Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/arch/csky/kernel/process.c b/arch/csky/kernel/process.c
new file mode 100644
index 0000000..f320d92
--- /dev/null
+++ b/arch/csky/kernel/process.c
@@ -0,0 +1,141 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
+
+#include <linux/module.h>
+#include <linux/version.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/sched/debug.h>
+#include <linux/delay.h>
+#include <linux/kallsyms.h>
+#include <linux/uaccess.h>
+#include <linux/ptrace.h>
+
+#include <asm/elf.h>
+#include <abi/reg_ops.h>
+
+struct cpuinfo_csky cpu_data[NR_CPUS];
+
+asmlinkage void ret_from_fork(void);
+asmlinkage void ret_from_kernel_thread(void);
+
+/*
+ * Some archs flush debug and FPU info here
+ */
+void flush_thread(void){}
+
+/*
+ * Return saved PC from a blocked thread
+ */
+unsigned long thread_saved_pc(struct task_struct *tsk)
+{
+ struct switch_stack *sw = (struct switch_stack *)tsk->thread.ksp;
+
+ return sw->r15;
+}
+
+int copy_thread(unsigned long clone_flags,
+ unsigned long usp,
+ unsigned long kthread_arg,
+ struct task_struct *p)
+{
+ struct switch_stack *childstack;
+ struct pt_regs *childregs = task_pt_regs(p);
+
+#ifdef CONFIG_CPU_HAS_FPU
+ save_to_user_fp(&p->thread.user_fp);
+#endif
+
+ childstack = ((struct switch_stack *) childregs) - 1;
+ memset(childstack, 0, sizeof(struct switch_stack));
+
+ /* setup ksp for switch_to !!! */
+ p->thread.ksp = (unsigned long)childstack;
+
+ if (unlikely(p->flags & PF_KTHREAD)) {
+ memset(childregs, 0, sizeof(struct pt_regs));
+ childstack->r15 = (unsigned long) ret_from_kernel_thread;
+ childstack->r10 = kthread_arg;
+ childstack->r9 = usp;
+ childregs->sr = mfcr("psr");
+ } else {
+ *childregs = *(current_pt_regs());
+ if (usp)
+ childregs->usp = usp;
+ if (clone_flags & CLONE_SETTLS)
+ task_thread_info(p)->tp_value = childregs->tls
+ = childregs->regs[0];
+
+ childregs->a0 = 0;
+ childstack->r15 = (unsigned long) ret_from_fork;
+ }
+
+ return 0;
+}
+
+/* Fill in the fpu structure for a core dump. */
+int dump_fpu(struct pt_regs *regs, struct user_fp *fpu)
+{
+ memcpy(fpu, ¤t->thread.user_fp, sizeof(*fpu));
+ return 1;
+}
+EXPORT_SYMBOL(dump_fpu);
+
+int dump_task_regs(struct task_struct *tsk, elf_gregset_t *pr_regs)
+{
+ struct pt_regs *regs = task_pt_regs(tsk);
+
+ /* NOTE: usp is error value. */
+ ELF_CORE_COPY_REGS((*pr_regs), regs)
+
+ return 1;
+}
+
+unsigned long get_wchan(struct task_struct *p)
+{
+ unsigned long lr;
+ unsigned long *fp, *stack_start, *stack_end;
+ int count = 0;
+
+ if (!p || p == current || p->state == TASK_RUNNING)
+ return 0;
+
+ stack_start = (unsigned long *)end_of_stack(p);
+ stack_end = (unsigned long *)(task_stack_page(p) + THREAD_SIZE);
+
+ fp = (unsigned long *) thread_saved_fp(p);
+ do {
+ if (fp < stack_start || fp > stack_end)
+ return 0;
+#ifdef CONFIG_STACKTRACE
+ lr = fp[1];
+ fp = (unsigned long *)fp[0];
+#else
+ lr = *fp++;
+#endif
+ if (!in_sched_functions(lr) &&
+ __kernel_text_address(lr))
+ return lr;
+ } while (count++ < 16);
+
+ return 0;
+}
+EXPORT_SYMBOL(get_wchan);
+
+#ifndef CONFIG_CPU_PM_NONE
+void arch_cpu_idle(void)
+{
+#ifdef CONFIG_CPU_PM_WAIT
+ asm volatile("wait\n");
+#endif
+
+#ifdef CONFIG_CPU_PM_DOZE
+ asm volatile("doze\n");
+#endif
+
+#ifdef CONFIG_CPU_PM_STOP
+ asm volatile("stop\n");
+#endif
+ local_irq_enable();
+}
+#endif