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/*
* Low level exception handling
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1994, 1995 by Ralf Baechle
*/
/*
* entry.S contains the system-call and fault low-level handling routines.
* This also contains the timer-interrupt handler, as well as all interrupts
* and faults that can result in a task-switch. The ISA dependent TLB
* code is in arch/mips/kernel/<cputype>.S
*/
#include <linux/sys.h>
#include <asm/asm.h>
#include <asm/errno.h>
#include <asm/segment.h>
#include <asm/mipsregs.h>
#include <asm/mipsconfig.h>
#include <asm/page.h>
#include <asm/pgtable.h>
#include <asm/stackframe.h>
#include <asm/processor.h>
#include <asm/unistd.h>
/*
* These are offsets into the task-struct.
*/
state = 0
counter = 4
priority = 8
signal = 12
blocked = 16
flags = 20
errno = 24
exec_domain = 60
#ifdef __SMP__
#error "Fix this for SMP"
#else
#define current current_set
#endif
/*
* Heia ... The %lo, %hi and %HI stuff is too strong for the ELF assembler
* and the ABI to cope with ...
*/
.text
.set noreorder
.align 4
handle_bottom_half:
lui s0,%hi(intr_count)
lw s1,%lo(intr_count)(s0)
mfc0 s3,CP0_STATUS # Enable IRQs
addiu s2,s1,1
sw s2,%lo(intr_count)(s0)
ori t0,s3,0x1f
xori t0,0x1e
jal do_bottom_half
mtc0 t0,CP0_STATUS # delay slot
mtc0 s3,CP0_STATUS # Restore old IRQ state
b 9f
sw s1,%lo(intr_count)(s0) # delay slot
reschedule: jal schedule
nop # delay slot
EXPORT(ret_from_sys_call)
lw t0,intr_count # bottom half
bnez t0,return
9: lw t0,bh_mask # delay slot
lw t1,bh_active # unused delay slot
and t0,t1
bnez t0,handle_bottom_half
lw t0,FR_STATUS(sp) # returning to kernel mode?
andi t1,t0,0x10
beqz t1,return # -> yes
mfc0 t0,CP0_STATUS # delay slot
lw t1,need_resched
ori t0,0x1f # enable irqs
xori t0,0x1e
bnez t1,reschedule
mtc0 t0,CP0_STATUS # delay slot
lw s0,current
lw t0,task
lw a0,blocked(s0)
beq s0,t0,return # task[0] cannot have signals
# save blocked in a0 for
# signal handling
lw t0,signal(s0)
nor t1,zero,a0
and t1,t0,t1
beqz t1,return
nop
jal do_signal
move a1,sp # delay slot
.set noat
EXPORT(return) RESTORE_ALL
ERET
.set at
/*
* Beware: interrupt, fast_interrupt and bad_interrupt have unusual
* calling conventions to speedup the mess.
*
* t1 - interrupt number
* s2 - destroyed
* return values:
* v0 - return routine
*/
.text
.set at
.align 5
NESTED(interrupt, FR_SIZE, sp)
move s2,ra
mfc0 t0,CP0_STATUS # enable IRQs
ori t0,0x1f
xori t0,0x1e
mtc0 t0,CP0_STATUS
move a0,t1
jal do_IRQ
move a1,sp # delay slot
mfc0 t0,CP0_STATUS # disable IRQs
ori t0,1
xori t0,1
la v0,ret_from_sys_call
jr s2
mtc0 t0,CP0_STATUS # delay slot
END(interrupt)
.align 5
NESTED(fast_interrupt, FR_SIZE, sp)
move s2,ra
move a0,t1
jal do_fast_IRQ
move a1,sp # delay slot
lui v0,%hi(return)
jr s2
addiu v0,%lo(return) # delay slot
END(fast_interrupt)
LEAF(bad_interrupt)
/*
* Don't return & unblock the pic
*/
j return
nop
END(bad_interrupt)
/*
* do_syscall calls the function in a1 with upto 7 arguments. If over
* four arguments are being requested, the additional arguments will
* be copied from the user stack pointed to by a0->reg29.
* Note that this routine relies on the GNU assemblers weak instruction
* scheduling abilities to generate the best possible code for all MIPS CPUs.
*
* a0 (struct pt_regs *) pointer to user registers
* a1 (syscall_t) pointer to syscall to do
* a2 (int) number of arguments to syscall
*/
.set noreorder
.text
NESTED(do_syscalls, 32, sp)
subu sp,32
sw ra,28(sp)
sll a2,a2,PTRLOG
lw t0,dst(a2)
move t2,a1
jalr t0
lw t0,FR_REG29(a0) # get old user stack pointer
.set reorder # for sake of R3000
7: lw t1,24(t0) # parameter #7 from usp
sw t1,24(t0)
6: lw t1,20(t0) # parameter #6 from usp
sw t1,20(t0)
5: lw t1,16(t0) # parameter #5 from usp
sw t1,16(t0)
.set noreorder
4: lw a3,FR_REG7(a0) # 4 args
3: lw a2,FR_REG6(a0) # 3 args
2: lw a1,FR_REG5(a0) # 2 args
1: jalr t2 # 1 args
lw a0,FR_REG4(a0) # delay slot
.set reorder
lw ra,28(sp)
addiu sp,32
jr ra
0: jalr t2 # 0 args, just pass a0
lw ra,28(sp)
addiu sp,32
jr ra
END(do_syscalls)
.set noreorder
.rdata
.align PTRLOG
dst: PTR 0b, 1b, 2b, 3b, 4b, 5b, 6b, 7b
/*
* Build a default exception handler for the exceptions that don't need
* special handlers. If you didn't know yet - I *like* playing games with
* the C preprocessor ...
*/
#define __BUILD_silent(exception)
#define __BUILD_verbose(exception) \
la a1,8f; \
TEXT (#exception); \
lw a2,FR_EPC(sp); \
PRINT("Got %s at %08x.\n")
#define __BUILD_count(exception) \
.set reorder; \
lw t0,exception_count_##exception; \
addiu t0,1; \
sw t0,exception_count_##exception; \
.set noreorder; \
.data; \
EXPORT(exception_count_##exception); \
.word 0; \
.text;
#define BUILD_HANDLER(exception,verbose) \
.text; \
.align 5; \
NESTED(handle_##exception, FR_SIZE, sp); \
.set noat; \
SAVE_ALL; \
STI; \
.set at; \
__BUILD_##verbose(exception); \
li t0,-1; /* not a sys call */ \
sw t0,FR_ORIG_REG2(sp); \
jal do_##exception; \
move a0,sp; /* delay slot */ \
j ret_from_sys_call; \
nop; /* delay slot */ \
END(handle_##exception)
BUILD_HANDLER(adel,verbose) /* #4 */
BUILD_HANDLER(ades,verbose) /* #5 */
BUILD_HANDLER(ibe,verbose) /* #6 */
BUILD_HANDLER(dbe,verbose) /* #7 */
BUILD_HANDLER(sys,silent) /* #8 */
BUILD_HANDLER(bp,verbose) /* #9 */
BUILD_HANDLER(ri,verbose) /* #10 */
BUILD_HANDLER(cpu,silent) /* #11 */
BUILD_HANDLER(ov,verbose) /* #12 */
BUILD_HANDLER(tr,verbose) /* #13 */
BUILD_HANDLER(vcei,verbose) /* #14 */
BUILD_HANDLER(fpe,verbose) /* #15 */
BUILD_HANDLER(watch,verbose) /* #23 */
BUILD_HANDLER(vced,verbose) /* #31 */
BUILD_HANDLER(reserved,verbose) /* others */
/*
* Exception handler table with 32 entries.
* This might be extended to handle software exceptions
*/
.bss
.align PTRLOG
EXPORT(exception_handlers)
.fill 32,PTRSIZE,0
/*
* Interrupt handler table with 16 entries.
*/
EXPORT(IRQ_vectors)
.fill 16,PTRSIZE,0
/*
* Table of syscalls
*/
.data
.align PTRLOG
EXPORT(sys_call_table)
/*
* Reserved space for all the SVR4, SVR, BSD43 and POSIX
* flavoured syscalls.
*/
.space (__NR_Linux)*PTRSIZE
/*
* Linux flavoured syscalls.
*/
#define SYS(call, narg) PTR call
#include "syscalls.h"
/*
* Number of arguments of each syscall
*/
EXPORT(sys_narg_table)
/*
* Reserved space for all the SVR4, SVR, BSD43 and POSIX
* flavoured syscalls.
*/
.space (__NR_Linux)
/*
* Linux flavoured syscalls.
*/
#undef SYS
#define SYS(call, narg) .byte narg
#include "syscalls.h"
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