kernel-ark/arch/um/kernel/process.c
Jeff Dike b160fb6309 uml: eliminate interrupts in the idle loop
Now, the idle loop now longer needs SIGALRM firing - it can just sleep for the
requisite amount of time and fake a timer interrupt when it finishes.

Any use of ITIMER_REAL now goes away.  disable_timer only turns off
ITIMER_VIRTUAL.  switch_timers is no longer needed, so it, and all calls, goes
away.

disable_timer now returns the amount of time remaining on the timer.
default_idle uses this to tell idle_sleep how long to sleep.  idle_sleep will
call alarm_handler if nanosleep returns 0, which is the case if it didn't
return early due to an interrupt.  Otherwise, it just returns.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-16 09:43:08 -07:00

462 lines
9.3 KiB
C

/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Copyright 2003 PathScale, Inc.
* Licensed under the GPL
*/
#include "linux/stddef.h"
#include "linux/err.h"
#include "linux/hardirq.h"
#include "linux/mm.h"
#include "linux/personality.h"
#include "linux/proc_fs.h"
#include "linux/ptrace.h"
#include "linux/random.h"
#include "linux/sched.h"
#include "linux/tick.h"
#include "linux/threads.h"
#include "asm/pgtable.h"
#include "asm/uaccess.h"
#include "as-layout.h"
#include "kern_util.h"
#include "os.h"
#include "skas.h"
#include "tlb.h"
/*
* This is a per-cpu array. A processor only modifies its entry and it only
* cares about its entry, so it's OK if another processor is modifying its
* entry.
*/
struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
static inline int external_pid(struct task_struct *task)
{
/* FIXME: Need to look up userspace_pid by cpu */
return userspace_pid[0];
}
int pid_to_processor_id(int pid)
{
int i;
for(i = 0; i < ncpus; i++) {
if (cpu_tasks[i].pid == pid)
return i;
}
return -1;
}
void free_stack(unsigned long stack, int order)
{
free_pages(stack, order);
}
unsigned long alloc_stack(int order, int atomic)
{
unsigned long page;
gfp_t flags = GFP_KERNEL;
if (atomic)
flags = GFP_ATOMIC;
page = __get_free_pages(flags, order);
if (page == 0)
return 0;
return page;
}
int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
{
int pid;
current->thread.request.u.thread.proc = fn;
current->thread.request.u.thread.arg = arg;
pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
&current->thread.regs, 0, NULL, NULL);
return pid;
}
static inline void set_current(struct task_struct *task)
{
cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
{ external_pid(task), task });
}
extern void arch_switch_to(struct task_struct *from, struct task_struct *to);
void *_switch_to(void *prev, void *next, void *last)
{
struct task_struct *from = prev;
struct task_struct *to= next;
to->thread.prev_sched = from;
set_current(to);
do {
current->thread.saved_task = NULL;
switch_threads(&from->thread.switch_buf,
&to->thread.switch_buf);
arch_switch_to(current->thread.prev_sched, current);
if (current->thread.saved_task)
show_regs(&(current->thread.regs));
next= current->thread.saved_task;
prev= current;
} while(current->thread.saved_task);
return current->thread.prev_sched;
}
void interrupt_end(void)
{
if (need_resched())
schedule();
if (test_tsk_thread_flag(current, TIF_SIGPENDING))
do_signal();
}
void exit_thread(void)
{
}
void *get_current(void)
{
return current;
}
extern void schedule_tail(struct task_struct *prev);
/*
* This is called magically, by its address being stuffed in a jmp_buf
* and being longjmp-d to.
*/
void new_thread_handler(void)
{
int (*fn)(void *), n;
void *arg;
if (current->thread.prev_sched != NULL)
schedule_tail(current->thread.prev_sched);
current->thread.prev_sched = NULL;
fn = current->thread.request.u.thread.proc;
arg = current->thread.request.u.thread.arg;
/*
* The return value is 1 if the kernel thread execs a process,
* 0 if it just exits
*/
n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
if (n == 1) {
/* Handle any immediate reschedules or signals */
interrupt_end();
userspace(&current->thread.regs.regs);
}
else do_exit(0);
}
/* Called magically, see new_thread_handler above */
void fork_handler(void)
{
force_flush_all();
if (current->thread.prev_sched == NULL)
panic("blech");
schedule_tail(current->thread.prev_sched);
/*
* XXX: if interrupt_end() calls schedule, this call to
* arch_switch_to isn't needed. We could want to apply this to
* improve performance. -bb
*/
arch_switch_to(current->thread.prev_sched, current);
current->thread.prev_sched = NULL;
/* Handle any immediate reschedules or signals */
interrupt_end();
userspace(&current->thread.regs.regs);
}
int copy_thread(int nr, unsigned long clone_flags, unsigned long sp,
unsigned long stack_top, struct task_struct * p,
struct pt_regs *regs)
{
void (*handler)(void);
int ret = 0;
p->thread = (struct thread_struct) INIT_THREAD;
if (current->thread.forking) {
memcpy(&p->thread.regs.regs, &regs->regs,
sizeof(p->thread.regs.regs));
REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);
if (sp != 0)
REGS_SP(p->thread.regs.regs.gp) = sp;
handler = fork_handler;
arch_copy_thread(&current->thread.arch, &p->thread.arch);
}
else {
init_thread_registers(&p->thread.regs.regs);
p->thread.request.u.thread = current->thread.request.u.thread;
handler = new_thread_handler;
}
new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
if (current->thread.forking) {
clear_flushed_tls(p);
/*
* Set a new TLS for the child thread?
*/
if (clone_flags & CLONE_SETTLS)
ret = arch_copy_tls(p);
}
return ret;
}
void initial_thread_cb(void (*proc)(void *), void *arg)
{
int save_kmalloc_ok = kmalloc_ok;
kmalloc_ok = 0;
initial_thread_cb_skas(proc, arg);
kmalloc_ok = save_kmalloc_ok;
}
void default_idle(void)
{
unsigned long long nsecs;
while(1) {
/* endless idle loop with no priority at all */
/*
* although we are an idle CPU, we do not want to
* get into the scheduler unnecessarily.
*/
if (need_resched())
schedule();
tick_nohz_stop_sched_tick();
nsecs = disable_timer();
idle_sleep(nsecs);
tick_nohz_restart_sched_tick();
}
}
void cpu_idle(void)
{
cpu_tasks[current_thread->cpu].pid = os_getpid();
default_idle();
}
void *um_virt_to_phys(struct task_struct *task, unsigned long addr,
pte_t *pte_out)
{
pgd_t *pgd;
pud_t *pud;
pmd_t *pmd;
pte_t *pte;
pte_t ptent;
if (task->mm == NULL)
return ERR_PTR(-EINVAL);
pgd = pgd_offset(task->mm, addr);
if (!pgd_present(*pgd))
return ERR_PTR(-EINVAL);
pud = pud_offset(pgd, addr);
if (!pud_present(*pud))
return ERR_PTR(-EINVAL);
pmd = pmd_offset(pud, addr);
if (!pmd_present(*pmd))
return ERR_PTR(-EINVAL);
pte = pte_offset_kernel(pmd, addr);
ptent = *pte;
if (!pte_present(ptent))
return ERR_PTR(-EINVAL);
if (pte_out != NULL)
*pte_out = ptent;
return (void *) (pte_val(ptent) & PAGE_MASK) + (addr & ~PAGE_MASK);
}
char *current_cmd(void)
{
#if defined(CONFIG_SMP) || defined(CONFIG_HIGHMEM)
return "(Unknown)";
#else
void *addr = um_virt_to_phys(current, current->mm->arg_start, NULL);
return IS_ERR(addr) ? "(Unknown)": __va((unsigned long) addr);
#endif
}
void dump_thread(struct pt_regs *regs, struct user *u)
{
}
int __cant_sleep(void) {
return in_atomic() || irqs_disabled() || in_interrupt();
/* Is in_interrupt() really needed? */
}
int user_context(unsigned long sp)
{
unsigned long stack;
stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
return stack != (unsigned long) current_thread;
}
extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
void do_uml_exitcalls(void)
{
exitcall_t *call;
call = &__uml_exitcall_end;
while (--call >= &__uml_exitcall_begin)
(*call)();
}
char *uml_strdup(char *string)
{
return kstrdup(string, GFP_KERNEL);
}
int copy_to_user_proc(void __user *to, void *from, int size)
{
return copy_to_user(to, from, size);
}
int copy_from_user_proc(void *to, void __user *from, int size)
{
return copy_from_user(to, from, size);
}
int clear_user_proc(void __user *buf, int size)
{
return clear_user(buf, size);
}
int strlen_user_proc(char __user *str)
{
return strlen_user(str);
}
int smp_sigio_handler(void)
{
#ifdef CONFIG_SMP
int cpu = current_thread->cpu;
IPI_handler(cpu);
if (cpu != 0)
return 1;
#endif
return 0;
}
int cpu(void)
{
return current_thread->cpu;
}
static atomic_t using_sysemu = ATOMIC_INIT(0);
int sysemu_supported;
void set_using_sysemu(int value)
{
if (value > sysemu_supported)
return;
atomic_set(&using_sysemu, value);
}
int get_using_sysemu(void)
{
return atomic_read(&using_sysemu);
}
static int proc_read_sysemu(char *buf, char **start, off_t offset, int size,int *eof, void *data)
{
if (snprintf(buf, size, "%d\n", get_using_sysemu()) < size)
/* No overflow */
*eof = 1;
return strlen(buf);
}
static int proc_write_sysemu(struct file *file,const char __user *buf, unsigned long count,void *data)
{
char tmp[2];
if (copy_from_user(tmp, buf, 1))
return -EFAULT;
if (tmp[0] >= '0' && tmp[0] <= '2')
set_using_sysemu(tmp[0] - '0');
/* We use the first char, but pretend to write everything */
return count;
}
int __init make_proc_sysemu(void)
{
struct proc_dir_entry *ent;
if (!sysemu_supported)
return 0;
ent = create_proc_entry("sysemu", 0600, &proc_root);
if (ent == NULL)
{
printk(KERN_WARNING "Failed to register /proc/sysemu\n");
return 0;
}
ent->read_proc = proc_read_sysemu;
ent->write_proc = proc_write_sysemu;
return 0;
}
late_initcall(make_proc_sysemu);
int singlestepping(void * t)
{
struct task_struct *task = t ? t : current;
if ( ! (task->ptrace & PT_DTRACE) )
return 0;
if (task->thread.singlestep_syscall)
return 1;
return 2;
}
/*
* Only x86 and x86_64 have an arch_align_stack().
* All other arches have "#define arch_align_stack(x) (x)"
* in their asm/system.h
* As this is included in UML from asm-um/system-generic.h,
* we can use it to behave as the subarch does.
*/
#ifndef arch_align_stack
unsigned long arch_align_stack(unsigned long sp)
{
if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
sp -= get_random_int() % 8192;
return sp & ~0xf;
}
#endif