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/compat.h>
  24 #include <linux/export.h>
  25 #include <linux/sched.h>
  26 #include <linux/kernel.h>
  27 #include <linux/mm.h>
  28 #include <linux/stddef.h>
  29 #include <linux/unistd.h>
  30 #include <linux/user.h>
  31 #include <linux/delay.h>
  32 #include <linux/reboot.h>
  33 #include <linux/interrupt.h>
  34 #include <linux/kallsyms.h>
  35 #include <linux/init.h>
  36 #include <linux/cpu.h>
  37 #include <linux/elfcore.h>
  38 #include <linux/pm.h>
  39 #include <linux/tick.h>
  40 #include <linux/utsname.h>
  41 #include <linux/uaccess.h>
  42 #include <linux/random.h>
  43 #include <linux/hw_breakpoint.h>
  44 #include <linux/personality.h>
  45 #include <linux/notifier.h>
  46
  47 #include <asm/compat.h>
  48 #include <asm/cacheflush.h>
  49 #include <asm/fpsimd.h>
  50 #include <asm/mmu_context.h>
  51 #include <asm/processor.h>
  52 #include <asm/stacktrace.h>
  53
  54 #ifdef CONFIG_CC_STACKPROTECTOR
  55 #include <linux/stackprotector.h>
  56 unsigned long __stack_chk_guard __read_mostly;
  57 EXPORT_SYMBOL(__stack_chk_guard);
  58 #endif
  59
  60 static void setup_restart(void)
  61 {
  62         /*
  63          * Tell the mm system that we are going to reboot -
  64          * we may need it to insert some 1:1 mappings so that
  65          * soft boot works.
  66          */
  67         setup_mm_for_reboot();
  68
  69         /* Clean and invalidate caches */
  70         flush_cache_all();
  71
  72         /* Turn D-cache off */
  73         cpu_cache_off();
  74
  75         /* Push out any further dirty data, and ensure cache is empty */
  76         flush_cache_all();
  77 }
  78
  79 void soft_restart(unsigned long addr)
  80 {
  81         typedef void (*phys_reset_t)(unsigned long);
  82         phys_reset_t phys_reset;
  83
  84         setup_restart();
  85
  86         /* Switch to the identity mapping */
  87         phys_reset = (phys_reset_t)virt_to_phys(cpu_reset);
  88         phys_reset(addr);
  89
  90         /* Should never get here */
  91         BUG();
  92 }
  93
  94 /*
  95  * Function pointers to optional machine specific functions
  96  */
  97 void (*pm_power_off)(void);
  98 EXPORT_SYMBOL_GPL(pm_power_off);
  99
 100 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
 101 EXPORT_SYMBOL_GPL(arm_pm_restart);
 102
 103 /*
 104  * This is our default idle handler.
 105  */
 106 void arch_cpu_idle(void)
 107 {
 108         /*
 109          * This should do all the clock switching and wait for interrupt
 110          * tricks
 111          */
 112         cpu_do_idle();
 113         local_irq_enable();
 114 }
 115
 116 #ifdef CONFIG_HOTPLUG_CPU
 117 void arch_cpu_idle_dead(void)
 118 {
 119        cpu_die();
 120 }
 121 #endif
 122
 123 /*
 124  * Called by kexec, immediately prior to machine_kexec().
 125  *
 126  * This must completely disable all secondary CPUs; simply causing those CPUs
 127  * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
 128  * kexec'd kernel to use any and all RAM as it sees fit, without having to
 129  * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
 130  * functionality embodied in disable_nonboot_cpus() to achieve this.
 131  */
 132 void machine_shutdown(void)
 133 {
 134         disable_nonboot_cpus();
 135 }
 136
 137 /*
 138  * Halting simply requires that the secondary CPUs stop performing any
 139  * activity (executing tasks, handling interrupts). smp_send_stop()
 140  * achieves this.
 141  */
 142 void machine_halt(void)
 143 {
 144         local_irq_disable();
 145         smp_send_stop();
 146         while (1);
 147 }
 148
 149 /*
 150  * Power-off simply requires that the secondary CPUs stop performing any
 151  * activity (executing tasks, handling interrupts). smp_send_stop()
 152  * achieves this. When the system power is turned off, it will take all CPUs
 153  * with it.
 154  */
 155 void machine_power_off(void)
 156 {
 157         local_irq_disable();
 158         smp_send_stop();
 159         if (pm_power_off)
 160                 pm_power_off();
 161 }
 162
 163 /*
 164  * Restart requires that the secondary CPUs stop performing any activity
 165  * while the primary CPU resets the system. Systems with a single CPU can
 166  * use soft_restart() as their machine descriptor's .restart hook, since that
 167  * will cause the only available CPU to reset. Systems with multiple CPUs must
 168  * provide a HW restart implementation, to ensure that all CPUs reset at once.
 169  * This is required so that any code running after reset on the primary CPU
 170  * doesn't have to co-ordinate with other CPUs to ensure they aren't still
 171  * executing pre-reset code, and using RAM that the primary CPU's code wishes
 172  * to use. Implementing such co-ordination would be essentially impossible.
 173  */
 174 void machine_restart(char *cmd)
 175 {
 176         /* Disable interrupts first */
 177         local_irq_disable();
 178         smp_send_stop();
 179
 180         /* Now call the architecture specific reboot code. */
 181         if (arm_pm_restart)
 182                 arm_pm_restart(reboot_mode, cmd);
 183
 184         /*
 185          * Whoops - the architecture was unable to reboot.
 186          */
 187         printk("Reboot failed -- System halted\n");
 188         while (1);
 189 }
 190
 191 void __show_regs(struct pt_regs *regs)
 192 {
 193         int i, top_reg;
 194         u64 lr, sp;
 195
 196         if (compat_user_mode(regs)) {
 197                 lr = regs->compat_lr;
 198                 sp = regs->compat_sp;
 199                 top_reg = 12;
 200         } else {
 201                 lr = regs->regs[30];
 202                 sp = regs->sp;
 203                 top_reg = 29;
 204         }
 205
 206         show_regs_print_info(KERN_DEFAULT);
 207         print_symbol("PC is at %s\n", instruction_pointer(regs));
 208         print_symbol("LR is at %s\n", lr);
 209         printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
 210                regs->pc, lr, regs->pstate);
 211         printk("sp : %016llx\n", sp);
 212         for (i = top_reg; i >= 0; i--) {
 213                 printk("x%-2d: %016llx ", i, regs->regs[i]);
 214                 if (i % 2 == 0)
 215                         printk("\n");
 216         }
 217         printk("\n");
 218 }
 219
 220 void show_regs(struct pt_regs * regs)
 221 {
 222         printk("\n");
 223         __show_regs(regs);
 224 }
 225
 226 /*
 227  * Free current thread data structures etc..
 228  */
 229 void exit_thread(void)
 230 {
 231 }
 232
 233 void flush_thread(void)
 234 {
 235         fpsimd_flush_thread();
 236         flush_ptrace_hw_breakpoint(current);
 237 }
 238
 239 void release_thread(struct task_struct *dead_task)
 240 {
 241 }
 242
 243 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 244 {
 245         fpsimd_preserve_current_state();
 246         *dst = *src;
 247         return 0;
 248 }
 249
 250 asmlinkage void ret_from_fork(void) asm("ret_from_fork");
 251
 252 int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 253                 unsigned long stk_sz, struct task_struct *p)
 254 {
 255         struct pt_regs *childregs = task_pt_regs(p);
 256         unsigned long tls = p->thread.tp_value;
 257
 258         memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
 259
 260         if (likely(!(p->flags & PF_KTHREAD))) {
 261                 *childregs = *current_pt_regs();
 262                 childregs->regs[0] = 0;
 263                 if (is_compat_thread(task_thread_info(p))) {
 264                         if (stack_start)
 265                                 childregs->compat_sp = stack_start;
 266                 } else {
 267                         /*
 268                          * Read the current TLS pointer from tpidr_el0 as it may be
 269                          * out-of-sync with the saved value.
 270                          */
 271                         asm("mrs %0, tpidr_el0" : "=r" (tls));
 272                         if (stack_start) {
 273                                 /* 16-byte aligned stack mandatory on AArch64 */
 274                                 if (stack_start & 15)
 275                                         return -EINVAL;
 276                                 childregs->sp = stack_start;
 277                         }
 278                 }
 279                 /*
 280                  * If a TLS pointer was passed to clone (4th argument), use it
 281                  * for the new thread.
 282                  */
 283                 if (clone_flags & CLONE_SETTLS)
 284                         tls = childregs->regs[3];
 285         } else {
 286                 memset(childregs, 0, sizeof(struct pt_regs));
 287                 childregs->pstate = PSR_MODE_EL1h;
 288                 p->thread.cpu_context.x19 = stack_start;
 289                 p->thread.cpu_context.x20 = stk_sz;
 290         }
 291         p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
 292         p->thread.cpu_context.sp = (unsigned long)childregs;
 293         p->thread.tp_value = tls;
 294
 295         ptrace_hw_copy_thread(p);
 296
 297         return 0;
 298 }
 299
 300 static void tls_thread_switch(struct task_struct *next)
 301 {
 302         unsigned long tpidr, tpidrro;
 303
 304         if (!is_compat_task()) {
 305                 asm("mrs %0, tpidr_el0" : "=r" (tpidr));
 306                 current->thread.tp_value = tpidr;
 307         }
 308
 309         if (is_compat_thread(task_thread_info(next))) {
 310                 tpidr = 0;
 311                 tpidrro = next->thread.tp_value;
 312         } else {
 313                 tpidr = next->thread.tp_value;
 314                 tpidrro = 0;
 315         }
 316
 317         asm(
 318         "       msr     tpidr_el0, %0\n"
 319         "       msr     tpidrro_el0, %1"
 320         : : "r" (tpidr), "r" (tpidrro));
 321 }
 322
 323 /*
 324  * Thread switching.
 325  */
 326 struct task_struct *__switch_to(struct task_struct *prev,
 327                                 struct task_struct *next)
 328 {
 329         struct task_struct *last;
 330
 331         fpsimd_thread_switch(next);
 332         tls_thread_switch(next);
 333         hw_breakpoint_thread_switch(next);
 334         contextidr_thread_switch(next);
 335
 336         /*
 337          * Complete any pending TLB or cache maintenance on this CPU in case
 338          * the thread migrates to a different CPU.
 339          */
 340         dsb(ish);
 341
 342         /* the actual thread switch */
 343         last = cpu_switch_to(prev, next);
 344
 345         return last;
 346 }
 347
 348 unsigned long get_wchan(struct task_struct *p)
 349 {
 350         struct stackframe frame;
 351         unsigned long stack_page;
 352         int count = 0;
 353         if (!p || p == current || p->state == TASK_RUNNING)
 354                 return 0;
 355
 356         frame.fp = thread_saved_fp(p);
 357         frame.sp = thread_saved_sp(p);
 358         frame.pc = thread_saved_pc(p);
 359         stack_page = (unsigned long)task_stack_page(p);
 360         do {
 361                 if (frame.sp < stack_page ||
 362                     frame.sp >= stack_page + THREAD_SIZE ||
 363                     unwind_frame(&frame))
 364                         return 0;
 365                 if (!in_sched_functions(frame.pc))
 366                         return frame.pc;
 367         } while (count ++ < 16);
 368         return 0;
 369 }
 370
 371 unsigned long arch_align_stack(unsigned long sp)
 372 {
 373         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 374                 sp -= get_random_int() & ~PAGE_MASK;
 375         return sp & ~0xf;
 376 }
 377
 378 static unsigned long randomize_base(unsigned long base)
 379 {
 380         unsigned long range_end = base + (STACK_RND_MASK << PAGE_SHIFT) + 1;
 381         return randomize_range(base, range_end, 0) ? : base;
 382 }
 383
 384 unsigned long arch_randomize_brk(struct mm_struct *mm)
 385 {
 386         return randomize_base(mm->brk);
 387 }
 388
 389 unsigned long randomize_et_dyn(unsigned long base)
 390 {
 391         return randomize_base(base);
 392 }