/* * Based on arch/arm/kernel/process.c * * Original Copyright (C) 1995  Linus Torvalds * Copyright (C) 1996-2000 Russell King - Converted to ARM. * Copyright (C) 2012 ARM Ltd. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program.  If not, see <http://www.gnu.org/licenses/>. */ #include <stdarg.h> #include <linux/compat.h>#include <linux/efi.h>#include <linux/export.h>#include <linux/sched.h>#include <linux/sched/debug.h>#include <linux/sched/task.h>#include <linux/sched/task_stack.h>#include <linux/kernel.h>#include <linux/mm.h>#include <linux/stddef.h>#include <linux/unistd.h>#include <linux/user.h>#include <linux/delay.h>#include <linux/reboot.h>#include <linux/interrupt.h>#include <linux/kallsyms.h>#include <linux/init.h>#include <linux/cpu.h>#include <linux/elfcore.h>#include <linux/pm.h>#include <linux/tick.h>#include <linux/utsname.h>#include <linux/uaccess.h>#include <linux/random.h>#include <linux/hw_breakpoint.h>#include <linux/personality.h>#include <linux/notifier.h>#include <trace/events/power.h>#include <linux/percpu.h> #include <asm/alternative.h>#include <asm/compat.h>#include <asm/cacheflush.h>#include <asm/exec.h>#include <asm/fpsimd.h>#include <asm/mmu_context.h>#include <asm/processor.h>#include <asm/stacktrace.h> #ifdef CONFIG_CC_STACKPROTECTOR#include <linux/stackprotector.h>unsigned long __stack_chk_guard __read_mostly;EXPORT_SYMBOL(__stack_chk_guard);#endif /* * Function pointers to optional machine specific functions */void (*pm_power_off)(void);EXPORT_SYMBOL_GPL(pm_power_off); void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd); /* * This is our default idle handler. */void arch_cpu_idle(void){	/*	 * This should do all the clock switching and wait for interrupt	 * tricks	 */	trace_cpu_idle_rcuidle(1, smp_processor_id());	cpu_do_idle();	local_irq_enable();	trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());} #ifdef CONFIG_HOTPLUG_CPUvoid arch_cpu_idle_dead(void){       cpu_die();}#endif /* * Called by kexec, immediately prior to machine_kexec(). * * This must completely disable all secondary CPUs; simply causing those CPUs * to execute e.g. a RAM-based pin loop is not sufficient. This allows the * kexec'd kernel to use any and all RAM as it sees fit, without having to * avoid any code or data used by any SW CPU pin loop. The CPU hotplug * functionality embodied in disable_nonboot_cpus() to achieve this. */void machine_shutdown(void){	disable_nonboot_cpus();} /* * Halting simply requires that the secondary CPUs stop performing any * activity (executing tasks, handling interrupts). smp_send_stop() * achieves this. */void machine_halt(void){	local_irq_disable();	smp_send_stop();	while (1);} /* * Power-off simply requires that the secondary CPUs stop performing any * activity (executing tasks, handling interrupts). smp_send_stop() * achieves this. When the system power is turned off, it will take all CPUs * with it. */void machine_power_off(void){	local_irq_disable();	smp_send_stop();	if (pm_power_off)		pm_power_off();} /* * Restart requires that the secondary CPUs stop performing any activity * while the primary CPU resets the system. Systems with multiple CPUs must * provide a HW restart implementation, to ensure that all CPUs reset at once. * This is required so that any code running after reset on the primary CPU * doesn't have to co-ordinate with other CPUs to ensure they aren't still * executing pre-reset code, and using RAM that the primary CPU's code wishes * to use. Implementing such co-ordination would be essentially impossible. */void machine_restart(char *cmd){	/* Disable interrupts first */	local_irq_disable();	smp_send_stop(); 	/*	 * UpdateCapsule() depends on the system being reset via	 * ResetSystem().	 */	if (efi_enabled(EFI_RUNTIME_SERVICES))		efi_reboot(reboot_mode, NULL); 	/* Now call the architecture specific reboot code. */	if (arm_pm_restart)		arm_pm_restart(reboot_mode, cmd);	else		do_kernel_restart(cmd); 	/*	 * Whoops - the architecture was unable to reboot.	 */	printk("Reboot failed -- System halted\n");	while (1);} void __show_regs(struct pt_regs *regs){	int i, top_reg;	u64 lr, sp; 	if (compat_user_mode(regs)) {		lr = regs->compat_lr;		sp = regs->compat_sp;		top_reg = 12;	} else {		lr = regs->regs[30];		sp = regs->sp;		top_reg = 29;	} 	show_regs_print_info(KERN_DEFAULT);	print_symbol("PC is at %s\n", instruction_pointer(regs));	print_symbol("LR is at %s\n", lr);	printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",	       regs->pc, lr, regs->pstate);	printk("sp : %016llx\n", sp); 	i = top_reg; 	while (i >= 0) {		printk("x%-2d: %016llx ", i, regs->regs[i]);		i--; 		if (i % 2 == 0) {			pr_cont("x%-2d: %016llx ", i, regs->regs[i]);			i--;		} 		pr_cont("\n");	}} void show_regs(struct pt_regs * regs){	__show_regs(regs);	dump_backtrace(regs, NULL);} static void tls_thread_flush(void){	write_sysreg(0, tpidr_el0); 	if (is_compat_task()) {		current->thread.tp_value = 0; 		/*		 * We need to ensure ordering between the shadow state and the		 * hardware state, so that we don't corrupt the hardware state		 * with a stale shadow state during context switch.		 */		barrier();		write_sysreg(0, tpidrro_el0);	}} void flush_thread(void){	fpsimd_flush_thread();	tls_thread_flush();	flush_ptrace_hw_breakpoint(current);} void release_thread(struct task_struct *dead_task){} int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src){	if (current->mm)		fpsimd_preserve_current_state();	*dst = *src;	return 0;} asmlinkage void ret_from_fork(void) asm("ret_from_fork"); int copy_thread(unsigned long clone_flags, unsigned long stack_start,		unsigned long stk_sz, struct task_struct *p){	struct pt_regs *childregs = task_pt_regs(p); 	memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context)); 	if (likely(!(p->flags & PF_KTHREAD))) {		*childregs = *current_pt_regs();		childregs->regs[0] = 0; 		/*		 * Read the current TLS pointer from tpidr_el0 as it may be		 * out-of-sync with the saved value.		 */		*task_user_tls(p) = read_sysreg(tpidr_el0); 		if (stack_start) {			if (is_compat_thread(task_thread_info(p)))				childregs->compat_sp = stack_start;			else				childregs->sp = stack_start;		} 		/*		 * If a TLS pointer was passed to clone (4th argument), use it		 * for the new thread.		 */		if (clone_flags & CLONE_SETTLS)			p->thread.tp_value = childregs->regs[3];	} else {		memset(childregs, 0, sizeof(struct pt_regs));		childregs->pstate = PSR_MODE_EL1h;		if (IS_ENABLED(CONFIG_ARM64_UAO) &&		    cpus_have_const_cap(ARM64_HAS_UAO))			childregs->pstate |= PSR_UAO_BIT;		p->thread.cpu_context.x19 = stack_start;		p->thread.cpu_context.x20 = stk_sz;	}	p->thread.cpu_context.pc = (unsigned long)ret_from_fork;	p->thread.cpu_context.sp = (unsigned long)childregs; 	ptrace_hw_copy_thread(p); 	return 0;} void tls_preserve_current_state(void){	*task_user_tls(current) = read_sysreg(tpidr_el0);} static void tls_thread_switch(struct task_struct *next){	unsigned long tpidr, tpidrro; 	tls_preserve_current_state(); 	tpidr = *task_user_tls(next);	tpidrro = is_compat_thread(task_thread_info(next)) ?		  next->thread.tp_value : 0; 	write_sysreg(tpidr, tpidr_el0);	write_sysreg(tpidrro, tpidrro_el0);} /* Restore the UAO state depending on next's addr_limit */void uao_thread_switch(struct task_struct *next){	if (IS_ENABLED(CONFIG_ARM64_UAO)) {		if (task_thread_info(next)->addr_limit == KERNEL_DS)			asm(ALTERNATIVE("nop", SET_PSTATE_UAO(1), ARM64_HAS_UAO));		else			asm(ALTERNATIVE("nop", SET_PSTATE_UAO(0), ARM64_HAS_UAO));	}} /* * We store our current task in sp_el0, which is clobbered by userspace. Keep a * shadow copy so that we can restore this upon entry from userspace. * * This is *only* for exception entry from EL0, and is not valid until we * __switch_to() a user task. */DEFINE_PER_CPU(struct task_struct *, __entry_task); static void entry_task_switch(struct task_struct *next){	__this_cpu_write(__entry_task, next);} /* * Thread switching. */__notrace_funcgraph struct task_struct *__switch_to(struct task_struct *prev,				struct task_struct *next){	struct task_struct *last; 	fpsimd_thread_switch(next);	tls_thread_switch(next);	hw_breakpoint_thread_switch(next);	contextidr_thread_switch(next);	entry_task_switch(next);	uao_thread_switch(next); 	/*	 * Complete any pending TLB or cache maintenance on this CPU in case	 * the thread migrates to a different CPU.	 */	dsb(ish); 	/* the actual thread switch */	last = cpu_switch_to(prev, next); 	return last;} unsigned long get_wchan(struct task_struct *p){	struct stackframe frame;	unsigned long stack_page, ret = 0;	int count = 0;	if (!p || p == current || p->state == TASK_RUNNING)		return 0; 	stack_page = (unsigned long)try_get_task_stack(p);	if (!stack_page)		return 0; 	frame.fp = thread_saved_fp(p);	frame.sp = thread_saved_sp(p);	frame.pc = thread_saved_pc(p);#ifdef CONFIG_FUNCTION_GRAPH_TRACER	frame.graph = p->curr_ret_stack;#endif	do {		if (frame.sp < stack_page ||		    frame.sp >= stack_page + THREAD_SIZE ||		    unwind_frame(p, &frame))			goto out;		if (!in_sched_functions(frame.pc)) {			ret = frame.pc;			goto out;		}	} while (count ++ < 16); out:	put_task_stack(p);	return ret;} unsigned long arch_align_stack(unsigned long sp){	if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)		sp -= get_random_int() & ~PAGE_MASK;	return sp & ~0xf;} unsigned long arch_randomize_brk(struct mm_struct *mm){	if (is_compat_task())		return randomize_page(mm->brk, SZ_32M);	else		return randomize_page(mm->brk, SZ_1G);}