# step through a DTLB-miss handler from kernel mode
.globl __break_kernel_data_tlb_miss
__break_kernel_data_tlb_miss:
# we'll want to try the trap stub again
sethi.p %hi(__trap_kernel_data_tlb_miss),gr2
setlo %lo(__trap_kernel_data_tlb_miss),gr2
movgs gr2,bpcsr
bra __break_tlb_miss_common
#endif
###############################################################################
#
# handle debug events originating with userspace
#
###############################################################################
__break_maybe_userspace:
LEDS 0x3003,gr2
setlos #BPSR_BS,gr2
andcc gr3,gr2,gr0,icc0
bne icc0,#0,__break_continue /* skip if PSR.S was 1 */
movsg brr,gr2
andicc gr2,#BRR_ST|BRR_SB,gr0,icc0
beq icc0,#0,__break_continue /* jump if not BREAK or single-step */
LEDS 0x3007,gr2
# do the first part of the exception prologue here
sethi.p %hi(__kernel_frame0_ptr),gr28
setlo %lo(__kernel_frame0_ptr),gr28
ldi @(gr28,#0),gr28
andi gr28,#~7,gr28
# set up the kernel stack pointer
sti sp ,@(gr28,#REG_SP)
ori gr28,0,sp
sti gr0 ,@(gr28,#REG_GR(28))
stdi gr20,@(gr28,#REG_GR(20))
stdi gr22,@(gr28,#REG_GR(22))
movsg tbr,gr20
movsg bpcsr,gr21
movsg psr,gr22
# determine the exception type and cancel single-stepping mode
or gr0,gr0,gr23
movsg dcr,gr2
sethi.p %hi(DCR_SE),gr3
setlo %lo(DCR_SE),gr3
andcc gr2,gr3,gr0,icc0
beq icc0,#0,__break_no_user_sstep /* must have been a BREAK insn */
not gr3,gr3
and gr2,gr3,gr2
movgs gr2,dcr
ori gr23,#REG__STATUS_STEP,gr23
__break_no_user_sstep:
LEDS 0x300f,gr2
movsg brr,gr2
andi gr2,#BRR_ST|BRR_SB,gr2
slli gr2,#1,gr2
or gr23,gr2,gr23
sti.p gr23,@(gr28,#REG__STATUS) /* record single step status */
# adjust the value acquired from TBR - this indicates the exception
setlos #~TBR_TT,gr2
and.p gr20,gr2,gr20
setlos #TBR_TT_BREAK,gr2
or.p gr20,gr2,gr20
# fudge PSR.PS and BPSR.BS to return to kernel mode through the trap
# table as trap 126
andi gr22,#~PSR_PS,gr22 /* PSR.PS should be 0 */
movgs gr22,psr
setlos #BPSR_BS,gr2 /* BPSR.BS should be 1 and BPSR.BET 0 */
movgs gr2,bpsr
# return through remainder of the exception prologue
# - need to load gr23 with return handler address
sethi.p %hi(__entry_return_from_user_exception),gr23
setlo %lo(__entry_return_from_user_exception),gr23
sethi.p %hi(__entry_common),gr3
setlo %lo(__entry_common),gr3
movgs gr3,bpcsr
LEDS 0x301f,gr2
ldi @(gr31,#REG_CCR),gr3
movgs gr3,ccr
lddi.p @(gr31,#REG_GR(2)),gr2
xor gr31,gr31,gr31
movgs gr0,brr
#ifdef CONFIG_MMU
movsg scr3,gr31
#endif
rett #1
###############################################################################
#
# resume normal debug-mode entry
#
###############################################################################
__break_continue:
LEDS 0x4003,gr2
# set up the kernel stack pointer
sti sp,@(gr31,#REG_SP)
sethi.p %hi(__break_stack_tos),sp
setlo %lo(__break_stack_tos),sp
# finish building the exception frame
stdi gr4 ,@(gr31,#REG_GR(4))
stdi gr6 ,@(gr31,#REG_GR(6))
stdi gr8 ,@(gr31,#REG_GR(8))
stdi gr10,@(gr31,#REG_GR(10))
stdi gr12,@(gr31,#REG_GR(12))
stdi gr14,@(gr31,#REG_GR(14))
stdi gr16,@(gr31,#REG_GR(16))
stdi gr18,@(gr31,#REG_GR(18))
stdi gr20,@(gr31,#REG_GR(20))
stdi gr22,@(gr31,#REG_GR(22))
stdi gr24,@(gr31,#REG_GR(24))
stdi gr26,@(gr31,#REG_GR(26))
sti gr0 ,@(gr31,#REG_GR(28)) /* NULL frame pointer */
sti gr29,@(gr31,#REG_GR(29))
sti gr30,@(gr31,#REG_GR(30))
sti gr8 ,@(gr31,#REG_ORIG_GR8)
#ifdef CONFIG_MMU
movsg scr3,gr19
sti gr19,@(gr31,#REG_GR(31))
#endif
movsg bpsr ,gr19
movsg tbr ,gr20
movsg bpcsr,gr21
movsg psr ,gr22
movsg isr ,gr23
movsg cccr ,gr25
movsg lr ,gr26
movsg lcr ,gr27
andi.p gr22,#~(PSR_S|PSR_ET),gr5 /* rebuild PSR */
andi gr19,#PSR_ET,gr4
or.p gr4,gr5,gr5
srli gr19,#10,gr4
andi gr4,#PSR_S,gr4
or.p gr4,gr5,gr5
setlos #-1,gr6
sti gr20,@(gr31,#REG_TBR)
sti gr21,@(gr31,#REG_PC)
sti gr5 ,@(gr31,#REG_PSR)
sti gr23,@(gr31,#REG_ISR)
sti gr25,@(gr31,#REG_CCCR)
stdi gr26,@(gr31,#REG_LR)
sti gr6 ,@(gr31,#REG_SYSCALLNO)
# store CPU-specific regs
movsg iacc0h,gr4
movsg iacc0l,gr5
stdi gr4,@(gr31,#REG_IACC0)
movsg gner0,gr4
movsg gner1,gr5
stdi gr4,@(gr31,#REG_GNER0)
# build the debug register frame
movsg brr,gr4
movgs gr0,brr
movsg nmar,gr5
movsg dcr,gr6
stdi gr4 ,@(gr31,#REG_BRR)
sti gr19,@(gr31,#REG_BPSR)
sti.p gr6 ,@(gr31,#REG_DCR)
# trap exceptions during break handling and disable h/w breakpoints/watchpoints
sethi %hi(DCR_EBE),gr5
setlo.p %lo(DCR_EBE),gr5
sethi %hi(__entry_breaktrap_table),gr4
setlo %lo(__entry_breaktrap_table),gr4
movgs gr5,dcr
movgs gr4,tbr
# set up kernel global registers
sethi.p %hi(__kernel_current_task),gr5
setlo %lo(__kernel_current_task),gr5
ld @(gr5,gr0),gr29
ldi.p @(gr29,#4),gr15 ; __current_thread_info = current->thread_info
sethi %hi(_gp),gr16
setlo.p %lo(_gp),gr16
# make sure we (the kernel) get div-zero and misalignment exceptions
setlos #ISR_EDE|ISR_DTT_DIVBYZERO|ISR_EMAM_EXCEPTION,gr5
movgs gr5,isr
# enter the GDB stub
LEDS 0x4007,gr2
or.p gr0,gr0,fp
call debug_stub
LEDS 0x403f,gr2
# return from break
lddi @(gr31,#REG_IACC0),gr4
movgs gr4,iacc0h
movgs gr5,iacc0l
lddi @(gr31,#REG_GNER0),gr4
movgs gr4,gner0
movgs gr5,gner1
lddi @(gr31,#REG_LR) ,gr26
lddi @(gr31,#REG_CCR) ,gr24
lddi @(gr31,#REG_PSR) ,gr22
ldi @(gr31,#REG_PC) ,gr21
ldi @(gr31,#REG_TBR) ,gr20
ldi.p @(gr31,#REG_DCR) ,gr6
andi gr22,#PSR_S,gr19 /* rebuild BPSR */
andi.p gr22,#PSR_ET,gr5
slli gr19,#10,gr19
or gr5,gr19,gr19
movgs gr6 ,dcr
movgs gr19,bpsr
movgs gr20,tbr
movgs gr21,bpcsr
movgs gr23,isr
movgs gr24,ccr
movgs gr25,cccr
movgs gr26,lr
movgs gr27,lcr
LEDS 0x407f,gr2
#ifdef CONFIG_MMU
ldi @(gr31,#REG_GR(31)),gr2
movgs gr2,scr3
#endif
ldi @(gr31,#REG_GR(30)),gr30
ldi @(gr31,#REG_GR(29)),gr29
lddi @(gr31,#REG_GR(26)),gr26
lddi @(gr31,#REG_GR(24)),gr24
lddi @(gr31,#REG_GR(22)),gr22
lddi @(gr31,#REG_GR(20)),gr20
lddi @(gr31,#REG_GR(18)),gr18
lddi @(gr31,#REG_GR(16)),gr16
lddi @(gr31,#REG_GR(14)),gr14
lddi @(gr31,#REG_GR(12)),gr12
lddi @(gr31,#REG_GR(10)),gr10
lddi @(gr31,#REG_GR(8)) ,gr8
lddi @(gr31,#REG_GR(6)) ,gr6
lddi @(gr31,#REG_GR(4)) ,gr4
lddi @(gr31,#REG_GR(2)) ,gr2
ldi.p @(gr31,#REG_SP) ,sp
xor gr31,gr31,gr31
movgs gr0,brr
#ifdef CONFIG_MMU
movsg scr3,gr31
#endif
rett #1
###################################################################################################
#
# GDB stub "system calls"
#
###################################################################################################
#ifdef CONFIG_GDBSTUB
# void gdbstub_console_write(struct console *con, const char *p, unsigned n)
.globl gdbstub_console_write
gdbstub_console_write:
break
bralr
#endif
# GDB stub BUG() trap
# GR8 is the proposed signal number
.globl __debug_bug_trap
__debug_bug_trap:
break
bralr
# transfer kernel exeception to GDB for handling
.globl __break_hijack_kernel_event
__break_hijack_kernel_event:
break
.globl __break_hijack_kernel_event_breaks_here
__break_hijack_kernel_event_breaks_here:
nop
#ifdef CONFIG_MMU
# handle a return from TLB-miss that requires single-step reactivation
.globl __break_tlb_miss_return_break
__break_tlb_miss_return_break:
break
__break_tlb_miss_return_breaks_here:
nop
#endif
# guard the first .text label in the next file from confusion
nop
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