summaryrefslogtreecommitdiff
path: root/arch/xtensa/kernel/process.c
blob: 08ef6d82ee5144d1e30d98195a9d91de57af5806 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
// TODO	verify coprocessor handling
/*
 * arch/xtensa/kernel/process.c
 *
 * Xtensa Processor version.
 *
 * 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) 2001 - 2005 Tensilica Inc.
 *
 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
 * Chris Zankel <chris@zankel.net>
 * Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
 * Kevin Chea
 */

#include <linux/config.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/elf.h>
#include <linux/init.h>
#include <linux/prctl.h>
#include <linux/init_task.h>
#include <linux/module.h>
#include <linux/mqueue.h>

#include <asm/pgtable.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/processor.h>
#include <asm/platform.h>
#include <asm/mmu.h>
#include <asm/irq.h>
#include <asm/atomic.h>
#include <asm/asm-offsets.h>
#include <asm/coprocessor.h>

extern void ret_from_fork(void);

static struct fs_struct init_fs = INIT_FS;
static struct files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
struct mm_struct init_mm = INIT_MM(init_mm);
EXPORT_SYMBOL(init_mm);

union thread_union init_thread_union
	__attribute__((__section__(".data.init_task"))) =
{ INIT_THREAD_INFO(init_task) };

struct task_struct init_task = INIT_TASK(init_task);
EXPORT_SYMBOL(init_task);

struct task_struct *current_set[NR_CPUS] = {&init_task, };


#if XCHAL_CP_NUM > 0

/*
 * Coprocessor ownership.
 */

coprocessor_info_t coprocessor_info[] = {
	{ 0, XTENSA_CPE_CP0_OFFSET },
	{ 0, XTENSA_CPE_CP1_OFFSET },
	{ 0, XTENSA_CPE_CP2_OFFSET },
	{ 0, XTENSA_CPE_CP3_OFFSET },
	{ 0, XTENSA_CPE_CP4_OFFSET },
	{ 0, XTENSA_CPE_CP5_OFFSET },
	{ 0, XTENSA_CPE_CP6_OFFSET },
	{ 0, XTENSA_CPE_CP7_OFFSET },
};

#endif

/*
 * Powermanagement idle function, if any is provided by the platform.
 */

void cpu_idle(void)
{
  	local_irq_enable();

	/* endless idle loop with no priority at all */
	while (1) {
		while (!need_resched())
			platform_idle();
		preempt_enable();
		schedule();
	}
}

/*
 * Free current thread data structures etc..
 */

void exit_thread(void)
{
	release_coprocessors(current);	/* Empty macro if no CPs are defined */
}

void flush_thread(void)
{
	release_coprocessors(current);	/* Empty macro if no CPs are defined */
}

/*
 * Copy thread.
 *
 * The stack layout for the new thread looks like this:
 *
 *	+------------------------+ <- sp in childregs (= tos)
 *	|       childregs        |
 *	+------------------------+ <- thread.sp = sp in dummy-frame
 *	|      dummy-frame       |    (saved in dummy-frame spill-area)
 *	+------------------------+
 *
 * We create a dummy frame to return to ret_from_fork:
 *   a0 points to ret_from_fork (simulating a call4)
 *   sp points to itself (thread.sp)
 *   a2, a3 are unused.
 *
 * Note: This is a pristine frame, so we don't need any spill region on top of
 *       childregs.
 */

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
		unsigned long unused,
                struct task_struct * p, struct pt_regs * regs)
{
	struct pt_regs *childregs;
	unsigned long tos;
	int user_mode = user_mode(regs);

	/* Set up new TSS. */
	tos = (unsigned long)p->thread_info + THREAD_SIZE;
	if (user_mode)
		childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
	else
		childregs = (struct pt_regs*)tos - 1;

	*childregs = *regs;

	/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
	*((int*)childregs - 3) = (unsigned long)childregs;
	*((int*)childregs - 4) = 0;

	childregs->areg[1] = tos;
	childregs->areg[2] = 0;
	p->set_child_tid = p->clear_child_tid = NULL;
	p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
	p->thread.sp = (unsigned long)childregs;
	if (user_mode(regs)) {

		int len = childregs->wmask & ~0xf;
		childregs->areg[1] = usp;
		memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
		       &regs->areg[XCHAL_NUM_AREGS - len/4], len);

		if (clone_flags & CLONE_SETTLS)
			childregs->areg[2] = childregs->areg[6];

	} else {
		/* In kernel space, we start a new thread with a new stack. */
		childregs->wmask = 1;
	}
	return 0;
}


/*
 * Create a kernel thread
 */

int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
	long retval;
	__asm__ __volatile__
		("mov           a5, %4\n\t" /* preserve fn in a5 */
		 "mov           a6, %3\n\t" /* preserve and setup arg in a6 */
		 "movi		a2, %1\n\t" /* load __NR_clone for syscall*/
		 "mov		a3, sp\n\t" /* sp check and sys_clone */
		 "mov		a4, %5\n\t" /* load flags for syscall */
		 "syscall\n\t"
		 "beq		a3, sp, 1f\n\t" /* branch if parent */
		 "callx4	a5\n\t"     /* call fn */
		 "movi		a2, %2\n\t" /* load __NR_exit for syscall */
		 "mov		a3, a6\n\t" /* load fn return value */
		 "syscall\n"
		 "1:\n\t"
		 "mov		%0, a2\n\t" /* parent returns zero */
		 :"=r" (retval)
		 :"i" (__NR_clone), "i" (__NR_exit),
		 "r" (arg), "r" (fn),
		 "r" (flags | CLONE_VM)
		 : "a2", "a3", "a4", "a5", "a6" );
	return retval;
}


/*
 * These bracket the sleeping functions..
 */

unsigned long get_wchan(struct task_struct *p)
{
	unsigned long sp, pc;
	unsigned long stack_page = (unsigned long) p->thread_info;
	int count = 0;

	if (!p || p == current || p->state == TASK_RUNNING)
		return 0;

	sp = p->thread.sp;
	pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);

	do {
		if (sp < stack_page + sizeof(struct task_struct) ||
		    sp >= (stack_page + THREAD_SIZE) ||
		    pc == 0)
			return 0;
		if (!in_sched_functions(pc))
			return pc;

		/* Stack layout: sp-4: ra, sp-3: sp' */

		pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
		sp = *(unsigned long *)sp - 3;
	} while (count++ < 16);
	return 0;
}

/*
 * do_copy_regs() gathers information from 'struct pt_regs' and
 * 'current->thread.areg[]' to fill in the xtensa_gregset_t
 * structure.
 *
 * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
 * of processor registers.  Besides different ordering,
 * xtensa_gregset_t contains non-live register information that
 * 'struct pt_regs' does not.  Exception handling (primarily) uses
 * 'struct pt_regs'.  Core files and ptrace use xtensa_gregset_t.
 *
 */

void do_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
		   struct task_struct *tsk)
{
	int i, n, wb_offset;

	elfregs->xchal_config_id0 = XCHAL_HW_CONFIGID0;
	elfregs->xchal_config_id1 = XCHAL_HW_CONFIGID1;

	__asm__ __volatile__ ("rsr  %0, 176\n" : "=a" (i));
 	elfregs->cpux = i;
	__asm__ __volatile__ ("rsr  %0, 208\n" : "=a" (i));
 	elfregs->cpuy = i;

	/* Note:  PS.EXCM is not set while user task is running; its
	 * being set in regs->ps is for exception handling convenience.
	 */

	elfregs->pc		= regs->pc;
	elfregs->ps		= (regs->ps & ~XCHAL_PS_EXCM_MASK);
	elfregs->exccause	= regs->exccause;
	elfregs->excvaddr	= regs->excvaddr;
	elfregs->windowbase	= regs->windowbase;
	elfregs->windowstart	= regs->windowstart;
	elfregs->lbeg		= regs->lbeg;
	elfregs->lend		= regs->lend;
	elfregs->lcount		= regs->lcount;
	elfregs->sar		= regs->sar;
	elfregs->syscall	= regs->syscall;

	/* Copy register file.
	 * The layout looks like this:
	 *
	 * |  a0 ... a15  | Z ... Z |  arX ... arY  |
	 *  current window  unused    saved frames
	 */

	memset (elfregs->ar, 0, sizeof(elfregs->ar));

	wb_offset = regs->windowbase * 4;
	n = (regs->wmask&1)? 4 : (regs->wmask&2)? 8 : (regs->wmask&4)? 12 : 16;

	for (i = 0; i < n; i++)
		elfregs->ar[(wb_offset + i) % XCHAL_NUM_AREGS] = regs->areg[i];

	n = (regs->wmask >> 4) * 4;

	for (i = XCHAL_NUM_AREGS - n; n > 0; i++, n--)
		elfregs->ar[(wb_offset + i) % XCHAL_NUM_AREGS] = regs->areg[i];
}

void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
{
	do_copy_regs ((xtensa_gregset_t *)elfregs, regs, current);
}


/* The inverse of do_copy_regs().  No error or sanity checking. */

void do_restore_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
		      struct task_struct *tsk)
{
	int i, n, wb_offset;

	/* Note:  PS.EXCM is not set while user task is running; it
	 * needs to be set in regs->ps is for exception handling convenience.
	 */

	regs->pc		= elfregs->pc;
	regs->ps		= (elfregs->ps | XCHAL_PS_EXCM_MASK);
	regs->exccause		= elfregs->exccause;
	regs->excvaddr		= elfregs->excvaddr;
	regs->windowbase	= elfregs->windowbase;
	regs->windowstart	= elfregs->windowstart;
	regs->lbeg		= elfregs->lbeg;
	regs->lend		= elfregs->lend;
	regs->lcount		= elfregs->lcount;
	regs->sar		= elfregs->sar;
	regs->syscall	= elfregs->syscall;

	/* Clear everything. */

	memset (regs->areg, 0, sizeof(regs->areg));

	/* Copy regs from live window frame. */

	wb_offset = regs->windowbase * 4;
	n = (regs->wmask&1)? 4 : (regs->wmask&2)? 8 : (regs->wmask&4)? 12 : 16;

	for (i = 0; i < n; i++)
		regs->areg[(wb_offset+i) % XCHAL_NUM_AREGS] = elfregs->ar[i];

	n = (regs->wmask >> 4) * 4;

	for (i = XCHAL_NUM_AREGS - n; n > 0; i++, n--)
		regs->areg[(wb_offset+i) % XCHAL_NUM_AREGS] = elfregs->ar[i];
}

/*
 * do_save_fpregs() gathers information from 'struct pt_regs' and
 * 'current->thread' to fill in the elf_fpregset_t structure.
 *
 * Core files and ptrace use elf_fpregset_t.
 */

void do_save_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
		     struct task_struct *tsk)
{
#if XCHAL_HAVE_CP

	extern unsigned char	_xtensa_reginfo_tables[];
	extern unsigned		_xtensa_reginfo_table_size;
	int i;
	unsigned long flags;

	/* Before dumping coprocessor state from memory,
	 * ensure any live coprocessor contents for this
	 * task are first saved to memory:
	 */
	local_irq_save(flags);

	for (i = 0; i < XCHAL_CP_MAX; i++) {
		if (tsk == coprocessor_info[i].owner) {
			enable_coprocessor(i);
			save_coprocessor_registers(
			    tsk->thread.cp_save+coprocessor_info[i].offset,i);
			disable_coprocessor(i);
		}
	}

	local_irq_restore(flags);

	/* Now dump coprocessor & extra state: */
	memcpy((unsigned char*)fpregs,
		_xtensa_reginfo_tables, _xtensa_reginfo_table_size);
	memcpy((unsigned char*)fpregs + _xtensa_reginfo_table_size,
		tsk->thread.cp_save, XTENSA_CP_EXTRA_SIZE);
#endif
}

/*
 * The inverse of do_save_fpregs().
 * Copies coprocessor and extra state from fpregs into regs and tsk->thread.
 * Returns 0 on success, non-zero if layout doesn't match.
 */

int  do_restore_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
		        struct task_struct *tsk)
{
#if XCHAL_HAVE_CP

	extern unsigned char	_xtensa_reginfo_tables[];
	extern unsigned		_xtensa_reginfo_table_size;
	int i;
	unsigned long flags;

	/* Make sure save area layouts match.
	 * FIXME:  in the future we could allow restoring from
	 * a different layout of the same registers, by comparing
	 * fpregs' table with _xtensa_reginfo_tables and matching
	 * entries and copying registers one at a time.
	 * Not too sure yet whether that's very useful.
	 */

	if( memcmp((unsigned char*)fpregs,
		_xtensa_reginfo_tables, _xtensa_reginfo_table_size) ) {
	    return -1;
	}

	/* Before restoring coprocessor state from memory,
	 * ensure any live coprocessor contents for this
	 * task are first invalidated.
	 */

	local_irq_save(flags);

	for (i = 0; i < XCHAL_CP_MAX; i++) {
		if (tsk == coprocessor_info[i].owner) {
			enable_coprocessor(i);
			save_coprocessor_registers(
			    tsk->thread.cp_save+coprocessor_info[i].offset,i);
			coprocessor_info[i].owner = 0;
			disable_coprocessor(i);
		}
	}

	local_irq_restore(flags);

	/*  Now restore coprocessor & extra state:  */

	memcpy(tsk->thread.cp_save,
		(unsigned char*)fpregs + _xtensa_reginfo_table_size,
		XTENSA_CP_EXTRA_SIZE);
#endif
	return 0;
}
/*
 * Fill in the CP structure for a core dump for a particular task.
 */

int
dump_task_fpu(struct pt_regs *regs, struct task_struct *task, elf_fpregset_t *r)
{
/* see asm/coprocessor.h for this magic number 16 */
#if XTENSA_CP_EXTRA_SIZE > 16
	do_save_fpregs (r, regs, task);

	/*  For now, bit 16 means some extra state may be present:  */
// FIXME!! need to track to return more accurate mask
	return 0x10000 | XCHAL_CP_MASK;
#else
	return 0;	/* no coprocessors active on this processor */
#endif
}

/*
 * Fill in the CP structure for a core dump.
 * This includes any FPU coprocessor.
 * Here, we dump all coprocessors, and other ("extra") custom state.
 *
 * This function is called by elf_core_dump() in fs/binfmt_elf.c
 * (in which case 'regs' comes from calls to do_coredump, see signals.c).
 */
int  dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
{
	return dump_task_fpu(regs, current, r);
}