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26 results

process.c

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  • process.c 8.58 KiB
    /*
     * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
     * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
     * 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/module.h>
    #include <linux/personality.h>
    #include <linux/proc_fs.h>
    #include <linux/ptrace.h>
    #include <linux/random.h>
    #include <linux/slab.h>
    #include <linux/sched.h>
    #include <linux/sched/debug.h>
    #include <linux/sched/task.h>
    #include <linux/sched/task_stack.h>
    #include <linux/seq_file.h>
    #include <linux/tick.h>
    #include <linux/threads.h>
    #include <linux/tracehook.h>
    #include <asm/current.h>
    #include <asm/pgtable.h>
    #include <asm/mmu_context.h>
    #include <linux/uaccess.h>
    #include <as-layout.h>
    #include <kern_util.h>
    #include <os.h>
    #include <skas.h>
    #include <timer-internal.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(void)
    {
    	/* 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);
    
    	return page;
    }
    
    static inline void set_current(struct task_struct *task)
    {
    	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
    		{ external_pid(), task });
    }
    
    extern void arch_switch_to(struct task_struct *to);
    
    void *__switch_to(struct task_struct *from, struct task_struct *to)
    {
    	to->thread.prev_sched = from;
    	set_current(to);
    
    	switch_threads(&from->thread.switch_buf, &to->thread.switch_buf);
    	arch_switch_to(current);
    
    	return current->thread.prev_sched;
    }
    
    void interrupt_end(void)
    {
    	struct pt_regs *regs = &current->thread.regs;
    
    	if (need_resched())
    		schedule();
    	if (test_thread_flag(TIF_SIGPENDING))
    		do_signal(regs);
    	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
    		tracehook_notify_resume(regs);
    }
    
    int get_current_pid(void)
    {
    	return task_pid_nr(current);
    }
    
    /*
     * 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;
    
    	/*
    	 * callback returns only if the kernel thread execs a process
    	 */
    	n = fn(arg);
    	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
    }
    
    /* Called magically, see new_thread_handler above */
    void fork_handler(void)
    {
    	force_flush_all();
    
    	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);
    
    	current->thread.prev_sched = NULL;
    
    	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
    }
    
    int copy_thread(unsigned long clone_flags, unsigned long sp,
    		unsigned long arg, struct task_struct * p)
    {
    	void (*handler)(void);
    	int kthread = current->flags & PF_KTHREAD;
    	int ret = 0;
    
    	p->thread = (struct thread_struct) INIT_THREAD;
    
    	if (!kthread) {
    	  	memcpy(&p->thread.regs.regs, current_pt_regs(),
    		       sizeof(p->thread.regs.regs));
    		PT_REGS_SET_SYSCALL_RETURN(&p->thread.regs, 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 {
    		get_safe_registers(p->thread.regs.regs.gp, p->thread.regs.regs.fp);
    		p->thread.request.u.thread.proc = (int (*)(void *))sp;
    		p->thread.request.u.thread.arg = (void *)arg;
    		handler = new_thread_handler;
    	}
    
    	new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
    
    	if (!kthread) {
    		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 arch_cpu_idle(void)
    {
    	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
    	os_idle_sleep(UM_NSEC_PER_SEC);
    	local_irq_enable();
    }
    
    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_info();
    }
    
    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(const char *string)
    {
    	return kstrdup(string, GFP_KERNEL);
    }
    EXPORT_SYMBOL(uml_strdup);
    
    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 cpu(void)
    {
    	return current_thread_info()->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 sysemu_proc_show(struct seq_file *m, void *v)
    {
    	seq_printf(m, "%d\n", get_using_sysemu());
    	return 0;
    }
    
    static int sysemu_proc_open(struct inode *inode, struct file *file)
    {
    	return single_open(file, sysemu_proc_show, NULL);
    }
    
    static ssize_t sysemu_proc_write(struct file *file, const char __user *buf,
    				 size_t count, loff_t *pos)
    {
    	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;
    }
    
    static const struct file_operations sysemu_proc_fops = {
    	.owner		= THIS_MODULE,
    	.open		= sysemu_proc_open,
    	.read		= seq_read,
    	.llseek		= seq_lseek,
    	.release	= single_release,
    	.write		= sysemu_proc_write,
    };
    
    int __init make_proc_sysemu(void)
    {
    	struct proc_dir_entry *ent;
    	if (!sysemu_supported)
    		return 0;
    
    	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
    
    	if (ent == NULL)
    	{
    		printk(KERN_WARNING "Failed to register /proc/sysemu\n");
    		return 0;
    	}
    
    	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/exec.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
    
    unsigned long get_wchan(struct task_struct *p)
    {
    	unsigned long stack_page, sp, ip;
    	bool seen_sched = 0;
    
    	if ((p == NULL) || (p == current) || (p->state == TASK_RUNNING))
    		return 0;
    
    	stack_page = (unsigned long) task_stack_page(p);
    	/* Bail if the process has no kernel stack for some reason */
    	if (stack_page == 0)
    		return 0;
    
    	sp = p->thread.switch_buf->JB_SP;
    	/*
    	 * Bail if the stack pointer is below the bottom of the kernel
    	 * stack for some reason
    	 */
    	if (sp < stack_page)
    		return 0;
    
    	while (sp < stack_page + THREAD_SIZE) {
    		ip = *((unsigned long *) sp);
    		if (in_sched_functions(ip))
    			/* Ignore everything until we're above the scheduler */
    			seen_sched = 1;
    		else if (kernel_text_address(ip) && seen_sched)
    			return ip;
    
    		sp += sizeof(unsigned long);
    	}
    
    	return 0;
    }
    
    int elf_core_copy_fpregs(struct task_struct *t, elf_fpregset_t *fpu)
    {
    	int cpu = current_thread_info()->cpu;
    
    	return save_i387_registers(userspace_pid[cpu], (unsigned long *) fpu);
    }