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