1 files changed, 402 insertions, 0 deletions
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
new file mode 100644
index 0000000000..106b7da2f8
--- /dev/null
+++ b/arch/um/kernel/process.c
@@ -0,0 +1,402 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 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.
+ */
+
+#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/resume_user_mode.h>
+#include <asm/current.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 <registers.h>
+#include <linux/time-internal.h>
+#include <linux/elfcore.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) ||
+	    test_thread_flag(TIF_NOTIFY_SIGNAL))
+		do_signal(regs);
+	if (test_thread_flag(TIF_NOTIFY_RESUME))
+		resume_user_mode_work(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(struct task_struct * p, const struct kernel_clone_args *args)
+{
+	unsigned long clone_flags = args->flags;
+	unsigned long sp = args->stack;
+	unsigned long tls = args->tls;
+	void (*handler)(void);
+	int ret = 0;
+
+	p->thread = (struct thread_struct) INIT_THREAD;
+
+	if (!args->fn) {
+	  	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 = args->fn;
+		p->thread.request.u.thread.arg = args->fn_arg;
+		handler = new_thread_handler;
+	}
+
+	new_thread(task_stack_page(p), &p->thread.switch_buf, handler);
+
+	if (!args->fn) {
+		clear_flushed_tls(p);
+
+		/*
+		 * Set a new TLS for the child thread?
+		 */
+		if (clone_flags & CLONE_SETTLS)
+			ret = arch_set_tls(p, tls);
+	}
+
+	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 um_idle_sleep(void)
+{
+	if (time_travel_mode != TT_MODE_OFF)
+		time_travel_sleep();
+	else
+		os_idle_sleep();
+}
+
+void arch_cpu_idle(void)
+{
+	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
+	um_idle_sleep();
+}
+
+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);
+}
+
+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 proc_ops sysemu_proc_ops = {
+	.proc_open	= sysemu_proc_open,
+	.proc_read	= seq_read,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= single_release,
+	.proc_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_ops);
+
+	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 (!test_thread_flag(TIF_SINGLESTEP))
+		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_u32_below(8192);
+	return sp & ~0xf;
+}
+#endif
+
+unsigned long __get_wchan(struct task_struct *p)
+{
+	unsigned long stack_page, sp, ip;
+	bool seen_sched = 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_task_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);
+}
+