nds32: Process management

This patch includes copy_thread(), start_thread() implementation and cpu_context
structure definition. nds32 uses $r25 to get current task_struct.

Signed-off-by: Vincent Chen <vincentc@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/nds32/include/asm/current.h

@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#ifndef _ASM_NDS32_CURRENT_H
+#define _ASM_NDS32_CURRENT_H
+
+#ifndef __ASSEMBLY__
+register struct task_struct *current asm("$r25");
+#endif /* __ASSEMBLY__ */
+#define tsk $r25
+
+#endif /* _ASM_NDS32_CURRENT_H */

arch/nds32/include/asm/processor.h

@@ -0,0 +1,103 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#ifndef __ASM_NDS32_PROCESSOR_H
+#define __ASM_NDS32_PROCESSOR_H
+
+/*
+ * Default implementation of macro that returns current
+ * instruction pointer ("program counter").
+ */
+#define current_text_addr() ({ __label__ _l; _l: &&_l;})
+
+#ifdef __KERNEL__
+
+#include <asm/ptrace.h>
+#include <asm/types.h>
+#include <asm/sigcontext.h>
+
+#define KERNEL_STACK_SIZE	PAGE_SIZE
+#define STACK_TOP	TASK_SIZE
+#define STACK_TOP_MAX   TASK_SIZE
+
+struct cpu_context {
+	unsigned long r6;
+	unsigned long r7;
+	unsigned long r8;
+	unsigned long r9;
+	unsigned long r10;
+	unsigned long r11;
+	unsigned long r12;
+	unsigned long r13;
+	unsigned long r14;
+	unsigned long fp;
+	unsigned long pc;
+	unsigned long sp;
+};
+
+struct thread_struct {
+	struct cpu_context cpu_context;	/* cpu context */
+	/* fault info     */
+	unsigned long address;
+	unsigned long trap_no;
+	unsigned long error_code;
+};
+
+#define INIT_THREAD  {	}
+
+#ifdef __NDS32_EB__
+#define PSW_DE	PSW_mskBE
+#else
+#define PSW_DE	0x0
+#endif
+
+#ifdef CONFIG_WBNA
+#define PSW_valWBNA	PSW_mskWBNA
+#else
+#define PSW_valWBNA	0x0
+#endif
+
+#ifdef CONFIG_HWZOL
+#define	PSW_valINIT (PSW_CPL_ANY | PSW_mskAEN | PSW_valWBNA | PSW_mskDT | PSW_mskIT | PSW_DE | PSW_mskGIE)
+#else
+#define	PSW_valINIT (PSW_CPL_ANY | PSW_valWBNA | PSW_mskDT | PSW_mskIT | PSW_DE | PSW_mskGIE)
+#endif
+
+#define start_thread(regs,pc,stack)			\
+({							\
+	memzero(regs, sizeof(struct pt_regs));		\
+	forget_syscall(regs);				\
+	regs->ipsw = PSW_valINIT;			\
+	regs->ir0 = (PSW_CPL_ANY | PSW_valWBNA | PSW_mskDT | PSW_mskIT | PSW_DE | PSW_SYSTEM | PSW_INTL_1);	\
+	regs->ipc = pc;					\
+	regs->sp = stack;				\
+})
+
+/* Forward declaration, a strange C thing */
+struct task_struct;
+
+/* Free all resources held by a thread. */
+#define release_thread(thread) do { } while(0)
+
+/* Prepare to copy thread state - unlazy all lazy status */
+#define prepare_to_copy(tsk)	do { } while (0)
+
+unsigned long get_wchan(struct task_struct *p);
+
+#define cpu_relax()			barrier()
+
+#define task_pt_regs(task) \
+	((struct pt_regs *) (task_stack_page(task) + THREAD_SIZE \
+		- 8) - 1)
+
+/*
+ * Create a new kernel thread
+ */
+extern int kernel_thread(int (*fn) (void *), void *arg, unsigned long flags);
+
+#define KSTK_EIP(tsk)	instruction_pointer(task_pt_regs(tsk))
+#define KSTK_ESP(tsk)	user_stack_pointer(task_pt_regs(tsk))
+
+#endif
+
+#endif /* __ASM_NDS32_PROCESSOR_H */

arch/nds32/include/asm/thread_info.h

@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2005-2017 Andes Technology Corporation
+
+#ifndef __ASM_NDS32_THREAD_INFO_H
+#define __ASM_NDS32_THREAD_INFO_H
+
+#ifdef __KERNEL__
+
+#define THREAD_SIZE_ORDER 	(1)
+#define THREAD_SIZE		(PAGE_SIZE << THREAD_SIZE_ORDER)
+
+#ifndef __ASSEMBLY__
+
+struct task_struct;
+
+#include <asm/ptrace.h>
+#include <asm/types.h>
+
+typedef unsigned long mm_segment_t;
+
+/*
+ * low level task data that entry.S needs immediate access to.
+ * __switch_to() assumes cpu_context follows immediately after cpu_domain.
+ */
+struct thread_info {
+	unsigned long flags;	/* low level flags */
+	__s32 preempt_count;	/* 0 => preemptable, <0 => bug */
+	mm_segment_t addr_limit;	/* address limit */
+};
+#define INIT_THREAD_INFO(tsk)						\
+{									\
+	.preempt_count	= INIT_PREEMPT_COUNT,				\
+	.addr_limit	= KERNEL_DS,					\
+}
+#define thread_saved_pc(tsk) ((unsigned long)(tsk->thread.cpu_context.pc))
+#define thread_saved_fp(tsk) ((unsigned long)(tsk->thread.cpu_context.fp))
+#endif
+
+/*
+ * thread information flags:
+ *  TIF_SYSCALL_TRACE	- syscall trace active
+ *  TIF_SIGPENDING	- signal pending
+ *  TIF_NEED_RESCHED	- rescheduling necessary
+ *  TIF_NOTIFY_RESUME	- callback before returning to user
+ *  TIF_USEDFPU		- FPU was used by this task this quantum (SMP)
+ *  TIF_POLLING_NRFLAG	- true if poll_idle() is polling TIF_NEED_RESCHED
+ */
+#define TIF_SIGPENDING		1
+#define TIF_NEED_RESCHED	2
+#define TIF_SINGLESTEP		3
+#define TIF_NOTIFY_RESUME	4	/* callback before returning to user */
+#define TIF_SYSCALL_TRACE	8
+#define TIF_USEDFPU             16
+#define TIF_POLLING_NRFLAG	17
+#define TIF_MEMDIE		18
+#define TIF_FREEZE		19
+#define TIF_RESTORE_SIGMASK	20
+
+#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
+#define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
+#define _TIF_NOTIFY_RESUME	(1 << TIF_NOTIFY_RESUME)
+#define _TIF_SINGLESTEP		(1 << TIF_SINGLESTEP)
+#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)
+#define _TIF_POLLING_NRFLAG	(1 << TIF_POLLING_NRFLAG)
+#define _TIF_FREEZE		(1 << TIF_FREEZE)
+#define _TIF_RESTORE_SIGMASK	(1 << TIF_RESTORE_SIGMASK)
+
+/*
+ * Change these and you break ASM code in entry-common.S
+ */
+#define _TIF_WORK_MASK		0x000000ff
+#define _TIF_WORK_SYSCALL_ENTRY (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)
+#define _TIF_WORK_SYSCALL_LEAVE (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP)
+
+#endif /* __KERNEL__ */
+#endif /* __ASM_NDS32_THREAD_INFO_H */