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/sched/debug.h>
21 #include <linux/sched/task.h>
22 #include <linux/sched/task_stack.h>
23 #include <linux/kernel.h>
24 #include <linux/mm.h>
25 #include <linux/smp.h>
26 #include <linux/stddef.h>
27 #include <linux/unistd.h>
28 #include <linux/ptrace.h>
29 #include <linux/elf.h>
30 #include <linux/hw_breakpoint.h>
31 #include <linux/init.h>
32 #include <linux/prctl.h>
33 #include <linux/init_task.h>
34 #include <linux/module.h>
35 #include <linux/mqueue.h>
36 #include <linux/fs.h>
37 #include <linux/slab.h>
38 #include <linux/rcupdate.h>
39
40 #include <linux/uaccess.h>
41 #include <asm/io.h>
42 #include <asm/processor.h>
43 #include <asm/platform.h>
44 #include <asm/mmu.h>
45 #include <asm/irq.h>
46 #include <linux/atomic.h>
47 #include <asm/asm-offsets.h>
48 #include <asm/regs.h>
49 #include <asm/hw_breakpoint.h>
50 #include <asm/sections.h>
51 #include <asm/traps.h>
52
53 extern void ret_from_fork(void);
54 extern void ret_from_kernel_thread(void);
55
56 void (*pm_power_off)(void) = NULL;
57 EXPORT_SYMBOL(pm_power_off);
58
59
60 #ifdef CONFIG_STACKPROTECTOR
61 #include <linux/stackprotector.h>
62 unsigned long __stack_chk_guard __read_mostly;
63 EXPORT_SYMBOL(__stack_chk_guard);
64 #endif
65
66 #if XTENSA_HAVE_COPROCESSORS
67
local_coprocessors_flush_release_all(void)68 void local_coprocessors_flush_release_all(void)
69 {
70 struct thread_info **coprocessor_owner;
71 struct thread_info *unique_owner[XCHAL_CP_MAX];
72 int n = 0;
73 int i, j;
74
75 coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
76 xtensa_set_sr(XCHAL_CP_MASK, cpenable);
77
78 for (i = 0; i < XCHAL_CP_MAX; i++) {
79 struct thread_info *ti = coprocessor_owner[i];
80
81 if (ti) {
82 coprocessor_flush(ti, i);
83
84 for (j = 0; j < n; j++)
85 if (unique_owner[j] == ti)
86 break;
87 if (j == n)
88 unique_owner[n++] = ti;
89
90 coprocessor_owner[i] = NULL;
91 }
92 }
93 for (i = 0; i < n; i++) {
94 /* pairs with memw (1) in fast_coprocessor and memw in switch_to */
95 smp_wmb();
96 unique_owner[i]->cpenable = 0;
97 }
98 xtensa_set_sr(0, cpenable);
99 }
100
local_coprocessor_release_all(void * info)101 static void local_coprocessor_release_all(void *info)
102 {
103 struct thread_info *ti = info;
104 struct thread_info **coprocessor_owner;
105 int i;
106
107 coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
108
109 /* Walk through all cp owners and release it for the requested one. */
110
111 for (i = 0; i < XCHAL_CP_MAX; i++) {
112 if (coprocessor_owner[i] == ti)
113 coprocessor_owner[i] = NULL;
114 }
115 /* pairs with memw (1) in fast_coprocessor and memw in switch_to */
116 smp_wmb();
117 ti->cpenable = 0;
118 if (ti == current_thread_info())
119 xtensa_set_sr(0, cpenable);
120 }
121
coprocessor_release_all(struct thread_info * ti)122 void coprocessor_release_all(struct thread_info *ti)
123 {
124 if (ti->cpenable) {
125 /* pairs with memw (2) in fast_coprocessor */
126 smp_rmb();
127 smp_call_function_single(ti->cp_owner_cpu,
128 local_coprocessor_release_all,
129 ti, true);
130 }
131 }
132
local_coprocessor_flush_all(void * info)133 static void local_coprocessor_flush_all(void *info)
134 {
135 struct thread_info *ti = info;
136 struct thread_info **coprocessor_owner;
137 unsigned long old_cpenable;
138 int i;
139
140 coprocessor_owner = this_cpu_ptr(&exc_table)->coprocessor_owner;
141 old_cpenable = xtensa_xsr(ti->cpenable, cpenable);
142
143 for (i = 0; i < XCHAL_CP_MAX; i++) {
144 if (coprocessor_owner[i] == ti)
145 coprocessor_flush(ti, i);
146 }
147 xtensa_set_sr(old_cpenable, cpenable);
148 }
149
coprocessor_flush_all(struct thread_info * ti)150 void coprocessor_flush_all(struct thread_info *ti)
151 {
152 if (ti->cpenable) {
153 /* pairs with memw (2) in fast_coprocessor */
154 smp_rmb();
155 smp_call_function_single(ti->cp_owner_cpu,
156 local_coprocessor_flush_all,
157 ti, true);
158 }
159 }
160
local_coprocessor_flush_release_all(void * info)161 static void local_coprocessor_flush_release_all(void *info)
162 {
163 local_coprocessor_flush_all(info);
164 local_coprocessor_release_all(info);
165 }
166
coprocessor_flush_release_all(struct thread_info * ti)167 void coprocessor_flush_release_all(struct thread_info *ti)
168 {
169 if (ti->cpenable) {
170 /* pairs with memw (2) in fast_coprocessor */
171 smp_rmb();
172 smp_call_function_single(ti->cp_owner_cpu,
173 local_coprocessor_flush_release_all,
174 ti, true);
175 }
176 }
177
178 #endif
179
180
181 /*
182 * Powermanagement idle function, if any is provided by the platform.
183 */
arch_cpu_idle(void)184 void arch_cpu_idle(void)
185 {
186 platform_idle();
187 raw_local_irq_disable();
188 }
189
190 /*
191 * This is called when the thread calls exit().
192 */
exit_thread(struct task_struct * tsk)193 void exit_thread(struct task_struct *tsk)
194 {
195 #if XTENSA_HAVE_COPROCESSORS
196 coprocessor_release_all(task_thread_info(tsk));
197 #endif
198 }
199
200 /*
201 * Flush thread state. This is called when a thread does an execve()
202 * Note that we flush coprocessor registers for the case execve fails.
203 */
flush_thread(void)204 void flush_thread(void)
205 {
206 #if XTENSA_HAVE_COPROCESSORS
207 struct thread_info *ti = current_thread_info();
208 coprocessor_flush_release_all(ti);
209 #endif
210 flush_ptrace_hw_breakpoint(current);
211 }
212
213 /*
214 * this gets called so that we can store coprocessor state into memory and
215 * copy the current task into the new thread.
216 */
arch_dup_task_struct(struct task_struct * dst,struct task_struct * src)217 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
218 {
219 #if XTENSA_HAVE_COPROCESSORS
220 coprocessor_flush_all(task_thread_info(src));
221 #endif
222 *dst = *src;
223 return 0;
224 }
225
226 /*
227 * Copy thread.
228 *
229 * There are two modes in which this function is called:
230 * 1) Userspace thread creation,
231 * regs != NULL, usp_thread_fn is userspace stack pointer.
232 * It is expected to copy parent regs (in case CLONE_VM is not set
233 * in the clone_flags) and set up passed usp in the childregs.
234 * 2) Kernel thread creation,
235 * regs == NULL, usp_thread_fn is the function to run in the new thread
236 * and thread_fn_arg is its parameter.
237 * childregs are not used for the kernel threads.
238 *
239 * The stack layout for the new thread looks like this:
240 *
241 * +------------------------+
242 * | childregs |
243 * +------------------------+ <- thread.sp = sp in dummy-frame
244 * | dummy-frame | (saved in dummy-frame spill-area)
245 * +------------------------+
246 *
247 * We create a dummy frame to return to either ret_from_fork or
248 * ret_from_kernel_thread:
249 * a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
250 * sp points to itself (thread.sp)
251 * a2, a3 are unused for userspace threads,
252 * a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
253 *
254 * Note: This is a pristine frame, so we don't need any spill region on top of
255 * childregs.
256 *
257 * The fun part: if we're keeping the same VM (i.e. cloning a thread,
258 * not an entire process), we're normally given a new usp, and we CANNOT share
259 * any live address register windows. If we just copy those live frames over,
260 * the two threads (parent and child) will overflow the same frames onto the
261 * parent stack at different times, likely corrupting the parent stack (esp.
262 * if the parent returns from functions that called clone() and calls new
263 * ones, before the child overflows its now old copies of its parent windows).
264 * One solution is to spill windows to the parent stack, but that's fairly
265 * involved. Much simpler to just not copy those live frames across.
266 */
267
copy_thread(struct task_struct * p,const struct kernel_clone_args * args)268 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
269 {
270 unsigned long clone_flags = args->flags;
271 unsigned long usp_thread_fn = args->stack;
272 unsigned long tls = args->tls;
273 struct pt_regs *childregs = task_pt_regs(p);
274
275 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
276 struct thread_info *ti;
277 #endif
278
279 #if defined(__XTENSA_WINDOWED_ABI__)
280 /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
281 SPILL_SLOT(childregs, 1) = (unsigned long)childregs;
282 SPILL_SLOT(childregs, 0) = 0;
283
284 p->thread.sp = (unsigned long)childregs;
285 #elif defined(__XTENSA_CALL0_ABI__)
286 /* Reserve 16 bytes for the _switch_to stack frame. */
287 p->thread.sp = (unsigned long)childregs - 16;
288 #else
289 #error Unsupported Xtensa ABI
290 #endif
291
292 if (!args->fn) {
293 struct pt_regs *regs = current_pt_regs();
294 unsigned long usp = usp_thread_fn ?
295 usp_thread_fn : regs->areg[1];
296
297 p->thread.ra = MAKE_RA_FOR_CALL(
298 (unsigned long)ret_from_fork, 0x1);
299
300 *childregs = *regs;
301 childregs->areg[1] = usp;
302 childregs->areg[2] = 0;
303
304 /* When sharing memory with the parent thread, the child
305 usually starts on a pristine stack, so we have to reset
306 windowbase, windowstart and wmask.
307 (Note that such a new thread is required to always create
308 an initial call4 frame)
309 The exception is vfork, where the new thread continues to
310 run on the parent's stack until it calls execve. This could
311 be a call8 or call12, which requires a legal stack frame
312 of the previous caller for the overflow handlers to work.
313 (Note that it's always legal to overflow live registers).
314 In this case, ensure to spill at least the stack pointer
315 of that frame. */
316
317 if (clone_flags & CLONE_VM) {
318 /* check that caller window is live and same stack */
319 int len = childregs->wmask & ~0xf;
320 if (regs->areg[1] == usp && len != 0) {
321 int callinc = (regs->areg[0] >> 30) & 3;
322 int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
323 put_user(regs->areg[caller_ars+1],
324 (unsigned __user*)(usp - 12));
325 }
326 childregs->wmask = 1;
327 childregs->windowstart = 1;
328 childregs->windowbase = 0;
329 }
330
331 if (clone_flags & CLONE_SETTLS)
332 childregs->threadptr = tls;
333 } else {
334 p->thread.ra = MAKE_RA_FOR_CALL(
335 (unsigned long)ret_from_kernel_thread, 1);
336
337 /* pass parameters to ret_from_kernel_thread: */
338 #if defined(__XTENSA_WINDOWED_ABI__)
339 /*
340 * a2 = thread_fn, a3 = thread_fn arg.
341 * Window underflow will load registers from the
342 * spill slots on the stack on return from _switch_to.
343 */
344 SPILL_SLOT(childregs, 2) = (unsigned long)args->fn;
345 SPILL_SLOT(childregs, 3) = (unsigned long)args->fn_arg;
346 #elif defined(__XTENSA_CALL0_ABI__)
347 /*
348 * a12 = thread_fn, a13 = thread_fn arg.
349 * _switch_to epilogue will load registers from the stack.
350 */
351 ((unsigned long *)p->thread.sp)[0] = (unsigned long)args->fn;
352 ((unsigned long *)p->thread.sp)[1] = (unsigned long)args->fn_arg;
353 #else
354 #error Unsupported Xtensa ABI
355 #endif
356
357 /* Childregs are only used when we're going to userspace
358 * in which case start_thread will set them up.
359 */
360 }
361
362 #if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
363 ti = task_thread_info(p);
364 ti->cpenable = 0;
365 #endif
366
367 clear_ptrace_hw_breakpoint(p);
368
369 return 0;
370 }
371
372
373 /*
374 * These bracket the sleeping functions..
375 */
376
__get_wchan(struct task_struct * p)377 unsigned long __get_wchan(struct task_struct *p)
378 {
379 unsigned long sp, pc;
380 unsigned long stack_page = (unsigned long) task_stack_page(p);
381 int count = 0;
382
383 sp = p->thread.sp;
384 pc = MAKE_PC_FROM_RA(p->thread.ra, _text);
385
386 do {
387 if (sp < stack_page + sizeof(struct task_struct) ||
388 sp >= (stack_page + THREAD_SIZE) ||
389 pc == 0)
390 return 0;
391 if (!in_sched_functions(pc))
392 return pc;
393
394 /* Stack layout: sp-4: ra, sp-3: sp' */
395
396 pc = MAKE_PC_FROM_RA(SPILL_SLOT(sp, 0), _text);
397 sp = SPILL_SLOT(sp, 1);
398 } while (count++ < 16);
399 return 0;
400 }
401