linux/arch/mips/kernel/process.c

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/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 1994 - 1999, 2000 by Ralf Baechle and others.
* Copyright (C) 1999, 2000 Silicon Graphics, Inc.
* Copyright (C) 2004 Thiemo Seufer
*/
#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/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/slab.h>
#include <linux/mman.h>
#include <linux/personality.h>
#include <linux/sys.h>
#include <linux/user.h>
#include <linux/a.out.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
#include <asm/fpu.h>
#include <asm/pgtable.h>
#include <asm/system.h>
#include <asm/mipsregs.h>
#include <asm/processor.h>
#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/elf.h>
#include <asm/isadep.h>
#include <asm/inst.h>
/*
* We use this if we don't have any better idle routine..
* (This to kill: kernel/platform.c.
*/
void default_idle (void)
{
}
/*
* 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)
*/
ATTRIB_NORET void cpu_idle(void)
{
/* endless idle loop with no priority at all */
while (1) {
while (!need_resched())
if (cpu_wait)
(*cpu_wait)();
schedule();
}
}
asmlinkage void ret_from_fork(void);
void start_thread(struct pt_regs * regs, unsigned long pc, unsigned long sp)
{
unsigned long status;
/* New thread loses kernel privileges. */
status = regs->cp0_status & ~(ST0_CU0|ST0_CU1|KU_MASK);
#ifdef CONFIG_MIPS64
status &= ~ST0_FR;
status |= (current->thread.mflags & MF_32BIT_REGS) ? 0 : ST0_FR;
#endif
status |= KU_USER;
regs->cp0_status = status;
clear_used_math();
lose_fpu();
regs->cp0_epc = pc;
regs->regs[29] = sp;
current_thread_info()->addr_limit = USER_DS;
}
void exit_thread(void)
{
}
void flush_thread(void)
{
}
int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
unsigned long unused, struct task_struct *p, struct pt_regs *regs)
{
struct thread_info *ti = p->thread_info;
struct pt_regs *childregs;
long childksp;
childksp = (unsigned long)ti + THREAD_SIZE - 32;
preempt_disable();
if (is_fpu_owner()) {
save_fp(p);
}
preempt_enable();
/* set up new TSS. */
childregs = (struct pt_regs *) childksp - 1;
*childregs = *regs;
childregs->regs[7] = 0; /* Clear error flag */
#if defined(CONFIG_BINFMT_IRIX)
if (current->personality != PER_LINUX) {
/* Under IRIX things are a little different. */
childregs->regs[3] = 1;
regs->regs[3] = 0;
}
#endif
childregs->regs[2] = 0; /* Child gets zero as return value */
regs->regs[2] = p->pid;
if (childregs->cp0_status & ST0_CU0) {
childregs->regs[28] = (unsigned long) ti;
childregs->regs[29] = childksp;
ti->addr_limit = KERNEL_DS;
} else {
childregs->regs[29] = usp;
ti->addr_limit = USER_DS;
}
p->thread.reg29 = (unsigned long) childregs;
p->thread.reg31 = (unsigned long) ret_from_fork;
/*
* New tasks lose permission to use the fpu. This accelerates context
* switching for most programs since they don't use the fpu.
*/
p->thread.cp0_status = read_c0_status() & ~(ST0_CU2|ST0_CU1);
childregs->cp0_status &= ~(ST0_CU2|ST0_CU1);
clear_tsk_thread_flag(p, TIF_USEDFPU);
return 0;
}
/* Fill in the fpu structure for a core dump.. */
int dump_fpu(struct pt_regs *regs, elf_fpregset_t *r)
{
memcpy(r, &current->thread.fpu, sizeof(current->thread.fpu));
return 1;
}
void dump_regs(elf_greg_t *gp, struct pt_regs *regs)
{
int i;
for (i = 0; i < EF_R0; i++)
gp[i] = 0;
gp[EF_R0] = 0;
for (i = 1; i <= 31; i++)
gp[EF_R0 + i] = regs->regs[i];
gp[EF_R26] = 0;
gp[EF_R27] = 0;
gp[EF_LO] = regs->lo;
gp[EF_HI] = regs->hi;
gp[EF_CP0_EPC] = regs->cp0_epc;
gp[EF_CP0_BADVADDR] = regs->cp0_badvaddr;
gp[EF_CP0_STATUS] = regs->cp0_status;
gp[EF_CP0_CAUSE] = regs->cp0_cause;
#ifdef EF_UNUSED0
gp[EF_UNUSED0] = 0;
#endif
}
int dump_task_fpu (struct task_struct *t, elf_fpregset_t *fpr)
{
memcpy(fpr, &t->thread.fpu, sizeof(current->thread.fpu));
return 1;
}
/*
* Create a kernel thread
*/
ATTRIB_NORET void kernel_thread_helper(void *arg, int (*fn)(void *))
{
do_exit(fn(arg));
}
long kernel_thread(int (*fn)(void *), void *arg, unsigned long flags)
{
struct pt_regs regs;
memset(&regs, 0, sizeof(regs));
regs.regs[4] = (unsigned long) arg;
regs.regs[5] = (unsigned long) fn;
regs.cp0_epc = (unsigned long) kernel_thread_helper;
regs.cp0_status = read_c0_status();
#if defined(CONFIG_CPU_R3000) || defined(CONFIG_CPU_TX39XX)
regs.cp0_status &= ~(ST0_KUP | ST0_IEC);
regs.cp0_status |= ST0_IEP;
#else
regs.cp0_status |= ST0_EXL;
#endif
/* Ok, create the new process.. */
return do_fork(flags | CLONE_VM | CLONE_UNTRACED, 0, &regs, 0, NULL, NULL);
}
struct mips_frame_info {
int frame_offset;
int pc_offset;
};
static struct mips_frame_info schedule_frame;
static struct mips_frame_info schedule_timeout_frame;
static struct mips_frame_info sleep_on_frame;
static struct mips_frame_info sleep_on_timeout_frame;
static struct mips_frame_info wait_for_completion_frame;
static int mips_frame_info_initialized;
static int __init get_frame_info(struct mips_frame_info *info, void *func)
{
int i;
union mips_instruction *ip = (union mips_instruction *)func;
info->pc_offset = -1;
info->frame_offset = -1;
for (i = 0; i < 128; i++, ip++) {
/* if jal, jalr, jr, stop. */
if (ip->j_format.opcode == jal_op ||
(ip->r_format.opcode == spec_op &&
(ip->r_format.func == jalr_op ||
ip->r_format.func == jr_op)))
break;
if (
#ifdef CONFIG_MIPS32
ip->i_format.opcode == sw_op &&
#endif
#ifdef CONFIG_MIPS64
ip->i_format.opcode == sd_op &&
#endif
ip->i_format.rs == 29)
{
/* sw / sd $ra, offset($sp) */
if (ip->i_format.rt == 31) {
if (info->pc_offset != -1)
break;
info->pc_offset =
ip->i_format.simmediate / sizeof(long);
}
/* sw / sd $s8, offset($sp) */
if (ip->i_format.rt == 30) {
if (info->frame_offset != -1)
break;
info->frame_offset =
ip->i_format.simmediate / sizeof(long);
}
}
}
if (info->pc_offset == -1 || info->frame_offset == -1) {
printk("Can't analyze prologue code at %p\n", func);
info->pc_offset = -1;
info->frame_offset = -1;
return -1;
}
return 0;
}
static int __init frame_info_init(void)
{
mips_frame_info_initialized =
!get_frame_info(&schedule_frame, schedule) &&
!get_frame_info(&schedule_timeout_frame, schedule_timeout) &&
!get_frame_info(&sleep_on_frame, sleep_on) &&
!get_frame_info(&sleep_on_timeout_frame, sleep_on_timeout) &&
!get_frame_info(&wait_for_completion_frame, wait_for_completion);
return 0;
}
arch_initcall(frame_info_init);
/*
* Return saved PC of a blocked thread.
*/
unsigned long thread_saved_pc(struct task_struct *tsk)
{
struct thread_struct *t = &tsk->thread;
/* New born processes are a special case */
if (t->reg31 == (unsigned long) ret_from_fork)
return t->reg31;
if (schedule_frame.pc_offset < 0)
return 0;
return ((unsigned long *)t->reg29)[schedule_frame.pc_offset];
}
/* get_wchan - a maintenance nightmare^W^Wpain in the ass ... */
unsigned long get_wchan(struct task_struct *p)
{
unsigned long frame, pc;
if (!p || p == current || p->state == TASK_RUNNING)
return 0;
if (!mips_frame_info_initialized)
return 0;
pc = thread_saved_pc(p);
if (!in_sched_functions(pc))
goto out;
if (pc >= (unsigned long) sleep_on_timeout)
goto schedule_timeout_caller;
if (pc >= (unsigned long) sleep_on)
goto schedule_caller;
if (pc >= (unsigned long) interruptible_sleep_on_timeout)
goto schedule_timeout_caller;
if (pc >= (unsigned long)interruptible_sleep_on)
goto schedule_caller;
if (pc >= (unsigned long)wait_for_completion)
goto schedule_caller;
goto schedule_timeout_caller;
schedule_caller:
frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
if (pc >= (unsigned long) sleep_on)
pc = ((unsigned long *)frame)[sleep_on_frame.pc_offset];
else
pc = ((unsigned long *)frame)[wait_for_completion_frame.pc_offset];
goto out;
schedule_timeout_caller:
/*
* The schedule_timeout frame
*/
frame = ((unsigned long *)p->thread.reg30)[schedule_frame.frame_offset];
/*
* frame now points to sleep_on_timeout's frame
*/
pc = ((unsigned long *)frame)[schedule_timeout_frame.pc_offset];
if (in_sched_functions(pc)) {
/* schedule_timeout called by [interruptible_]sleep_on_timeout */
frame = ((unsigned long *)frame)[schedule_timeout_frame.frame_offset];
pc = ((unsigned long *)frame)[sleep_on_timeout_frame.pc_offset];
}
out:
#ifdef CONFIG_MIPS64
if (current->thread.mflags & MF_32BIT_REGS) /* Kludge for 32-bit ps */
pc &= 0xffffffffUL;
#endif
return pc;
}
EXPORT_SYMBOL(get_wchan);