xref: /linux/arch/xtensa/kernel/process.c (revision ec2212088c42ff7d1362629ec26dda4f3e8bdad3) 
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/stddef.h>
24 #include <linux/unistd.h>
25 #include <linux/ptrace.h>
26 #include <linux/elf.h>
27 #include <linux/init.h>
28 #include <linux/prctl.h>
29 #include <linux/init_task.h>
30 #include <linux/module.h>
31 #include <linux/mqueue.h>
32 #include <linux/fs.h>
33 #include <linux/slab.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 <linux/atomic.h>
44 #include <asm/asm-offsets.h>
45 #include <asm/regs.h>
46 
47 extern void ret_from_fork(void);
48 
49 struct task_struct *current_set[NR_CPUS] = {&init_task, };
50 
51 void (*pm_power_off)(void) = NULL;
52 EXPORT_SYMBOL(pm_power_off);
53 
54 
55 #if XTENSA_HAVE_COPROCESSORS
56 
57 void coprocessor_release_all(struct thread_info *ti)
58 {
59 	unsigned long cpenable;
60 	int i;
61 
62 	/* Make sure we don't switch tasks during this operation. */
63 
64 	preempt_disable();
65 
66 	/* Walk through all cp owners and release it for the requested one. */
67 
68 	cpenable = ti->cpenable;
69 
70 	for (i = 0; i < XCHAL_CP_MAX; i++) {
71 		if (coprocessor_owner[i] == ti) {
72 			coprocessor_owner[i] = 0;
73 			cpenable &= ~(1 << i);
74 		}
75 	}
76 
77 	ti->cpenable = cpenable;
78 	coprocessor_clear_cpenable();
79 
80 	preempt_enable();
81 }
82 
83 void coprocessor_flush_all(struct thread_info *ti)
84 {
85 	unsigned long cpenable;
86 	int i;
87 
88 	preempt_disable();
89 
90 	cpenable = ti->cpenable;
91 
92 	for (i = 0; i < XCHAL_CP_MAX; i++) {
93 		if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
94 			coprocessor_flush(ti, i);
95 		cpenable >>= 1;
96 	}
97 
98 	preempt_enable();
99 }
100 
101 #endif
102 
103 
104 /*
105  * Powermanagement idle function, if any is provided by the platform.
106  */
107 
108 void cpu_idle(void)
109 {
110   	local_irq_enable();
111 
112 	/* endless idle loop with no priority at all */
113 	while (1) {
114 		while (!need_resched())
115 			platform_idle();
116 		schedule_preempt_disabled();
117 	}
118 }
119 
120 /*
121  * This is called when the thread calls exit().
122  */
123 void exit_thread(void)
124 {
125 #if XTENSA_HAVE_COPROCESSORS
126 	coprocessor_release_all(current_thread_info());
127 #endif
128 }
129 
130 /*
131  * Flush thread state. This is called when a thread does an execve()
132  * Note that we flush coprocessor registers for the case execve fails.
133  */
134 void flush_thread(void)
135 {
136 #if XTENSA_HAVE_COPROCESSORS
137 	struct thread_info *ti = current_thread_info();
138 	coprocessor_flush_all(ti);
139 	coprocessor_release_all(ti);
140 #endif
141 }
142 
143 /*
144  * This is called before the thread is copied.
145  */
146 void prepare_to_copy(struct task_struct *tsk)
147 {
148 #if XTENSA_HAVE_COPROCESSORS
149 	coprocessor_flush_all(task_thread_info(tsk));
150 #endif
151 }
152 
153 /*
154  * Copy thread.
155  *
156  * The stack layout for the new thread looks like this:
157  *
158  *	+------------------------+ <- sp in childregs (= tos)
159  *	|       childregs        |
160  *	+------------------------+ <- thread.sp = sp in dummy-frame
161  *	|      dummy-frame       |    (saved in dummy-frame spill-area)
162  *	+------------------------+
163  *
164  * We create a dummy frame to return to ret_from_fork:
165  *   a0 points to ret_from_fork (simulating a call4)
166  *   sp points to itself (thread.sp)
167  *   a2, a3 are unused.
168  *
169  * Note: This is a pristine frame, so we don't need any spill region on top of
170  *       childregs.
171  */
172 
173 int copy_thread(unsigned long clone_flags, unsigned long usp,
174 		unsigned long unused,
175                 struct task_struct * p, struct pt_regs * regs)
176 {
177 	struct pt_regs *childregs;
178 	struct thread_info *ti;
179 	unsigned long tos;
180 	int user_mode = user_mode(regs);
181 
182 	/* Set up new TSS. */
183 	tos = (unsigned long)task_stack_page(p) + THREAD_SIZE;
184 	if (user_mode)
185 		childregs = (struct pt_regs*)(tos - PT_USER_SIZE);
186 	else
187 		childregs = (struct pt_regs*)tos - 1;
188 
189 	*childregs = *regs;
190 
191 	/* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
192 	*((int*)childregs - 3) = (unsigned long)childregs;
193 	*((int*)childregs - 4) = 0;
194 
195 	childregs->areg[1] = tos;
196 	childregs->areg[2] = 0;
197 	p->set_child_tid = p->clear_child_tid = NULL;
198 	p->thread.ra = MAKE_RA_FOR_CALL((unsigned long)ret_from_fork, 0x1);
199 	p->thread.sp = (unsigned long)childregs;
200 
201 	if (user_mode(regs)) {
202 
203 		int len = childregs->wmask & ~0xf;
204 		childregs->areg[1] = usp;
205 		memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
206 		       &regs->areg[XCHAL_NUM_AREGS - len/4], len);
207 // FIXME: we need to set THREADPTR in thread_info...
208 		if (clone_flags & CLONE_SETTLS)
209 			childregs->areg[2] = childregs->areg[6];
210 
211 	} else {
212 		/* In kernel space, we start a new thread with a new stack. */
213 		childregs->wmask = 1;
214 	}
215 
216 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
217 	ti = task_thread_info(p);
218 	ti->cpenable = 0;
219 #endif
220 
221 	return 0;
222 }
223 
224 
225 /*
226  * These bracket the sleeping functions..
227  */
228 
229 unsigned long get_wchan(struct task_struct *p)
230 {
231 	unsigned long sp, pc;
232 	unsigned long stack_page = (unsigned long) task_stack_page(p);
233 	int count = 0;
234 
235 	if (!p || p == current || p->state == TASK_RUNNING)
236 		return 0;
237 
238 	sp = p->thread.sp;
239 	pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
240 
241 	do {
242 		if (sp < stack_page + sizeof(struct task_struct) ||
243 		    sp >= (stack_page + THREAD_SIZE) ||
244 		    pc == 0)
245 			return 0;
246 		if (!in_sched_functions(pc))
247 			return pc;
248 
249 		/* Stack layout: sp-4: ra, sp-3: sp' */
250 
251 		pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
252 		sp = *(unsigned long *)sp - 3;
253 	} while (count++ < 16);
254 	return 0;
255 }
256 
257 /*
258  * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
259  * of processor registers.  Besides different ordering,
260  * xtensa_gregset_t contains non-live register information that
261  * 'struct pt_regs' does not.  Exception handling (primarily) uses
262  * 'struct pt_regs'.  Core files and ptrace use xtensa_gregset_t.
263  *
264  */
265 
266 void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
267 {
268 	unsigned long wb, ws, wm;
269 	int live, last;
270 
271 	wb = regs->windowbase;
272 	ws = regs->windowstart;
273 	wm = regs->wmask;
274 	ws = ((ws >> wb) | (ws << (WSBITS - wb))) & ((1 << WSBITS) - 1);
275 
276 	/* Don't leak any random bits. */
277 
278 	memset(elfregs, 0, sizeof (elfregs));
279 
280 	/* Note:  PS.EXCM is not set while user task is running; its
281 	 * being set in regs->ps is for exception handling convenience.
282 	 */
283 
284 	elfregs->pc		= regs->pc;
285 	elfregs->ps		= (regs->ps & ~(1 << PS_EXCM_BIT));
286 	elfregs->lbeg		= regs->lbeg;
287 	elfregs->lend		= regs->lend;
288 	elfregs->lcount		= regs->lcount;
289 	elfregs->sar		= regs->sar;
290 	elfregs->windowstart	= ws;
291 
292 	live = (wm & 2) ? 4 : (wm & 4) ? 8 : (wm & 8) ? 12 : 16;
293 	last = XCHAL_NUM_AREGS - (wm >> 4) * 4;
294 	memcpy(elfregs->a, regs->areg, live * 4);
295 	memcpy(elfregs->a + last, regs->areg + last, (wm >> 4) * 16);
296 }
297 
298 int dump_fpu(void)
299 {
300 	return 0;
301 }
302 
303 asmlinkage
304 long xtensa_clone(unsigned long clone_flags, unsigned long newsp,
305                   void __user *parent_tid, void *child_tls,
306                   void __user *child_tid, long a5,
307                   struct pt_regs *regs)
308 {
309         if (!newsp)
310                 newsp = regs->areg[1];
311         return do_fork(clone_flags, newsp, regs, 0, parent_tid, child_tid);
312 }
313 
314 /*
315  * xtensa_execve() executes a new program.
316  */
317 
318 asmlinkage
319 long xtensa_execve(const char __user *name,
320 		   const char __user *const __user *argv,
321                    const char __user *const __user *envp,
322                    long a3, long a4, long a5,
323                    struct pt_regs *regs)
324 {
325 	long error;
326 	char * filename;
327 
328 	filename = getname(name);
329 	error = PTR_ERR(filename);
330 	if (IS_ERR(filename))
331 		goto out;
332 	error = do_execve(filename, argv, envp, regs);
333 	putname(filename);
334 out:
335 	return error;
336 }
337 
338