linux/arch/um/kernel/process.c
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   1/*
   2 * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3 * Copyright 2003 PathScale, Inc.
   4 * Licensed under the GPL
   5 */
   6
   7#include <linux/stddef.h>
   8#include <linux/err.h>
   9#include <linux/hardirq.h>
  10#include <linux/mm.h>
  11#include <linux/module.h>
  12#include <linux/personality.h>
  13#include <linux/proc_fs.h>
  14#include <linux/ptrace.h>
  15#include <linux/random.h>
  16#include <linux/slab.h>
  17#include <linux/sched.h>
  18#include <linux/seq_file.h>
  19#include <linux/tick.h>
  20#include <linux/threads.h>
  21#include <asm/current.h>
  22#include <asm/pgtable.h>
  23#include <asm/mmu_context.h>
  24#include <asm/uaccess.h>
  25#include "as-layout.h"
  26#include "kern_util.h"
  27#include "os.h"
  28#include "skas.h"
  29
  30/*
  31 * This is a per-cpu array.  A processor only modifies its entry and it only
  32 * cares about its entry, so it's OK if another processor is modifying its
  33 * entry.
  34 */
  35struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
  36
  37static inline int external_pid(void)
  38{
  39        /* FIXME: Need to look up userspace_pid by cpu */
  40        return userspace_pid[0];
  41}
  42
  43int pid_to_processor_id(int pid)
  44{
  45        int i;
  46
  47        for (i = 0; i < ncpus; i++) {
  48                if (cpu_tasks[i].pid == pid)
  49                        return i;
  50        }
  51        return -1;
  52}
  53
  54void free_stack(unsigned long stack, int order)
  55{
  56        free_pages(stack, order);
  57}
  58
  59unsigned long alloc_stack(int order, int atomic)
  60{
  61        unsigned long page;
  62        gfp_t flags = GFP_KERNEL;
  63
  64        if (atomic)
  65                flags = GFP_ATOMIC;
  66        page = __get_free_pages(flags, order);
  67
  68        return page;
  69}
  70
  71int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
  72{
  73        int pid;
  74
  75        current->thread.request.u.thread.proc = fn;
  76        current->thread.request.u.thread.arg = arg;
  77        pid = do_fork(CLONE_VM | CLONE_UNTRACED | flags, 0,
  78                      &current->thread.regs, 0, NULL, NULL);
  79        return pid;
  80}
  81EXPORT_SYMBOL(kernel_thread);
  82
  83static inline void set_current(struct task_struct *task)
  84{
  85        cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
  86                { external_pid(), task });
  87}
  88
  89extern void arch_switch_to(struct task_struct *to);
  90
  91void *__switch_to(struct task_struct *from, struct task_struct *to)
  92{
  93        to->thread.prev_sched = from;
  94        set_current(to);
  95
  96        do {
  97                current->thread.saved_task = NULL;
  98
  99                switch_threads(&from->thread.switch_buf,
 100                               &to->thread.switch_buf);
 101
 102                arch_switch_to(current);
 103
 104                if (current->thread.saved_task)
 105                        show_regs(&(current->thread.regs));
 106                to = current->thread.saved_task;
 107                from = current;
 108        } while (current->thread.saved_task);
 109
 110        return current->thread.prev_sched;
 111}
 112
 113void interrupt_end(void)
 114{
 115        if (need_resched())
 116                schedule();
 117        if (test_tsk_thread_flag(current, TIF_SIGPENDING))
 118                do_signal();
 119}
 120
 121void exit_thread(void)
 122{
 123}
 124
 125int get_current_pid(void)
 126{
 127        return task_pid_nr(current);
 128}
 129
 130/*
 131 * This is called magically, by its address being stuffed in a jmp_buf
 132 * and being longjmp-d to.
 133 */
 134void new_thread_handler(void)
 135{
 136        int (*fn)(void *), n;
 137        void *arg;
 138
 139        if (current->thread.prev_sched != NULL)
 140                schedule_tail(current->thread.prev_sched);
 141        current->thread.prev_sched = NULL;
 142
 143        fn = current->thread.request.u.thread.proc;
 144        arg = current->thread.request.u.thread.arg;
 145
 146        /*
 147         * The return value is 1 if the kernel thread execs a process,
 148         * 0 if it just exits
 149         */
 150        n = run_kernel_thread(fn, arg, &current->thread.exec_buf);
 151        if (n == 1) {
 152                /* Handle any immediate reschedules or signals */
 153                interrupt_end();
 154                userspace(&current->thread.regs.regs);
 155        }
 156        else do_exit(0);
 157}
 158
 159/* Called magically, see new_thread_handler above */
 160void fork_handler(void)
 161{
 162        force_flush_all();
 163
 164        schedule_tail(current->thread.prev_sched);
 165
 166        /*
 167         * XXX: if interrupt_end() calls schedule, this call to
 168         * arch_switch_to isn't needed. We could want to apply this to
 169         * improve performance. -bb
 170         */
 171        arch_switch_to(current);
 172
 173        current->thread.prev_sched = NULL;
 174
 175        /* Handle any immediate reschedules or signals */
 176        interrupt_end();
 177
 178        userspace(&current->thread.regs.regs);
 179}
 180
 181int copy_thread(unsigned long clone_flags, unsigned long sp,
 182                unsigned long stack_top, struct task_struct * p,
 183                struct pt_regs *regs)
 184{
 185        void (*handler)(void);
 186        int ret = 0;
 187
 188        p->thread = (struct thread_struct) INIT_THREAD;
 189
 190        if (current->thread.forking) {
 191                memcpy(&p->thread.regs.regs, &regs->regs,
 192                       sizeof(p->thread.regs.regs));
 193                REGS_SET_SYSCALL_RETURN(p->thread.regs.regs.gp, 0);
 194                if (sp != 0)
 195                        REGS_SP(p->thread.regs.regs.gp) = sp;
 196
 197                handler = fork_handler;
 198
 199                arch_copy_thread(&current->thread.arch, &p->thread.arch);
 200        }
 201        else {
 202                get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
 203                p->thread.request.u.thread = current->thread.request.u.thread;
 204                handler = new_thread_handler;
 205        }
 206
 207        new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
 208
 209        if (current->thread.forking) {
 210                clear_flushed_tls(p);
 211
 212                /*
 213                 * Set a new TLS for the child thread?
 214                 */
 215                if (clone_flags & CLONE_SETTLS)
 216                        ret = arch_copy_tls(p);
 217        }
 218
 219        return ret;
 220}
 221
 222void initial_thread_cb(void (*proc)(void *), void *arg)
 223{
 224        int save_kmalloc_ok = kmalloc_ok;
 225
 226        kmalloc_ok = 0;
 227        initial_thread_cb_skas(proc, arg);
 228        kmalloc_ok = save_kmalloc_ok;
 229}
 230
 231void default_idle(void)
 232{
 233        unsigned long long nsecs;
 234
 235        while (1) {
 236                /* endless idle loop with no priority at all */
 237
 238                /*
 239                 * although we are an idle CPU, we do not want to
 240                 * get into the scheduler unnecessarily.
 241                 */
 242                if (need_resched())
 243                        schedule();
 244
 245                tick_nohz_idle_enter();
 246                rcu_idle_enter();
 247                nsecs = disable_timer();
 248                idle_sleep(nsecs);
 249                rcu_idle_exit();
 250                tick_nohz_idle_exit();
 251        }
 252}
 253
 254void cpu_idle(void)
 255{
 256        cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 257        default_idle();
 258}
 259
 260int __cant_sleep(void) {
 261        return in_atomic() || irqs_disabled() || in_interrupt();
 262        /* Is in_interrupt() really needed? */
 263}
 264
 265int user_context(unsigned long sp)
 266{
 267        unsigned long stack;
 268
 269        stack = sp & (PAGE_MASK << CONFIG_KERNEL_STACK_ORDER);
 270        return stack != (unsigned long) current_thread_info();
 271}
 272
 273extern exitcall_t __uml_exitcall_begin, __uml_exitcall_end;
 274
 275void do_uml_exitcalls(void)
 276{
 277        exitcall_t *call;
 278
 279        call = &__uml_exitcall_end;
 280        while (--call >= &__uml_exitcall_begin)
 281                (*call)();
 282}
 283
 284char *uml_strdup(const char *string)
 285{
 286        return kstrdup(string, GFP_KERNEL);
 287}
 288EXPORT_SYMBOL(uml_strdup);
 289
 290int copy_to_user_proc(void __user *to, void *from, int size)
 291{
 292        return copy_to_user(to, from, size);
 293}
 294
 295int copy_from_user_proc(void *to, void __user *from, int size)
 296{
 297        return copy_from_user(to, from, size);
 298}
 299
 300int clear_user_proc(void __user *buf, int size)
 301{
 302        return clear_user(buf, size);
 303}
 304
 305int strlen_user_proc(char __user *str)
 306{
 307        return strlen_user(str);
 308}
 309
 310int smp_sigio_handler(void)
 311{
 312#ifdef CONFIG_SMP
 313        int cpu = current_thread_info()->cpu;
 314        IPI_handler(cpu);
 315        if (cpu != 0)
 316                return 1;
 317#endif
 318        return 0;
 319}
 320
 321int cpu(void)
 322{
 323        return current_thread_info()->cpu;
 324}
 325
 326static atomic_t using_sysemu = ATOMIC_INIT(0);
 327int sysemu_supported;
 328
 329void set_using_sysemu(int value)
 330{
 331        if (value > sysemu_supported)
 332                return;
 333        atomic_set(&using_sysemu, value);
 334}
 335
 336int get_using_sysemu(void)
 337{
 338        return atomic_read(&using_sysemu);
 339}
 340
 341static int sysemu_proc_show(struct seq_file *m, void *v)
 342{
 343        seq_printf(m, "%d\n", get_using_sysemu());
 344        return 0;
 345}
 346
 347static int sysemu_proc_open(struct inode *inode, struct file *file)
 348{
 349        return single_open(file, sysemu_proc_show, NULL);
 350}
 351
 352static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
 353                                 size_t count, loff_t *pos)
 354{
 355        char tmp[2];
 356
 357        if (copy_from_user(tmp, buf, 1))
 358                return -EFAULT;
 359
 360        if (tmp[0] >= '0' && tmp[0] <= '2')
 361                set_using_sysemu(tmp[0] - '0');
 362        /* We use the first char, but pretend to write everything */
 363        return count;
 364}
 365
 366static const struct file_operations sysemu_proc_fops = {
 367        .owner          = THIS_MODULE,
 368        .open           = sysemu_proc_open,
 369        .read           = seq_read,
 370        .llseek         = seq_lseek,
 371        .release        = single_release,
 372        .write          = sysemu_proc_write,
 373};
 374
 375int __init make_proc_sysemu(void)
 376{
 377        struct proc_dir_entry *ent;
 378        if (!sysemu_supported)
 379                return 0;
 380
 381        ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
 382
 383        if (ent == NULL)
 384        {
 385                printk(KERN_WARNING "Failed to register /proc/sysemu\n");
 386                return 0;
 387        }
 388
 389        return 0;
 390}
 391
 392late_initcall(make_proc_sysemu);
 393
 394int singlestepping(void * t)
 395{
 396        struct task_struct *task = t ? t : current;
 397
 398        if (!(task->ptrace & PT_DTRACE))
 399                return 0;
 400
 401        if (task->thread.singlestep_syscall)
 402                return 1;
 403
 404        return 2;
 405}
 406
 407/*
 408 * Only x86 and x86_64 have an arch_align_stack().
 409 * All other arches have "#define arch_align_stack(x) (x)"
 410 * in their asm/system.h
 411 * As this is included in UML from asm-um/system-generic.h,
 412 * we can use it to behave as the subarch does.
 413 */
 414#ifndef arch_align_stack
 415unsigned long arch_align_stack(unsigned long sp)
 416{
 417        if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
 418                sp -= get_random_int() % 8192;
 419        return sp & ~0xf;
 420}
 421#endif
 422
 423unsigned long get_wchan(struct task_struct *p)
 424{
 425        unsigned long stack_page, sp, ip;
 426        bool seen_sched = 0;
 427
 428        if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
 429                return 0;
 430
 431        stack_page = (unsigned long) task_stack_page(p);
 432        /* Bail if the process has no kernel stack for some reason */
 433        if (stack_page == 0)
 434                return 0;
 435
 436        sp = p->thread.switch_buf->JB_SP;
 437        /*
 438         * Bail if the stack pointer is below the bottom of the kernel
 439         * stack for some reason
 440         */
 441        if (sp < stack_page)
 442                return 0;
 443
 444        while (sp < stack_page + THREAD_SIZE) {
 445                ip = *((unsigned long *) sp);
 446                if (in_sched_functions(ip))
 447                        /* Ignore everything until we're above the scheduler */
 448                        seen_sched = 1;
 449                else if (kernel_text_address(ip) && seen_sched)
 450                        return ip;
 451
 452                sp += sizeof(unsigned long);
 453        }
 454
 455        return 0;
 456}
 457
 458int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
 459{
 460        int cpu = current_thread_info()->cpu;
 461
 462        return save_fp_registers(userspace_pid[cpu], (unsigned long *) fpu);
 463}
 464
 465
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