path: root/litmus/color_dev.c

#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/spinlock.h>
#include <linux/module.h>
#include <linux/highmem.h>
#include <asm/io.h> /* page_to_phys on SPARC */

#include <litmus/litmus.h>
#include <litmus/color.h>

#define ALLOC_NAME	"litmus/color_alloc"
#define CTRL_NAME	"litmus/color_ctrl"

extern unsigned long nr_colors;

/***********************************************************
 * Control device
***********************************************************/

static void litmus_color_ctrl_vm_close(struct vm_area_struct *vma)
{
	TRACE_CUR("%s flags=0x%lx prot=0x%lx\n", __FUNCTION__,
			vma->vm_flags, pgprot_val(vma->vm_page_prot));

	TRACE_CUR(CTRL_NAME ": %p:%p vma:%p vma->vm_private_data:%p closed.\n",
			(void*) vma->vm_start, (void*) vma->vm_end, vma,
			vma->vm_private_data);
}

static int litmus_color_ctrl_vm_fault(struct vm_area_struct *vma,
		struct vm_fault *vmf)
{
	/* This function should never be called, since
	 * all pages should have been mapped by mmap()
	 * already. */
	TRACE_CUR("%s flags=0x%lx\n", __FUNCTION__, vma->vm_flags);
	printk(KERN_WARNING "fault: %s flags=0x%lx\n", __FUNCTION__,
			vma->vm_flags);

	/* nope, you only get one page */
	return VM_FAULT_SIGBUS;
}

static struct vm_operations_struct litmus_color_ctrl_vm_ops = {
	.close	= litmus_color_ctrl_vm_close,
	.fault	= litmus_color_ctrl_vm_fault,
};

static int mmap_common_checks(struct vm_area_struct *vma)
{
	/* you can only map the "first" page */
	if (vma->vm_pgoff != 0)
		return -EINVAL;

#if 0
	/* you can't share it with anyone */
	/* well, maybe you can... */
	if (vma->vm_flags & (VM_MAYSHARE | VM_SHARED))
		return -EINVAL;
#endif

	return 0;
}

static int alloc_color_ctrl_page(void)
{
	struct task_struct *t;
	int err = 0;

	t = current;
	/* only allocate if the task doesn't have one yet */
	if (!tsk_rt(t)->color_ctrl_page) {
		tsk_rt(t)->color_ctrl_page = (void*) get_zeroed_page(GFP_KERNEL);
		if (!tsk_rt(t)->color_ctrl_page)
			err = -ENOMEM;
		/* will get de-allocated in task teardown */
		TRACE_TASK(t, "%s color_ctrl_page = %p\n", __FUNCTION__,
			   tsk_rt(t)->color_ctrl_page);
	}
	return err;
}

static int map_color_ctrl_page(struct vm_area_struct *vma)
{
	int err;
	unsigned long pfn;
	struct task_struct *t = current;
	struct page *color_ctrl = virt_to_page(tsk_rt(t)->color_ctrl_page);

	t = current;
	/* Increase ref count. Is decreased when vma is destroyed. */
	get_page(color_ctrl);
	pfn = page_to_pfn(color_ctrl);

	TRACE_CUR(CTRL_NAME
		  ": mapping %p (pfn:%lx, %lx) to 0x%lx (flags:%lx prot:%lx)\n",
		  tsk_rt(t)->color_ctrl_page, pfn, page_to_pfn(color_ctrl),
		  vma->vm_start, vma->vm_flags, pgprot_val(vma->vm_page_prot));

	/* Map it into the vma. Make sure to use PAGE_SHARED, otherwise
	 * userspace actually gets a copy-on-write page. */
	err = remap_pfn_range(vma, vma->vm_start, pfn, PAGE_SIZE, PAGE_SHARED);

	if (err)
		TRACE_CUR(CTRL_NAME ": remap_pfn_range() failed (%d)\n", err);

	return err;
}

static int litmus_color_ctrl_mmap(struct file *filp, struct vm_area_struct *vma)
{
	int err = 0;

	/* you can only get one page */
	if (vma->vm_end - vma->vm_start != PAGE_SIZE) {
		TRACE_CUR(CTRL_NAME ": must allocate a multiple of PAGE_SIZE\n");
		err = -EINVAL;
		goto out;
	}

	err = mmap_common_checks(vma);
	if (err) {
		TRACE_CUR(CTRL_NAME ": failed common mmap checks.\n");
		goto out;
	}

	vma->vm_ops = &litmus_color_ctrl_vm_ops;
	/* this mapping should not be kept across forks,
	 * and cannot be expanded */
	vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND;

	err = alloc_color_ctrl_page();
	if (!err)
		err = map_color_ctrl_page(vma);

	TRACE_CUR("%s flags=0x%lx prot=0x%lx\n", __FUNCTION__, vma->vm_flags,
			pgprot_val(vma->vm_page_prot));
out:
	return err;
}


/***********************************************************
 * Allocation device
***********************************************************/

#define vma_nr_pages(vma) \
	({unsigned long v = ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT); v;})

static int do_map_colored_pages(struct vm_area_struct *vma)
{
	const unsigned long nr_pages = vma_nr_pages(vma);
	struct color_ctrl_page *color_ctrl = tsk_rt(current)->color_ctrl_page;
	unsigned long nr_mapped;
	int i, err = 0;

	TRACE_CUR(ALLOC_NAME ": allocating %lu pages (flags:%lx prot:%lx)\n",
			nr_pages, vma->vm_flags, pgprot_val(vma->vm_page_prot));

	for (i = 0, nr_mapped = 0; nr_mapped < nr_pages; ++i) {
		const unsigned long color_no = color_ctrl->colors[i];
		unsigned int page_no = 0;

		for (; page_no < color_ctrl->pages[i]; ++page_no, ++nr_mapped) {
			const unsigned long addr = vma->vm_start +
				(nr_mapped << PAGE_SHIFT);
			struct page *page = get_colored_page(color_no);

			if (!page) {
				TRACE_CUR(ALLOC_NAME ": Could not get page with"
					  " color %lu.\n", color_no);
				/* TODO unmap mapped pages */
				err = -ENOMEM;
				goto out;
			}

#ifdef CONFIG_SPARC
			clear_user_highpage(page, addr);
#endif

			TRACE_CUR(ALLOC_NAME ": insert page (pa:0x%10llx, "
				  "pfn:%8lu, color:%3lu) at 0x%lx (flags:%16lx "
				  "prot:%16lx) PAGE_SHARED:0x%16lx\n",
				  page_to_phys(page),
				  page_to_pfn(page), color_no, addr,
				  vma->vm_flags, pgprot_val(vma->vm_page_prot),
				  PAGE_SHARED);

			err = remap_pfn_range(vma, addr, page_to_pfn(page),
					      PAGE_SIZE, PAGE_SHARED);

			if (err) {
				TRACE_CUR(ALLOC_NAME ": remap_pfn_range() fail "
					  "(%d) (flags:%lx prot:%lx)\n", err,
					  vma->vm_flags,
					  pgprot_val(vma->vm_page_prot));
				/* TODO unmap mapped pages */
				err = -EINVAL;
				goto out;
			}
			add_page_to_alloced_list(page, vma);
		}

		if (!page_no) {
			TRACE_CUR(ALLOC_NAME ": 0 pages given for color %lu\n",
				  color_no);
			err = -EINVAL;
			goto out;
		}
	}
 out:
	return err;
}

static int map_colored_pages(struct vm_area_struct *vma)
{
	int err = 0;

	if (!tsk_rt(current)->color_ctrl_page) {
		TRACE_CUR("Process has no color control page.\n");
		err = -EINVAL;
		goto out;
	}

	if (COLORS_PER_CONTROL_PAGE < vma_nr_pages(vma)) {
		TRACE_CUR("Max page request %lu but want %lu.\n",
				COLORS_PER_CONTROL_PAGE, vma_nr_pages(vma));
		err = -EINVAL;
		goto out;
	}
	err = do_map_colored_pages(vma);
out:
	return err;
}

static void litmus_color_alloc_vm_close(struct vm_area_struct *vma)
{
	TRACE_CUR("%s flags=0x%lx prot=0x%lx\n", __FUNCTION__,
			vma->vm_flags, pgprot_val(vma->vm_page_prot));

	TRACE_CUR(ALLOC_NAME ": %p:%p vma:%p vma->vm_private_data:%p closed.\n",
			(void*) vma->vm_start, (void*) vma->vm_end, vma,
			vma->vm_private_data);
	reclaim_pages(vma);
}

static int litmus_color_alloc_vm_fault(struct vm_area_struct *vma,
		struct vm_fault *vmf)
{
	/* This function should never be called, since
	 * all pages should have been mapped by mmap()
	 * already. */
	TRACE_CUR("%s flags=0x%lx\n", __FUNCTION__, vma->vm_flags);
	printk(KERN_WARNING "fault: %s flags=0x%lx\n", __FUNCTION__,
			vma->vm_flags);

	/* nope, you only get one page */
	return VM_FAULT_SIGBUS;
}

static struct vm_operations_struct litmus_color_alloc_vm_ops = {
	.close	= litmus_color_alloc_vm_close,
	.fault	= litmus_color_alloc_vm_fault,
};

static int litmus_color_alloc_mmap(struct file *filp, struct vm_area_struct *vma)
{
	int err = 0;

	/* you may only request integer multiple of PAGE_SIZE */
	if (offset_in_page(vma->vm_end - vma->vm_start)) {
		err = -EINVAL;
		goto out;
	}

	err = mmap_common_checks(vma);
	if (err)
		goto out;

	vma->vm_ops = &litmus_color_alloc_vm_ops;
	/* this mapping should not be kept across forks,
	 * and cannot be expanded */
	vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND;

	err = map_colored_pages(vma);

	TRACE_CUR("%s flags=0x%lx prot=0x%lx\n", __FUNCTION__, vma->vm_flags,
			pgprot_val(vma->vm_page_prot));
out:
	return err;
}

/***********************************************************
 * Initilization
***********************************************************/

static struct file_operations litmus_color_ctrl_fops = {
	.owner	= THIS_MODULE,
	.mmap	= litmus_color_ctrl_mmap,
};

static struct miscdevice litmus_color_ctrl_dev = {
	.name	= CTRL_NAME,
	.minor	= MISC_DYNAMIC_MINOR,
	.fops	= &litmus_color_ctrl_fops,
};

static struct file_operations litmus_color_alloc_fops = {
	.owner	= THIS_MODULE,
	.mmap	= litmus_color_alloc_mmap,
};

static struct miscdevice litmus_color_alloc_dev = {
	.name	= ALLOC_NAME,
	.minor	= MISC_DYNAMIC_MINOR,
	.fops	= &litmus_color_alloc_fops,
};

static int __init init_dev(const char* name, struct miscdevice *dev)
{
	int err;
	err = misc_register(dev);
	if (err)
		printk(KERN_WARNING "Could not allocate %s device (%d).\n",
				name, err);
	return err;
}

static int __init init_color_devices(void)
{
	int err;

	printk("Allocating LITMUS^RT color devices.\n");
	err = init_dev(ALLOC_NAME, &litmus_color_alloc_dev);
	if (err)
		goto out;
	err = init_dev(CTRL_NAME, &litmus_color_ctrl_dev);
out:
	return err;
}

module_init(init_color_devices);