util/size.h - main - githubmirror/ndctl

util/size.h
252 строки8 KB
Vaibhav Jain
util/size.h: Fix build error for GCC < 10
02 мар 2022, 23:23
02 мар 2022, 23:233b5fb8b
/* SPDX-License-Identifier: GPL-2.0 */
/* Copyright (C) 2015-2020 Intel Corporation. All rights reserved. */

#ifndef _NDCTL_SIZE_H_
#define _NDCTL_SIZE_H_
#include <stdbool.h>
#include <stdint.h>
#include <util/util.h>
#include <ccan/short_types/short_types.h>

#define SZ_1K     0x00000400
#define SZ_4K     0x00001000
#define SZ_8K     0x00002000
#define SZ_1M     0x00100000
#define SZ_2M     0x00200000
#define SZ_4M     0x00400000
#define SZ_16M    0x01000000
#define SZ_64M    0x04000000
#define SZ_256M	  0x10000000
#define SZ_1G     0x40000000
#define SZ_1T 0x10000000000ULL

unsigned long long parse_size64(const char *str);
unsigned long long __parse_size64(const char *str, unsigned long long *units);

static inline bool is_power_of_2(unsigned long long v)
{
	return v && ((v & (v - 1)) == 0);
}

#define ALIGN(x, a) ((((unsigned long long) x) + (a - 1)) & ~(a - 1))
#define ALIGN_DOWN(x, a) (((((unsigned long long) x) + a) & ~(a - 1)) - a)
#define IS_ALIGNED(x, a) (((x) & ((typeof(x))(a) - 1)) == 0)
#define BITS_PER_LONG (sizeof(unsigned long) * 8)
#define HPAGE_SIZE (2 << 20)

/*
 * Helpers for struct_size() copied from include/linux/overflow.h (GPL-2.0)
 *
 * For simplicity and code hygiene, the fallback code below insists on
 * a, b and *d having the same type (similar to the min() and max()
 * macros), whereas gcc's type-generic overflow checkers accept
 * different types. Hence we don't just make check_add_overflow an
 * alias for __builtin_add_overflow, but add type checks similar to
 * below.
 */
#define is_signed_type(type)       (((type)(-1)) < (type)1)
#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
#define type_min(T) ((T)((T)-type_max(T)-(T)1))

#if GCC_VERSION >= 50100
#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
#endif

#if __clang__
#if __has_builtin(__builtin_mul_overflow) && \
    __has_builtin(__builtin_add_overflow)
#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
#endif
#endif

#if COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW

#define check_add_overflow(a, b, d) ({		\
	typeof(a) __a = (a);			\
	typeof(b) __b = (b);			\
	typeof(d) __d = (d);			\
	(void) (&__a == &__b);			\
	(void) (&__a == __d);			\
	__builtin_add_overflow(__a, __b, __d);	\
})

#define check_sub_overflow(a, b, d) ({		\
	typeof(a) __a = (a);			\
	typeof(b) __b = (b);			\
	typeof(d) __d = (d);			\
	(void) (&__a == &__b);			\
	(void) (&__a == __d);			\
	__builtin_sub_overflow(__a, __b, __d);	\
})

#define check_mul_overflow(a, b, d) ({		\
	typeof(a) __a = (a);			\
	typeof(b) __b = (b);			\
	typeof(d) __d = (d);			\
	(void) (&__a == &__b);			\
	(void) (&__a == __d);			\
	__builtin_mul_overflow(__a, __b, __d);	\
})


#else /* !COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */

/* Checking for unsigned overflow is relatively easy without causing UB. */
#define __unsigned_add_overflow(a, b, d) ({	\
	typeof(a) __a = (a);			\
	typeof(b) __b = (b);			\
	typeof(d) __d = (d);			\
	(void) (&__a == &__b);			\
	(void) (&__a == __d);			\
	*__d = __a + __b;			\
	*__d < __a;				\
})
#define __unsigned_sub_overflow(a, b, d) ({	\
	typeof(a) __a = (a);			\
	typeof(b) __b = (b);			\
	typeof(d) __d = (d);			\
	(void) (&__a == &__b);			\
	(void) (&__a == __d);			\
	*__d = __a - __b;			\
	__a < __b;				\
})
/*
 * If one of a or b is a compile-time constant, this avoids a division.
 */
#define __unsigned_mul_overflow(a, b, d) ({		\
	typeof(a) __a = (a);				\
	typeof(b) __b = (b);				\
	typeof(d) __d = (d);				\
	(void) (&__a == &__b);				\
	(void) (&__a == __d);				\
	*__d = __a * __b;				\
	__builtin_constant_p(__b) ?			\
	  __b > 0 && __a > type_max(typeof(__a)) / __b : \
	  __a > 0 && __b > type_max(typeof(__b)) / __a;	 \
})

/*
 * For signed types, detecting overflow is much harder, especially if
 * we want to avoid UB. But the interface of these macros is such that
 * we must provide a result in *d, and in fact we must produce the
 * result promised by gcc's builtins, which is simply the possibly
 * wrapped-around value. Fortunately, we can just formally do the
 * operations in the widest relevant unsigned type (u64) and then
 * truncate the result - gcc is smart enough to generate the same code
 * with and without the (u64) casts.
 */

/*
 * Adding two signed integers can overflow only if they have the same
 * sign, and overflow has happened iff the result has the opposite
 * sign.
 */
#define __signed_add_overflow(a, b, d) ({	\
	typeof(a) __a = (a);			\
	typeof(b) __b = (b);			\
	typeof(d) __d = (d);			\
	(void) (&__a == &__b);			\
	(void) (&__a == __d);			\
	*__d = (u64)__a + (u64)__b;		\
	(((~(__a ^ __b)) & (*__d ^ __a))	\
		& type_min(typeof(__a))) != 0;	\
})

/*
 * Subtraction is similar, except that overflow can now happen only
 * when the signs are opposite. In this case, overflow has happened if
 * the result has the opposite sign of a.
 */
#define __signed_sub_overflow(a, b, d) ({	\
	typeof(a) __a = (a);			\
	typeof(b) __b = (b);			\
	typeof(d) __d = (d);			\
	(void) (&__a == &__b);			\
	(void) (&__a == __d);			\
	*__d = (u64)__a - (u64)__b;		\
	((((__a ^ __b)) & (*__d ^ __a))		\
		& type_min(typeof(__a))) != 0;	\
})

/*
 * Signed multiplication is rather hard. gcc always follows C99, so
 * division is truncated towards 0. This means that we can write the
 * overflow check like this:
 *
 * (a > 0 && (b > MAX/a || b < MIN/a)) ||
 * (a < -1 && (b > MIN/a || b < MAX/a) ||
 * (a == -1 && b == MIN)
 *
 * The redundant casts of -1 are to silence an annoying -Wtype-limits
 * (included in -Wextra) warning: When the type is u8 or u16, the
 * __b_c_e in check_mul_overflow obviously selects
 * __unsigned_mul_overflow, but unfortunately gcc still parses this
 * code and warns about the limited range of __b.
 */

#define __signed_mul_overflow(a, b, d) ({				\
	typeof(a) __a = (a);						\
	typeof(b) __b = (b);						\
	typeof(d) __d = (d);						\
	typeof(a) __tmax = type_max(typeof(a));				\
	typeof(a) __tmin = type_min(typeof(a));				\
	(void) (&__a == &__b);						\
	(void) (&__a == __d);						\
	*__d = (u64)__a * (u64)__b;					\
	(__b > 0   && (__a > __tmax/__b || __a < __tmin/__b)) ||	\
	(__b < (typeof(__b))-1  && (__a > __tmin/__b || __a < __tmax/__b)) || \
	(__b == (typeof(__b))-1 && __a == __tmin);			\
})


#define check_add_overflow(a, b, d)					\
	__builtin_choose_expr(is_signed_type(typeof(a)),		\
			__signed_add_overflow(a, b, d),			\
			__unsigned_add_overflow(a, b, d))

#define check_sub_overflow(a, b, d)					\
	__builtin_choose_expr(is_signed_type(typeof(a)),		\
			__signed_sub_overflow(a, b, d),			\
			__unsigned_sub_overflow(a, b, d))

#define check_mul_overflow(a, b, d)					\
	__builtin_choose_expr(is_signed_type(typeof(a)),		\
			__signed_mul_overflow(a, b, d),			\
			__unsigned_mul_overflow(a, b, d))

#endif

/*
 * Compute a*b+c, returning SIZE_MAX on overflow. Internal helper for
 * struct_size() below.
 */
static inline size_t __ab_c_size(size_t a, size_t b, size_t c)
{
	size_t bytes;

	if (check_mul_overflow(a, b, &bytes))
		return SIZE_MAX;
	if (check_add_overflow(bytes, c, &bytes))
		return SIZE_MAX;

	return bytes;
}

/**
 * struct_size() - Calculate size of structure with trailing array.
 * @p: Pointer to the structure.
 * @member: Name of the array member.
 * @count: Number of elements in the array.
 *
 * Calculates size of memory needed for structure @p followed by an
 * array of @count number of @member elements.
 *
 * Return: number of bytes needed or SIZE_MAX on overflow.
 */
#define struct_size(p, member, count)					\
	__ab_c_size(count,						\
		    sizeof(*(p)->member) + __must_be_array((p)->member),\
		    sizeof(*(p)))

#endif /* _NDCTL_SIZE_H_ */