// SPDX-License-Identifier: GPL-2.0/* *  linux/arch/alpha/kernel/process.c * *  Copyright (C) 1995  Linus Torvalds */ /* * This file handles the architecture-dependent parts of process handling. */ #include <linux/errno.h>#include <linux/module.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/smp.h>#include <linux/stddef.h>#include <linux/unistd.h>#include <linux/ptrace.h>#include <linux/user.h>#include <linux/time.h>#include <linux/major.h>#include <linux/stat.h>#include <linux/vt.h>#include <linux/mman.h>#include <linux/elfcore.h>#include <linux/reboot.h>#include <linux/tty.h>#include <linux/console.h>#include <linux/slab.h>#include <linux/rcupdate.h> #include <asm/reg.h>#include <linux/uaccess.h>#include <asm/io.h>#include <asm/hwrpb.h>#include <asm/fpu.h> #include "proto.h"#include "pci_impl.h" /* * Power off function, if any */void (*pm_power_off)(void) = machine_power_off;EXPORT_SYMBOL(pm_power_off); #ifdef CONFIG_ALPHA_WTINT/* * Sleep the CPU. * EV6, LCA45 and QEMU know how to power down, skipping N timer interrupts. */void arch_cpu_idle(void){	wtint(0);	local_irq_enable();} void arch_cpu_idle_dead(void){	wtint(INT_MAX);}#endif /* ALPHA_WTINT */ struct halt_info {	int mode;	char *restart_cmd;}; static voidcommon_shutdown_1(void *generic_ptr){	struct halt_info *how = (struct halt_info *)generic_ptr;	struct percpu_struct *cpup;	unsigned long *pflags, flags;	int cpuid = smp_processor_id(); 	/* No point in taking interrupts anymore. */	local_irq_disable(); 	cpup = (struct percpu_struct *)			((unsigned long)hwrpb + hwrpb->processor_offset			 + hwrpb->processor_size * cpuid);	pflags = &cpup->flags;	flags = *pflags; 	/* Clear reason to "default"; clear "bootstrap in progress". */	flags &= ~0x00ff0001UL; #ifdef CONFIG_SMP	/* Secondaries halt here. */	if (cpuid != boot_cpuid) {		flags |= 0x00040000UL; /* "remain halted" */		*pflags = flags;		set_cpu_present(cpuid, false);		set_cpu_possible(cpuid, false);		halt();	}#endif 	if (how->mode == LINUX_REBOOT_CMD_RESTART) {		if (!how->restart_cmd) {			flags |= 0x00020000UL; /* "cold bootstrap" */		} else {			/* For SRM, we could probably set environment			   variables to get this to work.  We'd have to			   delay this until after srm_paging_stop unless			   we ever got srm_fixup working. 			   At the moment, SRM will use the last boot device,			   but the file and flags will be the defaults, when			   doing a "warm" bootstrap.  */			flags |= 0x00030000UL; /* "warm bootstrap" */		}	} else {		flags |= 0x00040000UL; /* "remain halted" */	}	*pflags = flags; #ifdef CONFIG_SMP	/* Wait for the secondaries to halt. */	set_cpu_present(boot_cpuid, false);	set_cpu_possible(boot_cpuid, false);	while (cpumask_weight(cpu_present_mask))		barrier();#endif 	/* If booted from SRM, reset some of the original environment. */	if (alpha_using_srm) {#ifdef CONFIG_DUMMY_CONSOLE		/* If we've gotten here after SysRq-b, leave interrupt		   context before taking over the console. */		if (in_interrupt())			irq_exit();		/* This has the effect of resetting the VGA video origin.  */		console_lock();		do_take_over_console(&dummy_con, 0, MAX_NR_CONSOLES-1, 1);		console_unlock();#endif		pci_restore_srm_config();		set_hae(srm_hae);	} 	if (alpha_mv.kill_arch)		alpha_mv.kill_arch(how->mode); 	if (! alpha_using_srm && how->mode != LINUX_REBOOT_CMD_RESTART) {		/* Unfortunately, since MILO doesn't currently understand		   the hwrpb bits above, we can't reliably halt the 		   processor and keep it halted.  So just loop.  */		return;	} 	if (alpha_using_srm)		srm_paging_stop(); 	halt();} static voidcommon_shutdown(int mode, char *restart_cmd){	struct halt_info args;	args.mode = mode;	args.restart_cmd = restart_cmd;	on_each_cpu(common_shutdown_1, &args, 0);} voidmachine_restart(char *restart_cmd){	common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd);}  voidmachine_halt(void){	common_shutdown(LINUX_REBOOT_CMD_HALT, NULL);}  voidmachine_power_off(void){	common_shutdown(LINUX_REBOOT_CMD_POWER_OFF, NULL);}  /* Used by sysrq-p, among others.  I don't believe r9-r15 are ever   saved in the context it's used.  */ voidshow_regs(struct pt_regs *regs){	show_regs_print_info(KERN_DEFAULT);	dik_show_regs(regs, NULL);} /* * Re-start a thread when doing execve() */voidstart_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp){	regs->pc = pc;	regs->ps = 8;	wrusp(sp);}EXPORT_SYMBOL(start_thread); voidflush_thread(void){	/* Arrange for each exec'ed process to start off with a clean slate	   with respect to the FPU.  This is all exceptions disabled.  */	current_thread_info()->ieee_state = 0;	wrfpcr(FPCR_DYN_NORMAL | ieee_swcr_to_fpcr(0)); 	/* Clean slate for TLS.  */	current_thread_info()->pcb.unique = 0;} voidrelease_thread(struct task_struct *dead_task){} /* * Copy architecture-specific thread state */int copy_thread(unsigned long clone_flags, unsigned long usp,		unsigned long kthread_arg, struct task_struct *p,		unsigned long tls){	extern void ret_from_fork(void);	extern void ret_from_kernel_thread(void); 	struct thread_info *childti = task_thread_info(p);	struct pt_regs *childregs = task_pt_regs(p);	struct pt_regs *regs = current_pt_regs();	struct switch_stack *childstack, *stack; 	childstack = ((struct switch_stack *) childregs) - 1;	childti->pcb.ksp = (unsigned long) childstack;	childti->pcb.flags = 1;	/* set FEN, clear everything else */ 	if (unlikely(p->flags & PF_KTHREAD)) {		/* kernel thread */		memset(childstack, 0,			sizeof(struct switch_stack) + sizeof(struct pt_regs));		childstack->r26 = (unsigned long) ret_from_kernel_thread;		childstack->r9 = usp;	/* function */		childstack->r10 = kthread_arg;		childregs->hae = alpha_mv.hae_cache,		childti->pcb.usp = 0;		return 0;	}	/* Note: if CLONE_SETTLS is not set, then we must inherit the	   value from the parent, which will have been set by the block	   copy in dup_task_struct.  This is non-intuitive, but is	   required for proper operation in the case of a threaded	   application calling fork.  */	if (clone_flags & CLONE_SETTLS)		childti->pcb.unique = tls;	else		regs->r20 = 0;	/* OSF/1 has some strange fork() semantics.  */	childti->pcb.usp = usp ?: rdusp();	*childregs = *regs;	childregs->r0 = 0;	childregs->r19 = 0;	childregs->r20 = 1;	/* OSF/1 has some strange fork() semantics.  */	stack = ((struct switch_stack *) regs) - 1;	*childstack = *stack;	childstack->r26 = (unsigned long) ret_from_fork;	return 0;} /* * Fill in the user structure for a ELF core dump. */voiddump_elf_thread(elf_greg_t *dest, struct pt_regs *pt, struct thread_info *ti){	/* switch stack follows right below pt_regs: */	struct switch_stack * sw = ((struct switch_stack *) pt) - 1; 	dest[ 0] = pt->r0;	dest[ 1] = pt->r1;	dest[ 2] = pt->r2;	dest[ 3] = pt->r3;	dest[ 4] = pt->r4;	dest[ 5] = pt->r5;	dest[ 6] = pt->r6;	dest[ 7] = pt->r7;	dest[ 8] = pt->r8;	dest[ 9] = sw->r9;	dest[10] = sw->r10;	dest[11] = sw->r11;	dest[12] = sw->r12;	dest[13] = sw->r13;	dest[14] = sw->r14;	dest[15] = sw->r15;	dest[16] = pt->r16;	dest[17] = pt->r17;	dest[18] = pt->r18;	dest[19] = pt->r19;	dest[20] = pt->r20;	dest[21] = pt->r21;	dest[22] = pt->r22;	dest[23] = pt->r23;	dest[24] = pt->r24;	dest[25] = pt->r25;	dest[26] = pt->r26;	dest[27] = pt->r27;	dest[28] = pt->r28;	dest[29] = pt->gp;	dest[30] = ti == current_thread_info() ? rdusp() : ti->pcb.usp;	dest[31] = pt->pc; 	/* Once upon a time this was the PS value.  Which is stupid	   since that is always 8 for usermode.  Usurped for the more	   useful value of the thread's UNIQUE field.  */	dest[32] = ti->pcb.unique;}EXPORT_SYMBOL(dump_elf_thread); intdump_elf_task(elf_greg_t *dest, struct task_struct *task){	dump_elf_thread(dest, task_pt_regs(task), task_thread_info(task));	return 1;}EXPORT_SYMBOL(dump_elf_task); intdump_elf_task_fp(elf_fpreg_t *dest, struct task_struct *task){	struct switch_stack *sw = (struct switch_stack *)task_pt_regs(task) - 1;	memcpy(dest, sw->fp, 32 * 8);	return 1;}EXPORT_SYMBOL(dump_elf_task_fp); /* * Return saved PC of a blocked thread.  This assumes the frame * pointer is the 6th saved long on the kernel stack and that the * saved return address is the first long in the frame.  This all * holds provided the thread blocked through a call to schedule() ($15 * is the frame pointer in schedule() and $15 is saved at offset 48 by * entry.S:do_switch_stack). * * Under heavy swap load I've seen this lose in an ugly way.  So do * some extra sanity checking on the ranges we expect these pointers * to be in so that we can fail gracefully.  This is just for ps after * all.  -- r~ */ static unsigned longthread_saved_pc(struct task_struct *t){	unsigned long base = (unsigned long)task_stack_page(t);	unsigned long fp, sp = task_thread_info(t)->pcb.ksp; 	if (sp > base && sp+6*8 < base + 16*1024) {		fp = ((unsigned long*)sp)[6];		if (fp > sp && fp < base + 16*1024)			return *(unsigned long *)fp;	} 	return 0;} unsigned longget_wchan(struct task_struct *p){	unsigned long schedule_frame;	unsigned long pc;	if (!p || p == current || p->state == TASK_RUNNING)		return 0;	/*	 * This one depends on the frame size of schedule().  Do a	 * "disass schedule" in gdb to find the frame size.  Also, the	 * code assumes that sleep_on() follows immediately after	 * interruptible_sleep_on() and that add_timer() follows	 * immediately after interruptible_sleep().  Ugly, isn't it?	 * Maybe adding a wchan field to task_struct would be better,	 * after all...	 */ 	pc = thread_saved_pc(p);	if (in_sched_functions(pc)) {		schedule_frame = ((unsigned long *)task_thread_info(p)->pcb.ksp)[6];		return ((unsigned long *)schedule_frame)[12];	}	return pc;}