// 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/cpu.h>
#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);
}
void __noreturn arch_cpu_idle_dead(void)
{
wtint(INT_MAX);
BUG();
}
#endif /* ALPHA_WTINT */
struct halt_info {
int mode;
char *restart_cmd;
};
static void
common_shutdown_1(void *generic_ptr)
{
struct halt_info *how = 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_empty(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_hardirq())
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;
}
/*
* Copy architecture-specific thread state
*/
int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
{
unsigned long clone_flags = args->flags;
unsigned long usp = args->stack;
unsigned long tls = args->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 */
childti->status |= TS_SAVED_FP | TS_RESTORE_FP;
if (unlikely(args->fn)) {
/* kernel thread */
memset(childstack, 0,
sizeof(struct switch_stack) + sizeof(struct pt_regs));
childstack->r26 = (unsigned long) ret_from_kernel_thread;
childstack->r9 = (unsigned long) args->fn;
childstack->r10 = (unsigned long) args->fn_arg;
childregs->hae = alpha_mv.hae_cache;
memset(childti->fp, '\0', sizeof(childti->fp));
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.
*/
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 elf_core_copy_task_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
{
memcpy(fpu, task_thread_info(t)->fp, 32 * 8);
return 1;
}
/*
* 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;
/*
* 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;
}
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