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 #include <linux/rcupdate.h>
35
36 #include <asm/pgtable.h>
37 #include <asm/uaccess.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 extern void ret_from_kernel_thread(void);
49
50 struct task_struct *current_set[NR_CPUS] = {&init_task, };
51
52 void (*pm_power_off)(void) = NULL;
53 EXPORT_SYMBOL(pm_power_off);
54
55
56 #if XTENSA_HAVE_COPROCESSORS
57
coprocessor_release_all(struct thread_info * ti)58 void coprocessor_release_all(struct thread_info *ti)
59 {
60 unsigned long cpenable;
61 int i;
62
63 /* Make sure we don't switch tasks during this operation. */
64
65 preempt_disable();
66
67 /* Walk through all cp owners and release it for the requested one. */
68
69 cpenable = ti->cpenable;
70
71 for (i = 0; i < XCHAL_CP_MAX; i++) {
72 if (coprocessor_owner[i] == ti) {
73 coprocessor_owner[i] = 0;
74 cpenable &= ~(1 << i);
75 }
76 }
77
78 ti->cpenable = cpenable;
79 coprocessor_clear_cpenable();
80
81 preempt_enable();
82 }
83
coprocessor_flush_all(struct thread_info * ti)84 void coprocessor_flush_all(struct thread_info *ti)
85 {
86 unsigned long cpenable, old_cpenable;
87 int i;
88
89 preempt_disable();
90
91 RSR_CPENABLE(old_cpenable);
92 cpenable = ti->cpenable;
93 WSR_CPENABLE(cpenable);
94
95 for (i = 0; i < XCHAL_CP_MAX; i++) {
96 if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
97 coprocessor_flush(ti, i);
98 cpenable >>= 1;
99 }
100 WSR_CPENABLE(old_cpenable);
101
102 preempt_enable();
103 }
104
105 #endif
106
107
108 /*
109 * Powermanagement idle function, if any is provided by the platform.
110 */
arch_cpu_idle(void)111 void arch_cpu_idle(void)
112 {
113 platform_idle();
114 }
115
116 /*
117 * This is called when the thread calls exit().
118 */
exit_thread(struct task_struct * tsk)119 void exit_thread(struct task_struct *tsk)
120 {
121 #if XTENSA_HAVE_COPROCESSORS
122 coprocessor_release_all(task_thread_info(tsk));
123 #endif
124 }
125
126 /*
127 * Flush thread state. This is called when a thread does an execve()
128 * Note that we flush coprocessor registers for the case execve fails.
129 */
flush_thread(void)130 void flush_thread(void)
131 {
132 #if XTENSA_HAVE_COPROCESSORS
133 struct thread_info *ti = current_thread_info();
134 coprocessor_flush_all(ti);
135 coprocessor_release_all(ti);
136 #endif
137 }
138
139 /*
140 * this gets called so that we can store coprocessor state into memory and
141 * copy the current task into the new thread.
142 */
arch_dup_task_struct(struct task_struct * dst,struct task_struct * src)143 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
144 {
145 #if XTENSA_HAVE_COPROCESSORS
146 coprocessor_flush_all(task_thread_info(src));
147 #endif
148 *dst = *src;
149 return 0;
150 }
151
152 /*
153 * Copy thread.
154 *
155 * There are two modes in which this function is called:
156 * 1) Userspace thread creation,
157 * regs != NULL, usp_thread_fn is userspace stack pointer.
158 * It is expected to copy parent regs (in case CLONE_VM is not set
159 * in the clone_flags) and set up passed usp in the childregs.
160 * 2) Kernel thread creation,
161 * regs == NULL, usp_thread_fn is the function to run in the new thread
162 * and thread_fn_arg is its parameter.
163 * childregs are not used for the kernel threads.
164 *
165 * The stack layout for the new thread looks like this:
166 *
167 * +------------------------+
168 * | childregs |
169 * +------------------------+ <- thread.sp = sp in dummy-frame
170 * | dummy-frame | (saved in dummy-frame spill-area)
171 * +------------------------+
172 *
173 * We create a dummy frame to return to either ret_from_fork or
174 * ret_from_kernel_thread:
175 * a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
176 * sp points to itself (thread.sp)
177 * a2, a3 are unused for userspace threads,
178 * a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
179 *
180 * Note: This is a pristine frame, so we don't need any spill region on top of
181 * childregs.
182 *
183 * The fun part: if we're keeping the same VM (i.e. cloning a thread,
184 * not an entire process), we're normally given a new usp, and we CANNOT share
185 * any live address register windows. If we just copy those live frames over,
186 * the two threads (parent and child) will overflow the same frames onto the
187 * parent stack at different times, likely corrupting the parent stack (esp.
188 * if the parent returns from functions that called clone() and calls new
189 * ones, before the child overflows its now old copies of its parent windows).
190 * One solution is to spill windows to the parent stack, but that's fairly
191 * involved. Much simpler to just not copy those live frames across.
192 */
193
copy_thread(unsigned long clone_flags,unsigned long usp_thread_fn,unsigned long thread_fn_arg,struct task_struct * p)194 int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
195 unsigned long thread_fn_arg, struct task_struct *p)
196 {
197 struct pt_regs *childregs = task_pt_regs(p);
198
199 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
200 struct thread_info *ti;
201 #endif
202
203 /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
204 *((int*)childregs - 3) = (unsigned long)childregs;
205 *((int*)childregs - 4) = 0;
206
207 p->thread.sp = (unsigned long)childregs;
208
209 if (!(p->flags & PF_KTHREAD)) {
210 struct pt_regs *regs = current_pt_regs();
211 unsigned long usp = usp_thread_fn ?
212 usp_thread_fn : regs->areg[1];
213
214 p->thread.ra = MAKE_RA_FOR_CALL(
215 (unsigned long)ret_from_fork, 0x1);
216
217 /* This does not copy all the regs.
218 * In a bout of brilliance or madness,
219 * ARs beyond a0-a15 exist past the end of the struct.
220 */
221 *childregs = *regs;
222 childregs->areg[1] = usp;
223 childregs->areg[2] = 0;
224
225 /* When sharing memory with the parent thread, the child
226 usually starts on a pristine stack, so we have to reset
227 windowbase, windowstart and wmask.
228 (Note that such a new thread is required to always create
229 an initial call4 frame)
230 The exception is vfork, where the new thread continues to
231 run on the parent's stack until it calls execve. This could
232 be a call8 or call12, which requires a legal stack frame
233 of the previous caller for the overflow handlers to work.
234 (Note that it's always legal to overflow live registers).
235 In this case, ensure to spill at least the stack pointer
236 of that frame. */
237
238 if (clone_flags & CLONE_VM) {
239 /* check that caller window is live and same stack */
240 int len = childregs->wmask & ~0xf;
241 if (regs->areg[1] == usp && len != 0) {
242 int callinc = (regs->areg[0] >> 30) & 3;
243 int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
244 put_user(regs->areg[caller_ars+1],
245 (unsigned __user*)(usp - 12));
246 }
247 childregs->wmask = 1;
248 childregs->windowstart = 1;
249 childregs->windowbase = 0;
250 } else {
251 int len = childregs->wmask & ~0xf;
252 memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
253 ®s->areg[XCHAL_NUM_AREGS - len/4], len);
254 }
255
256 /* The thread pointer is passed in the '4th argument' (= a5) */
257 if (clone_flags & CLONE_SETTLS)
258 childregs->threadptr = childregs->areg[5];
259 } else {
260 p->thread.ra = MAKE_RA_FOR_CALL(
261 (unsigned long)ret_from_kernel_thread, 1);
262
263 /* pass parameters to ret_from_kernel_thread:
264 * a2 = thread_fn, a3 = thread_fn arg
265 */
266 *((int *)childregs - 1) = thread_fn_arg;
267 *((int *)childregs - 2) = usp_thread_fn;
268
269 /* Childregs are only used when we're going to userspace
270 * in which case start_thread will set them up.
271 */
272 }
273
274 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
275 ti = task_thread_info(p);
276 ti->cpenable = 0;
277 #endif
278
279 return 0;
280 }
281
282
283 /*
284 * These bracket the sleeping functions..
285 */
286
get_wchan(struct task_struct * p)287 unsigned long get_wchan(struct task_struct *p)
288 {
289 unsigned long sp, pc;
290 unsigned long stack_page = (unsigned long) task_stack_page(p);
291 int count = 0;
292
293 if (!p || p == current || p->state == TASK_RUNNING)
294 return 0;
295
296 sp = p->thread.sp;
297 pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
298
299 do {
300 if (sp < stack_page + sizeof(struct task_struct) ||
301 sp >= (stack_page + THREAD_SIZE) ||
302 pc == 0)
303 return 0;
304 if (!in_sched_functions(pc))
305 return pc;
306
307 /* Stack layout: sp-4: ra, sp-3: sp' */
308
309 pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
310 sp = *(unsigned long *)sp - 3;
311 } while (count++ < 16);
312 return 0;
313 }
314
315 /*
316 * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
317 * of processor registers. Besides different ordering,
318 * xtensa_gregset_t contains non-live register information that
319 * 'struct pt_regs' does not. Exception handling (primarily) uses
320 * 'struct pt_regs'. Core files and ptrace use xtensa_gregset_t.
321 *
322 */
323
xtensa_elf_core_copy_regs(xtensa_gregset_t * elfregs,struct pt_regs * regs)324 void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
325 {
326 unsigned long wb, ws, wm;
327 int live, last;
328
329 wb = regs->windowbase;
330 ws = regs->windowstart;
331 wm = regs->wmask;
332 ws = ((ws >> wb) | (ws << (WSBITS - wb))) & ((1 << WSBITS) - 1);
333
334 /* Don't leak any random bits. */
335
336 memset(elfregs, 0, sizeof(*elfregs));
337
338 /* Note: PS.EXCM is not set while user task is running; its
339 * being set in regs->ps is for exception handling convenience.
340 */
341
342 elfregs->pc = regs->pc;
343 elfregs->ps = (regs->ps & ~(1 << PS_EXCM_BIT));
344 elfregs->lbeg = regs->lbeg;
345 elfregs->lend = regs->lend;
346 elfregs->lcount = regs->lcount;
347 elfregs->sar = regs->sar;
348 elfregs->windowstart = ws;
349
350 live = (wm & 2) ? 4 : (wm & 4) ? 8 : (wm & 8) ? 12 : 16;
351 last = XCHAL_NUM_AREGS - (wm >> 4) * 4;
352 memcpy(elfregs->a, regs->areg, live * 4);
353 memcpy(elfregs->a + last, regs->areg + last, (wm >> 4) * 16);
354 }
355
dump_fpu(void)356 int dump_fpu(void)
357 {
358 return 0;
359 }
360