Commit c77369b4 authored by David Hildenbrand's avatar David Hildenbrand Committed by Andrew Morton
Browse files

mm/gup_test: start/stop/read functionality for PIN LONGTERM test 

We want an easy way to take a R/O or R/W longterm pin on a range and be
able to observe the content of the pinned pages, so we can properly test
how longterm puns interact with our COW logic.

[david@redhat.com: silence a warning on 32-bit]
  Link: https://lkml.kernel.org/r/74adbb51-6e33-f636-8a9c-2ad87bd9007e@redhat.com
[yang.lee@linux.alibaba.com: ./mm/gup_test.c:281:2-3: Unneeded semicolon]
  Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=2455
  Link: https://lkml.kernel.org/r/20221020024035.113619-1-yang.lee@linux.alibaba.com
Link: https://lkml.kernel.org/r/20220927110120.106906-7-david@redhat.com


Signed-off-by: default avatarDavid Hildenbrand <david@redhat.com>
Signed-off-by: default avatarYang Li <yang.lee@linux.alibaba.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph von Recklinghausen <crecklin@redhat.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent e487ebbd

mm/gup_test.c

+141 −0
Original line number Diff line number Diff line
@@ -203,6 +203,135 @@ static int __gup_test_ioctl(unsigned int cmd, 
	return ret;

}



static DEFINE_MUTEX(pin_longterm_test_mutex);

static struct page **pin_longterm_test_pages;

static unsigned long pin_longterm_test_nr_pages;



static inline void pin_longterm_test_stop(void)

{

	if (pin_longterm_test_pages) {

		if (pin_longterm_test_nr_pages)

			unpin_user_pages(pin_longterm_test_pages,

					 pin_longterm_test_nr_pages);

		kfree(pin_longterm_test_pages);

		pin_longterm_test_pages = NULL;

		pin_longterm_test_nr_pages = 0;

	}

}



static inline int pin_longterm_test_start(unsigned long arg)

{

	long nr_pages, cur_pages, addr, remaining_pages;

	int gup_flags = FOLL_LONGTERM;

	struct pin_longterm_test args;

	struct page **pages;

	int ret = 0;

	bool fast;



	if (pin_longterm_test_pages)

		return -EINVAL;



	if (copy_from_user(&args, (void __user *)arg, sizeof(args)))

		return -EFAULT;



	if (args.flags &

	    ~(PIN_LONGTERM_TEST_FLAG_USE_WRITE|PIN_LONGTERM_TEST_FLAG_USE_FAST))

		return -EINVAL;

	if (!IS_ALIGNED(args.addr | args.size, PAGE_SIZE))

		return -EINVAL;

	if (args.size > LONG_MAX)

		return -EINVAL;

	nr_pages = args.size / PAGE_SIZE;

	if (!nr_pages)

		return -EINVAL;



	pages = kvcalloc(nr_pages, sizeof(void *), GFP_KERNEL);

	if (!pages)

		return -ENOMEM;



	if (args.flags & PIN_LONGTERM_TEST_FLAG_USE_WRITE)

		gup_flags |= FOLL_WRITE;

	fast = !!(args.flags & PIN_LONGTERM_TEST_FLAG_USE_FAST);



	if (!fast && mmap_read_lock_killable(current->mm)) {

		kfree(pages);

		return -EINTR;

	}



	pin_longterm_test_pages = pages;

	pin_longterm_test_nr_pages = 0;



	while (nr_pages - pin_longterm_test_nr_pages) {

		remaining_pages = nr_pages - pin_longterm_test_nr_pages;

		addr = args.addr + pin_longterm_test_nr_pages * PAGE_SIZE;



		if (fast)

			cur_pages = pin_user_pages_fast(addr, remaining_pages,

							gup_flags, pages);

		else

			cur_pages = pin_user_pages(addr, remaining_pages,

						   gup_flags, pages, NULL);

		if (cur_pages < 0) {

			pin_longterm_test_stop();

			ret = cur_pages;

			break;

		}

		pin_longterm_test_nr_pages += cur_pages;

		pages += cur_pages;

	}



	if (!fast)

		mmap_read_unlock(current->mm);

	return ret;

}



static inline int pin_longterm_test_read(unsigned long arg)

{

	__u64 user_addr;

	unsigned long i;



	if (!pin_longterm_test_pages)

		return -EINVAL;



	if (copy_from_user(&user_addr, (void __user *)arg, sizeof(user_addr)))

		return -EFAULT;



	for (i = 0; i < pin_longterm_test_nr_pages; i++) {

		void *addr = page_to_virt(pin_longterm_test_pages[i]);



		if (copy_to_user((void __user *)(unsigned long)user_addr, addr,

				 PAGE_SIZE))

			return -EFAULT;

		user_addr += PAGE_SIZE;

	}

	return 0;

}



static long pin_longterm_test_ioctl(struct file *filep, unsigned int cmd,

				    unsigned long arg)

{

	int ret = -EINVAL;



	if (mutex_lock_killable(&pin_longterm_test_mutex))

		return -EINTR;



	switch (cmd) {

	case PIN_LONGTERM_TEST_START:

		ret = pin_longterm_test_start(arg);

		break;

	case PIN_LONGTERM_TEST_STOP:

		pin_longterm_test_stop();

		ret = 0;

		break;

	case PIN_LONGTERM_TEST_READ:

		ret = pin_longterm_test_read(arg);

		break;

	}



	mutex_unlock(&pin_longterm_test_mutex);

	return ret;

}



static long gup_test_ioctl(struct file *filep, unsigned int cmd,

		unsigned long arg)

{
@@ -217,6 +346,10 @@ static long gup_test_ioctl(struct file *filep, unsigned int cmd, 
	case PIN_BASIC_TEST:

	case DUMP_USER_PAGES_TEST:

		break;

	case PIN_LONGTERM_TEST_START:

	case PIN_LONGTERM_TEST_STOP:

	case PIN_LONGTERM_TEST_READ:

		return pin_longterm_test_ioctl(filep, cmd, arg);

	default:

		return -EINVAL;

	}
@@ -234,9 +367,17 @@ static long gup_test_ioctl(struct file *filep, unsigned int cmd, 
	return 0;

}



static int gup_test_release(struct inode *inode, struct file *file)

{

	pin_longterm_test_stop();



	return 0;

}



static const struct file_operations gup_test_fops = {

	.open = nonseekable_open,

	.unlocked_ioctl = gup_test_ioctl,

	.release = gup_test_release,

};



static int __init gup_test_init(void)

mm/gup_test.h

+12 −0
Original line number Diff line number Diff line
@@ -10,6 +10,9 @@ 
#define GUP_BASIC_TEST		_IOWR('g', 4, struct gup_test)

#define PIN_BASIC_TEST		_IOWR('g', 5, struct gup_test)

#define DUMP_USER_PAGES_TEST	_IOWR('g', 6, struct gup_test)

#define PIN_LONGTERM_TEST_START	_IOW('g', 7, struct pin_longterm_test)

#define PIN_LONGTERM_TEST_STOP	_IO('g', 8)

#define PIN_LONGTERM_TEST_READ	_IOW('g', 9, __u64)



#define GUP_TEST_MAX_PAGES_TO_DUMP		8
@@ -30,4 +33,13 @@ struct gup_test { 
	__u32 which_pages[GUP_TEST_MAX_PAGES_TO_DUMP];

};



#define PIN_LONGTERM_TEST_FLAG_USE_WRITE	1

#define PIN_LONGTERM_TEST_FLAG_USE_FAST		2



struct pin_longterm_test {

	__u64 addr;

	__u64 size;

	__u32 flags;

};



#endif	/* __GUP_TEST_H */