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/fpsimd.h>
  49 #include <asm/mmu_context.h>
  50 #include <asm/processor.h>
  51 #include <asm/stacktrace.h>
  52
  53 static void setup_restart(void)
  54 {
  55         /*
  56          * Tell the mm system that we are going to reboot -
  57          * we may need it to insert some 1:1 mappings so that
  58          * soft boot works.
  59          */
  60         setup_mm_for_reboot();
  61
  62         /* Clean and invalidate caches */
  63         flush_cache_all();
  64
  65         /* Turn D-cache off */
  66         cpu_cache_off();
  67
  68         /* Push out any further dirty data, and ensure cache is empty */
  69         flush_cache_all();
  70 }
  71
  72 void soft_restart(unsigned long addr)
  73 {
  74         setup_restart();
  75         cpu_reset(addr);
  76 }
  77
  78 /*
  79  * Function pointers to optional machine specific functions
  80  */
  81 void (*pm_power_off)(void);
  82 EXPORT_SYMBOL_GPL(pm_power_off);
  83
  84 void (*pm_restart)(const char *cmd);
  85 EXPORT_SYMBOL_GPL(pm_restart);
  86
  87
  88 /*
  89  * This is our default idle handler.
  90  */
  91 static void default_idle(void)
  92 {
  93         /*
  94          * This should do all the clock switching and wait for interrupt
  95          * tricks
  96          */
  97         cpu_do_idle();
  98         local_irq_enable();
  99 }
 100
 101 void (*pm_idle)(void) = default_idle;
 102 EXPORT_SYMBOL_GPL(pm_idle);
 103
 104 /*
 105  * The idle thread, has rather strange semantics for calling pm_idle,
 106  * but this is what x86 does and we need to do the same, so that
 107  * things like cpuidle get called in the same way.  The only difference
 108  * is that we always respect 'hlt_counter' to prevent low power idle.
 109  */
 110 void cpu_idle(void)
 111 {
 112         local_fiq_enable();
 113
 114         /* endless idle loop with no priority at all */
 115         while (1) {
 116                 tick_nohz_idle_enter();
 117                 rcu_idle_enter();
 118                 while (!need_resched()) {
 119                         /*
 120                          * We need to disable interrupts here to ensure
 121                          * we don't miss a wakeup call.
 122                          */
 123                         local_irq_disable();
 124                         if (!need_resched()) {
 125                                 stop_critical_timings();
 126                                 pm_idle();
 127                                 start_critical_timings();
 128                                 /*
 129                                  * pm_idle functions should always return
 130                                  * with IRQs enabled.
 131                                  */
 132                                 WARN_ON(irqs_disabled());
 133                         } else {
 134                                 local_irq_enable();
 135                         }
 136                 }
 137                 rcu_idle_exit();
 138                 tick_nohz_idle_exit();
 139                 schedule_preempt_disabled();
 140         }
 141 }
 142
 143 void machine_shutdown(void)
 144 {
 145 #ifdef CONFIG_SMP
 146         smp_send_stop();
 147 #endif
 148 }
 149
 150 void machine_halt(void)
 151 {
 152         machine_shutdown();
 153         while (1);
 154 }
 155
 156 void machine_power_off(void)
 157 {
 158         machine_shutdown();
 159         if (pm_power_off)
 160                 pm_power_off();
 161 }
 162
 163 void machine_restart(char *cmd)
 164 {
 165         machine_shutdown();
 166
 167         /* Disable interrupts first */
 168         local_irq_disable();
 169         local_fiq_disable();
 170
 171         /* Now call the architecture specific reboot code. */
 172         if (pm_restart)
 173                 pm_restart(cmd);
 174
 175         /*
 176          * Whoops - the architecture was unable to reboot.
 177          */
 178         printk("Reboot failed -- System halted\n");
 179         while (1);
 180 }
 181
 182 void __show_regs(struct pt_regs *regs)
 183 {
 184         int i;
 185
 186         printk("CPU: %d    %s  (%s %.*s)\n",
 187                 raw_smp_processor_id(), print_tainted(),
 188                 init_utsname()->release,
 189                 (int)strcspn(init_utsname()->version, " "),
 190                 init_utsname()->version);
 191         print_symbol("PC is at %s\n", instruction_pointer(regs));
 192         print_symbol("LR is at %s\n", regs->regs[30]);
 193         printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
 194                regs->pc, regs->regs[30], regs->pstate);
 195         printk("sp : %016llx\n", regs->sp);
 196         for (i = 29; i >= 0; i--) {
 197                 printk("x%-2d: %016llx ", i, regs->regs[i]);
 198                 if (i % 2 == 0)
 199                         printk("\n");
 200         }
 201         printk("\n");
 202 }
 203
 204 void show_regs(struct pt_regs * regs)
 205 {
 206         printk("\n");
 207         printk("Pid: %d, comm: %20s\n", task_pid_nr(current), current->comm);
 208         __show_regs(regs);
 209 }
 210
 211 /*
 212  * Free current thread data structures etc..
 213  */
 214 void exit_thread(void)
 215 {
 216 }
 217
 218 void flush_thread(void)
 219 {
 220         fpsimd_flush_thread();
 221         flush_ptrace_hw_breakpoint(current);
 222 }
 223
 224 void release_thread(struct task_struct *dead_task)
 225 {
 226 }
 227
 228 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 229 {
 230         fpsimd_save_state(&current->thread.fpsimd_state);
 231         *dst = *src;
 232         return 0;
 233 }
 234
 235 asmlinkage void ret_from_fork(void) asm("ret_from_fork");
 236
 237 int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 238                 unsigned long stk_sz, struct task_struct *p)
 239 {
 240         struct pt_regs *childregs = task_pt_regs(p);
 241         unsigned long tls = p->thread.tp_value;
 242
 243         memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
 244
 245         if (likely(!(p->flags & PF_KTHREAD))) {
 246                 *childregs = *current_pt_regs();
 247                 childregs->regs[0] = 0;
 248                 if (is_compat_thread(task_thread_info(p))) {
 249                         if (stack_start)
 250                                 childregs->compat_sp = stack_start;
 251                 } else {
 252                         /*
 253                          * Read the current TLS pointer from tpidr_el0 as it may be
 254                          * out-of-sync with the saved value.
 255                          */
 256                         asm("mrs %0, tpidr_el0" : "=r" (tls));
 257                         if (stack_start) {
 258                                 /* 16-byte aligned stack mandatory on AArch64 */
 259                                 if (stack_start & 15)
 260                                         return -EINVAL;
 261                                 childregs->sp = stack_start;
 262                         }
 263                 }
 264                 /*
 265                  * If a TLS pointer was passed to clone (4th argument), use it
 266                  * for the new thread.
 267                  */
 268                 if (clone_flags & CLONE_SETTLS)
 269                         tls = childregs->regs[3];
 270         } else {
 271                 memset(childregs, 0, sizeof(struct pt_regs));
 272                 childregs->pstate = PSR_MODE_EL1h;
 273                 p->thread.cpu_context.x19 = stack_start;
 274                 p->thread.cpu_context.x20 = stk_sz;
 275         }
 276         p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
 277         p->thread.cpu_context.sp = (unsigned long)childregs;
 278         p->thread.tp_value = tls;
 279
 280         ptrace_hw_copy_thread(p);
 281
 282         return 0;
 283 }
 284
 285 static void tls_thread_switch(struct task_struct *next)
 286 {
 287         unsigned long tpidr, tpidrro;
 288
 289         if (!is_compat_task()) {
 290                 asm("mrs %0, tpidr_el0" : "=r" (tpidr));
 291                 current->thread.tp_value = tpidr;
 292         }
 293
 294         if (is_compat_thread(task_thread_info(next))) {
 295                 tpidr = 0;
 296                 tpidrro = next->thread.tp_value;
 297         } else {
 298                 tpidr = next->thread.tp_value;
 299                 tpidrro = 0;
 300         }
 301
 302         asm(
 303         "       msr     tpidr_el0, %0\n"
 304         "       msr     tpidrro_el0, %1"
 305         : : "r" (tpidr), "r" (tpidrro));
 306 }
 307
 308 /*
 309  * Thread switching.
 310  */
 311 struct task_struct *__switch_to(struct task_struct *prev,
 312                                 struct task_struct *next)
 313 {
 314         struct task_struct *last;
 315
 316         fpsimd_thread_switch(next);
 317         tls_thread_switch(next);
 318         hw_breakpoint_thread_switch(next);
 319
 320         /* the actual thread switch */
 321         last = cpu_switch_to(prev, next);
 322
 323         contextidr_thread_switch(next);
 324         return last;
 325 }
 326
 327 unsigned long get_wchan(struct task_struct *p)
 328 {
 329         struct stackframe frame;
 330         int count = 0;
 331         if (!p || p == current || p->state == TASK_RUNNING)
 332                 return 0;
 333
 334         frame.fp = thread_saved_fp(p);
 335         frame.sp = thread_saved_sp(p);
 336         frame.pc = thread_saved_pc(p);
 337         do {
 338                 int ret = unwind_frame(&frame);
 339                 if (ret < 0)
 340                         return 0;
 341                 if (!in_sched_functions(frame.pc))
 342                         return frame.pc;
 343         } while (count ++ < 16);
 344         return 0;
 345 }
 346
 347 unsigned long arch_align_stack(unsigned long sp)
 348 {
 349         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 350                 sp -= get_random_int() & ~PAGE_MASK;
 351         return sp & ~0xf;
 352 }
 353
 354 static unsigned long randomize_base(unsigned long base)
 355 {
 356         unsigned long range_end = base + (STACK_RND_MASK << PAGE_SHIFT) + 1;
 357         return randomize_range(base, range_end, 0) ? : base;
 358 }
 359
 360 unsigned long arch_randomize_brk(struct mm_struct *mm)
 361 {
 362         return randomize_base(mm->brk);
 363 }
 364
 365 unsigned long randomize_et_dyn(unsigned long base)
 366 {
 367         return randomize_base(base);
 368 }