1 /* $NetBSD: exception.S,v 1.13 2003/10/31 16:30:15 scw Exp $ */
2
3 /*-
4 * Copyright (c) 1994-1997 Mark Brinicombe.
5 * Copyright (c) 1994 Brini.
6 * All rights reserved.
7 *
8 * This code is derived from software written for Brini by Mark Brinicombe
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by Brini.
21 * 4. The name of the company nor the name of the author may be used to
22 * endorse or promote products derived from this software without specific
23 * prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY BRINI ``AS IS'' AND ANY EXPRESS OR IMPLIED
26 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
27 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
28 * IN NO EVENT SHALL BRINI OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
29 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
30 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
31 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 *
37 * RiscBSD kernel project
38 *
39 * exception.S
40 *
41 * Low level handlers for exception vectors
42 *
43 * Created : 24/09/94
44 *
45 * Based on kate/display/abort.s
46 *
47 */
48
49 #include "assym.s"
50
51 #include <machine/asm.h>
52 #include <machine/armreg.h>
53 #include <machine/asmacros.h>
54 __FBSDID("$FreeBSD$");
55
56 .text
57 .align 2
58
59 /*
60 * ASM macros for pushing and pulling trapframes from the stack
61 *
62 * These macros are used to handle the irqframe and trapframe structures
63 * defined above.
64 */
65
66 /*
67 * PUSHFRAME - macro to push a trap frame on the stack in the current mode
68 * Since the current mode is used, the SVC lr field is not defined.
69 *
70 * NOTE: r13 and r14 are stored separately as a work around for the
71 * SA110 rev 2 STM^ bug
72 */
73 #ifdef ARM_TP_ADDRESS
74 #define PUSHFRAME \
75 sub sp, sp, #4; /* Align the stack */ \
76 str lr, [sp, #-4]!; /* Push the return address */ \
77 sub sp, sp, #(4*17); /* Adjust the stack pointer */ \
78 stmia sp, {r0-r12}; /* Push the user mode registers */ \
79 add r0, sp, #(4*13); /* Adjust the stack pointer */ \
80 stmia r0, {r13-r14}^; /* Push the user mode registers */ \
81 mov r0, r0; /* NOP for previous instruction */ \
82 mrs r0, spsr; /* Put the SPSR on the stack */ \
83 str r0, [sp, #-4]!; \
84 ldr r0, =ARM_RAS_START; \
85 mov r1, #0; \
86 str r1, [r0]; \
87 mov r1, #0xffffffff; \
88 str r1, [r0, #4];
89 #else
90 #define PUSHFRAME \
91 sub sp, sp, #4; /* Align the stack */ \
92 str lr, [sp, #-4]!; /* Push the return address */ \
93 sub sp, sp, #(4*17); /* Adjust the stack pointer */ \
94 stmia sp, {r0-r12}; /* Push the user mode registers */ \
95 add r0, sp, #(4*13); /* Adjust the stack pointer */ \
96 stmia r0, {r13-r14}^; /* Push the user mode registers */ \
97 mov r0, r0; /* NOP for previous instruction */ \
98 mrs r0, spsr; /* Put the SPSR on the stack */ \
99 str r0, [sp, #-4]!;
100 #endif
101
102 /*
103 * PULLFRAME - macro to pull a trap frame from the stack in the current mode
104 * Since the current mode is used, the SVC lr field is ignored.
105 */
106
107 #ifdef ARM_TP_ADDRESS
108 #define PULLFRAME \
109 ldr r0, [sp], #4; /* Get the SPSR from stack */ \
110 msr spsr_fsxc, r0; \
111 ldmia sp, {r0-r14}^; /* Restore registers (usr mode) */ \
112 mov r0, r0; /* NOP for previous instruction */ \
113 add sp, sp, #(4*17); /* Adjust the stack pointer */ \
114 ldr lr, [sp], #4; /* Pull the return address */ \
115 add sp, sp, #4 /* Align the stack */
116 #else
117 #define PULLFRAME \
118 ldr r0, [sp], #4 ; /* Get the SPSR from stack */ \
119 msr spsr_fsxc, r0; \
120 clrex; \
121 ldmia sp, {r0-r14}^; /* Restore registers (usr mode) */ \
122 mov r0, r0; /* NOP for previous instruction */ \
123 add sp, sp, #(4*17); /* Adjust the stack pointer */ \
124 ldr lr, [sp], #4; /* Pull the return address */ \
125 add sp, sp, #4 /* Align the stack */
126 #endif
127
128 /*
129 * PUSHFRAMEINSVC - macro to push a trap frame on the stack in SVC32 mode
130 * This should only be used if the processor is not currently in SVC32
131 * mode. The processor mode is switched to SVC mode and the trap frame is
132 * stored. The SVC lr field is used to store the previous value of
133 * lr in SVC mode.
134 *
135 * NOTE: r13 and r14 are stored separately as a work around for the
136 * SA110 rev 2 STM^ bug
137 */
138 #ifdef ARM_TP_ADDRESS
139 #define PUSHFRAMEINSVC \
140 stmdb sp, {r0-r3}; /* Save 4 registers */ \
141 mov r0, lr; /* Save xxx32 r14 */ \
142 mov r1, sp; /* Save xxx32 sp */ \
143 mrs r3, spsr; /* Save xxx32 spsr */ \
144 mrs r2, cpsr; /* Get the CPSR */ \
145 bic r2, r2, #(PSR_MODE); /* Fix for SVC mode */ \
146 orr r2, r2, #(PSR_SVC32_MODE); \
147 msr cpsr_c, r2; /* Punch into SVC mode */ \
148 mov r2, sp; /* Save SVC sp */ \
149 bic sp, sp, #7; /* Align sp to an 8-byte addrress */ \
150 sub sp, sp, #4; /* Pad trapframe to keep alignment */ \
151 str r0, [sp, #-4]!; /* Push return address */ \
152 str lr, [sp, #-4]!; /* Push SVC lr */ \
153 str r2, [sp, #-4]!; /* Push SVC sp */ \
154 msr spsr_fsxc, r3; /* Restore correct spsr */ \
155 ldmdb r1, {r0-r3}; /* Restore 4 regs from xxx mode */ \
156 sub sp, sp, #(4*15); /* Adjust the stack pointer */ \
157 stmia sp, {r0-r12}; /* Push the user mode registers */ \
158 add r0, sp, #(4*13); /* Adjust the stack pointer */ \
159 stmia r0, {r13-r14}^; /* Push the user mode registers */ \
160 mov r0, r0; /* NOP for previous instruction */ \
161 ldr r5, =ARM_RAS_START; /* Check if there's any RAS */ \
162 ldr r4, [r5, #4]; /* reset it to point at the */ \
163 cmp r4, #0xffffffff; /* end of memory if necessary; */ \
164 movne r1, #0xffffffff; /* leave value in r4 for later */ \
165 strne r1, [r5, #4]; /* comparision against PC. */ \
166 ldr r3, [r5]; /* Retrieve global RAS_START */ \
167 cmp r3, #0; /* and reset it if non-zero. */ \
168 movne r1, #0; /* If non-zero RAS_START and */ \
169 strne r1, [r5]; /* PC was lower than RAS_END, */ \
170 ldrne r1, [r0, #16]; /* adjust the saved PC so that */ \
171 cmpne r4, r1; /* execution later resumes at */ \
172 strhi r3, [r0, #16]; /* the RAS_START location. */ \
173 mrs r0, spsr; \
174 str r0, [sp, #-4]!
175 #else
176 #define PUSHFRAMEINSVC \
177 stmdb sp, {r0-r3}; /* Save 4 registers */ \
178 mov r0, lr; /* Save xxx32 r14 */ \
179 mov r1, sp; /* Save xxx32 sp */ \
180 mrs r3, spsr; /* Save xxx32 spsr */ \
181 mrs r2, cpsr; /* Get the CPSR */ \
182 bic r2, r2, #(PSR_MODE); /* Fix for SVC mode */ \
183 orr r2, r2, #(PSR_SVC32_MODE); \
184 msr cpsr_c, r2; /* Punch into SVC mode */ \
185 mov r2, sp; /* Save SVC sp */ \
186 bic sp, sp, #7; /* Align sp to an 8-byte addrress */ \
187 sub sp, sp, #4; /* Pad trapframe to keep alignment */ \
188 str r0, [sp, #-4]!; /* Push return address */ \
189 str lr, [sp, #-4]!; /* Push SVC lr */ \
190 str r2, [sp, #-4]!; /* Push SVC sp */ \
191 msr spsr_fsxc, r3; /* Restore correct spsr */ \
192 ldmdb r1, {r0-r3}; /* Restore 4 regs from xxx mode */ \
193 sub sp, sp, #(4*15); /* Adjust the stack pointer */ \
194 stmia sp, {r0-r12}; /* Push the user mode registers */ \
195 add r0, sp, #(4*13); /* Adjust the stack pointer */ \
196 stmia r0, {r13-r14}^; /* Push the user mode registers */ \
197 mov r0, r0; /* NOP for previous instruction */ \
198 mrs r0, spsr; /* Put the SPSR on the stack */ \
199 str r0, [sp, #-4]!
200 #endif
201
202 /*
203 * PULLFRAMEFROMSVCANDEXIT - macro to pull a trap frame from the stack
204 * in SVC32 mode and restore the saved processor mode and PC.
205 * This should be used when the SVC lr register needs to be restored on
206 * exit.
207 */
208
209 #ifdef ARM_TP_ADDRESS
210 #define PULLFRAMEFROMSVCANDEXIT \
211 ldr r0, [sp], #4; /* Get the SPSR from stack */ \
212 msr spsr_fsxc, r0; /* restore SPSR */ \
213 ldmia sp, {r0-r14}^; /* Restore registers (usr mode) */ \
214 mov r0, r0; /* NOP for previous instruction */ \
215 add sp, sp, #(4*15); /* Adjust the stack pointer */ \
216 ldmia sp, {sp, lr, pc}^ /* Restore lr and exit */
217 #else
218 #define PULLFRAMEFROMSVCANDEXIT \
219 ldr r0, [sp], #4; /* Get the SPSR from stack */ \
220 msr spsr_fsxc, r0; /* restore SPSR */ \
221 clrex; \
222 ldmia sp, {r0-r14}^; /* Restore registers (usr mode) */ \
223 mov r0, r0; /* NOP for previous instruction */ \
224 add sp, sp, #(4*15); /* Adjust the stack pointer */ \
225 ldmia sp, {sp, lr, pc}^ /* Restore lr and exit */
226 #endif
227
228 #if defined(__ARM_EABI__)
229 /*
230 * Unwind hints so we can unwind past functions that use
231 * PULLFRAMEFROMSVCANDEXIT. They are run in reverse order.
232 * As the last thing we do is restore the stack pointer
233 * we can ignore the padding at the end of struct trapframe.
234 */
235 #define UNWINDSVCFRAME \
236 .save {r13-r15}; /* Restore sp, lr, pc */ \
237 .pad #(2*4); /* Skip user sp and lr */ \
238 .save {r0-r12}; /* Restore r0-r12 */ \
239 .pad #(4) /* Skip spsr */
240 #else
241 #define UNWINDSVCFRAME
242 #endif
243
244 #define DO_AST \
245 ldr r0, [sp]; /* Get the SPSR from stack */ \
246 mrs r4, cpsr; /* save CPSR */ \
247 orr r1, r4, #(PSR_I|PSR_F); \
248 msr cpsr_c, r1; /* Disable interrupts */ \
249 and r0, r0, #(PSR_MODE); /* Returning to USR mode? */ \
250 teq r0, #(PSR_USR32_MODE); \
251 bne 2f; /* Nope, get out now */ \
252 bic r4, r4, #(PSR_I|PSR_F); \
253 1: GET_CURTHREAD_PTR(r5); \
254 ldr r1, [r5, #(TD_FLAGS)]; \
255 and r1, r1, #(TDF_ASTPENDING|TDF_NEEDRESCHED); \
256 teq r1, #0; \
257 beq 2f; /* Nope. Just bail */ \
258 msr cpsr_c, r4; /* Restore interrupts */ \
259 mov r0, sp; \
260 bl _C_LABEL(ast); /* ast(frame) */ \
261 orr r0, r4, #(PSR_I|PSR_F); \
262 msr cpsr_c, r0; \
263 b 1b; \
264 2:
265
266
267 /*
268 * Entry point for a Software Interrupt (SWI).
269 *
270 * The hardware switches to svc32 mode on a swi, so we're already on the
271 * right stack; just build a trapframe and call the handler.
272 */
273 ASENTRY_NP(swi_entry)
274 PUSHFRAME /* Build the trapframe on the */
275 mov r0, sp /* scv32 stack, pass it to the */
276 bl _C_LABEL(swi_handler) /* swi handler. */
277 /*
278 * The fork_trampoline() code in swtch.S aranges for the MI fork_exit()
279 * to return to swi_exit here, to return to userland. The net effect is
280 * that a newly created thread appears to return from a SWI just like
281 * the parent thread that created it.
282 */
283 ASEENTRY_NP(swi_exit)
284 DO_AST /* Handle pending signals. */
285 PULLFRAME /* Deallocate trapframe. */
286 movs pc, lr /* Return to userland. */
287 STOP_UNWINDING /* Don't unwind into user mode. */
288 EEND(swi_exit)
289 END(swi_entry)
290
291 /*
292 * Standard exception exit handler.
293 *
294 * This is used to return from all exceptions except SWI. It uses DO_AST and
295 * PULLFRAMEFROMSVCANDEXIT and can only be called if the exception entry code
296 * used PUSHFRAMEINSVC.
297 *
298 * If the return is to user mode, this uses DO_AST to deliver any pending
299 * signals and/or handle TDF_NEEDRESCHED first.
300 */
301 ASENTRY_NP(exception_exit)
302 DO_AST /* Handle pending signals. */
303 PULLFRAMEFROMSVCANDEXIT /* Return. */
304 UNWINDSVCFRAME /* Special unwinding for exceptions. */
305 END(exception_exit)
306
307 /*
308 * Entry point for a Prefetch Abort exception.
309 *
310 * The hardware switches to the abort mode stack; we switch to svc32 before
311 * calling the handler, then return directly to the original mode/stack
312 * on exit (without transitioning back through the abort mode stack).
313 */
314 ASENTRY_NP(prefetch_abort_entry)
315 #ifdef __XSCALE__
316 nop /* Make absolutely sure any pending */
317 nop /* imprecise aborts have occurred. */
318 #endif
319 sub lr, lr, #4 /* Adjust the lr. Transition to scv32 */
320 PUSHFRAMEINSVC /* mode stack, build trapframe there. */
321 adr lr, exception_exit /* Return from handler via standard */
322 mov r0, sp /* exception exit routine. Pass the */
323 mov r1, #1 /* Type flag */
324 b _C_LABEL(abort_handler)
325 END(prefetch_abort_entry)
326
327 /*
328 * Entry point for a Data Abort exception.
329 *
330 * The hardware switches to the abort mode stack; we switch to svc32 before
331 * calling the handler, then return directly to the original mode/stack
332 * on exit (without transitioning back through the abort mode stack).
333 */
334 ASENTRY_NP(data_abort_entry)
335 #ifdef __XSCALE__
336 nop /* Make absolutely sure any pending */
337 nop /* imprecise aborts have occurred. */
338 #endif
339 sub lr, lr, #8 /* Adjust the lr. Transition to scv32 */
340 PUSHFRAMEINSVC /* mode stack, build trapframe there. */
341 adr lr, exception_exit /* Exception exit routine */
342 mov r0, sp /* Trapframe to the handler */
343 mov r1, #0 /* Type flag */
344 b _C_LABEL(abort_handler)
345 END(data_abort_entry)
346
347 /*
348 * Entry point for an Undefined Instruction exception.
349 *
350 * The hardware switches to the undefined mode stack; we switch to svc32 before
351 * calling the handler, then return directly to the original mode/stack
352 * on exit (without transitioning back through the undefined mode stack).
353 */
354 ASENTRY_NP(undefined_entry)
355 sub lr, lr, #4 /* Adjust the lr. Transition to scv32 */
356 PUSHFRAMEINSVC /* mode stack, build trapframe there. */
357 adr lr, exception_exit /* Return from handler via standard */
358 mov r0, sp /* exception exit routine. Pass the */
359 b undefinedinstruction /* trapframe to the handler. */
360 END(undefined_entry)
361
362 /*
363 * Entry point for a normal IRQ.
364 *
365 * The hardware switches to the IRQ mode stack; we switch to svc32 before
366 * calling the handler, then return directly to the original mode/stack
367 * on exit (without transitioning back through the IRQ mode stack).
368 */
369 ASENTRY_NP(irq_entry)
370 sub lr, lr, #4 /* Adjust the lr. Transition to scv32 */
371 PUSHFRAMEINSVC /* mode stack, build trapframe there. */
372 adr lr, exception_exit /* Return from handler via standard */
373 mov r0, sp /* exception exit routine. Pass the */
374 b _C_LABEL(arm_irq_handler)/* trapframe to the handler. */
375 END(irq_entry)
376
377 /*
378 * Entry point for an FIQ interrupt.
379 *
380 * We don't currently support FIQ handlers very much. Something can
381 * install itself in the FIQ vector using code (that may or may not work
382 * these days) in fiq.c. If nobody does that and an FIQ happens, this
383 * default handler just disables FIQs and otherwise ignores it.
384 */
385 ASENTRY_NP(fiq_entry)
386 mrs r8, cpsr /* FIQ handling isn't supported, */
387 bic r8, #(PSR_F) /* just disable FIQ and return. */
388 msr cpsr_c, r8 /* The r8 we trash here is the */
389 subs pc, lr, #4 /* banked FIQ-mode r8. */
390 END(fiq_entry)
391
392 /*
393 * Entry point for an Address Exception exception.
394 * This is an arm26 exception that should never happen.
395 */
396 ASENTRY_NP(addr_exception_entry)
397 mov r3, lr
398 mrs r2, spsr
399 mrs r1, cpsr
400 adr r0, Laddr_exception_msg
401 b _C_LABEL(panic)
402 Laddr_exception_msg:
403 .asciz "Address Exception CPSR=0x%08x SPSR=0x%08x LR=0x%08x\n"
404 .balign 4
405 END(addr_exception_entry)
406
407 /*
408 * Entry point for the system Reset vector.
409 * This should never happen, so panic.
410 */
411 ASENTRY_NP(reset_entry)
412 mov r1, lr
413 adr r0, Lreset_panicmsg
414 b _C_LABEL(panic)
415 /* NOTREACHED */
416 Lreset_panicmsg:
417 .asciz "Reset vector called, LR = 0x%08x"
418 .balign 4
419 END(reset_entry)
420
421 /*
422 * page0 and page0_data -- An image of the ARM vectors which is copied to
423 * the ARM vectors page (high or low) as part of CPU initialization. The
424 * code that does the copy assumes that page0_data holds one 32-bit word
425 * of data for each of the predefined ARM vectors. It also assumes that
426 * page0_data follows the vectors in page0, but other stuff can appear
427 * between the two. We currently leave room between the two for some fiq
428 * handler code to be copied in.
429 */
430 .global _C_LABEL(page0), _C_LABEL(page0_data)
431
432 _C_LABEL(page0):
433 ldr pc, .Lreset_entry
434 ldr pc, .Lundefined_entry
435 ldr pc, .Lswi_entry
436 ldr pc, .Lprefetch_abort_entry
437 ldr pc, .Ldata_abort_entry
438 ldr pc, .Laddr_exception_entry
439 ldr pc, .Lirq_entry
440 .fiqv: ldr pc, .Lfiq_entry
441 .space 256 /* room for some fiq handler code */
442
443 _C_LABEL(page0_data):
444 .Lreset_entry: .word reset_entry
445 .Lundefined_entry: .word undefined_entry
446 .Lswi_entry: .word swi_entry
447 .Lprefetch_abort_entry: .word prefetch_abort_entry
448 .Ldata_abort_entry: .word data_abort_entry
449 .Laddr_exception_entry: .word addr_exception_entry
450 .Lirq_entry: .word irq_entry
451 .Lfiq_entry: .word fiq_entry
452
453 /*
454 * These items are used by the code in fiq.c to install what it calls the
455 * "null" handler. It's actually our default vector entry that just jumps
456 * to the default handler which just disables FIQs and returns.
457 */
458 .global _C_LABEL(fiq_nullhandler_code), _C_LABEL(fiq_nullhandler_size)
459
460 _C_LABEL(fiq_nullhandler_code):
461 .word .fiqv
462 _C_LABEL(fiq_nullhandler_size):
463 .word 4
464
465
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