qemu/util/bitmap.c
Stefan Hajnoczi d73415a315 qemu/atomic.h: rename atomic_ to qatomic_
clang's C11 atomic_fetch_*() functions only take a C11 atomic type
pointer argument. QEMU uses direct types (int, etc) and this causes a
compiler error when a QEMU code calls these functions in a source file
that also included <stdatomic.h> via a system header file:

  $ CC=clang CXX=clang++ ./configure ... && make
  ../util/async.c:79:17: error: address argument to atomic operation must be a pointer to _Atomic type ('unsigned int *' invalid)

Avoid using atomic_*() names in QEMU's atomic.h since that namespace is
used by <stdatomic.h>. Prefix QEMU's APIs with 'q' so that atomic.h
and <stdatomic.h> can co-exist. I checked /usr/include on my machine and
searched GitHub for existing "qatomic_" users but there seem to be none.

This patch was generated using:

  $ git grep -h -o '\<atomic\(64\)\?_[a-z0-9_]\+' include/qemu/atomic.h | \
    sort -u >/tmp/changed_identifiers
  $ for identifier in $(</tmp/changed_identifiers); do
        sed -i "s%\<$identifier\>%q$identifier%g" \
            $(git grep -I -l "\<$identifier\>")
    done

I manually fixed line-wrap issues and misaligned rST tables.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200923105646.47864-1-stefanha@redhat.com>
2020-09-23 16:07:44 +01:00

490 lines
12 KiB
C

/*
* Bitmap Module
*
* Stolen from linux/src/lib/bitmap.c
*
* Copyright (C) 2010 Corentin Chary
*
* This source code is licensed under the GNU General Public License,
* Version 2.
*/
#include "qemu/osdep.h"
#include "qemu/bitops.h"
#include "qemu/bitmap.h"
#include "qemu/atomic.h"
/*
* bitmaps provide an array of bits, implemented using an
* array of unsigned longs. The number of valid bits in a
* given bitmap does _not_ need to be an exact multiple of
* BITS_PER_LONG.
*
* The possible unused bits in the last, partially used word
* of a bitmap are 'don't care'. The implementation makes
* no particular effort to keep them zero. It ensures that
* their value will not affect the results of any operation.
* The bitmap operations that return Boolean (bitmap_empty,
* for example) or scalar (bitmap_weight, for example) results
* carefully filter out these unused bits from impacting their
* results.
*
* These operations actually hold to a slightly stronger rule:
* if you don't input any bitmaps to these ops that have some
* unused bits set, then they won't output any set unused bits
* in output bitmaps.
*
* The byte ordering of bitmaps is more natural on little
* endian architectures.
*/
int slow_bitmap_empty(const unsigned long *bitmap, long bits)
{
long k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
if (bitmap[k]) {
return 0;
}
}
if (bits % BITS_PER_LONG) {
if (bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {
return 0;
}
}
return 1;
}
int slow_bitmap_full(const unsigned long *bitmap, long bits)
{
long k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
if (~bitmap[k]) {
return 0;
}
}
if (bits % BITS_PER_LONG) {
if (~bitmap[k] & BITMAP_LAST_WORD_MASK(bits)) {
return 0;
}
}
return 1;
}
int slow_bitmap_equal(const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits)
{
long k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
if (bitmap1[k] != bitmap2[k]) {
return 0;
}
}
if (bits % BITS_PER_LONG) {
if ((bitmap1[k] ^ bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {
return 0;
}
}
return 1;
}
void slow_bitmap_complement(unsigned long *dst, const unsigned long *src,
long bits)
{
long k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
dst[k] = ~src[k];
}
if (bits % BITS_PER_LONG) {
dst[k] = ~src[k] & BITMAP_LAST_WORD_MASK(bits);
}
}
int slow_bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits)
{
long k;
long nr = BITS_TO_LONGS(bits);
unsigned long result = 0;
for (k = 0; k < nr; k++) {
result |= (dst[k] = bitmap1[k] & bitmap2[k]);
}
return result != 0;
}
void slow_bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits)
{
long k;
long nr = BITS_TO_LONGS(bits);
for (k = 0; k < nr; k++) {
dst[k] = bitmap1[k] | bitmap2[k];
}
}
void slow_bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits)
{
long k;
long nr = BITS_TO_LONGS(bits);
for (k = 0; k < nr; k++) {
dst[k] = bitmap1[k] ^ bitmap2[k];
}
}
int slow_bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits)
{
long k;
long nr = BITS_TO_LONGS(bits);
unsigned long result = 0;
for (k = 0; k < nr; k++) {
result |= (dst[k] = bitmap1[k] & ~bitmap2[k]);
}
return result != 0;
}
void bitmap_set(unsigned long *map, long start, long nr)
{
unsigned long *p = map + BIT_WORD(start);
const long size = start + nr;
int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
assert(start >= 0 && nr >= 0);
while (nr - bits_to_set >= 0) {
*p |= mask_to_set;
nr -= bits_to_set;
bits_to_set = BITS_PER_LONG;
mask_to_set = ~0UL;
p++;
}
if (nr) {
mask_to_set &= BITMAP_LAST_WORD_MASK(size);
*p |= mask_to_set;
}
}
void bitmap_set_atomic(unsigned long *map, long start, long nr)
{
unsigned long *p = map + BIT_WORD(start);
const long size = start + nr;
int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
assert(start >= 0 && nr >= 0);
/* First word */
if (nr - bits_to_set > 0) {
qatomic_or(p, mask_to_set);
nr -= bits_to_set;
bits_to_set = BITS_PER_LONG;
mask_to_set = ~0UL;
p++;
}
/* Full words */
if (bits_to_set == BITS_PER_LONG) {
while (nr >= BITS_PER_LONG) {
*p = ~0UL;
nr -= BITS_PER_LONG;
p++;
}
}
/* Last word */
if (nr) {
mask_to_set &= BITMAP_LAST_WORD_MASK(size);
qatomic_or(p, mask_to_set);
} else {
/* If we avoided the full barrier in qatomic_or(), issue a
* barrier to account for the assignments in the while loop.
*/
smp_mb();
}
}
void bitmap_clear(unsigned long *map, long start, long nr)
{
unsigned long *p = map + BIT_WORD(start);
const long size = start + nr;
int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
assert(start >= 0 && nr >= 0);
while (nr - bits_to_clear >= 0) {
*p &= ~mask_to_clear;
nr -= bits_to_clear;
bits_to_clear = BITS_PER_LONG;
mask_to_clear = ~0UL;
p++;
}
if (nr) {
mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
*p &= ~mask_to_clear;
}
}
bool bitmap_test_and_clear_atomic(unsigned long *map, long start, long nr)
{
unsigned long *p = map + BIT_WORD(start);
const long size = start + nr;
int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
unsigned long dirty = 0;
unsigned long old_bits;
assert(start >= 0 && nr >= 0);
/* First word */
if (nr - bits_to_clear > 0) {
old_bits = qatomic_fetch_and(p, ~mask_to_clear);
dirty |= old_bits & mask_to_clear;
nr -= bits_to_clear;
bits_to_clear = BITS_PER_LONG;
mask_to_clear = ~0UL;
p++;
}
/* Full words */
if (bits_to_clear == BITS_PER_LONG) {
while (nr >= BITS_PER_LONG) {
if (*p) {
old_bits = qatomic_xchg(p, 0);
dirty |= old_bits;
}
nr -= BITS_PER_LONG;
p++;
}
}
/* Last word */
if (nr) {
mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
old_bits = qatomic_fetch_and(p, ~mask_to_clear);
dirty |= old_bits & mask_to_clear;
} else {
if (!dirty) {
smp_mb();
}
}
return dirty != 0;
}
void bitmap_copy_and_clear_atomic(unsigned long *dst, unsigned long *src,
long nr)
{
while (nr > 0) {
*dst = qatomic_xchg(src, 0);
dst++;
src++;
nr -= BITS_PER_LONG;
}
}
#define ALIGN_MASK(x,mask) (((x)+(mask))&~(mask))
/**
* bitmap_find_next_zero_area - find a contiguous aligned zero area
* @map: The address to base the search on
* @size: The bitmap size in bits
* @start: The bitnumber to start searching at
* @nr: The number of zeroed bits we're looking for
* @align_mask: Alignment mask for zero area
*
* The @align_mask should be one less than a power of 2; the effect is that
* the bit offset of all zero areas this function finds is multiples of that
* power of 2. A @align_mask of 0 means no alignment is required.
*/
unsigned long bitmap_find_next_zero_area(unsigned long *map,
unsigned long size,
unsigned long start,
unsigned long nr,
unsigned long align_mask)
{
unsigned long index, end, i;
again:
index = find_next_zero_bit(map, size, start);
/* Align allocation */
index = ALIGN_MASK(index, align_mask);
end = index + nr;
if (end > size) {
return end;
}
i = find_next_bit(map, end, index);
if (i < end) {
start = i + 1;
goto again;
}
return index;
}
int slow_bitmap_intersects(const unsigned long *bitmap1,
const unsigned long *bitmap2, long bits)
{
long k, lim = bits/BITS_PER_LONG;
for (k = 0; k < lim; ++k) {
if (bitmap1[k] & bitmap2[k]) {
return 1;
}
}
if (bits % BITS_PER_LONG) {
if ((bitmap1[k] & bitmap2[k]) & BITMAP_LAST_WORD_MASK(bits)) {
return 1;
}
}
return 0;
}
long slow_bitmap_count_one(const unsigned long *bitmap, long nbits)
{
long k, lim = nbits / BITS_PER_LONG, result = 0;
for (k = 0; k < lim; k++) {
result += ctpopl(bitmap[k]);
}
if (nbits % BITS_PER_LONG) {
result += ctpopl(bitmap[k] & BITMAP_LAST_WORD_MASK(nbits));
}
return result;
}
static void bitmap_to_from_le(unsigned long *dst,
const unsigned long *src, long nbits)
{
long len = BITS_TO_LONGS(nbits);
#ifdef HOST_WORDS_BIGENDIAN
long index;
for (index = 0; index < len; index++) {
# if HOST_LONG_BITS == 64
dst[index] = bswap64(src[index]);
# else
dst[index] = bswap32(src[index]);
# endif
}
#else
memcpy(dst, src, len * sizeof(unsigned long));
#endif
}
void bitmap_from_le(unsigned long *dst, const unsigned long *src,
long nbits)
{
bitmap_to_from_le(dst, src, nbits);
}
void bitmap_to_le(unsigned long *dst, const unsigned long *src,
long nbits)
{
bitmap_to_from_le(dst, src, nbits);
}
/*
* Copy "src" bitmap with a positive offset and put it into the "dst"
* bitmap. The caller needs to make sure the bitmap size of "src"
* is bigger than (shift + nbits).
*/
void bitmap_copy_with_src_offset(unsigned long *dst, const unsigned long *src,
unsigned long shift, unsigned long nbits)
{
unsigned long left_mask, right_mask, last_mask;
/* Proper shift src pointer to the first word to copy from */
src += BIT_WORD(shift);
shift %= BITS_PER_LONG;
if (!shift) {
/* Fast path */
bitmap_copy(dst, src, nbits);
return;
}
right_mask = (1ul << shift) - 1;
left_mask = ~right_mask;
while (nbits >= BITS_PER_LONG) {
*dst = (*src & left_mask) >> shift;
*dst |= (src[1] & right_mask) << (BITS_PER_LONG - shift);
dst++;
src++;
nbits -= BITS_PER_LONG;
}
if (nbits > BITS_PER_LONG - shift) {
*dst = (*src & left_mask) >> shift;
nbits -= BITS_PER_LONG - shift;
last_mask = (1ul << nbits) - 1;
*dst |= (src[1] & last_mask) << (BITS_PER_LONG - shift);
} else if (nbits) {
last_mask = (1ul << nbits) - 1;
*dst = (*src >> shift) & last_mask;
}
}
/*
* Copy "src" bitmap into the "dst" bitmap with an offset in the
* "dst". The caller needs to make sure the bitmap size of "dst" is
* bigger than (shift + nbits).
*/
void bitmap_copy_with_dst_offset(unsigned long *dst, const unsigned long *src,
unsigned long shift, unsigned long nbits)
{
unsigned long left_mask, right_mask, last_mask;
/* Proper shift dst pointer to the first word to copy from */
dst += BIT_WORD(shift);
shift %= BITS_PER_LONG;
if (!shift) {
/* Fast path */
bitmap_copy(dst, src, nbits);
return;
}
right_mask = (1ul << (BITS_PER_LONG - shift)) - 1;
left_mask = ~right_mask;
*dst &= (1ul << shift) - 1;
while (nbits >= BITS_PER_LONG) {
*dst |= (*src & right_mask) << shift;
dst[1] = (*src & left_mask) >> (BITS_PER_LONG - shift);
dst++;
src++;
nbits -= BITS_PER_LONG;
}
if (nbits > BITS_PER_LONG - shift) {
*dst |= (*src & right_mask) << shift;
nbits -= BITS_PER_LONG - shift;
last_mask = ((1ul << nbits) - 1) << (BITS_PER_LONG - shift);
dst[1] = (*src & last_mask) >> (BITS_PER_LONG - shift);
} else if (nbits) {
last_mask = (1ul << nbits) - 1;
*dst |= (*src & last_mask) << shift;
}
}