// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0/* Copyright 2016-2018 NXP * Copyright (c) 2018-2019, Vladimir Oltean <olteanv@gmail.com> */#include <linux/packing.h>#include <linux/module.h>#include <linux/bitops.h>#include <linux/bits.h>#include <linux/errno.h>#include <linux/types.h>#include <linux/bitrev.h> #define __pack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks)	\	({									\		for (size_t i = 0; i < (num_fields); i++) {			\			typeof(&(fields)[0]) field = &(fields)[i];		\			u64 uval;						\										\			uval = ustruct_field_to_u64(ustruct, field->offset, field->size); \										\			__pack(pbuf, uval, field->startbit, field->endbit,	\			       pbuflen, quirks);				\		}								\	}) #define __unpack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks)	\	({									\		for (size_t i = 0; i < (num_fields); i++) {			\			typeof(&(fields)[0]) field = &fields[i];		\			u64 uval;						\										\			__unpack(pbuf, &uval, field->startbit, field->endbit,	\				 pbuflen, quirks);				\										\			u64_to_ustruct_field(ustruct, field->offset, field->size, uval); \		}								\	}) /** * calculate_box_addr - Determine physical location of byte in buffer * @box: Index of byte within buffer seen as a logical big-endian big number * @len: Size of buffer in bytes * @quirks: mask of QUIRK_LSW32_IS_FIRST and QUIRK_LITTLE_ENDIAN * * Function interprets the buffer as a @len byte sized big number, and returns * the physical offset of the @box logical octet within it. Internally, it * treats the big number as groups of 4 bytes. If @len is not a multiple of 4, * the last group may be shorter. * * @QUIRK_LSW32_IS_FIRST gives the ordering of groups of 4 octets relative to * each other. If set, the most significant group of 4 octets is last in the * buffer (and may be truncated if @len is not a multiple of 4). * * @QUIRK_LITTLE_ENDIAN gives the ordering of bytes within each group of 4. * If set, the most significant byte is last in the group. If @len takes the * form of 4k+3, the last group will only be able to represent 24 bits, and its * most significant octet is byte 2. * * Return: the physical offset into the buffer corresponding to the logical box. */static size_t calculate_box_addr(size_t box, size_t len, u8 quirks){	size_t offset_of_group, offset_in_group, this_group = box / 4;	size_t group_size; 	if (quirks & QUIRK_LSW32_IS_FIRST)		offset_of_group = this_group * 4;	else		offset_of_group = len - ((this_group + 1) * 4); 	group_size = min(4, len - offset_of_group); 	if (quirks & QUIRK_LITTLE_ENDIAN)		offset_in_group = box - this_group * 4;	else		offset_in_group = group_size - (box - this_group * 4) - 1; 	return offset_of_group + offset_in_group;} static void __pack(void *pbuf, u64 uval, size_t startbit, size_t endbit,		   size_t pbuflen, u8 quirks){	/* Logical byte indices corresponding to the	 * start and end of the field.	 */	int plogical_first_u8 = startbit / BITS_PER_BYTE;	int plogical_last_u8 = endbit / BITS_PER_BYTE;	int value_width = startbit - endbit + 1;	int box; 	/* Check if "uval" fits in "value_width" bits.	 * The test only works for value_width < 64, but in the latter case,	 * any 64-bit uval will surely fit.	 */	WARN(value_width < 64 && uval >= (1ull << value_width),	     "Cannot store 0x%llx inside bits %zu-%zu - will truncate\n",	     uval, startbit, endbit); 	/* Iterate through an idealistic view of the pbuf as an u64 with	 * no quirks, u8 by u8 (aligned at u8 boundaries), from high to low	 * logical bit significance. "box" denotes the current logical u8.	 */	for (box = plogical_first_u8; box >= plogical_last_u8; box--) {		/* Bit indices into the currently accessed 8-bit box */		size_t box_start_bit, box_end_bit, box_addr;		u8  box_mask;		/* Corresponding bits from the unpacked u64 parameter */		size_t proj_start_bit, proj_end_bit;		u64 proj_mask;		u64 pval; 		/* This u8 may need to be accessed in its entirety		 * (from bit 7 to bit 0), or not, depending on the		 * input arguments startbit and endbit.		 */		if (box == plogical_first_u8)			box_start_bit = startbit % BITS_PER_BYTE;		else			box_start_bit = 7;		if (box == plogical_last_u8)			box_end_bit = endbit % BITS_PER_BYTE;		else			box_end_bit = 0; 		/* We have determined the box bit start and end.		 * Now we calculate where this (masked) u8 box would fit		 * in the unpacked (CPU-readable) u64 - the u8 box's		 * projection onto the unpacked u64. Though the		 * box is u8, the projection is u64 because it may fall		 * anywhere within the unpacked u64.		 */		proj_start_bit = ((box * BITS_PER_BYTE) + box_start_bit) - endbit;		proj_end_bit = ((box * BITS_PER_BYTE) + box_end_bit) - endbit;		proj_mask = GENMASK_ULL(proj_start_bit, proj_end_bit);		box_mask = GENMASK(box_start_bit, box_end_bit); 		/* Determine the offset of the u8 box inside the pbuf,		 * adjusted for quirks. The adjusted box_addr will be used for		 * effective addressing inside the pbuf (so it's not		 * logical any longer).		 */		box_addr = calculate_box_addr(box, pbuflen, quirks); 		/* Write to pbuf, read from uval */		pval = uval & proj_mask;		pval >>= proj_end_bit;		pval <<= box_end_bit; 		if (quirks & QUIRK_MSB_ON_THE_RIGHT) {			pval = bitrev8(pval);			box_mask = bitrev8(box_mask);		} 		((u8 *)pbuf)[box_addr] &= ~box_mask;		((u8 *)pbuf)[box_addr] |= pval;	}} /** * pack - Pack u64 number into bitfield of buffer. * * @pbuf: Pointer to a buffer holding the packed value. * @uval: CPU-readable unpacked value to pack. * @startbit: The index (in logical notation, compensated for quirks) where *	      the packed value starts within pbuf. Must be larger than, or *	      equal to, endbit. * @endbit: The index (in logical notation, compensated for quirks) where *	    the packed value ends within pbuf. Must be smaller than, or equal *	    to, startbit. * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf. * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and *	    QUIRK_MSB_ON_THE_RIGHT. * * Return: 0 on success, EINVAL or ERANGE if called incorrectly. Assuming *	   correct usage, return code may be discarded. The @pbuf memory will *	   be modified on success. */int pack(void *pbuf, u64 uval, size_t startbit, size_t endbit, size_t pbuflen,	 u8 quirks){	/* startbit is expected to be larger than endbit, and both are	 * expected to be within the logically addressable range of the buffer.	 */	if (unlikely(startbit < endbit || startbit >= BITS_PER_BYTE * pbuflen))		/* Invalid function call */		return -EINVAL; 	if (unlikely(startbit - endbit >= 64))		return -ERANGE; 	__pack(pbuf, uval, startbit, endbit, pbuflen, quirks); 	return 0;}EXPORT_SYMBOL(pack); static void __unpack(const void *pbuf, u64 *uval, size_t startbit, size_t endbit,		     size_t pbuflen, u8 quirks){	/* Logical byte indices corresponding to the	 * start and end of the field.	 */	int plogical_first_u8 = startbit / BITS_PER_BYTE;	int plogical_last_u8 = endbit / BITS_PER_BYTE;	int box; 	/* Initialize parameter */	*uval = 0; 	/* Iterate through an idealistic view of the pbuf as an u64 with	 * no quirks, u8 by u8 (aligned at u8 boundaries), from high to low	 * logical bit significance. "box" denotes the current logical u8.	 */	for (box = plogical_first_u8; box >= plogical_last_u8; box--) {		/* Bit indices into the currently accessed 8-bit box */		size_t box_start_bit, box_end_bit, box_addr;		u8  box_mask;		/* Corresponding bits from the unpacked u64 parameter */		size_t proj_start_bit, proj_end_bit;		u64 proj_mask;		u64 pval; 		/* This u8 may need to be accessed in its entirety		 * (from bit 7 to bit 0), or not, depending on the		 * input arguments startbit and endbit.		 */		if (box == plogical_first_u8)			box_start_bit = startbit % BITS_PER_BYTE;		else			box_start_bit = 7;		if (box == plogical_last_u8)			box_end_bit = endbit % BITS_PER_BYTE;		else			box_end_bit = 0; 		/* We have determined the box bit start and end.		 * Now we calculate where this (masked) u8 box would fit		 * in the unpacked (CPU-readable) u64 - the u8 box's		 * projection onto the unpacked u64. Though the		 * box is u8, the projection is u64 because it may fall		 * anywhere within the unpacked u64.		 */		proj_start_bit = ((box * BITS_PER_BYTE) + box_start_bit) - endbit;		proj_end_bit = ((box * BITS_PER_BYTE) + box_end_bit) - endbit;		proj_mask = GENMASK_ULL(proj_start_bit, proj_end_bit);		box_mask = GENMASK(box_start_bit, box_end_bit); 		/* Determine the offset of the u8 box inside the pbuf,		 * adjusted for quirks. The adjusted box_addr will be used for		 * effective addressing inside the pbuf (so it's not		 * logical any longer).		 */		box_addr = calculate_box_addr(box, pbuflen, quirks); 		/* Read from pbuf, write to uval */		pval = ((u8 *)pbuf)[box_addr]; 		if (quirks & QUIRK_MSB_ON_THE_RIGHT)			pval = bitrev8(pval); 		pval &= box_mask; 		pval >>= box_end_bit;		pval <<= proj_end_bit;		*uval &= ~proj_mask;		*uval |= pval;	}} /** * unpack - Unpack u64 number from packed buffer. * * @pbuf: Pointer to a buffer holding the packed value. * @uval: Pointer to an u64 holding the unpacked value. * @startbit: The index (in logical notation, compensated for quirks) where *	      the packed value starts within pbuf. Must be larger than, or *	      equal to, endbit. * @endbit: The index (in logical notation, compensated for quirks) where *	    the packed value ends within pbuf. Must be smaller than, or equal *	    to, startbit. * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf. * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and *	    QUIRK_MSB_ON_THE_RIGHT. * * Return: 0 on success, EINVAL or ERANGE if called incorrectly. Assuming *	   correct usage, return code may be discarded. The @uval will be *	   modified on success. */int unpack(const void *pbuf, u64 *uval, size_t startbit, size_t endbit,	   size_t pbuflen, u8 quirks){	/* width of the field to access in the pbuf */	u64 value_width; 	/* startbit is expected to be larger than endbit, and both are	 * expected to be within the logically addressable range of the buffer.	 */	if (startbit < endbit || startbit >= BITS_PER_BYTE * pbuflen)		/* Invalid function call */		return -EINVAL; 	value_width = startbit - endbit + 1;	if (value_width > 64)		return -ERANGE; 	__unpack(pbuf, uval, startbit, endbit, pbuflen, quirks); 	return 0;}EXPORT_SYMBOL(unpack); /** * packing - Convert numbers (currently u64) between a packed and an unpacked *	     format. Unpacked means laid out in memory in the CPU's native *	     understanding of integers, while packed means anything else that *	     requires translation. * * @pbuf: Pointer to a buffer holding the packed value. * @uval: Pointer to an u64 holding the unpacked value. * @startbit: The index (in logical notation, compensated for quirks) where *	      the packed value starts within pbuf. Must be larger than, or *	      equal to, endbit. * @endbit: The index (in logical notation, compensated for quirks) where *	    the packed value ends within pbuf. Must be smaller than, or equal *	    to, startbit. * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf. * @op: If PACK, then uval will be treated as const pointer and copied (packed) *	into pbuf, between startbit and endbit. *	If UNPACK, then pbuf will be treated as const pointer and the logical *	value between startbit and endbit will be copied (unpacked) to uval. * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and *	    QUIRK_MSB_ON_THE_RIGHT. * * Note: this is deprecated, prefer to use pack() or unpack() in new code. * * Return: 0 on success, EINVAL or ERANGE if called incorrectly. Assuming *	   correct usage, return code may be discarded. *	   If op is PACK, pbuf is modified. *	   If op is UNPACK, uval is modified. */int packing(void *pbuf, u64 *uval, int startbit, int endbit, size_t pbuflen,	    enum packing_op op, u8 quirks){	if (op == PACK)		return pack(pbuf, *uval, startbit, endbit, pbuflen, quirks); 	return unpack(pbuf, uval, startbit, endbit, pbuflen, quirks);}EXPORT_SYMBOL(packing); static u64 ustruct_field_to_u64(const void *ustruct, size_t field_offset,				size_t field_size){	switch (field_size) {	case 1:		return *((u8 *)(ustruct + field_offset));	case 2:		return *((u16 *)(ustruct + field_offset));	case 4:		return *((u32 *)(ustruct + field_offset));	default:		return *((u64 *)(ustruct + field_offset));	}} static void u64_to_ustruct_field(void *ustruct, size_t field_offset,				 size_t field_size, u64 uval){	switch (field_size) {	case 1:		*((u8 *)(ustruct + field_offset)) = uval;		break;	case 2:		*((u16 *)(ustruct + field_offset)) = uval;		break;	case 4:		*((u32 *)(ustruct + field_offset)) = uval;		break;	default:		*((u64 *)(ustruct + field_offset)) = uval;		break;	}} /** * pack_fields_u8 - Pack array of fields * * @pbuf: Pointer to a buffer holding the packed value. * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf. * @ustruct: Pointer to CPU-readable structure holding the unpacked value. *	     It is expected (but not checked) that this has the same data type *	     as all struct packed_field_u8 definitions. * @fields: Array of packed_field_u8 field definition. They must not overlap. * @num_fields: Length of @fields array. * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and *	    QUIRK_MSB_ON_THE_RIGHT. * * Use the pack_fields() macro instead of calling this directly. */void pack_fields_u8(void *pbuf, size_t pbuflen, const void *ustruct,		    const struct packed_field_u8 *fields, size_t num_fields,		    u8 quirks){	__pack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks);}EXPORT_SYMBOL(pack_fields_u8); /** * pack_fields_u16 - Pack array of fields * * @pbuf: Pointer to a buffer holding the packed value. * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf. * @ustruct: Pointer to CPU-readable structure holding the unpacked value. *	     It is expected (but not checked) that this has the same data type *	     as all struct packed_field_u16 definitions. * @fields: Array of packed_field_u16 field definitions. They must not overlap. * @num_fields: Length of @fields array. * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and *	    QUIRK_MSB_ON_THE_RIGHT. * * Use the pack_fields() macro instead of calling this directly. */void pack_fields_u16(void *pbuf, size_t pbuflen, const void *ustruct,		     const struct packed_field_u16 *fields, size_t num_fields,		     u8 quirks){	__pack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks);}EXPORT_SYMBOL(pack_fields_u16); /** * unpack_fields_u8 - Unpack array of fields * * @pbuf: Pointer to a buffer holding the packed value. * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf. * @ustruct: Pointer to CPU-readable structure holding the unpacked value. *	     It is expected (but not checked) that this has the same data type *	     as all struct packed_field_u8 definitions. * @fields: Array of packed_field_u8 field definitions. They must not overlap. * @num_fields: Length of @fields array. * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and *	    QUIRK_MSB_ON_THE_RIGHT. * * Use the unpack_fields() macro instead of calling this directly. */void unpack_fields_u8(const void *pbuf, size_t pbuflen, void *ustruct,		      const struct packed_field_u8 *fields, size_t num_fields,		      u8 quirks){	__unpack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks);}EXPORT_SYMBOL(unpack_fields_u8); /** * unpack_fields_u16 - Unpack array of fields * * @pbuf: Pointer to a buffer holding the packed value. * @pbuflen: The length in bytes of the packed buffer pointed to by @pbuf. * @ustruct: Pointer to CPU-readable structure holding the unpacked value. *	     It is expected (but not checked) that this has the same data type *	     as all struct packed_field_u16 definitions. * @fields: Array of packed_field_u16 field definitions. They must not overlap. * @num_fields: Length of @fields array. * @quirks: A bit mask of QUIRK_LITTLE_ENDIAN, QUIRK_LSW32_IS_FIRST and *	    QUIRK_MSB_ON_THE_RIGHT. * * Use the unpack_fields() macro instead of calling this directly. */void unpack_fields_u16(const void *pbuf, size_t pbuflen, void *ustruct,		       const struct packed_field_u16 *fields, size_t num_fields,		       u8 quirks){	__unpack_fields(pbuf, pbuflen, ustruct, fields, num_fields, quirks);}EXPORT_SYMBOL(unpack_fields_u16); MODULE_DESCRIPTION("Generic bitfield packing and unpacking");