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*/
1 /*
2 * Low level exception handling
3 *
4 * This file is subject to the terms and conditions of the GNU General Public
5 * License. See the file "COPYING" in the main directory of this archive
6 * for more details.
7 *
8 * Copyright (C) 1994, 1995 by Ralf Baechle
9 */
10
11 /*
12 * entry.S contains the system-call and fault low-level handling routines.
13 * This also contains the timer-interrupt handler, as well as all interrupts
14 * and faults that can result in a task-switch. The ISA dependent TLB
15 * code is in arch/mips/kernel/<cputype>.S
16 */
17 #include <linux/sys.h>
18
19 #include <asm/asm.h>
20 #include <asm/errno.h>
21 #include <asm/segment.h>
22 #include <asm/mipsregs.h>
23 #include <asm/mipsconfig.h>
24 #include <asm/page.h>
25 #include <asm/pgtable.h>
26 #include <asm/stackframe.h>
27 #include <asm/processor.h>
28 #include <asm/unistd.h>
29
30 /*
31 * These are offsets into the task-struct.
32 */
33 state = 0
34 counter = 4
35 priority = 8
36 signal = 12
37 blocked = 16
38 flags = 20
39 errno = 24
40 exec_domain = 60
41
42 #ifdef __SMP__
43 #error "Fix this for SMP"
44 #else
45 #define current current_set
46 #endif
47
48 /*
49 * Heia ... The %lo, %hi and %HI stuff is too strong for the ELF assembler
50 * and the ABI to cope with ...
51 */
52 .text
53 .set noreorder
54 .align 4
55 handle_bottom_half:
56 lui s0,%hi(intr_count)
57 lw s1,%lo(intr_count)(s0)
58 mfc0 s3,CP0_STATUS # Enable IRQs
59 addiu s2,s1,1
60 sw s2,%lo(intr_count)(s0)
61 ori t0,s3,0x1f
62 xori t0,0x1e
63 jal do_bottom_half
64 mtc0 t0,CP0_STATUS # delay slot
65 mtc0 s3,CP0_STATUS # Restore old IRQ state
66 b 9f
67 sw s1,%lo(intr_count)(s0) # delay slot
68
69 reschedule: jal schedule
70 nop # delay slot
71 EXPORT(ret_from_sys_call)
72 lw t0,intr_count # bottom half
73 bnez t0,return
74
75 9: lw t0,bh_mask # delay slot
76 lw t1,bh_active # unused delay slot
77 and t0,t1
78 bnez t0,handle_bottom_half
79
80 lw t0,FR_STATUS(sp) # returning to kernel mode?
81 andi t1,t0,0x10
82 beqz t1,return # -> yes
83
84 mfc0 t0,CP0_STATUS # delay slot
85 lw t1,need_resched
86 ori t0,0x1f # enable irqs
87 xori t0,0x1e
88 bnez t1,reschedule
89 mtc0 t0,CP0_STATUS # delay slot
90
91 lw s0,current
92 lw t0,task
93 lw a0,blocked(s0)
94 beq s0,t0,return # task[0] cannot have signals
95 # save blocked in a0 for
96 # signal handling
97 lw t0,signal(s0)
98 nor t1,zero,a0
99 and t1,t0,t1
100 beqz t1,return
101 nop
102
103 jal do_signal
104 move a1,sp # delay slot
105
106 .set noat
107 EXPORT(return) RESTORE_ALL
108 ERET
109 .set at
110
111 /*
112 * Beware: interrupt, fast_interrupt and bad_interrupt have unusual
113 * calling conventions to speedup the mess.
114 *
115 * t1 - interrupt number
116 * s2 - destroyed
117 * return values:
118 * v0 - return routine
119 */
120 .text
121 .set at
122 .align 5
123 NESTED(interrupt, FR_SIZE, sp)
124 move s2,ra
125 mfc0 t0,CP0_STATUS # enable IRQs
126 ori t0,0x1f
127 xori t0,0x1e
128 mtc0 t0,CP0_STATUS
129 move a0,t1
130 jal do_IRQ
131 move a1,sp # delay slot
132 mfc0 t0,CP0_STATUS # disable IRQs
133 ori t0,1
134 xori t0,1
135 la v0,ret_from_sys_call
136 jr s2
137 mtc0 t0,CP0_STATUS # delay slot
138 END(interrupt)
139
140 .align 5
141 NESTED(fast_interrupt, FR_SIZE, sp)
142 move s2,ra
143 move a0,t1
144 jal do_fast_IRQ
145 move a1,sp # delay slot
146 lui v0,%hi(return)
147 jr s2
148 addiu v0,%lo(return) # delay slot
149 END(fast_interrupt)
150
151 LEAF(bad_interrupt)
152 /*
153 * Don't return & unblock the pic
154 */
155 j return
156 nop
157 END(bad_interrupt)
158
159 /*
160 * do_syscall calls the function in a1 with upto 7 arguments. If over
161 * four arguments are being requested, the additional arguments will
162 * be copied from the user stack pointed to by a0->reg29.
163 * Note that this routine relies on the GNU assemblers weak instruction
164 * scheduling abilities to generate the best possible code for all MIPS CPUs.
165 *
166 * a0 (struct pt_regs *) pointer to user registers
167 * a1 (syscall_t) pointer to syscall to do
168 * a2 (int) number of arguments to syscall
169 */
170 .set noreorder
171 .text
172 NESTED(do_syscalls, 32, sp)
173 subu sp,32
174 sw ra,28(sp)
175 sll a2,a2,PTRLOG
176 lw t0,dst(a2)
177 move t2,a1
178 jalr t0
179 lw t0,FR_REG29(a0) # get old user stack pointer
180
181 .set reorder # for sake of R3000
182 7: lw t1,24(t0) # parameter #7 from usp
183 sw t1,24(t0)
184 6: lw t1,20(t0) # parameter #6 from usp
185 sw t1,20(t0)
186 5: lw t1,16(t0) # parameter #5 from usp
187 sw t1,16(t0)
188 .set noreorder
189 4: lw a3,FR_REG7(a0) # 4 args
190 3: lw a2,FR_REG6(a0) # 3 args
191 2: lw a1,FR_REG5(a0) # 2 args
192 1: jalr t2 # 1 args
193 lw a0,FR_REG4(a0) # delay slot
194 .set reorder
195 lw ra,28(sp)
196 addiu sp,32
197 jr ra
198 0: jalr t2 # 0 args, just pass a0
199 lw ra,28(sp)
200 addiu sp,32
201 jr ra
202 END(do_syscalls)
203 .set noreorder
204
205 .rdata
206 .align PTRLOG
207 dst: PTR 0b, 1b, 2b, 3b, 4b, 5b, 6b, 7b
208
209 /*
210 * Build a default exception handler for the exceptions that don't need
211 * special handlers. If you didn't know yet - I *like* playing games with
212 * the C preprocessor ...
213 */
214 #define __BUILD_silent(exception)
215 #define __BUILD_verbose(exception) \
216 la a1,8f; \
217 TEXT (#exception); \
218 lw a2,FR_EPC(sp); \
219 PRINT("Got %s at %08x.\n")
220 #define __BUILD_count(exception) \
221 .set reorder; \
222 lw t0,exception_count_##exception; \
223 addiu t0,1; \
224 sw t0,exception_count_##exception; \
225 .set noreorder; \
226 .data; \
227 EXPORT(exception_count_##exception); \
228 .word 0; \
229 .text;
230 #define BUILD_HANDLER(exception,verbose) \
231 .text; \
232 .align 5; \
233 NESTED(handle_##exception, FR_SIZE, sp); \
234 .set noat; \
235 SAVE_ALL; \
236 STI; \
237 .set at; \
238 __BUILD_##verbose(exception); \
239 li t0,-1; /* not a sys call */ \
240 sw t0,FR_ORIG_REG2(sp); \
241 jal do_##exception; \
242 move a0,sp; /* delay slot */ \
243 j ret_from_sys_call; \
244 nop; /* delay slot */ \
245 END(handle_##exception)
246
247 BUILD_HANDLER(adel,verbose) /* #4 */
248 BUILD_HANDLER(ades,verbose) /* #5 */
249 BUILD_HANDLER(ibe,verbose) /* #6 */
250 BUILD_HANDLER(dbe,verbose) /* #7 */
251 BUILD_HANDLER(sys,silent) /* #8 */
252 BUILD_HANDLER(bp,verbose) /* #9 */
253 BUILD_HANDLER(ri,verbose) /* #10 */
254 BUILD_HANDLER(cpu,silent) /* #11 */
255 BUILD_HANDLER(ov,verbose) /* #12 */
256 BUILD_HANDLER(tr,verbose) /* #13 */
257 BUILD_HANDLER(vcei,verbose) /* #14 */
258 BUILD_HANDLER(fpe,verbose) /* #15 */
259 BUILD_HANDLER(watch,verbose) /* #23 */
260 BUILD_HANDLER(vced,verbose) /* #31 */
261 BUILD_HANDLER(reserved,verbose) /* others */
262
263 /*
264 * Exception handler table with 32 entries.
265 * This might be extended to handle software exceptions
266 */
267 .bss
268 .align PTRLOG
269 EXPORT(exception_handlers)
270 .fill 32,PTRSIZE,0
271
272 /*
273 * Interrupt handler table with 16 entries.
274 */
275 EXPORT(IRQ_vectors)
276 .fill 16,PTRSIZE,0
277
278 /*
279 * Table of syscalls
280 */
281 .data
282 .align PTRLOG
283 EXPORT(sys_call_table)
284 /*
285 * Reserved space for all the SVR4, SVR, BSD43 and POSIX
286 * flavoured syscalls.
287 */
288 .space (__NR_Linux)*PTRSIZE
289
290 /*
291 * Linux flavoured syscalls.
292 */
293 #define SYS(call, narg) PTR call
294 #include "syscalls.h"
295
296 /*
297 * Number of arguments of each syscall
298 */
299 EXPORT(sys_narg_table)
300 /*
301 * Reserved space for all the SVR4, SVR, BSD43 and POSIX
302 * flavoured syscalls.
303 */
304 .space (__NR_Linux)
305
306 /*
307 * Linux flavoured syscalls.
308 */
309 #undef SYS
310 #define SYS(call, narg) .byte narg
311 #include "syscalls.h"
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*/