summaryrefslogtreecommitdiff
path: root/arch/mips/kernel/process.c
blob: 4fe3d5715c416c6b2aa74152f974348f757b2c41 (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
/*
 * 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 - 1999, 2000 by Ralf Baechle and others.
 * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
 * Copyright (C) 2004 Thiemo Seufer
 */
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/mman.h>
#include <linux/personality.h>
#include <linux/sys.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/init.h>
#include <linux/completion.h>

#include <asm/abi.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/mipsregs.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/elf.h>
#include <asm/isadep.h>
#include <asm/inst.h>

/*
 * The idle thread. There's no useful work to be done, so just try to conserve
 * power and have a low exit latency (ie sit in a loop waiting for somebody to
 * say that they'd like to reschedule)
 */
ATTRIB_NORET void cpu_idle(void)
{
	/* endless idle loop with no priority at all */
	while (1) {
		while (!need_resched())
			if (cpu_wait)
				(*cpu_wait)();
		schedule();
	}
}

extern int do_signal(sigset_t *oldset, struct pt_regs *regs);
extern int do_signal32(sigset_t *oldset, struct pt_regs *regs);

/*
 * Native o32 and N64 ABI without DSP ASE
 */
extern int setup_frame(struct k_sigaction * ka, struct pt_regs *regs,
        int signr, sigset_t *set);
extern int setup_rt_frame(struct k_sigaction * ka, struct pt_regs *regs,
        int signr, sigset_t *set, siginfo_t *info);

struct mips_abi mips_abi = {
	.do_signal	= do_signal,
#ifdef CONFIG_TRAD_SIGNALS
	.setup_frame	= setup_frame,
#endif
	.setup_rt_frame	= setup_rt_frame
};

#ifdef CONFIG_MIPS32_O32
/*
 * o32 compatibility on 64-bit kernels, without DSP ASE
 */
extern int setup_frame_32(struct k_sigaction * ka, struct pt_regs *regs,
        int signr, sigset_t *set);
extern int setup_rt_frame_32(struct k_sigaction * ka, struct pt_regs *regs,
        int signr, sigset_t *set, siginfo_t *info);

struct mips_abi mips_abi_32 = {
	.do_signal	= do_signal32,
	.setup_frame	= setup_frame_32,
	.setup_rt_frame	= setup_rt_frame_32
};
#endif /* CONFIG_MIPS32_O32 */

#ifdef CONFIG_MIPS32_N32
/*
 * N32 on 64-bit kernels, without DSP ASE
 */
extern int setup_rt_frame_n32(struct k_sigaction * ka, struct pt_regs *regs,
        int signr, sigset_t *set, siginfo_t *info);

struct mips_abi mips_abi_n32 = {
	.do_signal	= do_signal,
	.setup_rt_frame	= setup_rt_frame_n32
};
#endif /* CONFIG_MIPS32_N32 */

asmlinkage void ret_from_fork(void);

void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
{
	unsigned long status;

	/* New thread loses kernel privileges. */
	status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK);
#ifdef CONFIG_64BIT
	status &= ~ST0_FR;
	status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
#endif
	status |= KU_USER;
	regs->cp0_status = status;
	clear_used_math();
	lose_fpu();
	if (cpu_has_dsp)
		__init_dsp();
	regs->cp0_epc = pc;
	regs->regs[29] = sp;
	current_thread_info()->addr_limit = USER_DS;
}

void exit_thread(void)
{
}

void flush_thread(void)
{
}

int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
	unsigned long unused, struct task_struct *p, struct pt_regs *regs)
{
	struct thread_info *ti = p->thread_info;
	struct pt_regs *childregs;
	long childksp;
	p->set_child_tid = p->clear_child_tid = NULL;

	childksp = (unsigned long)ti + THREAD_SIZE - 32;

	preempt_disable();

	if (is_fpu_owner())
		save_fp(p);

	if (cpu_has_dsp)
		save_dsp(p);

	preempt_enable();

	/* set up new TSS. */
	childregs = (struct pt_regs *) childksp - 1;
	*childregs = *regs;
	childregs->regs[7] = 0;	/* Clear error flag */

#if defined(CONFIG_BINFMT_IRIX)
	if (current->personality != PER_LINUX) {
		/* Under IRIX things are a little different. */
		childregs->regs[3] = 1;
		regs->regs[3] = 0;
	}
#endif
	childregs->regs[2] = 0;	/* Child gets zero as return value */
	regs->regs[2] = p->pid;

	if (childregs->cp0_status & ST0_CU0) {
		childregs->regs[28] = (unsigned long) ti;
		childregs->regs[29] = childksp;
		ti->addr_limit = KERNEL_DS;
	} else {
		childregs->regs[29] = usp;
		ti->addr_limit = USER_DS;
	}
	p->thread.reg29 = (unsigned long) childregs;
	p->thread.reg31 = (unsigned long) ret_from_fork;

	/*
	 * New tasks lose permission to use the fpu. This accelerates context
	 * switching for most programs since they don't use the fpu.
	 */
	p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
	childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
	clear_tsk_thread_flag(p, TIF_USEDFPU);

	if (clone_flags & CLONE_SETTLS)
		ti->tp_value = regs->regs[7];

	return 0;
}

/* Fill in the fpu structure for a core dump.. */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
{
	memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));

	return 1;
}

void dump_regs(elf_greg_t *gp, struct pt_regs *regs)
{
	int i;

	for (i = 0; i < EF_R0; i++)
		gp[i] = 0;
	gp[EF_R0] = 0;
	for (i = 1; i <= 31; i++)
		gp[EF_R0 + i] = regs->regs[i];
	gp[EF_R26] = 0;
	gp[EF_R27] = 0;
	gp[EF_LO] = regs->lo;
	gp[EF_HI] = regs->hi;
	gp[EF_CP0_EPC] = regs->cp0_epc;
	gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
	gp[EF_CP0_STATUS] = regs->cp0_status;
	gp[EF_CP0_CAUSE] = regs->cp0_cause;
#ifdef EF_UNUSED0
	gp[EF_UNUSED0] = 0;
#endif
}

int dump_task_regs (struct task_struct *tsk, elf_gregset_t *regs)
{
	struct thread_info *ti = tsk->thread_info;
	long ksp = (unsigned long)ti + THREAD_SIZE - 32;
	dump_regs(&(*regs)[0], (struct pt_regs *) ksp - 1);
	return 1;
}

int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr)
{
	memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));

	return 1;
}

/*
 * Create a kernel thread
 */
ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
{
	do_exit(fn(arg));
}

long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
	struct pt_regs regs;

	memset(&regs, 0, sizeof(regs));

	regs.regs[4] = (unsigned long) arg;
	regs.regs[5] = (unsigned long) fn;
	regs.cp0_epc = (unsigned long) kernel_thread_helper;
	regs.cp0_status = read_c0_status();
#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
	regs.cp0_status &= ~(ST0_KUP | ST0_IEC);
	regs.cp0_status |= ST0_IEP;
#else
	regs.cp0_status |= ST0_EXL;
#endif

	/* Ok, create the new process.. */
	return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
}

static struct mips_frame_info {
	void *func;
	int omit_fp;	/* compiled without fno-omit-frame-pointer */
	int frame_offset;
	int pc_offset;
} schedule_frame, mfinfo[] = {
	{ schedule, 0 },	/* must be first */
	/* arch/mips/kernel/semaphore.c */
	{ __down, 1 },
	{ __down_interruptible, 1 },
	/* kernel/sched.c */
#ifdef CONFIG_PREEMPT
	{ preempt_schedule, 0 },
#endif
	{ wait_for_completion, 0 },
	{ interruptible_sleep_on, 0 },
	{ interruptible_sleep_on_timeout, 0 },
	{ sleep_on, 0 },
	{ sleep_on_timeout, 0 },
	{ yield, 0 },
	{ io_schedule, 0 },
	{ io_schedule_timeout, 0 },
#if defined(CONFIG_SMP) && defined(CONFIG_PREEMPT)
	{ __preempt_spin_lock, 0 },
	{ __preempt_write_lock, 0 },
#endif
	/* kernel/timer.c */
	{ schedule_timeout, 1 },
/*	{ nanosleep_restart, 1 }, */
	/* lib/rwsem-spinlock.c */
	{ __down_read, 1 },
	{ __down_write, 1 },
};

static int mips_frame_info_initialized;
static int __init get_frame_info(struct mips_frame_info *info)
{
	int i;
	void *func = info->func;
	union mips_instruction *ip = (union mips_instruction *)func;
	info->pc_offset = -1;
	info->frame_offset = info->omit_fp ? 0 : -1;
	for (i = 0; i < 128; i++, ip++) {
		/* if jal, jalr, jr, stop. */
		if (ip->j_format.opcode == jal_op ||
		    (ip->r_format.opcode == spec_op &&
		     (ip->r_format.func == jalr_op ||
		      ip->r_format.func == jr_op)))
			break;

		if (
#ifdef CONFIG_32BIT
		    ip->i_format.opcode == sw_op &&
#endif
#ifdef CONFIG_64BIT
		    ip->i_format.opcode == sd_op &&
#endif
		    ip->i_format.rs == 29)
		{
			/* sw / sd $ra, offset($sp) */
			if (ip->i_format.rt == 31) {
				if (info->pc_offset != -1)
					continue;
				info->pc_offset =
					ip->i_format.simmediate / sizeof(long);
			}
			/* sw / sd $s8, offset($sp) */
			if (ip->i_format.rt == 30) {
//#if 0	/* gcc 3.4 does aggressive optimization... */
				if (info->frame_offset != -1)
					continue;
//#endif
				info->frame_offset =
					ip->i_format.simmediate / sizeof(long);
			}
		}
	}
	if (info->pc_offset == -1 || info->frame_offset == -1) {
		printk("Can't analyze prologue code at %p\n", func);
		info->pc_offset = -1;
		info->frame_offset = -1;
		return -1;
	}

	return 0;
}

static int __init frame_info_init(void)
{
	int i, found;
	for (i = 0; i < ARRAY_SIZE(mfinfo); i++)
		if (get_frame_info(&mfinfo[i]))
			return -1;
	schedule_frame = mfinfo[0];
	/* bubble sort */
	do {
		struct mips_frame_info tmp;
		found = 0;
		for (i = 1; i < ARRAY_SIZE(mfinfo); i++) {
			if (mfinfo[i-1].func > mfinfo[i].func) {
				tmp = mfinfo[i];
				mfinfo[i] = mfinfo[i-1];
				mfinfo[i-1] = tmp;
				found = 1;
			}
		}
	} while (found);
	mips_frame_info_initialized = 1;
	return 0;
}

arch_initcall(frame_info_init);

/*
 * Return saved PC of a blocked thread.
 */
unsigned long thread_saved_pc(struct task_struct *tsk)
{
	struct thread_struct *t = &tsk->thread;

	/* New born processes are a special case */
	if (t->reg31 == (unsigned long) ret_from_fork)
		return t->reg31;

	if (schedule_frame.pc_offset < 0)
		return 0;
	return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
}

/* get_wchan - a maintenance nightmare^W^Wpain in the ass ...  */
unsigned long get_wchan(struct task_struct *p)
{
	unsigned long stack_page;
	unsigned long frame, pc;

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

	stack_page = (unsigned long)p->thread_info;
	if (!stack_page || !mips_frame_info_initialized)
		return 0;

	pc = thread_saved_pc(p);
	if (!in_sched_functions(pc))
		return pc;

	frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
	do {
		int i;

		if (frame < stack_page || frame > stack_page + THREAD_SIZE - 32)
			return 0;

		for (i = ARRAY_SIZE(mfinfo) - 1; i >= 0; i--) {
			if (pc >= (unsigned long) mfinfo[i].func)
				break;
		}
		if (i < 0)
			break;

		if (mfinfo[i].omit_fp)
			break;
		pc = ((unsigned long *)frame)[mfinfo[i].pc_offset];
		frame = ((unsigned long *)frame)[mfinfo[i].frame_offset];
	} while (in_sched_functions(pc));

	return pc;
}

EXPORT_SYMBOL(get_wchan);