Orange Pi5 kernel

// 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);
<------>raw_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,
<------><------>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.
 */
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;
}