1#include <linux/kernel.h>
  2#include <linux/mm.h>
  3#include <linux/slab.h>
  4#include <linux/uaccess.h>
  5#include <linux/ktime.h>
  6#include <linux/debugfs.h>
  7
  8#define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_benchmark)
  9
 10struct gup_benchmark {
 11	__u64 delta_usec;
 12	__u64 addr;
 13	__u64 size;
 14	__u32 nr_pages_per_call;
 15	__u32 flags;
 16};
 17
 18static int __gup_benchmark_ioctl(unsigned int cmd,
 19		struct gup_benchmark *gup)
 20{
 21	ktime_t start_time, end_time;
 22	unsigned long i, nr, nr_pages, addr, next;
 23	struct page **pages;
 24
 25	nr_pages = gup->size / PAGE_SIZE;
 26	pages = kvzalloc(sizeof(void *) * nr_pages, GFP_KERNEL);
 27	if (!pages)
 28		return -ENOMEM;
 29
 30	i = 0;
 31	nr = gup->nr_pages_per_call;
 32	start_time = ktime_get();
 33	for (addr = gup->addr; addr < gup->addr + gup->size; addr = next) {
 34		if (nr != gup->nr_pages_per_call)
 35			break;
 36
 37		next = addr + nr * PAGE_SIZE;
 38		if (next > gup->addr + gup->size) {
 39			next = gup->addr + gup->size;
 40			nr = (next - addr) / PAGE_SIZE;
 41		}
 42
 43		nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
 44		if (nr <= 0)
 45			break;
 46		i += nr;
 47	}
 48	end_time = ktime_get();
 49
 50	gup->delta_usec = ktime_us_delta(end_time, start_time);
 51	gup->size = addr - gup->addr;
 52
 53	for (i = 0; i < nr_pages; i++) {
 54		if (!pages[i])
 55			break;
 56		put_page(pages[i]);
 57	}
 58
 59	kvfree(pages);
 60	return 0;
 61}
 62
 63static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
 64		unsigned long arg)
 65{
 66	struct gup_benchmark gup;
 67	int ret;
 68
 69	if (cmd != GUP_FAST_BENCHMARK)
 70		return -EINVAL;
 71
 72	if (copy_from_user(&gup, (void __user *)arg, sizeof(gup)))
 73		return -EFAULT;
 74
 75	ret = __gup_benchmark_ioctl(cmd, &gup);
 76	if (ret)
 77		return ret;
 78
 79	if (copy_to_user((void __user *)arg, &gup, sizeof(gup)))
 80		return -EFAULT;
 81
 82	return 0;
 83}
 84
 85static const struct file_operations gup_benchmark_fops = {
 86	.open = nonseekable_open,
 87	.unlocked_ioctl = gup_benchmark_ioctl,
 88};
 89
 90static int gup_benchmark_init(void)
 91{
 92	void *ret;
 93
 94	ret = debugfs_create_file_unsafe("gup_benchmark", 0600, NULL, NULL,
 95			&gup_benchmark_fops);
 96	if (!ret)
 97		pr_warn("Failed to create gup_benchmark in debugfs");
 98
 99	return 0;
100}
101
102late_initcall(gup_benchmark_init);