From: Greentime Hu <greent...@andestech.com>

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 <vince...@andestech.com>
Signed-off-by: Greentime Hu <greent...@andestech.com>
---
 arch/nds32/include/asm/current.h     |   25 ++++
 arch/nds32/include/asm/processor.h   |  116 ++++++++++++++++++
 arch/nds32/include/asm/thread_info.h |   91 ++++++++++++++
 arch/nds32/kernel/process.c          |  217 ++++++++++++++++++++++++++++++++++
 4 files changed, 449 insertions(+)
 create mode 100644 arch/nds32/include/asm/current.h
 create mode 100644 arch/nds32/include/asm/processor.h
 create mode 100644 arch/nds32/include/asm/thread_info.h
 create mode 100644 arch/nds32/kernel/process.c

diff --git a/arch/nds32/include/asm/current.h b/arch/nds32/include/asm/current.h
new file mode 100644
index 0000000..027f7df
--- /dev/null
+++ b/arch/nds32/include/asm/current.h
@@ -0,0 +1,25 @@
+/*
+ * Copyright (C) 2005-2017 Andes Technology Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#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 */
diff --git a/arch/nds32/include/asm/processor.h 
b/arch/nds32/include/asm/processor.h
new file mode 100644
index 0000000..03dab61
--- /dev/null
+++ b/arch/nds32/include/asm/processor.h
@@ -0,0 +1,116 @@
+/*
+ * Copyright (C) 2005-2017 Andes Technology Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#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)                    \
+({                                                     \
+       set_fs(USER_DS);                                \
+       memzero(regs, sizeof(struct pt_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 */
diff --git a/arch/nds32/include/asm/thread_info.h 
b/arch/nds32/include/asm/thread_info.h
new file mode 100644
index 0000000..216cc85
--- /dev/null
+++ b/arch/nds32/include/asm/thread_info.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2005-2017 Andes Technology Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#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 init_thread_info       (init_thread_union.thread_info)
+#define init_stack             (init_thread_union.stack)
+#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 */
diff --git a/arch/nds32/kernel/process.c b/arch/nds32/kernel/process.c
new file mode 100644
index 0000000..6d7163c
--- /dev/null
+++ b/arch/nds32/kernel/process.c
@@ -0,0 +1,217 @@
+/*
+ * Copyright (C) 2005-2017 Andes Technology Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/sched.h>
+#include <linux/sched/debug.h>
+#include <linux/sched/task_stack.h>
+#include <linux/delay.h>
+#include <linux/kallsyms.h>
+#include <asm/uaccess.h>
+#include <asm/elf.h>
+#include <asm/proc-fns.h>
+#include <linux/ptrace.h>
+
+extern void setup_mm_for_reboot(char mode);
+#ifdef CONFIG_PROC_FS
+struct proc_dir_entry *proc_dir_cpu;
+EXPORT_SYMBOL(proc_dir_cpu);
+#endif
+
+extern inline void arch_reset(char mode)
+{
+       if (mode == 's') {
+               /* Use cpu handler, jump to 0 */
+               cpu_reset(0);
+       }
+}
+
+void (*pm_power_off) (void);
+EXPORT_SYMBOL(pm_power_off);
+
+static char reboot_mode = 'h';
+
+int __init reboot_setup(char *str)
+{
+       reboot_mode = str[0];
+       return 1;
+}
+
+static int cpub_pwroff(void)
+{
+       return 0;
+}
+
+__setup("reboot=", reboot_setup);
+
+void machine_halt(void)
+{
+       cpub_pwroff();
+}
+
+EXPORT_SYMBOL(machine_halt);
+
+void machine_power_off(void)
+{
+       if (pm_power_off)
+               pm_power_off();
+}
+
+EXPORT_SYMBOL(machine_power_off);
+
+void machine_restart(char *__unused)
+{
+       /*
+        * Clean and disable cache, and turn off interrupts
+        */
+       cpu_proc_fin();
+
+       /*
+        * Tell the mm system that we are going to reboot -
+        * we may need it to insert some 1:1 mappings so that
+        * soft boot works.
+        */
+       setup_mm_for_reboot(reboot_mode);
+
+       /*
+        * Now call the architecture specific reboot code.
+        */
+       arch_reset(reboot_mode);
+
+       /*
+        * Whoops - the architecture was unable to reboot.
+        * Tell the user!
+        */
+       mdelay(1000);
+       pr_info("Reboot failed -- System halted\n");
+       while (1) ;
+}
+
+EXPORT_SYMBOL(machine_restart);
+
+void show_regs(struct pt_regs *regs)
+{
+       print_symbol("PC is at %s\n", instruction_pointer(regs));
+       print_symbol("LP is at %s\n", regs->lp);
+       pr_info("pc : [<%08lx>]    lp : [<%08lx>]    %s\n"
+               "sp : %08lx  fp : %08lx  gp : %08lx\n",
+               instruction_pointer(regs),
+               regs->lp, print_tainted(), regs->sp, regs->fp, regs->gp);
+       pr_info("r25: %08lx  r24: %08lx\n", regs->uregs[25], regs->uregs[24]);
+
+       pr_info("r23: %08lx  r22: %08lx  r21: %08lx  r20: %08lx\n",
+               regs->uregs[23], regs->uregs[22],
+               regs->uregs[21], regs->uregs[20]);
+       pr_info("r19: %08lx  r18: %08lx  r17: %08lx  r16: %08lx\n",
+               regs->uregs[19], regs->uregs[18],
+               regs->uregs[17], regs->uregs[16]);
+       pr_info("r15: %08lx  r14: %08lx  r13: %08lx  r12: %08lx\n",
+               regs->uregs[15], regs->uregs[14],
+               regs->uregs[13], regs->uregs[12]);
+       pr_info("r11: %08lx  r10: %08lx  r9 : %08lx  r8 : %08lx\n",
+               regs->uregs[11], regs->uregs[10],
+               regs->uregs[9], regs->uregs[8]);
+       pr_info("r7 : %08lx  r6 : %08lx  r5 : %08lx  r4 : %08lx\n",
+               regs->uregs[7], regs->uregs[6], regs->uregs[5], regs->uregs[4]);
+       pr_info("r3 : %08lx  r2 : %08lx  r1 : %08lx  r0 : %08lx\n",
+               regs->uregs[3], regs->uregs[2], regs->uregs[1], regs->uregs[0]);
+       pr_info("  IRQs o%s  Segment %s\n",
+               interrupts_enabled(regs) ? "n" : "ff",
+               segment_eq(get_fs(), get_ds())? "kernel" : "user");
+}
+
+EXPORT_SYMBOL(show_regs);
+
+void flush_thread(void)
+{
+}
+
+DEFINE_PER_CPU(struct task_struct *, __entry_task);
+
+asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
+int copy_thread(unsigned long clone_flags, unsigned long stack_start,
+           unsigned long stk_sz, struct task_struct *p)
+{
+       struct pt_regs *childregs = task_pt_regs(p);
+
+       memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
+
+       if (unlikely(p->flags & PF_KTHREAD)) {
+               memset(childregs, 0, sizeof(struct pt_regs));
+               /* kernel thread fn */
+               p->thread.cpu_context.r6 = stack_start;
+               /* kernel thread argument */
+               p->thread.cpu_context.r7 = stk_sz;
+       } else {
+               *childregs = *current_pt_regs();
+               if (stack_start)
+                       childregs->sp = stack_start;
+               /* child get zero as ret. */
+               childregs->uregs[0] = 0;
+               childregs->osp = 0;
+               if (clone_flags & CLONE_SETTLS)
+                       childregs->uregs[25] = childregs->uregs[3];
+       }
+       /* cpu context switching  */
+       p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
+       p->thread.cpu_context.sp = (unsigned long)childregs;
+
+#ifdef CONFIG_HWZOL
+       childregs->lb = 0;
+       childregs->le = 0;
+       childregs->lc = 0;
+#endif
+
+       return 0;
+}
+
+/*
+ * fill in the fpe structure for a core dump...
+ */
+int dump_fpu(struct pt_regs *regs, elf_fpregset_t * fpu)
+{
+       int fpvalid = 0;
+       return fpvalid;
+}
+
+EXPORT_SYMBOL(dump_fpu);
+
+unsigned long get_wchan(struct task_struct *p)
+{
+       unsigned long fp, lr;
+       unsigned long stack_start, stack_end;
+       int count = 0;
+
+       if (!p || p == current || p->state == TASK_RUNNING)
+               return 0;
+
+       if (IS_ENABLED(CONFIG_FRAME_POINTER)) {
+               stack_start = (unsigned long)end_of_stack(p);
+               stack_end = (unsigned long)task_stack_page(p) + THREAD_SIZE;
+
+               fp = thread_saved_fp(p);
+               do {
+                       if (fp < stack_start || fp > stack_end)
+                               return 0;
+                       lr = ((unsigned long *)fp)[0];
+                       if (!in_sched_functions(lr))
+                               return lr;
+                       fp = *(unsigned long *)(fp + 4);
+               } while (count++ < 16);
+       }
+       return 0;
+}
+
+EXPORT_SYMBOL(get_wchan);
-- 
1.7.9.5

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