xref: /linux/arch/xtensa/kernel/process.c (revision 173d6681380aa1d60dfc35ed7178bd7811ba2784) 
1 /*
2  * arch/xtensa/kernel/process.c
3  *
4  * Xtensa Processor version.
5  *
6  * This file is subject to the terms and conditions of the GNU General Public
7  * License.  See the file "COPYING" in the main directory of this archive
8  * for more details.
9  *
10  * Copyright (C) 2001 - 2005 Tensilica Inc.
11  *
12  * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
13  * Chris Zankel <chris@zankel.net>
14  * Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
15  * Kevin Chea
16  */
17 
18 #include <linux/errno.h>
19 #include <linux/sched.h>
20 #include <linux/kernel.h>
21 #include <linux/mm.h>
22 #include <linux/smp.h>
23 #include <linux/smp_lock.h>
24 #include <linux/stddef.h>
25 #include <linux/unistd.h>
26 #include <linux/ptrace.h>
27 #include <linux/slab.h>
28 #include <linux/elf.h>
29 #include <linux/init.h>
30 #include <linux/prctl.h>
31 #include <linux/init_task.h>
32 #include <linux/module.h>
33 #include <linux/mqueue.h>
34 
35 #include <asm/pgtable.h>
36 #include <asm/uaccess.h>
37 #include <asm/system.h>
38 #include <asm/io.h>
39 #include <asm/processor.h>
40 #include <asm/platform.h>
41 #include <asm/mmu.h>
42 #include <asm/irq.h>
43 #include <asm/atomic.h>
44 #include <asm/asm-offsets.h>
45 #include <asm/regs.h>
46 
47 extern void ret_from_fork(void);
48 
49 static struct fs_struct init_fs = INIT_FS;
50 static struct files_struct init_files = INIT_FILES;
51 static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
52 static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
53 struct mm_struct init_mm = INIT_MM(init_mm);
54 EXPORT_SYMBOL(init_mm);
55 
56 union thread_union init_thread_union
57 	__attribute__((__section__(".data.init_task"))) =
58 { INIT_THREAD_INFO(init_task) };
59 
60 struct task_struct init_task = INIT_TASK(init_task);
61 EXPORT_SYMBOL(init_task);
62 
63 struct task_struct *current_set[NR_CPUS] = {&init_task, };
64 
65 void (*pm_power_off)(void) = NULL;
66 EXPORT_SYMBOL(pm_power_off);
67 
68 
69 /*
70  * Powermanagement idle function, if any is provided by the platform.
71  */
72 
73 void cpu_idle(void)
74 {
75   	local_irq_enable();
76 
77 	/* endless idle loop with no priority at all */
78 	while (1) {
79 		while (!need_resched())
80 			platform_idle();
81 		preempt_enable_no_resched();
82 		schedule();
83 		preempt_disable();
84 	}
85 }
86 
87 /*
88  * Free current thread data structures etc..
89  */
90 
91 void exit_thread(void)
92 {
93 }
94 
95 void flush_thread(void)
96 {
97 }
98 
99 /*
100  * Copy thread.
101  *
102  * The stack layout for the new thread looks like this:
103  *
104  *	+------------------------+ <- sp in childregs (= tos)
105  *	|       childregs        |
106  *	+------------------------+ <- thread.sp = sp in dummy-frame
107  *	|      dummy-frame       |    (saved in dummy-frame spill-area)
108  *	+------------------------+
109  *
110  * We create a dummy frame to return to ret_from_fork:
111  *   a0 points to ret_from_fork (simulating a call4)
112  *   sp points to itself (thread.sp)
113  *   a2, a3 are unused.
114  *
115  * Note: This is a pristine frame, so we don't need any spill region on top of
116  *       childregs.
117  */
118 
119 int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
120 		unsigned long unused,
121                 struct task_struct * p, struct pt_regs * regs)
122 {
123 	struct pt_regs *childregs;
124 	unsigned long tos;
125 	int user_mode = user_mode(regs);
126 
127 	/* Set up new TSS. */
128 	tos = (unsigned long)task_stack_page(p) + THREAD_SIZE;
129 	if (user_mode)
130 		childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
131 	else
132 		childregs = (struct pt_regs*)tos - 1;
133 
134 	*childregs = *regs;
135 
136 	/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
137 	*((int*)childregs - 3) = (unsigned long)childregs;
138 	*((int*)childregs - 4) = 0;
139 
140 	childregs->areg[1] = tos;
141 	childregs->areg[2] = 0;
142 	p->set_child_tid = p->clear_child_tid = NULL;
143 	p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
144 	p->thread.sp = (unsigned long)childregs;
145 	if (user_mode(regs)) {
146 
147 		int len = childregs->wmask & ~0xf;
148 		childregs->areg[1] = usp;
149 		memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
150 		       &regs->areg[XCHAL_NUM_AREGS - len/4], len);
151 
152 		if (clone_flags & CLONE_SETTLS)
153 			childregs->areg[2] = childregs->areg[6];
154 
155 	} else {
156 		/* In kernel space, we start a new thread with a new stack. */
157 		childregs->wmask = 1;
158 	}
159 	return 0;
160 }
161 
162 
163 /*
164  * Create a kernel thread
165  */
166 
167 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
168 {
169 	long retval;
170 	__asm__ __volatile__
171 		("mov           a5, %4\n\t" /* preserve fn in a5 */
172 		 "mov           a6, %3\n\t" /* preserve and setup arg in a6 */
173 		 "movi		a2, %1\n\t" /* load __NR_clone for syscall*/
174 		 "mov		a3, sp\n\t" /* sp check and sys_clone */
175 		 "mov		a4, %5\n\t" /* load flags for syscall */
176 		 "syscall\n\t"
177 		 "beq		a3, sp, 1f\n\t" /* branch if parent */
178 		 "callx4	a5\n\t"     /* call fn */
179 		 "movi		a2, %2\n\t" /* load __NR_exit for syscall */
180 		 "mov		a3, a6\n\t" /* load fn return value */
181 		 "syscall\n"
182 		 "1:\n\t"
183 		 "mov		%0, a2\n\t" /* parent returns zero */
184 		 :"=r" (retval)
185 		 :"i" (__NR_clone), "i" (__NR_exit),
186 		 "r" (arg), "r" (fn),
187 		 "r" (flags | CLONE_VM)
188 		 : "a2", "a3", "a4", "a5", "a6" );
189 	return retval;
190 }
191 
192 
193 /*
194  * These bracket the sleeping functions..
195  */
196 
197 unsigned long get_wchan(struct task_struct *p)
198 {
199 	unsigned long sp, pc;
200 	unsigned long stack_page = (unsigned long) task_stack_page(p);
201 	int count = 0;
202 
203 	if (!p || p == current || p->state == TASK_RUNNING)
204 		return 0;
205 
206 	sp = p->thread.sp;
207 	pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
208 
209 	do {
210 		if (sp < stack_page + sizeof(struct task_struct) ||
211 		    sp >= (stack_page + THREAD_SIZE) ||
212 		    pc == 0)
213 			return 0;
214 		if (!in_sched_functions(pc))
215 			return pc;
216 
217 		/* Stack layout: sp-4: ra, sp-3: sp' */
218 
219 		pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
220 		sp = *(unsigned long *)sp - 3;
221 	} while (count++ < 16);
222 	return 0;
223 }
224 
225 /*
226  * do_copy_regs() gathers information from 'struct pt_regs' and
227  * 'current->thread.areg[]' to fill in the xtensa_gregset_t
228  * structure.
229  *
230  * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
231  * of processor registers.  Besides different ordering,
232  * xtensa_gregset_t contains non-live register information that
233  * 'struct pt_regs' does not.  Exception handling (primarily) uses
234  * 'struct pt_regs'.  Core files and ptrace use xtensa_gregset_t.
235  *
236  */
237 
238 void do_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
239 		   struct task_struct *tsk)
240 {
241 	int i, n, wb_offset;
242 
243 	elfregs->xchal_config_id0 = XCHAL_HW_CONFIGID0;
244 	elfregs->xchal_config_id1 = XCHAL_HW_CONFIGID1;
245 
246 	__asm__ __volatile__ ("rsr  %0, 176\n" : "=a" (i));
247  	elfregs->cpux = i;
248 	__asm__ __volatile__ ("rsr  %0, 208\n" : "=a" (i));
249  	elfregs->cpuy = i;
250 
251 	/* Note:  PS.EXCM is not set while user task is running; its
252 	 * being set in regs->ps is for exception handling convenience.
253 	 */
254 
255 	elfregs->pc		= regs->pc;
256 	elfregs->ps		= (regs->ps & ~(1 << PS_EXCM_BIT));
257 	elfregs->exccause	= regs->exccause;
258 	elfregs->excvaddr	= regs->excvaddr;
259 	elfregs->windowbase	= regs->windowbase;
260 	elfregs->windowstart	= regs->windowstart;
261 	elfregs->lbeg		= regs->lbeg;
262 	elfregs->lend		= regs->lend;
263 	elfregs->lcount		= regs->lcount;
264 	elfregs->sar		= regs->sar;
265 	elfregs->syscall	= regs->syscall;
266 
267 	/* Copy register file.
268 	 * The layout looks like this:
269 	 *
270 	 * |  a0 ... a15  | Z ... Z |  arX ... arY  |
271 	 *  current window  unused    saved frames
272 	 */
273 
274 	memset (elfregs->ar, 0, sizeof(elfregs->ar));
275 
276 	wb_offset = regs->windowbase * 4;
277 	n = (regs->wmask&1)? 4 : (regs->wmask&2)? 8 : (regs->wmask&4)? 12 : 16;
278 
279 	for (i = 0; i < n; i++)
280 		elfregs->ar[(wb_offset + i) % XCHAL_NUM_AREGS] = regs->areg[i];
281 
282 	n = (regs->wmask >> 4) * 4;
283 
284 	for (i = XCHAL_NUM_AREGS - n; n > 0; i++, n--)
285 		elfregs->ar[(wb_offset + i) % XCHAL_NUM_AREGS] = regs->areg[i];
286 }
287 
288 void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
289 {
290 	do_copy_regs ((xtensa_gregset_t *)elfregs, regs, current);
291 }
292 
293 
294 /* The inverse of do_copy_regs().  No error or sanity checking. */
295 
296 void do_restore_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs,
297 		      struct task_struct *tsk)
298 {
299 	int i, n, wb_offset;
300 
301 	/* Note:  PS.EXCM is not set while user task is running; it
302 	 * needs to be set in regs->ps is for exception handling convenience.
303 	 */
304 
305 	regs->pc		= elfregs->pc;
306 	regs->ps		= (elfregs->ps | (1 << PS_EXCM_BIT));
307 	regs->exccause		= elfregs->exccause;
308 	regs->excvaddr		= elfregs->excvaddr;
309 	regs->windowbase	= elfregs->windowbase;
310 	regs->windowstart	= elfregs->windowstart;
311 	regs->lbeg		= elfregs->lbeg;
312 	regs->lend		= elfregs->lend;
313 	regs->lcount		= elfregs->lcount;
314 	regs->sar		= elfregs->sar;
315 	regs->syscall	= elfregs->syscall;
316 
317 	/* Clear everything. */
318 
319 	memset (regs->areg, 0, sizeof(regs->areg));
320 
321 	/* Copy regs from live window frame. */
322 
323 	wb_offset = regs->windowbase * 4;
324 	n = (regs->wmask&1)? 4 : (regs->wmask&2)? 8 : (regs->wmask&4)? 12 : 16;
325 
326 	for (i = 0; i < n; i++)
327 		regs->areg[(wb_offset+i) % XCHAL_NUM_AREGS] = elfregs->ar[i];
328 
329 	n = (regs->wmask >> 4) * 4;
330 
331 	for (i = XCHAL_NUM_AREGS - n; n > 0; i++, n--)
332 		regs->areg[(wb_offset+i) % XCHAL_NUM_AREGS] = elfregs->ar[i];
333 }
334 
335 /*
336  * do_save_fpregs() gathers information from 'struct pt_regs' and
337  * 'current->thread' to fill in the elf_fpregset_t structure.
338  *
339  * Core files and ptrace use elf_fpregset_t.
340  */
341 
342 void do_save_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
343 		     struct task_struct *tsk)
344 {
345 #if XCHAL_HAVE_CP
346 
347 	extern unsigned char	_xtensa_reginfo_tables[];
348 	extern unsigned		_xtensa_reginfo_table_size;
349 	int i;
350 	unsigned long flags;
351 
352 	/* Before dumping coprocessor state from memory,
353 	 * ensure any live coprocessor contents for this
354 	 * task are first saved to memory:
355 	 */
356 	local_irq_save(flags);
357 
358 	for (i = 0; i < XCHAL_CP_MAX; i++) {
359 		if (tsk == coprocessor_info[i].owner) {
360 			enable_coprocessor(i);
361 			save_coprocessor_registers(
362 			    tsk->thread.cp_save+coprocessor_info[i].offset,i);
363 			disable_coprocessor(i);
364 		}
365 	}
366 
367 	local_irq_restore(flags);
368 
369 	/* Now dump coprocessor & extra state: */
370 	memcpy((unsigned char*)fpregs,
371 		_xtensa_reginfo_tables, _xtensa_reginfo_table_size);
372 	memcpy((unsigned char*)fpregs + _xtensa_reginfo_table_size,
373 		tsk->thread.cp_save, XTENSA_CP_EXTRA_SIZE);
374 #endif
375 }
376 
377 /*
378  * The inverse of do_save_fpregs().
379  * Copies coprocessor and extra state from fpregs into regs and tsk->thread.
380  * Returns 0 on success, non-zero if layout doesn't match.
381  */
382 
383 int  do_restore_fpregs (elf_fpregset_t *fpregs, struct pt_regs *regs,
384 		        struct task_struct *tsk)
385 {
386 #if XCHAL_HAVE_CP
387 
388 	extern unsigned char	_xtensa_reginfo_tables[];
389 	extern unsigned		_xtensa_reginfo_table_size;
390 	int i;
391 	unsigned long flags;
392 
393 	/* Make sure save area layouts match.
394 	 * FIXME:  in the future we could allow restoring from
395 	 * a different layout of the same registers, by comparing
396 	 * fpregs' table with _xtensa_reginfo_tables and matching
397 	 * entries and copying registers one at a time.
398 	 * Not too sure yet whether that's very useful.
399 	 */
400 
401 	if( memcmp((unsigned char*)fpregs,
402 		_xtensa_reginfo_tables, _xtensa_reginfo_table_size) ) {
403 	    return -1;
404 	}
405 
406 	/* Before restoring coprocessor state from memory,
407 	 * ensure any live coprocessor contents for this
408 	 * task are first invalidated.
409 	 */
410 
411 	local_irq_save(flags);
412 
413 	for (i = 0; i < XCHAL_CP_MAX; i++) {
414 		if (tsk == coprocessor_info[i].owner) {
415 			enable_coprocessor(i);
416 			save_coprocessor_registers(
417 			    tsk->thread.cp_save+coprocessor_info[i].offset,i);
418 			coprocessor_info[i].owner = 0;
419 			disable_coprocessor(i);
420 		}
421 	}
422 
423 	local_irq_restore(flags);
424 
425 	/*  Now restore coprocessor & extra state:  */
426 
427 	memcpy(tsk->thread.cp_save,
428 		(unsigned char*)fpregs + _xtensa_reginfo_table_size,
429 		XTENSA_CP_EXTRA_SIZE);
430 #endif
431 	return 0;
432 }
433 /*
434  * Fill in the CP structure for a core dump for a particular task.
435  */
436 
437 int
438 dump_task_fpu(struct pt_regs *regs, struct task_struct *task, elf_fpregset_t *r)
439 {
440 	return 0;	/* no coprocessors active on this processor */
441 }
442 
443 /*
444  * Fill in the CP structure for a core dump.
445  * This includes any FPU coprocessor.
446  * Here, we dump all coprocessors, and other ("extra") custom state.
447  *
448  * This function is called by elf_core_dump() in fs/binfmt_elf.c
449  * (in which case 'regs' comes from calls to do_coredump, see signals.c).
450  */
451 int  dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
452 {
453 	return dump_task_fpu(regs, current, r);
454 }
455