OpenRISC: Scheduling/Process management

Signed-off-by: Jonas Bonn <jonas@southpole.se>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>

2 files changed, 445 insertions, 0 deletions

diff --git a/arch/openrisc/include/asm/thread_info.h b/arch/openrisc/include/asm/thread_info.h
new file mode 100644
index 00000000000..07a8bc080ef
--- /dev/null
+++ b/arch/openrisc/include/asm/thread_info.h
@@ -0,0 +1,134 @@
+/*
+ * OpenRISC Linux
+ *
+ * Linux architectural port borrowing liberally from similar works of
+ * others.  All original copyrights apply as per the original source
+ * declaration.
+ *
+ * OpenRISC implementation:
+ * Copyright (C) 2003 Matjaz Breskvar <phoenix@bsemi.com>
+ * Copyright (C) 2010-2011 Jonas Bonn <jonas@southpole.se>
+ * et al.
+ *
+ * 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.
+ */
+
+#ifndef _ASM_THREAD_INFO_H
+#define _ASM_THREAD_INFO_H
+
+#ifdef __KERNEL__
+
+#ifndef __ASSEMBLY__
+#include <asm/types.h>
+#include <asm/processor.h>
+#endif
+
+
+/* THREAD_SIZE is the size of the task_struct/kernel_stack combo.
+ * normally, the stack is found by doing something like p + THREAD_SIZE
+ * in or32, a page is 8192 bytes, which seems like a sane size
+ */
+
+#define THREAD_SIZE_ORDER 0
+#define THREAD_SIZE       (PAGE_SIZE << THREAD_SIZE_ORDER)
+
+/*
+ * low level task data that entry.S needs immediate access to
+ * - this struct should fit entirely inside of one cache line
+ * - this struct shares the supervisor stack pages
+ * - if the contents of this structure are changed, the assembly constants
+ *   must also be changed
+ */
+#ifndef __ASSEMBLY__
+
+typedef unsigned long mm_segment_t;
+
+struct thread_info {
+        struct task_struct      *task;          /* main task structure */
+        struct exec_domain      *exec_domain;   /* execution domain */
+        unsigned long           flags;          /* low level flags */
+        __u32                   cpu;            /* current CPU */
+        __s32                   preempt_count; /* 0 => preemptable, <0 => BUG */
+
+        mm_segment_t            addr_limit; /* thread address space:
+                                               0-0x7FFFFFFF for user-thead
+                                               0-0xFFFFFFFF for kernel-thread
+                                             */
+        struct restart_block    restart_block;
+        __u8                    supervisor_stack[0];
+
+        /* saved context data */
+        unsigned long           ksp;
+};
+#endif
+
+/*
+ * macros/functions for gaining access to the thread information structure
+ *
+ * preempt_count needs to be 1 initially, until the scheduler is functional.
+ */
+#ifndef __ASSEMBLY__
+#define INIT_THREAD_INFO(tsk)                           \
+{                                                       \
+        .task           = &tsk,                         \
+        .exec_domain    = &default_exec_domain,         \
+        .flags          = 0,                            \
+        .cpu            = 0,                            \
+        .preempt_count  = 1,                            \
+        .addr_limit     = KERNEL_DS,                    \
+        .restart_block  = {                             \
+                          .fn = do_no_restart_syscall,  \
+        },                                              \
+        .ksp            = 0,                            \
+}
+
+#define init_thread_info        (init_thread_union.thread_info)
+
+/* how to get the thread information struct from C */
+register struct thread_info *current_thread_info_reg asm("r10");
+#define current_thread_info()   (current_thread_info_reg)
+
+#define get_thread_info(ti) get_task_struct((ti)->task)
+#define put_thread_info(ti) put_task_struct((ti)->task)
+
+#endif /* !__ASSEMBLY__ */
+
+/*
+ * thread information flags
+ *   these are process state flags that various assembly files may need to
+ *   access
+ *   - pending work-to-be-done flags are in LSW
+ *   - other flags in MSW
+ */
+#define TIF_SYSCALL_TRACE       0       /* syscall trace active */
+#define TIF_NOTIFY_RESUME       1       /* resumption notification requested */
+#define TIF_SIGPENDING          2       /* signal pending */
+#define TIF_NEED_RESCHED        3       /* rescheduling necessary */
+#define TIF_SINGLESTEP          4       /* restore singlestep on return to user
+                                         * mode
+                                         */
+#define TIF_SYSCALL_TRACEPOINT  8       /* for ftrace syscall instrumentation */
+#define TIF_RESTORE_SIGMASK     9
+#define TIF_POLLING_NRFLAG      16      /* true if poll_idle() is polling                                                * TIF_NEED_RESCHED
+                                         */
+#define TIF_MEMDIE              17
+
+#define _TIF_SYSCALL_TRACE      (1<<TIF_SYSCALL_TRACE)
+#define _TIF_NOTIFY_RESUME      (1<<TIF_NOTIFY_RESUME)
+#define _TIF_SIGPENDING         (1<<TIF_SIGPENDING)
+#define _TIF_NEED_RESCHED       (1<<TIF_NEED_RESCHED)
+#define _TIF_SINGLESTEP         (1<<TIF_SINGLESTEP)
+#define _TIF_RESTORE_SIGMASK     (1<<TIF_RESTORE_SIGMASK)
+#define _TIF_POLLING_NRFLAG     (1<<TIF_POLLING_NRFLAG)
+
+
+/* Work to do when returning from interrupt/exception */
+/* For OpenRISC, this is anything in the LSW other than syscall trace */
+#define _TIF_WORK_MASK (0xff & ~(_TIF_SYSCALL_TRACE|_TIF_SINGLESTEP))
+
+#endif /* __KERNEL__ */
+
+#endif /* _ASM_THREAD_INFO_H */
diff --git a/arch/openrisc/kernel/process.c b/arch/openrisc/kernel/process.c
new file mode 100644
index 00000000000..e4209af879e
--- /dev/null
+++ b/arch/openrisc/kernel/process.c
@@ -0,0 +1,311 @@
+/*
+ * 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/system.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);
+
+        /* __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);
+
+int
+copy_thread(unsigned long clone_flags, unsigned long usp,
+            unsigned long unused, struct task_struct *p, struct pt_regs *regs)
+{
+        struct pt_regs *childregs;
+        struct pt_regs *kregs;
+        unsigned long sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
+        struct thread_info *ti;
+        unsigned long top_of_kernel_stack;
+
+        top_of_kernel_stack = sp;
+
+        p->set_child_tid = p->clear_child_tid = NULL;
+
+        /* Copy registers */
+        /* redzone */
+        sp -= STACK_FRAME_OVERHEAD;
+        sp -= sizeof(struct pt_regs);
+        childregs = (struct pt_regs *)sp;
+
+        /* Copy parent registers */
+        *childregs = *regs;
+
+        if ((childregs->sr & SPR_SR_SM) == 1) {
+                /* for kernel thread, set `current_thread_info'
+                 * and stackptr in new task
+                 */
+                childregs->sp = (unsigned long)task_stack_page(p) + THREAD_SIZE;
+                childregs->gpr[10] = (unsigned long)task_thread_info(p);
+        } else {
+                childregs->sp = usp;
+        }
+
+        childregs->gpr[11] = 0; /* Result from fork() */
+
+        /*
+         * The way this works is that at some point in the future
+         * some task will call _switch to switch to the new task.
+         * That will pop off the stack frame created below and start
+         * the new task running at ret_from_fork.  The new task will
+         * do some house keeping and then return from the fork or clone
+         * system call, using the stack frame created above.
+         */
+        /* redzone */
+        sp -= STACK_FRAME_OVERHEAD;
+        sp -= sizeof(struct pt_regs);
+        kregs = (struct pt_regs *)sp;
+
+        ti = task_thread_info(p);
+        ti->ksp = sp;
+
+        /* kregs->sp must store the location of the 'pre-switch' kernel stack
+         * pointer... for a newly forked process, this is simply the top of
+         * the kernel stack.
+         */
+        kregs->sp = top_of_kernel_stack;
+        kregs->gpr[3] = (unsigned long)current; /* arg to schedule_tail */
+        kregs->gpr[10] = (unsigned long)task_thread_info(p);
+        kregs->gpr[9] = (unsigned long)ret_from_fork;
+
+        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 = regs->sr & ~SPR_SR_SM;
+
+        set_fs(USER_DS);
+        memset(regs->gpr, 0, sizeof(regs->gpr));
+
+        regs->pc = pc;
+        regs->sr = sr;
+        regs->sp = sp;
+
+/*      printk("start thread, ksp = %lx\n", current_thread_info()->ksp);*/
+}
+
+/* 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;
+}
+
+extern void _kernel_thread_helper(void);
+
+void __noreturn kernel_thread_helper(int (*fn) (void *), void *arg)
+{
+        do_exit(fn(arg));
+}
+
+/*
+ * Create a kernel thread.
+ */
+int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags)
+{
+        struct pt_regs regs;
+
+        memset(&regs, 0, sizeof(regs));
+
+        regs.gpr[20] = (unsigned long)fn;
+        regs.gpr[22] = (unsigned long)arg;
+        regs.sr = mfspr(SPR_SR);
+        regs.pc = (unsigned long)_kernel_thread_helper;
+
+        return do_fork(flags | CLONE_VM | CLONE_UNTRACED,
+                       0, &regs, 0, NULL, NULL);
+}
+
+/*
+ * sys_execve() executes a new program.
+ */
+asmlinkage long _sys_execve(const char __user *name,
+                            const char __user * const __user *argv,
+                            const char __user * const __user *envp,
+                            struct pt_regs *regs)
+{
+        int error;
+        char *filename;
+
+        filename = getname(name);
+        error = PTR_ERR(filename);
+
+        if (IS_ERR(filename))
+                goto out;
+
+        error = do_execve(filename, argv, envp, regs);
+        putname(filename);
+
+out:
+        return error;
+}
+
+unsigned long get_wchan(struct task_struct *p)
+{
+        /* TODO */
+
+        return 0;
+}
+
+int kernel_execve(const char *filename, char *const argv[], char *const envp[])
+{
+        register long __res asm("r11") = __NR_execve;
+        register long __a asm("r3") = (long)(filename);
+        register long __b asm("r4") = (long)(argv);
+        register long __c asm("r5") = (long)(envp);
+        __asm__ volatile ("l.sys 1"
+                          : "=r" (__res), "=r"(__a), "=r"(__b), "=r"(__c)
+                          : "0"(__res), "1"(__a), "2"(__b), "3"(__c)
+                          : "r6", "r7", "r8", "r12", "r13", "r15",
+                            "r17", "r19", "r21", "r23", "r25", "r27",
+                            "r29", "r31");
+        __asm__ volatile ("l.nop");
+        return __res;
+}