xref: /kernel/linux/linux-6.6/arch/powerpc/include/asm/bitops.h

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * PowerPC atomic bit operations.
 *
 * Merged version by David Gibson <david@gibson.dropbear.id.au>.
 * 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.
 *
 * Within a word, bits are numbered LSB first.  Lot's of places make
 * this assumption by directly testing bits with (val & (1<<nr)).
 * This can cause confusion for large (> 1 word) bitmaps on a
 * big-endian system because, unlike little endian, the number of each
 * bit depends on the word size.
 *
 * The bitop functions are defined to work on unsigned longs, so for a
 * ppc64 system the bits end up numbered:
 *   |63..............0|127............64|191...........128|255...........192|
 * and on ppc32:
 *   |31.....0|63....32|95....64|127...96|159..128|191..160|223..192|255..224|
 *
 * There are a few little-endian macros used mostly for filesystem
 * bitmaps, these work on similar bit arrays layouts, but
 * byte-oriented:
 *   |7...0|15...8|23...16|31...24|39...32|47...40|55...48|63...56|
 *
 * The main difference is that bit 3-5 (64b) or 3-4 (32b) in the bit
 * number field needs to be reversed compared to the big-endian bit
 * fields. This can be achieved by XOR with 0x38 (64b) or 0x18 (32b).
 */

#ifndef _ASM_POWERPC_BITOPS_H
#define _ASM_POWERPC_BITOPS_H

#ifdef __KERNEL__

#ifndef _LINUX_BITOPS_H
#error only <linux/bitops.h> can be included directly
#endif

#include <linux/compiler.h>
#include <asm/asm-compat.h>
#include <asm/synch.h>

/* 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))

/* Put a PPC bit into a "normal" bit position */
#define PPC_BITEXTRACT(bits, ppc_bit, dst_bit)			\
	((((bits) >> PPC_BITLSHIFT(ppc_bit)) & 1) << (dst_bit))

#define PPC_BITLSHIFT32(be)	(32 - 1 - (be))
#define PPC_BIT32(bit)		(1UL << PPC_BITLSHIFT32(bit))
#define PPC_BITMASK32(bs, be)	((PPC_BIT32(bs) - PPC_BIT32(be))|PPC_BIT32(bs))

#define PPC_BITLSHIFT8(be)	(8 - 1 - (be))
#define PPC_BIT8(bit)		(1UL << PPC_BITLSHIFT8(bit))
#define PPC_BITMASK8(bs, be)	((PPC_BIT8(bs) - PPC_BIT8(be))|PPC_BIT8(bs))

#include <asm/barrier.h>

/* Macro for generating the ***_bits() functions */
#define DEFINE_BITOP(fn, op, prefix)		\
static inline void fn(unsigned long mask,	\
		volatile unsigned long *_p)	\
{						\
	unsigned long old;			\
	unsigned long *p = (unsigned long *)_p;	\
	__asm__ __volatile__ (			\
	prefix					\
"1:"	PPC_LLARX "%0,0,%3,0\n"			\
	#op "%I2 %0,%0,%2\n"			\
	PPC_STLCX "%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, "")

static __always_inline bool is_rlwinm_mask_valid(unsigned long x)
{
	if (!x)
		return false;
	if (x & 1)
		x = ~x;	// make the mask non-wrapping
	x += x & -x;	// adding the low set bit results in at most one bit set

	return !(x & (x - 1));
}

#define DEFINE_CLROP(fn, prefix)					\
static inline void fn(unsigned long mask, volatile unsigned long *_p)	\
{									\
	unsigned long old;						\
	unsigned long *p = (unsigned long *)_p;				\
									\
	if (IS_ENABLED(CONFIG_PPC32) &&					\
	    __builtin_constant_p(mask) && is_rlwinm_mask_valid(~mask)) {\
		asm volatile (						\
			prefix						\
		"1:"	"lwarx	%0,0,%3\n"				\
			"rlwinm	%0,%0,0,%2\n"				\
			"stwcx.	%0,0,%3\n"				\
			"bne- 1b\n"					\
			: "=&r" (old), "+m" (*p)			\
			: "n" (~mask), "r" (p)				\
			: "cc", "memory");				\
	} else {							\
		asm volatile (						\
			prefix						\
		"1:"	PPC_LLARX "%0,0,%3,0\n"				\
			"andc %0,%0,%2\n"				\
			PPC_STLCX "%0,0,%3\n"				\
			"bne- 1b\n"					\
			: "=&r" (old), "+m" (*p)			\
			: "r" (mask), "r" (p)				\
			: "cc", "memory");				\
	}								\
}

DEFINE_CLROP(clear_bits, "")
DEFINE_CLROP(clear_bits_unlock, PPC_RELEASE_BARRIER)

static inline void arch_set_bit(int nr, volatile unsigned long *addr)
{
	set_bits(BIT_MASK(nr), addr + BIT_WORD(nr));
}

static inline void arch_clear_bit(int nr, volatile unsigned long *addr)
{
	clear_bits(BIT_MASK(nr), addr + BIT_WORD(nr));
}

static inline void arch_clear_bit_unlock(int nr, volatile unsigned long *addr)
{
	clear_bits_unlock(BIT_MASK(nr), addr + BIT_WORD(nr));
}

static inline void arch_change_bit(int nr, volatile unsigned long *addr)
{
	change_bits(BIT_MASK(nr), addr + BIT_WORD(nr));
}

/* Like DEFINE_BITOP(), with changes to the arguments to 'op' and the output
 * operands. */
#define DEFINE_TESTOP(fn, op, prefix, postfix, eh)	\
static inline unsigned long fn(			\
		unsigned long mask,			\
		volatile unsigned long *_p)		\
{							\
	unsigned long old, t;				\
	unsigned long *p = (unsigned long *)_p;		\
	__asm__ __volatile__ (				\
	prefix						\
"1:"	PPC_LLARX "%0,0,%3,%4\n"			\
	#op "%I2 %1,%0,%2\n"				\
	PPC_STLCX "%1,0,%3\n"				\
	"bne- 1b\n"					\
	postfix						\
	: "=&r" (old), "=&r" (t)			\
	: "rK" (mask), "r" (p), "n" (eh)		\
	: "cc", "memory");				\
	return (old & mask);				\
}

DEFINE_TESTOP(test_and_set_bits, or, PPC_ATOMIC_ENTRY_BARRIER,
	      PPC_ATOMIC_EXIT_BARRIER, 0)
DEFINE_TESTOP(test_and_set_bits_lock, or, "",
	      PPC_ACQUIRE_BARRIER, IS_ENABLED(CONFIG_PPC64))
DEFINE_TESTOP(test_and_change_bits, xor, PPC_ATOMIC_ENTRY_BARRIER,
	      PPC_ATOMIC_EXIT_BARRIER, 0)

static inline unsigned long test_and_clear_bits(unsigned long mask, volatile unsigned long *_p)
{
	unsigned long old, t;
	unsigned long *p = (unsigned long *)_p;

	if (IS_ENABLED(CONFIG_PPC32) &&
	    __builtin_constant_p(mask) && is_rlwinm_mask_valid(~mask)) {
		asm volatile (
			PPC_ATOMIC_ENTRY_BARRIER
		"1:"	"lwarx %0,0,%3\n"
			"rlwinm	%1,%0,0,%2\n"
			"stwcx. %1,0,%3\n"
			"bne- 1b\n"
			PPC_ATOMIC_EXIT_BARRIER
			: "=&r" (old), "=&r" (t)
			: "n" (~mask), "r" (p)
			: "cc", "memory");
	} else {
		asm volatile (
			PPC_ATOMIC_ENTRY_BARRIER
		"1:"	PPC_LLARX "%0,0,%3,0\n"
			"andc	%1,%0,%2\n"
			PPC_STLCX "%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 arch_test_and_set_bit(unsigned long nr,
					volatile unsigned long *addr)
{
	return test_and_set_bits(BIT_MASK(nr), addr + BIT_WORD(nr)) != 0;
}

static inline int arch_test_and_set_bit_lock(unsigned long nr,
					     volatile unsigned long *addr)
{
	return test_and_set_bits_lock(BIT_MASK(nr),
				addr + BIT_WORD(nr)) != 0;
}

static inline int arch_test_and_clear_bit(unsigned long nr,
					  volatile unsigned long *addr)
{
	return test_and_clear_bits(BIT_MASK(nr), addr + BIT_WORD(nr)) != 0;
}

static inline int arch_test_and_change_bit(unsigned long nr,
					   volatile unsigned long *addr)
{
	return test_and_change_bits(BIT_MASK(nr), addr + BIT_WORD(nr)) != 0;
}

#ifdef CONFIG_PPC64
static inline unsigned long
clear_bit_unlock_return_word(int nr, volatile unsigned long *addr)
{
	unsigned long old, t;
	unsigned long *p = (unsigned long *)addr + BIT_WORD(nr);
	unsigned long mask = BIT_MASK(nr);

	__asm__ __volatile__ (
	PPC_RELEASE_BARRIER
"1:"	PPC_LLARX "%0,0,%3,0\n"
	"andc %1,%0,%2\n"
	PPC_STLCX "%1,0,%3\n"
	"bne- 1b\n"
	: "=&r" (old), "=&r" (t)
	: "r" (mask), "r" (p)
	: "cc", "memory");

	return old;
}

/*
 * This is a special function for mm/filemap.c
 * Bit 7 corresponds to PG_waiters.
 */
#define arch_clear_bit_unlock_is_negative_byte(nr, addr)		\
	(clear_bit_unlock_return_word(nr, addr) & BIT_MASK(7))

#endif /* CONFIG_PPC64 */

#include <asm-generic/bitops/non-atomic.h>

static inline void arch___clear_bit_unlock(int nr, volatile unsigned long *addr)
{
	__asm__ __volatile__(PPC_RELEASE_BARRIER "" ::: "memory");
	__clear_bit(nr, addr);
}

/*
 * Return the zero-based bit position (LE, not IBM bit numbering) of
 * the most significant 1-bit in a double word.
 */
#define __ilog2(x)	ilog2(x)

#include <asm-generic/bitops/ffz.h>

#include <asm-generic/bitops/builtin-__ffs.h>

#include <asm-generic/bitops/builtin-ffs.h>

/*
 * fls: find last (most-significant) bit set.
 * Note fls(0) = 0, fls(1) = 1, fls(0x80000000) = 32.
 */
static __always_inline int fls(unsigned int x)
{
	int lz;

	if (__builtin_constant_p(x))
		return x ? 32 - __builtin_clz(x) : 0;
	asm("cntlzw %0,%1" : "=r" (lz) : "r" (x));
	return 32 - lz;
}

#include <asm-generic/bitops/builtin-__fls.h>

/*
 * 64-bit can do this using one cntlzd (count leading zeroes doubleword)
 * instruction; for 32-bit we use the generic version, which does two
 * 32-bit fls calls.
 */
#ifdef CONFIG_PPC64
static __always_inline int fls64(__u64 x)
{
	int lz;

	if (__builtin_constant_p(x))
		return x ? 64 - __builtin_clzll(x) : 0;
	asm("cntlzd %0,%1" : "=r" (lz) : "r" (x));
	return 64 - lz;
}
#else
#include <asm-generic/bitops/fls64.h>
#endif

#ifdef CONFIG_PPC64
unsigned int __arch_hweight8(unsigned int w);
unsigned int __arch_hweight16(unsigned int w);
unsigned int __arch_hweight32(unsigned int w);
unsigned long __arch_hweight64(__u64 w);
#include <asm-generic/bitops/const_hweight.h>
#else
#include <asm-generic/bitops/hweight.h>
#endif

/* wrappers that deal with KASAN instrumentation */
#include <asm-generic/bitops/instrumented-atomic.h>
#include <asm-generic/bitops/instrumented-lock.h>

/* Little-endian versions */
#include <asm-generic/bitops/le.h>

/* Bitmap functions for the ext2 filesystem */

#include <asm-generic/bitops/ext2-atomic-setbit.h>

#include <asm-generic/bitops/sched.h>

#endif /* __KERNEL__ */

#endif /* _ASM_POWERPC_BITOPS_H */