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kernel-ark/arch/m68k/kernel/process.c
Nick Piggin 5bfb5d690f [PATCH] sched: disable preempt in idle tasks 
Run idle threads with preempt disabled.

Also corrected a bugs in arm26's cpu_idle (make it actually call schedule()).
How did it ever work before?

Might fix the CPU hotplugging hang which Nigel Cunningham noted.

We think the bug hits if the idle thread is preempted after checking
need_resched() and before going to sleep, then the CPU offlined.

After calling stop_machine_run, the CPU eventually returns from preemption and
into the idle thread and goes to sleep.  The CPU will continue executing
previous idle and have no chance to call play_dead.

By disabling preemption until we are ready to explicitly schedule, this bug is
fixed and the idle threads generally become more robust.

From: alexs <ashepard@u.washington.edu>

  PPC build fix

From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp>

  MIPS build fix

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Yoichi Yuasa <yuasa@hh.iij4u.or.jp>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-09 07:56:33 -08:00

402 lines
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/*
* linux/arch/m68k/kernel/process.c
*
* Copyright (C) 1995 Hamish Macdonald
*
* 68060 fixes by Jesper Skov
*/
/*
* This file handles the architecture-dependent parts of process handling..
*/
#include <linux/config.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/reboot.h>
#include <linux/init_task.h>
#include <linux/mqueue.h>
#include <asm/uaccess.h>
#include <asm/system.h>
#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/setup.h>
#include <asm/pgtable.h>
/*
* Initial task/thread structure. Make this a per-architecture thing,
* because different architectures tend to have different
* alignment requirements and potentially different initial
* setup.
*/
static struct fs_struct init_fs = INIT_FS;
static struct files_struct init_files = INIT_FILES;
static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
struct mm_struct init_mm = INIT_MM(init_mm);
EXPORT_SYMBOL(init_mm);
union thread_union init_thread_union
__attribute__((section(".data.init_task"), aligned(THREAD_SIZE)))
= { INIT_THREAD_INFO(init_task) };
/* initial task structure */
struct task_struct init_task = INIT_TASK(init_task);
EXPORT_SYMBOL(init_task);
asmlinkage void ret_from_fork(void);
/*
* Return saved PC from a blocked thread
*/
unsigned long thread_saved_pc(struct task_struct *tsk)
{
struct switch_stack *sw = (struct switch_stack *)tsk->thread.ksp;
/* Check whether the thread is blocked in resume() */
if (in_sched_functions(sw->retpc))
return ((unsigned long *)sw->a6)[1];
else
return sw->retpc;
}
/*
* The idle loop on an m68k..
*/
void default_idle(void)
{
if (!need_resched())
#if defined(MACH_ATARI_ONLY) && !defined(CONFIG_HADES)
/* block out HSYNC on the atari (falcon) */
__asm__("stop #0x2200" : : : "cc");
#else
__asm__("stop #0x2000" : : : "cc");
#endif
}
void (*idle)(void) = default_idle;
/*
* The idle thread. There's no useful work to be
* done, so just try to conserve power and have a
* low exit latency (ie sit in a loop waiting for
* somebody to say that they'd like to reschedule)
*/
void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
while (!need_resched())
idle();
preempt_enable_no_resched();
schedule();
preempt_disable();
}
}
void machine_restart(char * __unused)
{
if (mach_reset)
mach_reset();
for (;;);
}
void machine_halt(void)
{
if (mach_halt)
mach_halt();
for (;;);
}
void machine_power_off(void)
{
if (mach_power_off)
mach_power_off();
for (;;);
}
void show_regs(struct pt_regs * regs)
{
printk("\n");
printk("Format %02x Vector: %04x PC: %08lx Status: %04x %s\n",
regs->format, regs->vector, regs->pc, regs->sr, print_tainted());
printk("ORIG_D0: %08lx D0: %08lx A2: %08lx A1: %08lx\n",
regs->orig_d0, regs->d0, regs->a2, regs->a1);
printk("A0: %08lx D5: %08lx D4: %08lx\n",
regs->a0, regs->d5, regs->d4);
printk("D3: %08lx D2: %08lx D1: %08lx\n",
regs->d3, regs->d2, regs->d1);
if (!(regs->sr & PS_S))
printk("USP: %08lx\n", rdusp());
}
/*
* Create a kernel thread
*/
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
int pid;
mm_segment_t fs;
fs = get_fs();
set_fs (KERNEL_DS);
{
register long retval __asm__ ("d0");
register long clone_arg __asm__ ("d1") = flags | CLONE_VM | CLONE_UNTRACED;
retval = __NR_clone;
__asm__ __volatile__
("clrl %%d2\n\t"
"trap #0\n\t" /* Linux/m68k system call */
"tstl %0\n\t" /* child or parent */
"jne 1f\n\t" /* parent - jump */
"lea %%sp@(%c7),%6\n\t" /* reload current */
"movel %6@,%6\n\t"
"movel %3,%%sp@-\n\t" /* push argument */
"jsr %4@\n\t" /* call fn */
"movel %0,%%d1\n\t" /* pass exit value */
"movel %2,%%d0\n\t" /* exit */
"trap #0\n"
"1:"
: "+d" (retval)
: "i" (__NR_clone), "i" (__NR_exit),
"r" (arg), "a" (fn), "d" (clone_arg), "r" (current),
"i" (-THREAD_SIZE)
: "d2");
pid = retval;
}
set_fs (fs);
return pid;
}
void flush_thread(void)
{
unsigned long zero = 0;
set_fs(USER_DS);
current->thread.fs = __USER_DS;
if (!FPU_IS_EMU)
asm volatile (".chip 68k/68881\n\t"
"frestore %0@\n\t"
".chip 68k" : : "a" (&zero));
}
/*
* "m68k_fork()".. By the time we get here, the
* non-volatile registers have also been saved on the
* stack. We do some ugly pointer stuff here.. (see
* also copy_thread)
*/
asmlinkage int m68k_fork(struct pt_regs *regs)
{
return do_fork(SIGCHLD, rdusp(), regs, 0, NULL, NULL);
}
asmlinkage int m68k_vfork(struct pt_regs *regs)
{
return do_fork(CLONE_VFORK | CLONE_VM | SIGCHLD, rdusp(), regs, 0,
NULL, NULL);
}
asmlinkage int m68k_clone(struct pt_regs *regs)
{
unsigned long clone_flags;
unsigned long newsp;
int *parent_tidptr, *child_tidptr;
/* syscall2 puts clone_flags in d1 and usp in d2 */
clone_flags = regs->d1;
newsp = regs->d2;
parent_tidptr = (int *)regs->d3;
child_tidptr = (int *)regs->d4;
if (!newsp)
newsp = rdusp();
return do_fork(clone_flags, newsp, regs, 0,
parent_tidptr, child_tidptr);
}
int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
unsigned long unused,
struct task_struct * p, struct pt_regs * regs)
{
struct pt_regs * childregs;
struct switch_stack * childstack, *stack;
unsigned long stack_offset, *retp;
stack_offset = THREAD_SIZE - sizeof(struct pt_regs);
childregs = (struct pt_regs *) ((unsigned long) (p->thread_info) + stack_offset);
*childregs = *regs;
childregs->d0 = 0;
retp = ((unsigned long *) regs);
stack = ((struct switch_stack *) retp) - 1;
childstack = ((struct switch_stack *) childregs) - 1;
*childstack = *stack;
childstack->retpc = (unsigned long)ret_from_fork;
p->thread.usp = usp;
p->thread.ksp = (unsigned long)childstack;
/*
* Must save the current SFC/DFC value, NOT the value when
* the parent was last descheduled - RGH 10-08-96
*/
p->thread.fs = get_fs().seg;
if (!FPU_IS_EMU) {
/* Copy the current fpu state */
asm volatile ("fsave %0" : : "m" (p->thread.fpstate[0]) : "memory");
if (!CPU_IS_060 ? p->thread.fpstate[0] : p->thread.fpstate[2])
asm volatile ("fmovemx %/fp0-%/fp7,%0\n\t"
"fmoveml %/fpiar/%/fpcr/%/fpsr,%1"
: : "m" (p->thread.fp[0]), "m" (p->thread.fpcntl[0])
: "memory");
/* Restore the state in case the fpu was busy */
asm volatile ("frestore %0" : : "m" (p->thread.fpstate[0]));
}
return 0;
}
/* Fill in the fpu structure for a core dump. */
int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
{
char fpustate[216];
if (FPU_IS_EMU) {
int i;
memcpy(fpu->fpcntl, current->thread.fpcntl, 12);
memcpy(fpu->fpregs, current->thread.fp, 96);
/* Convert internal fpu reg representation
* into long double format
*/
for (i = 0; i < 24; i += 3)
fpu->fpregs[i] = ((fpu->fpregs[i] & 0xffff0000) << 15) |
((fpu->fpregs[i] & 0x0000ffff) << 16);
return 1;
}
/* First dump the fpu context to avoid protocol violation. */
asm volatile ("fsave %0" :: "m" (fpustate[0]) : "memory");
if (!CPU_IS_060 ? !fpustate[0] : !fpustate[2])
return 0;
asm volatile ("fmovem %/fpiar/%/fpcr/%/fpsr,%0"
:: "m" (fpu->fpcntl[0])
: "memory");
asm volatile ("fmovemx %/fp0-%/fp7,%0"
:: "m" (fpu->fpregs[0])
: "memory");
return 1;
}
/*
* fill in the user structure for a core dump..
*/
void dump_thread(struct pt_regs * regs, struct user * dump)
{
struct switch_stack *sw;
/* changed the size calculations - should hopefully work better. lbt */
dump->magic = CMAGIC;
dump->start_code = 0;
dump->start_stack = rdusp() & ~(PAGE_SIZE - 1);
dump->u_tsize = ((unsigned long) current->mm->end_code) >> PAGE_SHIFT;
dump->u_dsize = ((unsigned long) (current->mm->brk +
(PAGE_SIZE-1))) >> PAGE_SHIFT;
dump->u_dsize -= dump->u_tsize;
dump->u_ssize = 0;
if (dump->start_stack < TASK_SIZE)
dump->u_ssize = ((unsigned long) (TASK_SIZE - dump->start_stack)) >> PAGE_SHIFT;
dump->u_ar0 = (struct user_regs_struct *)((int)&dump->regs - (int)dump);
sw = ((struct switch_stack *)regs) - 1;
dump->regs.d1 = regs->d1;
dump->regs.d2 = regs->d2;
dump->regs.d3 = regs->d3;
dump->regs.d4 = regs->d4;
dump->regs.d5 = regs->d5;
dump->regs.d6 = sw->d6;
dump->regs.d7 = sw->d7;
dump->regs.a0 = regs->a0;
dump->regs.a1 = regs->a1;
dump->regs.a2 = regs->a2;
dump->regs.a3 = sw->a3;
dump->regs.a4 = sw->a4;
dump->regs.a5 = sw->a5;
dump->regs.a6 = sw->a6;
dump->regs.d0 = regs->d0;
dump->regs.orig_d0 = regs->orig_d0;
dump->regs.stkadj = regs->stkadj;
dump->regs.sr = regs->sr;
dump->regs.pc = regs->pc;
dump->regs.fmtvec = (regs->format << 12) | regs->vector;
/* dump floating point stuff */
dump->u_fpvalid = dump_fpu (regs, &dump->m68kfp);
}
/*
* sys_execve() executes a new program.
*/
asmlinkage int sys_execve(char *name, char **argv, char **envp)
{
int error;
char * filename;
struct pt_regs *regs = (struct pt_regs *) &name;
lock_kernel();
filename = getname(name);
error = PTR_ERR(filename);
if (IS_ERR(filename))
goto out;
error = do_execve(filename, argv, envp, regs);
putname(filename);
out:
unlock_kernel();
return error;
}
unsigned long get_wchan(struct task_struct *p)
{
unsigned long fp, pc;
unsigned long stack_page;
int count = 0;
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
stack_page = (unsigned long)(p->thread_info);
fp = ((struct switch_stack *)p->thread.ksp)->a6;
do {
if (fp < stack_page+sizeof(struct thread_info) ||
fp >= 8184+stack_page)
return 0;
pc = ((unsigned long *)fp)[1];
if (!in_sched_functions(pc))
return pc;
fp = *(unsigned long *) fp;
} while (count++ < 16);
return 0;
}
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