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/efi.h>
  25 #include <linux/export.h>
  26 #include <linux/sched.h>
  27 #include <linux/kernel.h>
  28 #include <linux/mm.h>
  29 #include <linux/stddef.h>
  30 #include <linux/unistd.h>
  31 #include <linux/user.h>
  32 #include <linux/delay.h>
  33 #include <linux/reboot.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/kallsyms.h>
  36 #include <linux/init.h>
  37 #include <linux/cpu.h>
  38 #include <linux/elfcore.h>
  39 #include <linux/pm.h>
  40 #include <linux/tick.h>
  41 #include <linux/utsname.h>
  42 #include <linux/uaccess.h>
  43 #include <linux/random.h>
  44 #include <linux/hw_breakpoint.h>
  45 #include <linux/personality.h>
  46 #include <linux/notifier.h>
  47 #include <trace/events/power.h>
  48
  49 #include <asm/alternative.h>
  50 #include <asm/compat.h>
  51 #include <asm/cacheflush.h>
  52 #include <asm/exec.h>
  53 #include <asm/fpsimd.h>
  54 #include <asm/mmu_context.h>
  55 #include <asm/processor.h>
  56 #include <asm/stacktrace.h>
  57
  58 #ifdef CONFIG_CC_STACKPROTECTOR
  59 #include <linux/stackprotector.h>
  60 unsigned long __stack_chk_guard __read_mostly;
  61 EXPORT_SYMBOL(__stack_chk_guard);
  62 #endif
  63
  64 /*
  65  * Function pointers to optional machine specific functions
  66  */
  67 void (*pm_power_off)(void);
  68 EXPORT_SYMBOL_GPL(pm_power_off);
  69
  70 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
  71
  72 /*
  73  * This is our default idle handler.
  74  */
  75 void arch_cpu_idle(void)
  76 {
  77         /*
  78          * This should do all the clock switching and wait for interrupt
  79          * tricks
  80          */
  81         trace_cpu_idle_rcuidle(1, smp_processor_id());
  82         cpu_do_idle();
  83         local_irq_enable();
  84         trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
  85 }
  86
  87 #ifdef CONFIG_HOTPLUG_CPU
  88 void arch_cpu_idle_dead(void)
  89 {
  90        cpu_die();
  91 }
  92 #endif
  93
  94 /*
  95  * Called by kexec, immediately prior to machine_kexec().
  96  *
  97  * This must completely disable all secondary CPUs; simply causing those CPUs
  98  * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
  99  * kexec'd kernel to use any and all RAM as it sees fit, without having to
 100  * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
 101  * functionality embodied in disable_nonboot_cpus() to achieve this.
 102  */
 103 void machine_shutdown(void)
 104 {
 105         disable_nonboot_cpus();
 106 }
 107
 108 /*
 109  * Halting simply requires that the secondary CPUs stop performing any
 110  * activity (executing tasks, handling interrupts). smp_send_stop()
 111  * achieves this.
 112  */
 113 void machine_halt(void)
 114 {
 115         local_irq_disable();
 116         smp_send_stop();
 117         while (1);
 118 }
 119
 120 /*
 121  * Power-off simply requires that the secondary CPUs stop performing any
 122  * activity (executing tasks, handling interrupts). smp_send_stop()
 123  * achieves this. When the system power is turned off, it will take all CPUs
 124  * with it.
 125  */
 126 void machine_power_off(void)
 127 {
 128         local_irq_disable();
 129         smp_send_stop();
 130         if (pm_power_off)
 131                 pm_power_off();
 132 }
 133
 134 /*
 135  * Restart requires that the secondary CPUs stop performing any activity
 136  * while the primary CPU resets the system. Systems with multiple CPUs must
 137  * provide a HW restart implementation, to ensure that all CPUs reset at once.
 138  * This is required so that any code running after reset on the primary CPU
 139  * doesn't have to co-ordinate with other CPUs to ensure they aren't still
 140  * executing pre-reset code, and using RAM that the primary CPU's code wishes
 141  * to use. Implementing such co-ordination would be essentially impossible.
 142  */
 143 void machine_restart(char *cmd)
 144 {
 145         /* Disable interrupts first */
 146         local_irq_disable();
 147         smp_send_stop();
 148
 149         /*
 150          * UpdateCapsule() depends on the system being reset via
 151          * ResetSystem().
 152          */
 153         if (efi_enabled(EFI_RUNTIME_SERVICES))
 154                 efi_reboot(reboot_mode, NULL);
 155
 156         /* Now call the architecture specific reboot code. */
 157         if (arm_pm_restart)
 158                 arm_pm_restart(reboot_mode, cmd);
 159         else
 160                 do_kernel_restart(cmd);
 161
 162         /*
 163          * Whoops - the architecture was unable to reboot.
 164          */
 165         printk("Reboot failed -- System halted\n");
 166         while (1);
 167 }
 168
 169 void __show_regs(struct pt_regs *regs)
 170 {
 171         int i, top_reg;
 172         u64 lr, sp;
 173
 174         if (compat_user_mode(regs)) {
 175                 lr = regs->compat_lr;
 176                 sp = regs->compat_sp;
 177                 top_reg = 12;
 178         } else {
 179                 lr = regs->regs[30];
 180                 sp = regs->sp;
 181                 top_reg = 29;
 182         }
 183
 184         show_regs_print_info(KERN_DEFAULT);
 185         print_symbol("PC is at %s\n", instruction_pointer(regs));
 186         print_symbol("LR is at %s\n", lr);
 187         printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
 188                regs->pc, lr, regs->pstate);
 189         printk("sp : %016llx\n", sp);
 190
 191         i = top_reg;
 192
 193         while (i >= 0) {
 194                 printk("x%-2d: %016llx ", i, regs->regs[i]);
 195                 i--;
 196
 197                 if (i % 2 == 0) {
 198                         pr_cont("x%-2d: %016llx ", i, regs->regs[i]);
 199                         i--;
 200                 }
 201
 202                 pr_cont("\n");
 203         }
 204         printk("\n");
 205 }
 206
 207 void show_regs(struct pt_regs * regs)
 208 {
 209         printk("\n");
 210         __show_regs(regs);
 211 }
 212
 213 static void tls_thread_flush(void)
 214 {
 215         write_sysreg(0, tpidr_el0);
 216
 217         if (is_compat_task()) {
 218                 current->thread.tp_value = 0;
 219
 220                 /*
 221                  * We need to ensure ordering between the shadow state and the
 222                  * hardware state, so that we don't corrupt the hardware state
 223                  * with a stale shadow state during context switch.
 224                  */
 225                 barrier();
 226                 write_sysreg(0, tpidrro_el0);
 227         }
 228 }
 229
 230 void flush_thread(void)
 231 {
 232         fpsimd_flush_thread();
 233         tls_thread_flush();
 234         flush_ptrace_hw_breakpoint(current);
 235 }
 236
 237 void release_thread(struct task_struct *dead_task)
 238 {
 239 }
 240
 241 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 242 {
 243         if (current->mm)
 244                 fpsimd_preserve_current_state();
 245         *dst = *src;
 246         return 0;
 247 }
 248
 249 asmlinkage void ret_from_fork(void) asm("ret_from_fork");
 250
 251 int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 252                 unsigned long stk_sz, struct task_struct *p)
 253 {
 254         struct pt_regs *childregs = task_pt_regs(p);
 255
 256         memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
 257
 258         if (likely(!(p->flags & PF_KTHREAD))) {
 259                 *childregs = *current_pt_regs();
 260                 childregs->regs[0] = 0;
 261
 262                 /*
 263                  * Read the current TLS pointer from tpidr_el0 as it may be
 264                  * out-of-sync with the saved value.
 265                  */
 266                 *task_user_tls(p) = read_sysreg(tpidr_el0);
 267
 268                 if (stack_start) {
 269                         if (is_compat_thread(task_thread_info(p)))
 270                                 childregs->compat_sp = stack_start;
 271                         else
 272                                 childregs->sp = stack_start;
 273                 }
 274
 275                 /*
 276                  * If a TLS pointer was passed to clone (4th argument), use it
 277                  * for the new thread.
 278                  */
 279                 if (clone_flags & CLONE_SETTLS)
 280                         p->thread.tp_value = childregs->regs[3];
 281         } else {
 282                 memset(childregs, 0, sizeof(struct pt_regs));
 283                 childregs->pstate = PSR_MODE_EL1h;
 284                 if (IS_ENABLED(CONFIG_ARM64_UAO) &&
 285                     cpus_have_cap(ARM64_HAS_UAO))
 286                         childregs->pstate |= PSR_UAO_BIT;
 287                 p->thread.cpu_context.x19 = stack_start;
 288                 p->thread.cpu_context.x20 = stk_sz;
 289         }
 290         p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
 291         p->thread.cpu_context.sp = (unsigned long)childregs;
 292
 293         ptrace_hw_copy_thread(p);
 294
 295         return 0;
 296 }
 297
 298 static void tls_thread_switch(struct task_struct *next)
 299 {
 300         unsigned long tpidr, tpidrro;
 301
 302         tpidr = read_sysreg(tpidr_el0);
 303         *task_user_tls(current) = tpidr;
 304
 305         tpidr = *task_user_tls(next);
 306         tpidrro = is_compat_thread(task_thread_info(next)) ?
 307                   next->thread.tp_value : 0;
 308
 309         write_sysreg(tpidr, tpidr_el0);
 310         write_sysreg(tpidrro, tpidrro_el0);
 311 }
 312
 313 /* Restore the UAO state depending on next's addr_limit */
 314 void uao_thread_switch(struct task_struct *next)
 315 {
 316         if (IS_ENABLED(CONFIG_ARM64_UAO)) {
 317                 if (task_thread_info(next)->addr_limit == KERNEL_DS)
 318                         asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO));
 319                 else
 320                         asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO));
 321         }
 322 }
 323
 324 /*
 325  * Thread switching.
 326  */
 327 struct task_struct *__switch_to(struct task_struct *prev,
 328                                 struct task_struct *next)
 329 {
 330         struct task_struct *last;
 331
 332         fpsimd_thread_switch(next);
 333         tls_thread_switch(next);
 334         hw_breakpoint_thread_switch(next);
 335         contextidr_thread_switch(next);
 336         uao_thread_switch(next);
 337
 338         /*
 339          * Complete any pending TLB or cache maintenance on this CPU in case
 340          * the thread migrates to a different CPU.
 341          */
 342         dsb(ish);
 343
 344         /* the actual thread switch */
 345         last = cpu_switch_to(prev, next);
 346
 347         return last;
 348 }
 349
 350 unsigned long get_wchan(struct task_struct *p)
 351 {
 352         struct stackframe frame;
 353         unsigned long stack_page;
 354         int count = 0;
 355         if (!p || p == current || p->state == TASK_RUNNING)
 356                 return 0;
 357
 358         frame.fp = thread_saved_fp(p);
 359         frame.sp = thread_saved_sp(p);
 360         frame.pc = thread_saved_pc(p);
 361 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 362         frame.graph = p->curr_ret_stack;
 363 #endif
 364         stack_page = (unsigned long)task_stack_page(p);
 365         do {
 366                 if (frame.sp < stack_page ||
 367                     frame.sp >= stack_page + THREAD_SIZE ||
 368                     unwind_frame(p, &frame))
 369                         return 0;
 370                 if (!in_sched_functions(frame.pc))
 371                         return frame.pc;
 372         } while (count ++ < 16);
 373         return 0;
 374 }
 375
 376 unsigned long arch_align_stack(unsigned long sp)
 377 {
 378         if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 379                 sp -= get_random_int() & ~PAGE_MASK;
 380         return sp & ~0xf;
 381 }
 382
 383 unsigned long arch_randomize_brk(struct mm_struct *mm)
 384 {
 385         if (is_compat_task())
 386                 return randomize_page(mm->brk, 0x02000000);
 387         else
 388                 return randomize_page(mm->brk, 0x40000000);
 389 }