1 /*
2 * linux/arch/alpha/kernel/process.c
3 *
4 * Copyright (C) 1995 Linus Torvalds
5 */
6
7 /*
8 * This file handles the architecture-dependent parts of process handling.
9 */
10
11 #include <linux/errno.h>
12 #include <linux/module.h>
13 #include <linux/sched.h>
14 #include <linux/kernel.h>
15 #include <linux/mm.h>
16 #include <linux/smp.h>
17 #include <linux/stddef.h>
18 #include <linux/unistd.h>
19 #include <linux/ptrace.h>
20 #include <linux/user.h>
21 #include <linux/time.h>
22 #include <linux/major.h>
23 #include <linux/stat.h>
24 #include <linux/vt.h>
25 #include <linux/mman.h>
26 #include <linux/elfcore.h>
27 #include <linux/reboot.h>
28 #include <linux/tty.h>
29 #include <linux/console.h>
30 #include <linux/slab.h>
31 #include <linux/rcupdate.h>
32
33 #include <asm/reg.h>
34 #include <asm/uaccess.h>
35 #include <asm/io.h>
36 #include <asm/pgtable.h>
37 #include <asm/hwrpb.h>
38 #include <asm/fpu.h>
39
40 #include "proto.h"
41 #include "pci_impl.h"
42
43 /*
44 * Power off function, if any
45 */
46 void (*pm_power_off)(void) = machine_power_off;
47 EXPORT_SYMBOL(pm_power_off);
48
49 #ifdef CONFIG_ALPHA_WTINT
50 /*
51 * Sleep the CPU.
52 * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts.
53 */
54 void arch_cpu_idle(void)
55 {
56 wtint(0);
57 local_irq_enable();
58 }
59
60 void arch_cpu_idle_dead(void)
61 {
62 wtint(INT_MAX);
63 }
64 #endif /* ALPHA_WTINT */
65
66 struct halt_info {
67 int mode;
68 char *restart_cmd;
69 };
70
71 static void
72 common_shutdown_1(void *generic_ptr)
73 {
74 struct halt_info *how = (struct halt_info *)generic_ptr;
75 struct percpu_struct *cpup;
76 unsigned long *pflags, flags;
77 int cpuid = smp_processor_id();
78
79 /* No point in taking interrupts anymore. */
80 local_irq_disable();
81
82 cpup = (struct percpu_struct *)
83 ((unsigned long)hwrpb + hwrpb->processor_offset
84 + hwrpb->processor_size * cpuid);
85 pflags = &cpup->flags;
86 flags = *pflags;
87
88 /* Clear reason to "default"; clear "bootstrap in progress". */
89 flags &= ~0x00ff0001UL;
90
91 #ifdef CONFIG_SMP
92 /* Secondaries halt here. */
93 if (cpuid != boot_cpuid) {
94 flags |= 0x00040000UL; /* "remain halted" */
95 *pflags = flags;
96 set_cpu_present(cpuid, false);
97 set_cpu_possible(cpuid, false);
98 halt();
99 }
100 #endif
101
102 if (how->mode == LINUX_REBOOT_CMD_RESTART) {
103 if (!how->restart_cmd) {
104 flags |= 0x00020000UL; /* "cold bootstrap" */
105 } else {
106 /* For SRM, we could probably set environment
107 variables to get this to work. We'd have to
108 delay this until after srm_paging_stop unless
109 we ever got srm_fixup working.
110
111 At the moment, SRM will use the last boot device,
112 but the file and flags will be the defaults, when
113 doing a "warm" bootstrap. */
114 flags |= 0x00030000UL; /* "warm bootstrap" */
115 }
116 } else {
117 flags |= 0x00040000UL; /* "remain halted" */
118 }
119 *pflags = flags;
120
121 #ifdef CONFIG_SMP
122 /* Wait for the secondaries to halt. */
123 set_cpu_present(boot_cpuid, false);
124 set_cpu_possible(boot_cpuid, false);
125 while (cpumask_weight(cpu_present_mask))
126 barrier();
127 #endif
128
129 /* If booted from SRM, reset some of the original environment. */
130 if (alpha_using_srm) {
131 #ifdef CONFIG_DUMMY_CONSOLE
132 /* If we've gotten here after SysRq-b, leave interrupt
133 context before taking over the console. */
134 if (in_interrupt())
135 irq_exit();
136 /* This has the effect of resetting the VGA video origin. */
137 console_lock();
138 do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);
139 console_unlock();
140 #endif
141 pci_restore_srm_config();
142 set_hae(srm_hae);
143 }
144
145 if (alpha_mv.kill_arch)
146 alpha_mv.kill_arch(how->mode);
147
148 if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {
149 /* Unfortunately, since MILO doesn't currently understand
150 the hwrpb bits above, we can't reliably halt the
151 processor and keep it halted. So just loop. */
152 return;
153 }
154
155 if (alpha_using_srm)
156 srm_paging_stop();
157
158 halt();
159 }
160
161 static void
162 common_shutdown(int mode, char *restart_cmd)
163 {
164 struct halt_info args;
165 args.mode = mode;
166 args.restart_cmd = restart_cmd;
167 on_each_cpu(common_shutdown_1, &args, 0);
168 }
169
170 void
171 machine_restart(char *restart_cmd)
172 {
173 common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);
174 }
175
176
177 void
178 machine_halt(void)
179 {
180 common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);
181 }
182
183
184 void
185 machine_power_off(void)
186 {
187 common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);
188 }
189
190
191 /* Used by sysrq-p, among others. I don't believe r9-r15 are ever
192 saved in the context it's used. */
193
194 void
195 show_regs(struct pt_regs *regs)
196 {
197 show_regs_print_info(KERN_DEFAULT);
198 dik_show_regs(regs, NULL);
199 }
200
201 /*
202 * Re-start a thread when doing execve()
203 */
204 void
205 start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
206 {
207 regs->pc = pc;
208 regs->ps = 8;
209 wrusp(sp);
210 }
211 EXPORT_SYMBOL(start_thread);
212
213 /*
214 * Free current thread data structures etc..
215 */
216 void
217 exit_thread(void)
218 {
219 }
220
221 void
222 flush_thread(void)
223 {
224 /* Arrange for each exec'ed process to start off with a clean slate
225 with respect to the FPU. This is all exceptions disabled. */
226 current_thread_info()->ieee_state = 0;
227 wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0));
228
229 /* Clean slate for TLS. */
230 current_thread_info()->pcb.unique = 0;
231 }
232
233 void
234 release_thread(struct task_struct *dead_task)
235 {
236 }
237
238 /*
239 * Copy architecture-specific thread state
240 */
241 int
242 copy_thread(unsigned long clone_flags, unsigned long usp,
243 unsigned long kthread_arg,
244 struct task_struct *p)
245 {
246 extern void ret_from_fork(void);
247 extern void ret_from_kernel_thread(void);
248
249 struct thread_info *childti = task_thread_info(p);
250 struct pt_regs *childregs = task_pt_regs(p);
251 struct pt_regs *regs = current_pt_regs();
252 struct switch_stack *childstack, *stack;
253
254 childstack = ((struct switch_stack *) childregs) - 1;
255 childti->pcb.ksp = (unsigned long) childstack;
256 childti->pcb.flags = 1; /* set FEN, clear everything else */
257
258 if (unlikely(p->flags & PF_KTHREAD)) {
259 /* kernel thread */
260 memset(childstack, 0,
261 sizeof(struct switch_stack) + sizeof(struct pt_regs));
262 childstack->r26 = (unsigned long) ret_from_kernel_thread;
263 childstack->r9 = usp; /* function */
264 childstack->r10 = kthread_arg;
265 childregs->hae = alpha_mv.hae_cache,
266 childti->pcb.usp = 0;
267 return 0;
268 }
269 /* Note: if CLONE_SETTLS is not set, then we must inherit the
270 value from the parent, which will have been set by the block
271 copy in dup_task_struct. This is non-intuitive, but is
272 required for proper operation in the case of a threaded
273 application calling fork. */
274 if (clone_flags & CLONE_SETTLS)
275 childti->pcb.unique = regs->r20;
276 childti->pcb.usp = usp ?: rdusp();
277 *childregs = *regs;
278 childregs->r0 = 0;
279 childregs->r19 = 0;
280 childregs->r20 = 1; /* OSF/1 has some strange fork() semantics. */
281 regs->r20 = 0;
282 stack = ((struct switch_stack *) regs) - 1;
283 *childstack = *stack;
284 childstack->r26 = (unsigned long) ret_from_fork;
285 return 0;
286 }
287
288 /*
289 * Fill in the user structure for a ELF core dump.
290 */
291 void
292 dump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti)
293 {
294 /* switch stack follows right below pt_regs: */
295 struct switch_stack * sw = ((struct switch_stack *) pt) - 1;
296
297 dest[ 0] = pt->r0;
298 dest[ 1] = pt->r1;
299 dest[ 2] = pt->r2;
300 dest[ 3] = pt->r3;
301 dest[ 4] = pt->r4;
302 dest[ 5] = pt->r5;
303 dest[ 6] = pt->r6;
304 dest[ 7] = pt->r7;
305 dest[ 8] = pt->r8;
306 dest[ 9] = sw->r9;
307 dest[10] = sw->r10;
308 dest[11] = sw->r11;
309 dest[12] = sw->r12;
310 dest[13] = sw->r13;
311 dest[14] = sw->r14;
312 dest[15] = sw->r15;
313 dest[16] = pt->r16;
314 dest[17] = pt->r17;
315 dest[18] = pt->r18;
316 dest[19] = pt->r19;
317 dest[20] = pt->r20;
318 dest[21] = pt->r21;
319 dest[22] = pt->r22;
320 dest[23] = pt->r23;
321 dest[24] = pt->r24;
322 dest[25] = pt->r25;
323 dest[26] = pt->r26;
324 dest[27] = pt->r27;
325 dest[28] = pt->r28;
326 dest[29] = pt->gp;
327 dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;
328 dest[31] = pt->pc;
329
330 /* Once upon a time this was the PS value. Which is stupid
331 since that is always 8 for usermode. Usurped for the more
332 useful value of the thread's UNIQUE field. */
333 dest[32] = ti->pcb.unique;
334 }
335 EXPORT_SYMBOL(dump_elf_thread);
336
337 int
338 dump_elf_task(elf_greg_t *dest, struct task_struct *task)
339 {
340 dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));
341 return 1;
342 }
343 EXPORT_SYMBOL(dump_elf_task);
344
345 int
346 dump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task)
347 {
348 struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;
349 memcpy(dest, sw->fp, 32 * 8);
350 return 1;
351 }
352 EXPORT_SYMBOL(dump_elf_task_fp);
353
354 /*
355 * Return saved PC of a blocked thread. This assumes the frame
356 * pointer is the 6th saved long on the kernel stack and that the
357 * saved return address is the first long in the frame. This all
358 * holds provided the thread blocked through a call to schedule() ($15
359 * is the frame pointer in schedule() and $15 is saved at offset 48 by
360 * entry.S:do_switch_stack).
361 *
362 * Under heavy swap load I've seen this lose in an ugly way. So do
363 * some extra sanity checking on the ranges we expect these pointers
364 * to be in so that we can fail gracefully. This is just for ps after
365 * all. -- r~
366 */
367
368 unsigned long
369 thread_saved_pc(struct task_struct *t)
370 {
371 unsigned long base = (unsigned long)task_stack_page(t);
372 unsigned long fp, sp = task_thread_info(t)->pcb.ksp;
373
374 if (sp > base && sp+6*8 < base + 16*1024) {
375 fp = ((unsigned long*)sp)[6];
376 if (fp > sp && fp < base + 16*1024)
377 return *(unsigned long *)fp;
378 }
379
380 return 0;
381 }
382
383 unsigned long
384 get_wchan(struct task_struct *p)
385 {
386 unsigned long schedule_frame;
387 unsigned long pc;
388 if (!p || p == current || p->state == TASK_RUNNING)
389 return 0;
390 /*
391 * This one depends on the frame size of schedule(). Do a
392 * "disass schedule" in gdb to find the frame size. Also, the
393 * code assumes that sleep_on() follows immediately after
394 * interruptible_sleep_on() and that add_timer() follows
395 * immediately after interruptible_sleep(). Ugly, isn't it?
396 * Maybe adding a wchan field to task_struct would be better,
397 * after all...
398 */
399
400 pc = thread_saved_pc(p);
401 if (in_sched_functions(pc)) {
402 schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];
403 return ((unsigned long *)schedule_frame)[12];
404 }
405 return pc;
406 }
407
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