nios2: Process management

This patch adds support for thread creation and context switching.

Signed-off-by: Ley Foon Tan <lftan@altera.com>

arch/nios2/include/asm/mmu_context.h

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 1996, 1997, 1998, 1999 by Ralf Baechle
+ * Copyright (C) 1999 Silicon Graphics, Inc.
+ *
+ * based on MIPS asm/mmu_context.h
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef _ASM_NIOS2_MMU_CONTEXT_H
+#define _ASM_NIOS2_MMU_CONTEXT_H
+
+#include <asm-generic/mm_hooks.h>
+
+extern void mmu_context_init(void);
+extern unsigned long get_pid_from_context(mm_context_t *ctx);
+
+/*
+ * For the fast tlb miss handlers, we keep a pointer to the current pgd.
+ * processor.
+ */
+extern pgd_t *pgd_current;
+
+static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+}
+
+/*
+ * Initialize the context related info for a new mm_struct instance.
+ *
+ * Set all new contexts to 0, that way the generation will never match
+ * the currently running generation when this context is switched in.
+ */
+static inline int init_new_context(struct task_struct *tsk,
+					struct mm_struct *mm)
+{
+	mm->context = 0;
+	return 0;
+}
+
+/*
+ * Destroy context related info for an mm_struct that is about
+ * to be put to rest.
+ */
+static inline void destroy_context(struct mm_struct *mm)
+{
+}
+
+void switch_mm(struct mm_struct *prev, struct mm_struct *next,
+		struct task_struct *tsk);
+
+static inline void deactivate_mm(struct task_struct *tsk,
+				struct mm_struct *mm)
+{
+}
+
+/*
+ * After we have set current->mm to a new value, this activates
+ * the context for the new mm so we see the new mappings.
+ */
+void activate_mm(struct mm_struct *prev, struct mm_struct *next);
+
+#endif /* _ASM_NIOS2_MMU_CONTEXT_H */

arch/nios2/include/asm/processor.h

@@ -0,0 +1,103 @@
+/*
+ * Copyright (C) 2013 Altera Corporation
+ * Copyright (C) 2010 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd
+ * Copyright (C) 2001 Ken Hill (khill@microtronix.com)
+ *                    Vic Phillips (vic@microtronix.com)
+ *
+ * based on SPARC asm/processor_32.h which is:
+ *
+ * Copyright (C) 1994 David S. Miller
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef _ASM_NIOS2_PROCESSOR_H
+#define _ASM_NIOS2_PROCESSOR_H
+
+#include <asm/ptrace.h>
+#include <asm/registers.h>
+#include <asm/page.h>
+
+#define NIOS2_FLAG_KTHREAD	0x00000001	/* task is a kernel thread */
+
+#define NIOS2_OP_NOP		0x1883a
+#define NIOS2_OP_BREAK		0x3da03a
+
+#ifdef __KERNEL__
+
+#define STACK_TOP	TASK_SIZE
+#define STACK_TOP_MAX	STACK_TOP
+
+#endif /* __KERNEL__ */
+
+/* Kuser helpers is mapped to this user space address */
+#define KUSER_BASE		0x1000
+#define KUSER_SIZE		(PAGE_SIZE)
+#ifndef __ASSEMBLY__
+
+/*
+ * Default implementation of macro that returns current
+ * instruction pointer ("program counter").
+ */
+#define current_text_addr() ({ __label__ _l; _l: &&_l; })
+
+# define TASK_SIZE		0x7FFF0000UL
+# define TASK_UNMAPPED_BASE	(PAGE_ALIGN(TASK_SIZE / 3))
+
+/* The Nios processor specific thread struct. */
+struct thread_struct {
+	struct pt_regs *kregs;
+
+	/* Context switch saved kernel state. */
+	unsigned long ksp;
+	unsigned long kpsr;
+};
+
+#define INIT_MMAP \
+	{ &init_mm, (0), (0), __pgprot(0x0), VM_READ | VM_WRITE | VM_EXEC }
+
+# define INIT_THREAD {			\
+	.kregs	= NULL,			\
+	.ksp	= 0,			\
+	.kpsr	= 0,			\
+}
+
+extern void start_thread(struct pt_regs *regs, unsigned long pc,
+			unsigned long sp);
+
+struct task_struct;
+
+/* Free all resources held by a thread. */
+static inline void release_thread(struct task_struct *dead_task)
+{
+}
+
+/* Free current thread data structures etc.. */
+static inline void exit_thread(void)
+{
+}
+
+/* Return saved PC of a blocked thread. */
+#define thread_saved_pc(tsk)	((tsk)->thread.kregs->ea)
+
+extern unsigned long get_wchan(struct task_struct *p);
+
+/* Prepare to copy thread state - unlazy all lazy status */
+#define prepare_to_copy(tsk)	do { } while (0)
+
+#define task_pt_regs(p) \
+	((struct pt_regs *)(THREAD_SIZE + task_stack_page(p)) - 1)
+
+/* Used by procfs */
+#define KSTK_EIP(tsk)	((tsk)->thread.kregs->ea)
+#define KSTK_ESP(tsk)	((tsk)->thread.kregs->sp)
+
+#define cpu_relax()	barrier()
+#define cpu_relax_lowlatency()  cpu_relax()
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _ASM_NIOS2_PROCESSOR_H */

arch/nios2/include/asm/switch_to.h

@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2004 Microtronix Datacom Ltd.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+#ifndef _ASM_NIOS2_SWITCH_TO_H
+#define _ASM_NIOS2_SWITCH_TO_H
+
+/*
+ * switch_to(n) should switch tasks to task ptr, first checking that
+ * ptr isn't the current task, in which case it does nothing.  This
+ * also clears the TS-flag if the task we switched to has used the
+ * math co-processor latest.
+ */
+#define switch_to(prev, next, last)			\
+{							\
+	void *_last;					\
+	__asm__ __volatile__ (				\
+		"mov	r4, %1\n"			\
+		"mov	r5, %2\n"			\
+		"call	resume\n"			\
+		"mov	%0,r4\n"			\
+		: "=r" (_last)				\
+		: "r" (prev), "r" (next)		\
+		: "r4", "r5", "r7", "r8", "ra");	\
+	(last) = _last;					\
+}
+
+#endif /* _ASM_NIOS2_SWITCH_TO_H */

arch/nios2/include/asm/thread_info.h

@@ -0,0 +1,120 @@
+/*
+ * NiosII low-level thread information
+ *
+ * Copyright (C) 2011 Tobias Klauser <tklauser@distanz.ch>
+ * Copyright (C) 2004 Microtronix Datacom Ltd.
+ *
+ * Based on asm/thread_info_no.h from m68k which is:
+ *
+ * Copyright (C) 2002 David Howells <dhowells@redhat.com>
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#ifndef _ASM_NIOS2_THREAD_INFO_H
+#define _ASM_NIOS2_THREAD_INFO_H
+
+#ifdef __KERNEL__
+
+/*
+ * Size of the kernel stack for each process.
+ */
+#define THREAD_SIZE_ORDER	1
+#define THREAD_SIZE		8192 /* 2 * PAGE_SIZE */
+
+#ifndef __ASSEMBLY__
+
+typedef struct {
+	unsigned long seg;
+} mm_segment_t;
+
+/*
+ * 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
+ */
+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 */
+	int			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;
+	struct pt_regs		*regs;
+};
+
+/*
+ * macros/functions for gaining access to the thread information structure
+ *
+ * preempt_count needs to be 1 initially, until the scheduler is functional.
+ */
+#define INIT_THREAD_INFO(tsk)			\
+{						\
+	.task		= &tsk,			\
+	.exec_domain	= &default_exec_domain,	\
+	.flags		= 0,			\
+	.cpu		= 0,			\
+	.preempt_count	= INIT_PREEMPT_COUNT,	\
+	.addr_limit	= KERNEL_DS,		\
+	.restart_block	= {			\
+		.fn = do_no_restart_syscall,	\
+	},					\
+}
+
+#define init_thread_info	(init_thread_union.thread_info)
+#define init_stack		(init_thread_union.stack)
+
+/* how to get the thread information struct from C */
+static inline struct thread_info *current_thread_info(void)
+{
+	register unsigned long sp asm("sp");
+
+	return (struct thread_info *)(sp & ~(THREAD_SIZE - 1));
+}
+#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_MEMDIE		4	/* is terminating due to OOM killer */
+#define TIF_SECCOMP		5	/* secure computing */
+#define TIF_SYSCALL_AUDIT	6	/* syscall auditing active */
+#define TIF_RESTORE_SIGMASK	9	/* restore signal mask in do_signal() */
+
+#define TIF_POLLING_NRFLAG	16	/* true if poll_idle() is polling
+					   TIF_NEED_RESCHED */
+
+#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_SECCOMP		(1 << TIF_SECCOMP)
+#define _TIF_SYSCALL_AUDIT	(1 << TIF_SYSCALL_AUDIT)
+#define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
+#define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
+
+/* work to do on interrupt/exception return */
+#define _TIF_WORK_MASK		0x0000FFFE
+
+/* work to do on any return to u-space */
+# define _TIF_ALLWORK_MASK	0x0000FFFF
+
+#endif /* __KERNEL__ */
+
+#endif /* _ASM_NIOS2_THREAD_INFO_H */