// SPDX-License-Identifier: GPL-2.0

  #include <linux/bitops.h>

  #include <linux/fault-inject-usercopy.h>

  #include <linux/instrumented.h>
  #include <linux/uaccess.h>

  
  /* out-of-line parts */
  
  #ifndef INLINE_COPY_FROM_USER
  unsigned long _copy_from_user(void *to, const void __user *from, unsigned long n)
  {
  	unsigned long res = n;

  	might_fault();

  	if (!should_fail_usercopy() && likely(access_ok(from, n))) {

  		instrument_copy_from_user(to, from, n);

  		res = raw_copy_from_user(to, from, n);

  	}

  	if (unlikely(res))
  		memset(to + (n - res), 0, res);
  	return res;
  }
  EXPORT_SYMBOL(_copy_from_user);
  #endif
  
  #ifndef INLINE_COPY_TO_USER

  unsigned long _copy_to_user(void __user *to, const void *from, unsigned long n)

  {

  	might_fault();

  	if (should_fail_usercopy())
  		return n;

  	if (likely(access_ok(to, n))) {

  		instrument_copy_to_user(to, from, n);

  		n = raw_copy_to_user(to, from, n);

  	}

  	return n;
  }
  EXPORT_SYMBOL(_copy_to_user);
  #endif

  
  /**
   * check_zeroed_user: check if a userspace buffer only contains zero bytes
   * @from: Source address, in userspace.
   * @size: Size of buffer.
   *
   * This is effectively shorthand for "memchr_inv(from, 0, size) == NULL" for
   * userspace addresses (and is more efficient because we don't care where the
   * first non-zero byte is).
   *
   * Returns:
   *  * 0: There were non-zero bytes present in the buffer.
   *  * 1: The buffer was full of zero bytes.
   *  * -EFAULT: access to userspace failed.
   */
  int check_zeroed_user(const void __user *from, size_t size)
  {
  	unsigned long val;
  	uintptr_t align = (uintptr_t) from % sizeof(unsigned long);
  
  	if (unlikely(size == 0))
  		return 1;
  
  	from -= align;
  	size += align;

  	if (!user_read_access_begin(from, size))

  		return -EFAULT;
  
  	unsafe_get_user(val, (unsigned long __user *) from, err_fault);
  	if (align)
  		val &= ~aligned_byte_mask(align);
  
  	while (size > sizeof(unsigned long)) {
  		if (unlikely(val))
  			goto done;
  
  		from += sizeof(unsigned long);
  		size -= sizeof(unsigned long);
  
  		unsafe_get_user(val, (unsigned long __user *) from, err_fault);
  	}
  
  	if (size < sizeof(unsigned long))
  		val &= aligned_byte_mask(size);
  
  done:

  	user_read_access_end();

  	return (val == 0);
  err_fault:

  	user_read_access_end();

  	return -EFAULT;
  }
  EXPORT_SYMBOL(check_zeroed_user);