linux_dsm_epyc7002/arch/nds32/kernel/ex-exit.S
Greentime Hu 2923f5ea77 nds32: Exception handling
This patch includes the exception/interrupt entries, pt_reg structure and
related accessors.

/* Unaligned accessing handling*/
Andes processors cannot load/store information which is not naturally
aligned on the bus, i.e., loading a 4 byte data whose start address must
be divisible by 4. If unaligned data accessing is happened, data
unaligned exception will be triggered and user will get SIGSEGV or
kernel oops according to the unaligned address. In order to make user be
able to load/store data from an unaligned address, software load/store
emulation is implemented in arch/nds32/mm/alignment.c to address data
unaligned exception.

Unaligned accessing handling is disabled by default because it is not a
normal case. User can enable this feature by following steps.

A. Compile time:
    1. Enable kernel config CONFIG_ALIGNMENT_TRAP
B. Run time:
    1. Enter /proc/sys/nds32/unaligned_acess folder
    2. Write 1 to file enable_mode to enable unaligned accessing
       handling. User can disable it by writing 0 to this file.
    3. Write 1 to file debug to show which unaligned address is under
       processing. User can disable it by writing 0 to this file.

However, unaligned accessing handler cannot work if this unaligned
address is not accessible such as protection violation. On this
condition, the default behaviors for addressing data unaligned exception
still happen

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
2018-02-22 10:44:31 +08:00

185 lines
3.7 KiB
ArmAsm

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2005-2017 Andes Technology Corporation
#include <linux/linkage.h>
#include <asm/unistd.h>
#include <asm/assembler.h>
#include <asm/nds32.h>
#include <asm/asm-offsets.h>
#include <asm/thread_info.h>
#include <asm/current.h>
#ifdef CONFIG_HWZOL
.macro pop_zol
mtusr $r14, $LB
mtusr $r15, $LE
mtusr $r16, $LC
.endm
#endif
.macro restore_user_regs_first
setgie.d
isb
addi $sp, $sp, FUCOP_CTL_OFFSET
lmw.adm $r12, [$sp], $r24, #0x0
mtsr $r12, $SP_USR
mtsr $r13, $IPC
#ifdef CONFIG_HWZOL
pop_zol
#endif
mtsr $r19, $PSW
mtsr $r20, $IPSW
mtsr $r21, $P_IPSW
mtsr $r22, $P_IPC
mtsr $r23, $P_P0
mtsr $r24, $P_P1
lmw.adm $sp, [$sp], $sp, #0xe
.endm
.macro restore_user_regs_last
pop $p0
cmovn $sp, $p0, $p0
iret
nop
.endm
.macro restore_user_regs
restore_user_regs_first
lmw.adm $r0, [$sp], $r25, #0x0
addi $sp, $sp, OSP_OFFSET
restore_user_regs_last
.endm
.macro fast_restore_user_regs
restore_user_regs_first
lmw.adm $r1, [$sp], $r25, #0x0
addi $sp, $sp, OSP_OFFSET-4
restore_user_regs_last
.endm
#ifdef CONFIG_PREEMPT
.macro preempt_stop
.endm
#else
.macro preempt_stop
setgie.d
isb
.endm
#define resume_kernel no_work_pending
#endif
ENTRY(ret_from_exception)
preempt_stop
ENTRY(ret_from_intr)
/*
* judge Kernel or user mode
*
*/
lwi $p0, [$sp+(#IPSW_OFFSET)] ! Check if in nested interrupt
andi $p0, $p0, #PSW_mskINTL
bnez $p0, resume_kernel ! done with iret
j resume_userspace
/*
* This is the fast syscall return path. We do as little as
* possible here, and this includes saving $r0 back into the SVC
* stack.
* fixed: tsk - $r25, syscall # - $r7, syscall table pointer - $r8
*/
ENTRY(ret_fast_syscall)
gie_disable
lwi $r1, [tsk+#TSK_TI_FLAGS]
andi $p1, $r1, #_TIF_WORK_MASK
bnez $p1, fast_work_pending
fast_restore_user_regs ! iret
/*
* Ok, we need to do extra processing,
* enter the slow path returning from syscall, while pending work.
*/
fast_work_pending:
swi $r0, [$sp+(#R0_OFFSET)] ! what is different from ret_from_exception
work_pending:
andi $p1, $r1, #_TIF_NEED_RESCHED
bnez $p1, work_resched
andi $p1, $r1, #_TIF_SIGPENDING|#_TIF_NOTIFY_RESUME
beqz $p1, no_work_pending
move $r0, $sp ! 'regs'
gie_enable
bal do_notify_resume
b ret_slow_syscall
work_resched:
bal schedule ! path, return to user mode
/*
* "slow" syscall return path.
*/
ENTRY(resume_userspace)
ENTRY(ret_slow_syscall)
gie_disable
lwi $p0, [$sp+(#IPSW_OFFSET)] ! Check if in nested interrupt
andi $p0, $p0, #PSW_mskINTL
bnez $p0, no_work_pending ! done with iret
lwi $r1, [tsk+#TSK_TI_FLAGS]
andi $p1, $r1, #_TIF_WORK_MASK
bnez $p1, work_pending ! handle work_resched, sig_pend
no_work_pending:
#ifdef CONFIG_TRACE_IRQFLAGS
lwi $p0, [$sp+(#IPSW_OFFSET)]
andi $p0, $p0, #0x1
la $r10, trace_hardirqs_off
la $r9, trace_hardirqs_on
cmovz $r9, $p0, $r10
jral $r9
#endif
restore_user_regs ! return from iret
/*
* preemptive kernel
*/
#ifdef CONFIG_PREEMPT
resume_kernel:
gie_disable
lwi $t0, [tsk+#TSK_TI_PREEMPT]
bnez $t0, no_work_pending
need_resched:
lwi $t0, [tsk+#TSK_TI_FLAGS]
andi $p1, $t0, #_TIF_NEED_RESCHED
beqz $p1, no_work_pending
lwi $t0, [$sp+(#IPSW_OFFSET)] ! Interrupts off?
andi $t0, $t0, #1
beqz $t0, no_work_pending
jal preempt_schedule_irq
b need_resched
#endif
/*
* This is how we return from a fork.
*/
ENTRY(ret_from_fork)
bal schedule_tail
beqz $r6, 1f ! r6 stores fn for kernel thread
move $r0, $r7 ! prepare kernel thread arg
jral $r6
1:
lwi $r1, [tsk+#TSK_TI_FLAGS] ! check for syscall tracing
andi $p1, $r1, #_TIF_WORK_SYSCALL_LEAVE ! are we tracing syscalls?
beqz $p1, ret_slow_syscall
move $r0, $sp
bal syscall_trace_leave
b ret_slow_syscall