arch/arm64/kernel/process.c

   1 /*
   2  * Based on arch/arm/kernel/process.c
   3  *
   4  * Original Copyright (C) 1995  Linus Torvalds
   5  * Copyright (C) 1996-2000 Russell King - Converted to ARM.
   6  * Copyright (C) 2012 ARM Ltd.
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <stdarg.h>
  22
  23 #include <linux/export.h>
  24 #include <linux/sched.h>
  25 #include <linux/kernel.h>
  26 #include <linux/mm.h>
  27 #include <linux/stddef.h>
  28 #include <linux/unistd.h>
  29 #include <linux/user.h>
  30 #include <linux/delay.h>
  31 #include <linux/reboot.h>
  32 #include <linux/interrupt.h>
  33 #include <linux/kallsyms.h>
  34 #include <linux/init.h>
  35 #include <linux/cpu.h>
  36 #include <linux/elfcore.h>
  37 #include <linux/pm.h>
  38 #include <linux/tick.h>
  39 #include <linux/utsname.h>
  40 #include <linux/uaccess.h>
  41 #include <linux/random.h>
  42 #include <linux/hw_breakpoint.h>
  43 #include <linux/personality.h>
  44 #include <linux/notifier.h>
  45
  46 #include <asm/compat.h>
  47 #include <asm/cacheflush.h>
  48 #include <asm/processor.h>
  49 #include <asm/stacktrace.h>
  50 #include <asm/fpsimd.h>
  51
  52 static void setup_restart(void)
  53 {
  54         /*
  55          * Tell the mm system that we are going to reboot -
  56          * we may need it to insert some 1:1 mappings so that
  57          * soft boot works.
  58          */
  59         setup_mm_for_reboot();
  60
  61         /* Clean and invalidate caches */
  62         flush_cache_all();
  63
  64         /* Turn D-cache off */
  65         cpu_cache_off();
  66
  67         /* Push out any further dirty data, and ensure cache is empty */
  68         flush_cache_all();
  69 }
  70
  71 void soft_restart(unsigned long addr)
  72 {
  73         setup_restart();
  74         cpu_reset(addr);
  75 }
  76
  77 /*
  78  * Function pointers to optional machine specific functions
  79  */
  80 void (*pm_power_off)(void);
  81 EXPORT_SYMBOL_GPL(pm_power_off);
  82
  83 void (*pm_restart)(const char *cmd);
  84 EXPORT_SYMBOL_GPL(pm_restart);
  85
  86
  87 /*
  88  * This is our default idle handler.
  89  */
  90 static void default_idle(void)
  91 {
  92         /*
  93          * This should do all the clock switching and wait for interrupt
  94          * tricks
  95          */
  96         cpu_do_idle();
  97         local_irq_enable();
  98 }
  99
 100 void (*pm_idle)(void) = default_idle;
 101 EXPORT_SYMBOL_GPL(pm_idle);
 102
 103 /*
 104  * The idle thread, has rather strange semantics for calling pm_idle,
 105  * but this is what x86 does and we need to do the same, so that
 106  * things like cpuidle get called in the same way.  The only difference
 107  * is that we always respect 'hlt_counter' to prevent low power idle.
 108  */
 109 void cpu_idle(void)
 110 {
 111         local_fiq_enable();
 112
 113         /* endless idle loop with no priority at all */
 114         while (1) {
 115                 tick_nohz_idle_enter();
 116                 rcu_idle_enter();
 117                 while (!need_resched()) {
 118                         /*
 119                          * We need to disable interrupts here to ensure
 120                          * we don't miss a wakeup call.
 121                          */
 122                         local_irq_disable();
 123                         if (!need_resched()) {
 124                                 stop_critical_timings();
 125                                 pm_idle();
 126                                 start_critical_timings();
 127                                 /*
 128                                  * pm_idle functions should always return
 129                                  * with IRQs enabled.
 130                                  */
 131                                 WARN_ON(irqs_disabled());
 132                         } else {
 133                                 local_irq_enable();
 134                         }
 135                 }
 136                 rcu_idle_exit();
 137                 tick_nohz_idle_exit();
 138                 schedule_preempt_disabled();
 139         }
 140 }
 141
 142 void machine_shutdown(void)
 143 {
 144 #ifdef CONFIG_SMP
 145         smp_send_stop();
 146 #endif
 147 }
 148
 149 void machine_halt(void)
 150 {
 151         machine_shutdown();
 152         while (1);
 153 }
 154
 155 void machine_power_off(void)
 156 {
 157         machine_shutdown();
 158         if (pm_power_off)
 159                 pm_power_off();
 160 }
 161
 162 void machine_restart(char *cmd)
 163 {
 164         machine_shutdown();
 165
 166         /* Disable interrupts first */
 167         local_irq_disable();
 168         local_fiq_disable();
 169
 170         /* Now call the architecture specific reboot code. */
 171         if (pm_restart)
 172                 pm_restart(cmd);
 173
 174         /*
 175          * Whoops - the architecture was unable to reboot.
 176          */
 177         printk("Reboot failed -- System halted\n");
 178         while (1);
 179 }
 180
 181 void __show_regs(struct pt_regs *regs)
 182 {
 183         int i;
 184
 185         printk("CPU: %d    %s  (%s %.*s)\n",
 186                 raw_smp_processor_id(), print_tainted(),
 187                 init_utsname()->release,
 188                 (int)strcspn(init_utsname()->version, " "),
 189                 init_utsname()->version);
 190         print_symbol("PC is at %s\n", instruction_pointer(regs));
 191         print_symbol("LR is at %s\n", regs->regs[30]);
 192         printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
 193                regs->pc, regs->regs[30], regs->pstate);
 194         printk("sp : %016llx\n", regs->sp);
 195         for (i = 29; i >= 0; i--) {
 196                 printk("x%-2d: %016llx ", i, regs->regs[i]);
 197                 if (i % 2 == 0)
 198                         printk("\n");
 199         }
 200         printk("\n");
 201 }
 202
 203 void show_regs(struct pt_regs * regs)
 204 {
 205         printk("\n");
 206         printk("Pid: %d, comm: %20s\n", task_pid_nr(current), current->comm);
 207         __show_regs(regs);
 208 }
 209
 210 /*
 211  * Free current thread data structures etc..
 212  */
 213 void exit_thread(void)
 214 {
 215 }
 216
 217 void flush_thread(void)
 218 {
 219         fpsimd_flush_thread();
 220         flush_ptrace_hw_breakpoint(current);
 221 }
 222
 223 void release_thread(struct task_struct *dead_task)
 224 {
 225 }
 226
 227 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 228 {
 229         fpsimd_save_state(&current->thread.fpsimd_state);
 230         *dst = *src;
 231         return 0;
 232 }
 233
 234 asmlinkage void ret_from_fork(void) asm("ret_from_fork");
 235
 236 int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 237                 unsigned long stk_sz, struct task_struct *p,
 238                 struct pt_regs *regs)
 239 {
 240         struct pt_regs *childregs = task_pt_regs(p);
 241         unsigned long tls = p->thread.tp_value;
 242
 243         *childregs = *regs;
 244         childregs->regs[0] = 0;
 245
 246         if (is_compat_thread(task_thread_info(p)))
 247                 childregs->compat_sp = stack_start;
 248         else {
 249                 /*
 250                  * Read the current TLS pointer from tpidr_el0 as it may be
 251                  * out-of-sync with the saved value.
 252                  */
 253                 asm("mrs %0, tpidr_el0" : "=r" (tls));
 254                 childregs->sp = stack_start;
 255         }
 256
 257         memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
 258         p->thread.cpu_context.sp = (unsigned long)childregs;
 259         p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
 260
 261         /* If a TLS pointer was passed to clone, use that for the new thread. */
 262         if (clone_flags & CLONE_SETTLS)
 263                 tls = regs->regs[3];
 264         p->thread.tp_value = tls;
 265
 266         ptrace_hw_copy_thread(p);
 267
 268         return 0;
 269 }
 270
 271 static void tls_thread_switch(struct task_struct *next)
 272 {
 273         unsigned long tpidr, tpidrro;
 274
 275         if (!is_compat_task()) {
 276                 asm("mrs %0, tpidr_el0" : "=r" (tpidr));
 277                 current->thread.tp_value = tpidr;
 278         }
 279
 280         if (is_compat_thread(task_thread_info(next))) {
 281                 tpidr = 0;
 282                 tpidrro = next->thread.tp_value;
 283         } else {
 284                 tpidr = next->thread.tp_value;
 285                 tpidrro = 0;
 286         }
 287
 288         asm(
 289         "       msr     tpidr_el0, %0\n"
 290         "       msr     tpidrro_el0, %1"
 291         : : "r" (tpidr), "r" (tpidrro));
 292 }
 293
 294 /*
 295  * Thread switching.
 296  */
 297 struct task_struct *__switch_to(struct task_struct *prev,
 298                                 struct task_struct *next)
 299 {
 300         struct task_struct *last;
 301
 302         fpsimd_thread_switch(next);
 303         tls_thread_switch(next);
 304         hw_breakpoint_thread_switch(next);
 305
 306         /* the actual thread switch */
 307         last = cpu_switch_to(prev, next);
 308
 309         return last;
 310 }
 311
 312 /*
 313  * Fill in the task's elfregs structure for a core dump.
 314  */
 315 int dump_task_regs(struct task_struct *t, elf_gregset_t *elfregs)
 316 {
 317         elf_core_copy_regs(elfregs, task_pt_regs(t));
 318         return 1;
 319 }
 320
 321 /*
 322  * fill in the fpe structure for a core dump...
 323  */
 324 int dump_fpu (struct pt_regs *regs, struct user_fp *fp)
 325 {
 326         return 0;
 327 }
 328 EXPORT_SYMBOL(dump_fpu);
 329
 330 /*
 331  * Shuffle the argument into the correct register before calling the
 332  * thread function.  x1 is the thread argument, x2 is the pointer to
 333  * the thread function, and x3 points to the exit function.
 334  */
 335 extern void kernel_thread_helper(void);
 336 asm(    ".section .text\n"
 337 "       .align\n"
 338 "       .type   kernel_thread_helper, #function\n"
 339 "kernel_thread_helper:\n"
 340 "       mov     x0, x1\n"
 341 "       mov     x30, x3\n"
 342 "       br      x2\n"
 343 "       .size   kernel_thread_helper, . - kernel_thread_helper\n"
 344 "       .previous");
 345
 346 #define kernel_thread_exit      do_exit
 347
 348 /*
 349  * Create a kernel thread.
 350  */
 351 pid_t kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
 352 {
 353         struct pt_regs regs;
 354
 355         memset(&regs, 0, sizeof(regs));
 356
 357         regs.regs[1] = (unsigned long)arg;
 358         regs.regs[2] = (unsigned long)fn;
 359         regs.regs[3] = (unsigned long)kernel_thread_exit;
 360         regs.pc = (unsigned long)kernel_thread_helper;
 361         regs.pstate = PSR_MODE_EL1h;
 362
 363         return do_fork(flags|CLONE_VM|CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
 364 }
 365 EXPORT_SYMBOL(kernel_thread);
 366
 367 unsigned long get_wchan(struct task_struct *p)
 368 {
 369         struct stackframe frame;
 370         int count = 0;
 371         if (!p || p == current || p->state == TASK_RUNNING)
 372                 return 0;
 373
 374         frame.fp = thread_saved_fp(p);
 375         frame.sp = thread_saved_sp(p);
 376         frame.pc = thread_saved_pc(p);
 377         do {
 378                 int ret = unwind_frame(&frame);
 379                 if (ret < 0)
 380                         return 0;
 381                 if (!in_sched_functions(frame.pc))
 382                         return frame.pc;
 383         } while (count ++ < 16);
 384         return 0;
 385 }
 386
 387 unsigned long arch_align_stack(unsigned long sp)
 388 {
 389         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 390                 sp -= get_random_int() & ~PAGE_MASK;
 391         return sp & ~0xf;
 392 }
 393
 394 static unsigned long randomize_base(unsigned long base)
 395 {
 396         unsigned long range_end = base + (STACK_RND_MASK << PAGE_SHIFT) + 1;
 397         return randomize_range(base, range_end, 0) ? : base;
 398 }
 399
 400 unsigned long arch_randomize_brk(struct mm_struct *mm)
 401 {
 402         return randomize_base(mm->brk);
 403 }
 404
 405 unsigned long randomize_et_dyn(unsigned long base)
 406 {
 407         return randomize_base(base);
 408 }