mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-23 19:43:54 +07:00
7dea927f70
Fixes sparse warning:
Function parameter or member 'pbuflen' not described in 'packing'
Fixes: 554aae3500 ("lib: Add support for generic packing operations")
Signed-off-by: Vladimir Oltean <olteanv@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
215 lines
6.6 KiB
C
215 lines
6.6 KiB
C
// SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0
|
|
/* Copyright (c) 2016-2018, NXP Semiconductors
|
|
* Copyright (c) 2018-2019, Vladimir Oltean <olteanv@gmail.com>
|
|
*/
|
|
#include <linux/packing.h>
|
|
#include <linux/module.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/errno.h>
|
|
#include <linux/types.h>
|
|
|
|
static int get_le_offset(int offset)
|
|
{
|
|
int closest_multiple_of_4;
|
|
|
|
closest_multiple_of_4 = (offset / 4) * 4;
|
|
offset -= closest_multiple_of_4;
|
|
return closest_multiple_of_4 + (3 - offset);
|
|
}
|
|
|
|
static int get_reverse_lsw32_offset(int offset, size_t len)
|
|
{
|
|
int closest_multiple_of_4;
|
|
int word_index;
|
|
|
|
word_index = offset / 4;
|
|
closest_multiple_of_4 = word_index * 4;
|
|
offset -= closest_multiple_of_4;
|
|
word_index = (len / 4) - word_index - 1;
|
|
return word_index * 4 + offset;
|
|
}
|
|
|
|
static u64 bit_reverse(u64 val, unsigned int width)
|
|
{
|
|
u64 new_val = 0;
|
|
unsigned int bit;
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < width; i++) {
|
|
bit = (val & (1 << i)) != 0;
|
|
new_val |= (bit << (width - i - 1));
|
|
}
|
|
return new_val;
|
|
}
|
|
|
|
static void adjust_for_msb_right_quirk(u64 *to_write, int *box_start_bit,
|
|
int *box_end_bit, u8 *box_mask)
|
|
{
|
|
int box_bit_width = *box_start_bit - *box_end_bit + 1;
|
|
int new_box_start_bit, new_box_end_bit;
|
|
|
|
*to_write >>= *box_end_bit;
|
|
*to_write = bit_reverse(*to_write, box_bit_width);
|
|
*to_write <<= *box_end_bit;
|
|
|
|
new_box_end_bit = box_bit_width - *box_start_bit - 1;
|
|
new_box_start_bit = box_bit_width - *box_end_bit - 1;
|
|
*box_mask = GENMASK_ULL(new_box_start_bit, new_box_end_bit);
|
|
*box_start_bit = new_box_start_bit;
|
|
*box_end_bit = new_box_end_bit;
|
|
}
|
|
|
|
/**
|
|
* 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.
|
|
*
|
|
* 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)
|
|
{
|
|
/* Number of bits for storing "uval"
|
|
* also width of the field to access in the pbuf
|
|
*/
|
|
u64 value_width;
|
|
/* Logical byte indices corresponding to the
|
|
* start and end of the field.
|
|
*/
|
|
int plogical_first_u8, plogical_last_u8, box;
|
|
|
|
/* startbit is expected to be larger than endbit */
|
|
if (startbit < endbit)
|
|
/* Invalid function call */
|
|
return -EINVAL;
|
|
|
|
value_width = startbit - endbit + 1;
|
|
if (value_width > 64)
|
|
return -ERANGE;
|
|
|
|
/* Check if "uval" fits in "value_width" bits.
|
|
* If value_width is 64, the check will fail, but any
|
|
* 64-bit uval will surely fit.
|
|
*/
|
|
if (op == PACK && value_width < 64 && (*uval >= (1ull << value_width)))
|
|
/* Cannot store "uval" inside "value_width" bits.
|
|
* Truncating "uval" is most certainly not desirable,
|
|
* so simply erroring out is appropriate.
|
|
*/
|
|
return -ERANGE;
|
|
|
|
/* Initialize parameter */
|
|
if (op == UNPACK)
|
|
*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.
|
|
*/
|
|
plogical_first_u8 = startbit / 8;
|
|
plogical_last_u8 = endbit / 8;
|
|
|
|
for (box = plogical_first_u8; box >= plogical_last_u8; box--) {
|
|
/* Bit indices into the currently accessed 8-bit box */
|
|
int box_start_bit, box_end_bit, box_addr;
|
|
u8 box_mask;
|
|
/* Corresponding bits from the unpacked u64 parameter */
|
|
int proj_start_bit, proj_end_bit;
|
|
u64 proj_mask;
|
|
|
|
/* 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 % 8;
|
|
else
|
|
box_start_bit = 7;
|
|
if (box == plogical_last_u8)
|
|
box_end_bit = endbit % 8;
|
|
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 * 8) + box_start_bit) - endbit;
|
|
proj_end_bit = ((box * 8) + box_end_bit) - endbit;
|
|
proj_mask = GENMASK_ULL(proj_start_bit, proj_end_bit);
|
|
box_mask = GENMASK_ULL(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 = pbuflen - box - 1;
|
|
if (quirks & QUIRK_LITTLE_ENDIAN)
|
|
box_addr = get_le_offset(box_addr);
|
|
if (quirks & QUIRK_LSW32_IS_FIRST)
|
|
box_addr = get_reverse_lsw32_offset(box_addr,
|
|
pbuflen);
|
|
|
|
if (op == UNPACK) {
|
|
u64 pval;
|
|
|
|
/* Read from pbuf, write to uval */
|
|
pval = ((u8 *)pbuf)[box_addr] & box_mask;
|
|
if (quirks & QUIRK_MSB_ON_THE_RIGHT)
|
|
adjust_for_msb_right_quirk(&pval,
|
|
&box_start_bit,
|
|
&box_end_bit,
|
|
&box_mask);
|
|
|
|
pval >>= box_end_bit;
|
|
pval <<= proj_end_bit;
|
|
*uval &= ~proj_mask;
|
|
*uval |= pval;
|
|
} else {
|
|
u64 pval;
|
|
|
|
/* Write to pbuf, read from uval */
|
|
pval = (*uval) & proj_mask;
|
|
pval >>= proj_end_bit;
|
|
if (quirks & QUIRK_MSB_ON_THE_RIGHT)
|
|
adjust_for_msb_right_quirk(&pval,
|
|
&box_start_bit,
|
|
&box_end_bit,
|
|
&box_mask);
|
|
|
|
pval <<= box_end_bit;
|
|
((u8 *)pbuf)[box_addr] &= ~box_mask;
|
|
((u8 *)pbuf)[box_addr] |= pval;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(packing);
|
|
|
|
MODULE_LICENSE("GPL v2");
|
|
MODULE_DESCRIPTION("Generic bitfield packing and unpacking");
|