1 files changed, 285 insertions, 0 deletions
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
new file mode 100644
index 0000000000..86e02929f3
--- /dev/null
+++ b/arch/openrisc/kernel/process.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * OpenRISC process.c
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * Modifications for the OpenRISC architecture:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ *
+ * This file handles the architecture-dependent parts of process handling...
+ */
+
+#define __KERNEL_SYSCALLS__
+#include <linux/cpu.h>
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
+#include <linux/kernel.h>
+#include <linux/export.h>
+#include <linux/mm.h>
+#include <linux/stddef.h>
+#include <linux/unistd.h>
+#include <linux/ptrace.h>
+#include <linux/slab.h>
+#include <linux/elfcore.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/init_task.h>
+#include <linux/mqueue.h>
+#include <linux/fs.h>
+#include <linux/reboot.h>
+
+#include <linux/uaccess.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+#include <asm/spr_defs.h>
+#include <asm/switch_to.h>
+
+#include <linux/smp.h>
+
+/*
+ * Pointer to Current thread info structure.
+ *
+ * Used at user space -> kernel transitions.
+ */
+struct thread_info *current_thread_info_set[NR_CPUS] = { &init_thread_info, };
+
+void machine_restart(char *cmd)
+{
+	do_kernel_restart(cmd);
+
+	__asm__("l.nop 13");
+
+	/* Give a grace period for failure to restart of 1s */
+	mdelay(1000);
+
+	/* Whoops - the platform was unable to reboot. Tell the user! */
+	pr_emerg("Reboot failed -- System halted\n");
+	while (1);
+}
+
+/*
+ * This is used if pm_power_off has not been set by a power management
+ * driver, in this case we can assume we are on a simulator.  On
+ * OpenRISC simulators l.nop 1 will trigger the simulator exit.
+ */
+static void default_power_off(void)
+{
+	__asm__("l.nop 1");
+}
+
+/*
+ * Similar to machine_power_off, but don't shut off power.  Add code
+ * here to freeze the system for e.g. post-mortem debug purpose when
+ * possible.  This halt has nothing to do with the idle halt.
+ */
+void machine_halt(void)
+{
+	printk(KERN_INFO "*** MACHINE HALT ***\n");
+	__asm__("l.nop 1");
+}
+
+/* If or when software power-off is implemented, add code here.  */
+void machine_power_off(void)
+{
+	printk(KERN_INFO "*** MACHINE POWER OFF ***\n");
+	if (pm_power_off != NULL)
+		pm_power_off();
+	else
+		default_power_off();
+}
+
+/*
+ * Send the doze signal to the cpu if available.
+ * Make sure, that all interrupts are enabled
+ */
+void arch_cpu_idle(void)
+{
+	raw_local_irq_enable();
+	if (mfspr(SPR_UPR) & SPR_UPR_PMP)
+		mtspr(SPR_PMR, mfspr(SPR_PMR) | SPR_PMR_DME);
+	raw_local_irq_disable();
+}
+
+void (*pm_power_off)(void) = NULL;
+EXPORT_SYMBOL(pm_power_off);
+
+/*
+ * When a process does an "exec", machine state like FPU and debug
+ * registers need to be reset.  This is a hook function for that.
+ * Currently we don't have any such state to reset, so this is empty.
+ */
+void flush_thread(void)
+{
+}
+
+void show_regs(struct pt_regs *regs)
+{
+	show_regs_print_info(KERN_DEFAULT);
+	/* __PHX__ cleanup this mess */
+	show_registers(regs);
+}
+
+/*
+ * Copy the thread-specific (arch specific) info from the current
+ * process to the new one p
+ */
+extern asmlinkage void ret_from_fork(void);
+
+/*
+ * copy_thread
+ * @clone_flags: flags
+ * @usp: user stack pointer or fn for kernel thread
+ * @arg: arg to fn for kernel thread; always NULL for userspace thread
+ * @p: the newly created task
+ * @tls: the Thread Local Storage pointer for the new process
+ *
+ * At the top of a newly initialized kernel stack are two stacked pt_reg
+ * structures.  The first (topmost) is the userspace context of the thread.
+ * The second is the kernelspace context of the thread.
+ *
+ * A kernel thread will not be returning to userspace, so the topmost pt_regs
+ * struct can be uninitialized; it _does_ need to exist, though, because
+ * a kernel thread can become a userspace thread by doing a kernel_execve, in
+ * which case the topmost context will be initialized and used for 'returning'
+ * to userspace.
+ *
+ * The second pt_reg struct needs to be initialized to 'return' to
+ * ret_from_fork.  A kernel thread will need to set r20 to the address of
+ * a function to call into (with arg in r22); userspace threads need to set
+ * r20 to NULL in which case ret_from_fork will just continue a return to
+ * userspace.
+ *
+ * A kernel thread 'fn' may return; this is effectively what happens when
+ * kernel_execve is called.  In that case, the userspace pt_regs must have
+ * been initialized (which kernel_execve takes care of, see start_thread
+ * below); ret_from_fork will then continue its execution causing the
+ * 'kernel thread' to return to userspace as a userspace thread.
+ */
+
+int
+copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
+{
+	unsigned long clone_flags = args->flags;
+	unsigned long usp = args->stack;
+	unsigned long tls = args->tls;
+	struct pt_regs *userregs;
+	struct pt_regs *kregs;
+	unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
+	unsigned long top_of_kernel_stack;
+
+	top_of_kernel_stack = sp;
+
+	/* Locate userspace context on stack... */
+	sp -= STACK_FRAME_OVERHEAD;	/* redzone */
+	sp -= sizeof(struct pt_regs);
+	userregs = (struct pt_regs *) sp;
+
+	/* ...and kernel context */
+	sp -= STACK_FRAME_OVERHEAD;	/* redzone */
+	sp -= sizeof(struct pt_regs);
+	kregs = (struct pt_regs *)sp;
+
+	if (unlikely(args->fn)) {
+		memset(kregs, 0, sizeof(struct pt_regs));
+		kregs->gpr[20] = (unsigned long)args->fn;
+		kregs->gpr[22] = (unsigned long)args->fn_arg;
+	} else {
+		*userregs = *current_pt_regs();
+
+		if (usp)
+			userregs->sp = usp;
+
+		/*
+		 * For CLONE_SETTLS set "tp" (r10) to the TLS pointer.
+		 */
+		if (clone_flags & CLONE_SETTLS)
+			userregs->gpr[10] = tls;
+
+		userregs->gpr[11] = 0;	/* Result from fork() */
+
+		kregs->gpr[20] = 0;	/* Userspace thread */
+	}
+
+	/*
+	 * _switch wants the kernel stack page in pt_regs->sp so that it
+	 * can restore it to thread_info->ksp... see _switch for details.
+	 */
+	kregs->sp = top_of_kernel_stack;
+	kregs->gpr[9] = (unsigned long)ret_from_fork;
+
+	task_thread_info(p)->ksp = (unsigned long)kregs;
+
+	return 0;
+}
+
+/*
+ * Set up a thread for executing a new program
+ */
+void start_thread(struct pt_regs *regs, unsigned long pc, unsigned long sp)
+{
+	unsigned long sr = mfspr(SPR_SR) & ~SPR_SR_SM;
+
+	memset(regs, 0, sizeof(struct pt_regs));
+
+	regs->pc = pc;
+	regs->sr = sr;
+	regs->sp = sp;
+}
+
+extern struct thread_info *_switch(struct thread_info *old_ti,
+				   struct thread_info *new_ti);
+extern int lwa_flag;
+
+struct task_struct *__switch_to(struct task_struct *old,
+				struct task_struct *new)
+{
+	struct task_struct *last;
+	struct thread_info *new_ti, *old_ti;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	/* current_set is an array of saved current pointers
+	 * (one for each cpu). we need them at user->kernel transition,
+	 * while we save them at kernel->user transition
+	 */
+	new_ti = new->stack;
+	old_ti = old->stack;
+
+	lwa_flag = 0;
+
+	current_thread_info_set[smp_processor_id()] = new_ti;
+	last = (_switch(old_ti, new_ti))->task;
+
+	local_irq_restore(flags);
+
+	return last;
+}
+
+/*
+ * Write out registers in core dump format, as defined by the
+ * struct user_regs_struct
+ */
+void dump_elf_thread(elf_greg_t *dest, struct pt_regs* regs)
+{
+	dest[0] = 0; /* r0 */
+	memcpy(dest+1, regs->gpr+1, 31*sizeof(unsigned long));
+	dest[32] = regs->pc;
+	dest[33] = regs->sr;
+	dest[34] = 0;
+	dest[35] = 0;
+}
+
+unsigned long __get_wchan(struct task_struct *p)
+{
+	/* TODO */
+
+	return 0;
+}