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