2 * Based on arch/arm/kernel/process.c
4 * Original Copyright (C) 1995 Linus Torvalds
5 * Copyright (C) 1996-2000 Russell King - Converted to ARM.
6 * Copyright (C) 2012 ARM Ltd.
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.
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.
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/>.
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>
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>
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>
49 #include <asm/alternative.h>
50 #include <asm/compat.h>
51 #include <asm/cacheflush.h>
52 #include <asm/fpsimd.h>
53 #include <asm/mmu_context.h>
54 #include <asm/processor.h>
55 #include <asm/stacktrace.h>
57 #ifdef CONFIG_CC_STACKPROTECTOR
58 #include <linux/stackprotector.h>
59 unsigned long __stack_chk_guard __read_mostly;
60 EXPORT_SYMBOL(__stack_chk_guard);
64 * Function pointers to optional machine specific functions
66 void (*pm_power_off)(void);
67 EXPORT_SYMBOL_GPL(pm_power_off);
69 void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
72 * This is our default idle handler.
74 void arch_cpu_idle(void)
77 * This should do all the clock switching and wait for interrupt
80 trace_cpu_idle_rcuidle(1, smp_processor_id());
83 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
86 #ifdef CONFIG_HOTPLUG_CPU
87 void arch_cpu_idle_dead(void)
94 * Called by kexec, immediately prior to machine_kexec().
96 * This must completely disable all secondary CPUs; simply causing those CPUs
97 * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
98 * kexec'd kernel to use any and all RAM as it sees fit, without having to
99 * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
100 * functionality embodied in disable_nonboot_cpus() to achieve this.
102 void machine_shutdown(void)
104 disable_nonboot_cpus();
108 * Halting simply requires that the secondary CPUs stop performing any
109 * activity (executing tasks, handling interrupts). smp_send_stop()
112 void machine_halt(void)
120 * Power-off simply requires that the secondary CPUs stop performing any
121 * activity (executing tasks, handling interrupts). smp_send_stop()
122 * achieves this. When the system power is turned off, it will take all CPUs
125 void machine_power_off(void)
134 * Restart requires that the secondary CPUs stop performing any activity
135 * while the primary CPU resets the system. Systems with multiple CPUs must
136 * provide a HW restart implementation, to ensure that all CPUs reset at once.
137 * This is required so that any code running after reset on the primary CPU
138 * doesn't have to co-ordinate with other CPUs to ensure they aren't still
139 * executing pre-reset code, and using RAM that the primary CPU's code wishes
140 * to use. Implementing such co-ordination would be essentially impossible.
142 void machine_restart(char *cmd)
144 /* Disable interrupts first */
149 * UpdateCapsule() depends on the system being reset via
152 if (efi_enabled(EFI_RUNTIME_SERVICES))
153 efi_reboot(reboot_mode, NULL);
155 /* Now call the architecture specific reboot code. */
157 arm_pm_restart(reboot_mode, cmd);
159 do_kernel_restart(cmd);
162 * Whoops - the architecture was unable to reboot.
164 printk("Reboot failed -- System halted\n");
169 * dump a block of kernel memory from around the given address
171 static void show_data(unsigned long addr, int nbytes, const char *name)
178 * don't attempt to dump non-kernel addresses or
179 * values that are probably just small negative numbers
181 if (addr < PAGE_OFFSET || addr > -256UL)
184 printk("\n%s: %#lx:\n", name, addr);
187 * round address down to a 32 bit boundary
188 * and always dump a multiple of 32 bytes
190 p = (u32 *)(addr & ~(sizeof(u32) - 1));
191 nbytes += (addr & (sizeof(u32) - 1));
192 nlines = (nbytes + 31) / 32;
195 for (i = 0; i < nlines; i++) {
197 * just display low 16 bits of address to keep
198 * each line of the dump < 80 characters
200 printk("%04lx ", (unsigned long)p & 0xffff);
201 for (j = 0; j < 8; j++) {
203 if (probe_kernel_address(p, data)) {
206 printk(" %08x", data);
214 static void show_extra_register_data(struct pt_regs *regs, int nbytes)
221 show_data(regs->pc - nbytes, nbytes * 2, "PC");
222 show_data(regs->regs[30] - nbytes, nbytes * 2, "LR");
223 show_data(regs->sp - nbytes, nbytes * 2, "SP");
224 for (i = 0; i < 30; i++) {
226 snprintf(name, sizeof(name), "X%u", i);
227 show_data(regs->regs[i] - nbytes, nbytes * 2, name);
232 void __show_regs(struct pt_regs *regs)
237 if (compat_user_mode(regs)) {
238 lr = regs->compat_lr;
239 sp = regs->compat_sp;
247 show_regs_print_info(KERN_DEFAULT);
248 print_symbol("PC is at %s\n", instruction_pointer(regs));
249 print_symbol("LR is at %s\n", lr);
250 printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
251 regs->pc, lr, regs->pstate);
252 printk("sp : %016llx\n", sp);
253 for (i = top_reg; i >= 0; i--) {
254 printk("x%-2d: %016llx ", i, regs->regs[i]);
258 if (!user_mode(regs))
259 show_extra_register_data(regs, 128);
263 void show_regs(struct pt_regs * regs)
270 * Free current thread data structures etc..
272 void exit_thread(void)
276 static void tls_thread_flush(void)
278 asm ("msr tpidr_el0, xzr");
280 if (is_compat_task()) {
281 current->thread.tp_value = 0;
284 * We need to ensure ordering between the shadow state and the
285 * hardware state, so that we don't corrupt the hardware state
286 * with a stale shadow state during context switch.
289 asm ("msr tpidrro_el0, xzr");
293 void flush_thread(void)
295 fpsimd_flush_thread();
297 flush_ptrace_hw_breakpoint(current);
300 void release_thread(struct task_struct *dead_task)
304 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
307 fpsimd_preserve_current_state();
312 asmlinkage void ret_from_fork(void) asm("ret_from_fork");
314 int copy_thread(unsigned long clone_flags, unsigned long stack_start,
315 unsigned long stk_sz, struct task_struct *p)
317 struct pt_regs *childregs = task_pt_regs(p);
319 memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
321 if (likely(!(p->flags & PF_KTHREAD))) {
322 *childregs = *current_pt_regs();
323 childregs->regs[0] = 0;
326 * Read the current TLS pointer from tpidr_el0 as it may be
327 * out-of-sync with the saved value.
329 asm("mrs %0, tpidr_el0" : "=r" (*task_user_tls(p)));
332 if (is_compat_thread(task_thread_info(p)))
333 childregs->compat_sp = stack_start;
334 /* 16-byte aligned stack mandatory on AArch64 */
335 else if (stack_start & 15)
338 childregs->sp = stack_start;
342 * If a TLS pointer was passed to clone (4th argument), use it
343 * for the new thread.
345 if (clone_flags & CLONE_SETTLS)
346 p->thread.tp_value = childregs->regs[3];
348 memset(childregs, 0, sizeof(struct pt_regs));
349 childregs->pstate = PSR_MODE_EL1h;
350 if (IS_ENABLED(CONFIG_ARM64_UAO) &&
351 cpus_have_cap(ARM64_HAS_UAO))
352 childregs->pstate |= PSR_UAO_BIT;
353 p->thread.cpu_context.x19 = stack_start;
354 p->thread.cpu_context.x20 = stk_sz;
356 p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
357 p->thread.cpu_context.sp = (unsigned long)childregs;
359 ptrace_hw_copy_thread(p);
364 static void tls_thread_switch(struct task_struct *next)
366 unsigned long tpidr, tpidrro;
368 asm("mrs %0, tpidr_el0" : "=r" (tpidr));
369 *task_user_tls(current) = tpidr;
371 tpidr = *task_user_tls(next);
372 tpidrro = is_compat_thread(task_thread_info(next)) ?
373 next->thread.tp_value : 0;
376 " msr tpidr_el0, %0\n"
377 " msr tpidrro_el0, %1"
378 : : "r" (tpidr), "r" (tpidrro));
381 /* Restore the UAO state depending on next's addr_limit */
382 static void uao_thread_switch(struct task_struct *next)
384 if (IS_ENABLED(CONFIG_ARM64_UAO)) {
385 if (task_thread_info(next)->addr_limit == KERNEL_DS)
386 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO));
388 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO));
395 struct task_struct *__switch_to(struct task_struct *prev,
396 struct task_struct *next)
398 struct task_struct *last;
400 fpsimd_thread_switch(next);
401 tls_thread_switch(next);
402 hw_breakpoint_thread_switch(next);
403 contextidr_thread_switch(next);
404 uao_thread_switch(next);
407 * Complete any pending TLB or cache maintenance on this CPU in case
408 * the thread migrates to a different CPU.
412 /* the actual thread switch */
413 last = cpu_switch_to(prev, next);
418 unsigned long get_wchan(struct task_struct *p)
420 struct stackframe frame;
421 unsigned long stack_page;
423 if (!p || p == current || p->state == TASK_RUNNING)
426 frame.fp = thread_saved_fp(p);
427 frame.sp = thread_saved_sp(p);
428 frame.pc = thread_saved_pc(p);
429 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
430 frame.graph = p->curr_ret_stack;
432 stack_page = (unsigned long)task_stack_page(p);
434 if (frame.sp < stack_page ||
435 frame.sp >= stack_page + THREAD_SIZE ||
436 unwind_frame(p, &frame))
438 if (!in_sched_functions(frame.pc))
440 } while (count ++ < 16);
444 unsigned long arch_align_stack(unsigned long sp)
446 if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
447 sp -= get_random_int() & ~PAGE_MASK;
451 static unsigned long randomize_base(unsigned long base)
453 unsigned long range_end = base + (STACK_RND_MASK << PAGE_SHIFT) + 1;
454 return randomize_range(base, range_end, 0) ? : base;
457 unsigned long arch_randomize_brk(struct mm_struct *mm)
459 return randomize_base(mm->brk);