// 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 void common_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 void common_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); } void machine_restart(char *restart_cmd) { common_shutdown(LINUX_REBOOT_CMD_RESTART, restart_cmd); } void machine_halt(void) { common_shutdown(LINUX_REBOOT_CMD_HALT, NULL); } void machine_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. */ void show_regs(struct pt_regs *regs) { show_regs_print_info(KERN_DEFAULT); dik_show_regs(regs, NULL); } /* * Re-start a thread when doing execve() */ void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp) { regs->pc = pc; regs->ps = 8; wrusp(sp); } EXPORT_SYMBOL(start_thread); void flush_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; } void release_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) { 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 = regs->r20; 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. */ void dump_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); int dump_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); int dump_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 long thread_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 long get_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; }