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authorAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
committerAndré Fabian Silva Delgado <emulatorman@parabola.nu>2015-08-05 17:04:01 -0300
commit57f0f512b273f60d52568b8c6b77e17f5636edc0 (patch)
tree5e910f0e82173f4ef4f51111366a3f1299037a7b /arch/openrisc/kernel/process.c
Initial import
Diffstat (limited to 'arch/openrisc/kernel/process.c')
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diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
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+/*
+ * 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 program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * This file handles the architecture-dependent parts of process handling...
+ */
+
+#define __KERNEL_SYSCALLS__
+#include <stdarg.h>
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/module.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 <asm/uaccess.h>
+#include <asm/pgtable.h>
+#include <asm/io.h>
+#include <asm/processor.h>
+#include <asm/spr_defs.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(void)
+{
+ printk(KERN_INFO "*** MACHINE RESTART ***\n");
+ __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");
+ __asm__("l.nop 1");
+}
+
+void (*pm_power_off) (void) = machine_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)
+{
+ extern void show_registers(struct pt_regs *regs);
+
+ show_regs_print_info(KERN_DEFAULT);
+ /* __PHX__ cleanup this mess */
+ show_registers(regs);
+}
+
+unsigned long thread_saved_pc(struct task_struct *t)
+{
+ return (unsigned long)user_regs(t->stack)->pc;
+}
+
+void release_thread(struct task_struct *dead_task)
+{
+}
+
+/*
+ * 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
+ * @regs: CPU context to copy for userspace thread; always NULL for kthread
+ *
+ * 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(unsigned long clone_flags, unsigned long usp,
+ unsigned long arg, struct task_struct *p)
+{
+ 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;
+
+ p->set_child_tid = p->clear_child_tid = NULL;
+
+ /* 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(p->flags & PF_KTHREAD)) {
+ memset(kregs, 0, sizeof(struct pt_regs));
+ kregs->gpr[20] = usp; /* fn, kernel thread */
+ kregs->gpr[22] = arg;
+ } else {
+ *userregs = *current_pt_regs();
+
+ if (usp)
+ userregs->sp = usp;
+ 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;
+}
+
+/* Fill in the fpu structure for a core dump. */
+int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
+{
+ /* TODO */
+ return 0;
+}
+
+extern struct thread_info *_switch(struct thread_info *old_ti,
+ struct thread_info *new_ti);
+
+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;
+
+ 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;
+}