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 } 390