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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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7d7c7b24e4
find_first_bit_left() and friends have nothing to do with the normal LSB0 bit numbering for big endian machines used in Linux (least significant bit has bit number 0). Instead they use MSB0 bit numbering, where the most signficant bit has bit number 0. So rename find_first_bit_left() and friends to find_first_bit_inv(), to avoid any confusion. Also provide inv versions of set_bit, clear_bit and test_bit. This also removes the confusing use of e.g. set_bit() in airq.c which uses a "be_to_le" bit number conversion, which could imply that instead set_bit_le() could be used. But that is entirely wrong since the _le bitops variant uses yet another bit numbering scheme. Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
78 lines
1.9 KiB
C
78 lines
1.9 KiB
C
/*
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* MSB0 numbered special bitops handling.
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*
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* On s390x the bits are numbered:
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* |0..............63|64............127|128...........191|192...........255|
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* and on s390:
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* |0.....31|31....63|64....95|96...127|128..159|160..191|192..223|224..255|
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*
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* The reason for this bit numbering is the fact that the hardware sets bits
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* in a bitmap starting at bit 0 (MSB) and we don't want to scan the bitmap
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* from the 'wrong end'.
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*/
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#include <linux/compiler.h>
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#include <linux/bitops.h>
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#include <linux/export.h>
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unsigned long find_first_bit_inv(const unsigned long *addr, unsigned long size)
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{
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const unsigned long *p = addr;
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unsigned long result = 0;
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unsigned long tmp;
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while (size & ~(BITS_PER_LONG - 1)) {
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if ((tmp = *(p++)))
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goto found;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = (*p) & (~0UL << (BITS_PER_LONG - size));
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if (!tmp) /* Are any bits set? */
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return result + size; /* Nope. */
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found:
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return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
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}
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EXPORT_SYMBOL(find_first_bit_inv);
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unsigned long find_next_bit_inv(const unsigned long *addr, unsigned long size,
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unsigned long offset)
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{
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const unsigned long *p = addr + (offset / BITS_PER_LONG);
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unsigned long result = offset & ~(BITS_PER_LONG - 1);
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unsigned long tmp;
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if (offset >= size)
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return size;
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size -= result;
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offset %= BITS_PER_LONG;
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if (offset) {
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tmp = *(p++);
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tmp &= (~0UL >> offset);
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if (size < BITS_PER_LONG)
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goto found_first;
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if (tmp)
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goto found_middle;
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size -= BITS_PER_LONG;
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result += BITS_PER_LONG;
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}
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while (size & ~(BITS_PER_LONG-1)) {
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if ((tmp = *(p++)))
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goto found_middle;
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result += BITS_PER_LONG;
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size -= BITS_PER_LONG;
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}
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if (!size)
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return result;
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tmp = *p;
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found_first:
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tmp &= (~0UL << (BITS_PER_LONG - size));
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if (!tmp) /* Are any bits set? */
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return result + size; /* Nope. */
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found_middle:
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return result + (__fls(tmp) ^ (BITS_PER_LONG - 1));
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}
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EXPORT_SYMBOL(find_next_bit_inv);
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