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/sched/debug.h>
28 #include <linux/sched/task.h>
29 #include <linux/sched/task_stack.h>
30 #include <linux/kernel.h>
32 #include <linux/stddef.h>
33 #include <linux/unistd.h>
34 #include <linux/user.h>
35 #include <linux/delay.h>
36 #include <linux/reboot.h>
37 #include <linux/interrupt.h>
38 #include <linux/kallsyms.h>
39 #include <linux/init.h>
40 #include <linux/cpu.h>
41 #include <linux/elfcore.h>
43 #include <linux/tick.h>
44 #include <linux/utsname.h>
45 #include <linux/uaccess.h>
46 #include <linux/random.h>
47 #include <linux/hw_breakpoint.h>
48 #include <linux/personality.h>
49 #include <linux/notifier.h>
50 #include <trace/events/power.h>
51 #include <linux/percpu.h>
53 #include <asm/alternative.h>
54 #include <asm/compat.h>
55 #include <asm/cacheflush.h>
57 #include <asm/fpsimd.h>
58 #include <asm/mmu_context.h>
59 #include <asm/processor.h>
60 #include <asm/stacktrace.h>
62 #ifdef CONFIG_CC_STACKPROTECTOR
63 #include <linux/stackprotector.h>
64 unsigned long __stack_chk_guard __read_mostly
;
65 EXPORT_SYMBOL(__stack_chk_guard
);
69 * Function pointers to optional machine specific functions
71 void (*pm_power_off
)(void);
72 EXPORT_SYMBOL_GPL(pm_power_off
);
74 void (*arm_pm_restart
)(enum reboot_mode reboot_mode
, const char *cmd
);
77 * This is our default idle handler.
79 void arch_cpu_idle(void)
82 * This should do all the clock switching and wait for interrupt
85 trace_cpu_idle_rcuidle(1, smp_processor_id());
88 trace_cpu_idle_rcuidle(PWR_EVENT_EXIT
, smp_processor_id());
91 #ifdef CONFIG_HOTPLUG_CPU
92 void arch_cpu_idle_dead(void)
99 * Called by kexec, immediately prior to machine_kexec().
101 * This must completely disable all secondary CPUs; simply causing those CPUs
102 * to execute e.g. a RAM-based pin loop is not sufficient. This allows the
103 * kexec'd kernel to use any and all RAM as it sees fit, without having to
104 * avoid any code or data used by any SW CPU pin loop. The CPU hotplug
105 * functionality embodied in disable_nonboot_cpus() to achieve this.
107 void machine_shutdown(void)
109 disable_nonboot_cpus();
113 * Halting simply requires that the secondary CPUs stop performing any
114 * activity (executing tasks, handling interrupts). smp_send_stop()
117 void machine_halt(void)
125 * Power-off simply requires that the secondary CPUs stop performing any
126 * activity (executing tasks, handling interrupts). smp_send_stop()
127 * achieves this. When the system power is turned off, it will take all CPUs
130 void machine_power_off(void)
139 * Restart requires that the secondary CPUs stop performing any activity
140 * while the primary CPU resets the system. Systems with multiple CPUs must
141 * provide a HW restart implementation, to ensure that all CPUs reset at once.
142 * This is required so that any code running after reset on the primary CPU
143 * doesn't have to co-ordinate with other CPUs to ensure they aren't still
144 * executing pre-reset code, and using RAM that the primary CPU's code wishes
145 * to use. Implementing such co-ordination would be essentially impossible.
147 void machine_restart(char *cmd
)
149 /* Disable interrupts first */
154 * UpdateCapsule() depends on the system being reset via
157 if (efi_enabled(EFI_RUNTIME_SERVICES
))
158 efi_reboot(reboot_mode
, NULL
);
160 /* Now call the architecture specific reboot code. */
162 arm_pm_restart(reboot_mode
, cmd
);
164 do_kernel_restart(cmd
);
167 * Whoops - the architecture was unable to reboot.
169 printk("Reboot failed -- System halted\n");
173 void __show_regs(struct pt_regs
*regs
)
178 if (compat_user_mode(regs
)) {
179 lr
= regs
->compat_lr
;
180 sp
= regs
->compat_sp
;
188 show_regs_print_info(KERN_DEFAULT
);
189 print_symbol("PC is at %s\n", instruction_pointer(regs
));
190 print_symbol("LR is at %s\n", lr
);
191 printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
192 regs
->pc
, lr
, regs
->pstate
);
193 printk("sp : %016llx\n", sp
);
198 printk("x%-2d: %016llx ", i
, regs
->regs
[i
]);
202 pr_cont("x%-2d: %016llx ", i
, regs
->regs
[i
]);
210 void show_regs(struct pt_regs
* regs
)
213 dump_backtrace(regs
, NULL
);
216 static void tls_thread_flush(void)
218 write_sysreg(0, tpidr_el0
);
220 if (is_compat_task()) {
221 current
->thread
.tp_value
= 0;
224 * We need to ensure ordering between the shadow state and the
225 * hardware state, so that we don't corrupt the hardware state
226 * with a stale shadow state during context switch.
229 write_sysreg(0, tpidrro_el0
);
233 void flush_thread(void)
235 fpsimd_flush_thread();
237 flush_ptrace_hw_breakpoint(current
);
240 void release_thread(struct task_struct
*dead_task
)
244 int arch_dup_task_struct(struct task_struct
*dst
, struct task_struct
*src
)
247 fpsimd_preserve_current_state();
252 asmlinkage
void ret_from_fork(void) asm("ret_from_fork");
254 int copy_thread(unsigned long clone_flags
, unsigned long stack_start
,
255 unsigned long stk_sz
, struct task_struct
*p
)
257 struct pt_regs
*childregs
= task_pt_regs(p
);
259 memset(&p
->thread
.cpu_context
, 0, sizeof(struct cpu_context
));
261 if (likely(!(p
->flags
& PF_KTHREAD
))) {
262 *childregs
= *current_pt_regs();
263 childregs
->regs
[0] = 0;
266 * Read the current TLS pointer from tpidr_el0 as it may be
267 * out-of-sync with the saved value.
269 *task_user_tls(p
) = read_sysreg(tpidr_el0
);
272 if (is_compat_thread(task_thread_info(p
)))
273 childregs
->compat_sp
= stack_start
;
275 childregs
->sp
= stack_start
;
279 * If a TLS pointer was passed to clone (4th argument), use it
280 * for the new thread.
282 if (clone_flags
& CLONE_SETTLS
)
283 p
->thread
.tp_value
= childregs
->regs
[3];
285 memset(childregs
, 0, sizeof(struct pt_regs
));
286 childregs
->pstate
= PSR_MODE_EL1h
;
287 if (IS_ENABLED(CONFIG_ARM64_UAO
) &&
288 cpus_have_const_cap(ARM64_HAS_UAO
))
289 childregs
->pstate
|= PSR_UAO_BIT
;
290 p
->thread
.cpu_context
.x19
= stack_start
;
291 p
->thread
.cpu_context
.x20
= stk_sz
;
293 p
->thread
.cpu_context
.pc
= (unsigned long)ret_from_fork
;
294 p
->thread
.cpu_context
.sp
= (unsigned long)childregs
;
296 ptrace_hw_copy_thread(p
);
301 void tls_preserve_current_state(void)
303 *task_user_tls(current
) = read_sysreg(tpidr_el0
);
306 static void tls_thread_switch(struct task_struct
*next
)
308 unsigned long tpidr
, tpidrro
;
310 tls_preserve_current_state();
312 tpidr
= *task_user_tls(next
);
313 tpidrro
= is_compat_thread(task_thread_info(next
)) ?
314 next
->thread
.tp_value
: 0;
316 write_sysreg(tpidr
, tpidr_el0
);
317 write_sysreg(tpidrro
, tpidrro_el0
);
320 /* Restore the UAO state depending on next's addr_limit */
321 void uao_thread_switch(struct task_struct
*next
)
323 if (IS_ENABLED(CONFIG_ARM64_UAO
)) {
324 if (task_thread_info(next
)->addr_limit
== KERNEL_DS
)
325 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO
));
327 asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO
));
332 * We store our current task in sp_el0, which is clobbered by userspace. Keep a
333 * shadow copy so that we can restore this upon entry from userspace.
335 * This is *only* for exception entry from EL0, and is not valid until we
336 * __switch_to() a user task.
338 DEFINE_PER_CPU(struct task_struct
*, __entry_task
);
340 static void entry_task_switch(struct task_struct
*next
)
342 __this_cpu_write(__entry_task
, next
);
348 __notrace_funcgraph
struct task_struct
*__switch_to(struct task_struct
*prev
,
349 struct task_struct
*next
)
351 struct task_struct
*last
;
353 fpsimd_thread_switch(next
);
354 tls_thread_switch(next
);
355 hw_breakpoint_thread_switch(next
);
356 contextidr_thread_switch(next
);
357 entry_task_switch(next
);
358 uao_thread_switch(next
);
361 * Complete any pending TLB or cache maintenance on this CPU in case
362 * the thread migrates to a different CPU.
366 /* the actual thread switch */
367 last
= cpu_switch_to(prev
, next
);
372 unsigned long get_wchan(struct task_struct
*p
)
374 struct stackframe frame
;
375 unsigned long stack_page
, ret
= 0;
377 if (!p
|| p
== current
|| p
->state
== TASK_RUNNING
)
380 stack_page
= (unsigned long)try_get_task_stack(p
);
384 frame
.fp
= thread_saved_fp(p
);
385 frame
.pc
= thread_saved_pc(p
);
386 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
387 frame
.graph
= p
->curr_ret_stack
;
390 if (unwind_frame(p
, &frame
))
392 if (!in_sched_functions(frame
.pc
)) {
396 } while (count
++ < 16);
403 unsigned long arch_align_stack(unsigned long sp
)
405 if (!(current
->personality
& ADDR_NO_RANDOMIZE
) && randomize_va_space
)
406 sp
-= get_random_int() & ~PAGE_MASK
;
410 unsigned long arch_randomize_brk(struct mm_struct
*mm
)
412 if (is_compat_task())
413 return randomize_page(mm
->brk
, SZ_32M
);
415 return randomize_page(mm
->brk
, SZ_1G
);
419 * Called from setup_new_exec() after (COMPAT_)SET_PERSONALITY.
421 void arch_setup_new_exec(void)
423 current
->mm
->context
.flags
= is_compat_task() ? MMCF_AARCH32
: 0;