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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v4 2/5] xen/ppc: Implement bitops.h
Implement bitops.h, based on Linux's implementation as of commit
5321d1b1afb9a17302c6cec79f0cbf823eb0d3fc. Though it is based off of
Linux's implementation, this code diverges significantly in a number of
ways:
- Bitmap entries changed to 32-bit words to match X86 and Arm on Xen
- PPC32-specific code paths dropped
- Formatting completely re-done to more closely line up with Xen.
Including 4 space indentation.
- Use GCC's __builtin_popcount* for hweight* implementation
Signed-off-by: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
---
v4:
- Mention __builtin_popcount impelmentation of hweight* in message
- Change type of BITOP_MASK expression from unsigned long to unsigned
int
- Fix remaining underscore-prefixed macro params/vars
- Fix line wrapping in test_and_clear_bit{,s}
- Change type of test_and_clear_bits' pointer parameter from void *
to unsigned int *. This was already done for other functions but
missed here.
- De-macroize test_and_set_bits.
- Fix formatting of ffs{,l} macro's unary operators
- Drop extra blank in ffz() macro definition
v3:
- Fix style of inline asm blocks.
- Fix underscore-prefixed macro parameters/variables
- Use __builtin_popcount for hweight* implementation
- Update C functions to use proper Xen coding style
v2:
- Clarify changes from Linux implementation in commit message
- Use PPC_ATOMIC_{ENTRY,EXIT}_BARRIER macros from <asm/memory.h> instead
of hardcoded "sync" instructions in inline assembly blocks.
- Fix macro line-continuing backslash spacing
- Fix hard-tab usage in find_*_bit C functions.
xen/arch/ppc/include/asm/bitops.h | 332 +++++++++++++++++++++++++++++-
1 file changed, 329 insertions(+), 3 deletions(-)
diff --git a/xen/arch/ppc/include/asm/bitops.h
b/xen/arch/ppc/include/asm/bitops.h
index 548e97b414..3e50778c4d 100644
--- a/xen/arch/ppc/include/asm/bitops.h
+++ b/xen/arch/ppc/include/asm/bitops.h
@@ -1,9 +1,335 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Adapted from Linux's arch/powerpc/include/asm/bitops.h.
+ *
+ * Merged version by David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>.
+ * Based on ppc64 versions by: Dave Engebretsen, Todd Inglett, Don
+ * Reed, Pat McCarthy, Peter Bergner, Anton Blanchard. They
+ * originally took it from the ppc32 code.
+ */
#ifndef _ASM_PPC_BITOPS_H
#define _ASM_PPC_BITOPS_H
+#include <asm/memory.h>
+
+#define __set_bit(n, p) set_bit(n, p)
+#define __clear_bit(n, p) clear_bit(n, p)
+
+#define BITOP_BITS_PER_WORD 32
+#define BITOP_MASK(nr) (1U << ((nr) % BITOP_BITS_PER_WORD))
+#define BITOP_WORD(nr) ((nr) / BITOP_BITS_PER_WORD)
+#define BITS_PER_BYTE 8
+
/* PPC bit number conversion */
-#define PPC_BITLSHIFT(be) (BITS_PER_LONG - 1 - (be))
-#define PPC_BIT(bit) (1UL << PPC_BITLSHIFT(bit))
-#define PPC_BITMASK(bs, be) ((PPC_BIT(bs) - PPC_BIT(be)) | PPC_BIT(bs))
+#define PPC_BITLSHIFT(be) (BITS_PER_LONG - 1 - (be))
+#define PPC_BIT(bit) (1UL << PPC_BITLSHIFT(bit))
+#define PPC_BITMASK(bs, be) ((PPC_BIT(bs) - PPC_BIT(be)) | PPC_BIT(bs))
+
+/* Macro for generating the ***_bits() functions */
+#define DEFINE_BITOP(fn, op, prefix)
\
+static inline void fn(unsigned long mask,
\
+ volatile unsigned int *p_)
\
+{
\
+ unsigned long old;
\
+ unsigned int *p = (unsigned int *)p_;
\
+ asm volatile ( prefix
\
+ "1: lwarx %0,0,%3,0\n"
\
+ #op "%I2 %0,%0,%2\n"
\
+ "stwcx. %0,0,%3\n"
\
+ "bne- 1b\n"
\
+ : "=&r" (old), "+m" (*p)
\
+ : "rK" (mask), "r" (p)
\
+ : "cc", "memory" );
\
+}
+
+DEFINE_BITOP(set_bits, or, "")
+DEFINE_BITOP(change_bits, xor, "")
+
+#define DEFINE_CLROP(fn, prefix)
\
+static inline void fn(unsigned long mask, volatile unsigned int *p_)
\
+{
\
+ unsigned long old;
\
+ unsigned int *p = (unsigned int *)p_;
\
+ asm volatile ( prefix
\
+ "1: lwarx %0,0,%3,0\n"
\
+ "andc %0,%0,%2\n"
\
+ "stwcx. %0,0,%3\n"
\
+ "bne- 1b\n"
\
+ : "=&r" (old), "+m" (*p)
\
+ : "r" (mask), "r" (p)
\
+ : "cc", "memory" );
\
+}
+
+DEFINE_CLROP(clear_bits, "")
+
+static inline void set_bit(int nr, volatile void *addr)
+{
+ set_bits(BITOP_MASK(nr), (volatile unsigned int *)addr + BITOP_WORD(nr));
+}
+static inline void clear_bit(int nr, volatile void *addr)
+{
+ clear_bits(BITOP_MASK(nr), (volatile unsigned int *)addr + BITOP_WORD(nr));
+}
+
+/**
+ * test_bit - Determine whether a bit is set
+ * @nr: bit number to test
+ * @addr: Address to start counting from
+ */
+static inline int test_bit(int nr, const volatile void *addr)
+{
+ const volatile unsigned long *p = (const volatile unsigned long *)addr;
+ return 1 & (p[BITOP_WORD(nr)] >> (nr & (BITOP_BITS_PER_WORD - 1)));
+}
+
+static inline unsigned long test_and_clear_bits(
+ unsigned long mask,
+ volatile unsigned int *p)
+{
+ unsigned long old, t;
+
+ asm volatile ( PPC_ATOMIC_ENTRY_BARRIER
+ "1: lwarx %0,0,%3,0\n"
+ "andc %1,%0,%2\n"
+ "stwcx. %1,0,%3\n"
+ "bne- 1b\n"
+ PPC_ATOMIC_EXIT_BARRIER
+ : "=&r" (old), "=&r" (t)
+ : "r" (mask), "r" (p)
+ : "cc", "memory" );
+
+ return (old & mask);
+}
+
+static inline int test_and_clear_bit(unsigned int nr,
+ volatile void *addr)
+{
+ return test_and_clear_bits(BITOP_MASK(nr), (volatile unsigned int *)addr +
+ BITOP_WORD(nr)) != 0;
+}
+
+static inline unsigned long test_and_set_bits(
+ unsigned long mask,
+ volatile unsigned int *p)
+{
+ unsigned long old, t;
+
+ asm volatile ( PPC_ATOMIC_ENTRY_BARRIER
+ "1: lwarx %0,0,%3,0\n"
+ "or%I2 %1,%0,%2\n"
+ "stwcx. %1,0,%3\n"
+ "bne- 1b\n"
+ PPC_ATOMIC_EXIT_BARRIER
+ : "=&r" (old), "=&r" (t)
+ : "rK" (mask), "r" (p)
+ : "cc", "memory" );
+
+ return (old & mask);
+}
+
+static inline int test_and_set_bit(unsigned long nr, volatile void *addr)
+{
+ return test_and_set_bits(BITOP_MASK(nr), (volatile unsigned int *)addr +
+ BITOP_WORD(nr)) != 0;
+}
+
+/**
+ * __test_and_set_bit - Set a bit and return its old value
+ * @nr: Bit to set
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ * If two examples of this operation race, one can appear to succeed
+ * but actually fail. You must protect multiple accesses with a lock.
+ */
+static inline int __test_and_set_bit(int nr, volatile void *addr)
+{
+ unsigned int mask = BITOP_MASK(nr);
+ volatile unsigned int *p = ((volatile unsigned int *)addr) +
BITOP_WORD(nr);
+ unsigned int old = *p;
+
+ *p = old | mask;
+ return (old & mask) != 0;
+}
+
+/**
+ * __test_and_clear_bit - Clear a bit and return its old value
+ * @nr: Bit to clear
+ * @addr: Address to count from
+ *
+ * This operation is non-atomic and can be reordered.
+ * If two examples of this operation race, one can appear to succeed
+ * but actually fail. You must protect multiple accesses with a lock.
+ */
+static inline int __test_and_clear_bit(int nr, volatile void *addr)
+{
+ unsigned int mask = BITOP_MASK(nr);
+ volatile unsigned int *p = ((volatile unsigned int *)addr) +
BITOP_WORD(nr);
+ unsigned int old = *p;
+
+ *p = old & ~mask;
+ return (old & mask) != 0;
+}
+
+#define flsl(x) generic_flsl(x)
+#define fls(x) generic_fls(x)
+#define ffs(x) ({ unsigned int t_ = (x); fls(t_ & -t_); })
+#define ffsl(x) ({ unsigned long t_ = (x); flsl(t_ & -t_); })
+
+/* Based on linux/include/asm-generic/bitops/ffz.h */
+/*
+ * ffz - find first zero in word.
+ * @word: The word to search
+ *
+ * Undefined if no zero exists, so code should check against ~0UL first.
+ */
+#define ffz(x) __ffs(~(x))
+
+/**
+ * hweightN - returns the hamming weight of a N-bit word
+ * @x: the word to weigh
+ *
+ * The Hamming Weight of a number is the total number of bits set in it.
+ */
+#define hweight64(x) __builtin_popcountll(x)
+#define hweight32(x) __builtin_popcount(x)
+#define hweight16(x) __builtin_popcount((uint16_t)(x))
+#define hweight8(x) __builtin_popcount((uint8_t)(x))
+
+/* Based on linux/include/asm-generic/bitops/builtin-__ffs.h */
+/**
+ * __ffs - find first bit in word.
+ * @word: The word to search
+ *
+ * Undefined if no bit exists, so code should check against 0 first.
+ */
+static always_inline unsigned long __ffs(unsigned long word)
+{
+ return __builtin_ctzl(word);
+}
+
+/**
+ * find_first_set_bit - find the first set bit in @word
+ * @word: the word to search
+ *
+ * Returns the bit-number of the first set bit (first bit being 0).
+ * The input must *not* be zero.
+ */
+#define find_first_set_bit(x) (ffsl(x) - 1)
+
+/*
+ * Find the first set bit in a memory region.
+ */
+static inline unsigned long find_first_bit(const unsigned long *addr,
+ unsigned long size)
+{
+ const unsigned long *p = addr;
+ unsigned long result = 0;
+ unsigned long tmp;
+
+ while ( size & ~(BITS_PER_LONG - 1) )
+ {
+ if ( (tmp = *(p++)) )
+ goto found;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if ( !size )
+ return result;
+
+ tmp = (*p) & (~0UL >> (BITS_PER_LONG - size));
+ if ( tmp == 0UL ) /* Are any bits set? */
+ return result + size; /* Nope. */
+ found:
+ return result + __ffs(tmp);
+}
+
+static inline unsigned long find_next_bit(const unsigned long *addr,
+ unsigned long size,
+ unsigned long offset)
+{
+ const unsigned long *p = addr + BITOP_WORD(offset);
+ unsigned long result = offset & ~(BITS_PER_LONG - 1);
+ unsigned long tmp;
+
+ if ( offset >= size )
+ return size;
+ size -= result;
+ offset %= BITS_PER_LONG;
+ if ( offset )
+ {
+ tmp = *(p++);
+ tmp &= (~0UL << offset);
+ if ( size < BITS_PER_LONG )
+ goto found_first;
+ if ( tmp )
+ goto found_middle;
+ size -= BITS_PER_LONG;
+ result += BITS_PER_LONG;
+ }
+ while ( size & ~(BITS_PER_LONG - 1) )
+ {
+ if ( (tmp = *(p++)) )
+ goto found_middle;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if ( !size )
+ return result;
+ tmp = *p;
+
+ found_first:
+ tmp &= (~0UL >> (BITS_PER_LONG - size));
+ if ( tmp == 0UL ) /* Are any bits set? */
+ return result + size; /* Nope. */
+ found_middle:
+ return result + __ffs(tmp);
+}
+
+/*
+ * This implementation of find_{first,next}_zero_bit was stolen from
+ * Linus' asm-alpha/bitops.h.
+ */
+static inline unsigned long find_next_zero_bit(const unsigned long *addr,
+ unsigned long size,
+ unsigned long offset)
+{
+ const unsigned long *p = addr + BITOP_WORD(offset);
+ unsigned long result = offset & ~(BITS_PER_LONG - 1);
+ unsigned long tmp;
+
+ if ( offset >= size )
+ return size;
+ size -= result;
+ offset %= BITS_PER_LONG;
+ if ( offset )
+ {
+ tmp = *(p++);
+ tmp |= ~0UL >> (BITS_PER_LONG - offset);
+ if ( size < BITS_PER_LONG )
+ goto found_first;
+ if ( ~tmp )
+ goto found_middle;
+ size -= BITS_PER_LONG;
+ result += BITS_PER_LONG;
+ }
+ while ( size & ~(BITS_PER_LONG - 1) )
+ {
+ if ( ~(tmp = *(p++)) )
+ goto found_middle;
+ result += BITS_PER_LONG;
+ size -= BITS_PER_LONG;
+ }
+ if ( !size )
+ return result;
+ tmp = *p;
+
+ found_first:
+ tmp |= ~0UL << size;
+ if ( tmp == ~0UL ) /* Are any bits zero? */
+ return result + size; /* Nope. */
+ found_middle:
+ return result + ffz(tmp);
+}
#endif /* _ASM_PPC_BITOPS_H */
--
2.30.2
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