1. 根目录:
2. arch
3. sh
4. kernel
5. process.c

#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/export.h>
#include <linux/stackprotector.h>
#include <asm/fpu.h>

struct kmem_cache *task_xstate_cachep = NULL;
unsigned int xstate_size;

#ifdef CONFIG_CC_STACKPROTECTOR
unsigned long __stack_chk_guard __read_mostly;
EXPORT_SYMBOL(__stack_chk_guard);
#endif

/*
 * this gets called so that we can store lazy state into memory and copy the
 * current task into the new thread.
 */
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
#ifdef CONFIG_SUPERH32
	unlazy_fpu(src, task_pt_regs(src));
#endif
	*dst = *src;

	if (src->thread.xstate) {
		dst->thread.xstate = kmem_cache_alloc(task_xstate_cachep,
						      GFP_KERNEL);
		if (!dst->thread.xstate)
			return -ENOMEM;
		memcpy(dst->thread.xstate, src->thread.xstate, xstate_size);
	}

	return 0;
}

void free_thread_xstate(struct task_struct *tsk)
{
	if (tsk->thread.xstate) {
		kmem_cache_free(task_xstate_cachep, tsk->thread.xstate);
		tsk->thread.xstate = NULL;
	}
}

void arch_release_task_struct(struct task_struct *tsk)
{
	free_thread_xstate(tsk);
}

void arch_task_cache_init(void)
{
	if (!xstate_size)
		return;

	task_xstate_cachep = kmem_cache_create("task_xstate", xstate_size,
					       __alignof__(union thread_xstate),
					       SLAB_PANIC | SLAB_NOTRACK, NULL);
}

#ifdef CONFIG_SH_FPU_EMU
# define HAVE_SOFTFP	1
#else
# define HAVE_SOFTFP	0
#endif

void init_thread_xstate(void)
{
	if (boot_cpu_data.flags & CPU_HAS_FPU)
		xstate_size = sizeof(struct sh_fpu_hard_struct);
	else if (HAVE_SOFTFP)
		xstate_size = sizeof(struct sh_fpu_soft_struct);
	else
		xstate_size = 0;
}