diff mbox series

[v2,21/39] xen/riscv: introduce bit operations

Message ID 20732007fb103115c0e01cefea7d113b8a7ad8e9.1700761381.git.oleksii.kurochko@gmail.com (mailing list archive)
State Superseded
Headers show
Series Enable build of full Xen for RISC-V | expand

Commit Message

Oleksii K. Nov. 24, 2023, 10:30 a.m. UTC 
Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
---
Changes in V2:
 - Nothing changed. Only rebase.
---
 xen/arch/riscv/Makefile            |   1 +
 xen/arch/riscv/lib/Makefile        |   1 +
 xen/arch/riscv/lib/find_next_bit.c | 278 +++++++++++++++++++++++++++++
 3 files changed, 280 insertions(+)
 create mode 100644 xen/arch/riscv/lib/Makefile
 create mode 100644 xen/arch/riscv/lib/find_next_bit.c

Comments

Jan Beulich Dec. 14, 2023, 1:27 p.m. UTC | #1 
On 24.11.2023 11:30, Oleksii Kurochko wrote:
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>

Did you write this code from scratch? If not, you need to at least point
out the origin. But: None of this looks RISC-V specific, so shouldn't it
instead be put under xen/lib/, as a fallback implementation for arch-es
not having optimized implementations? Looks also at least very similar
to Arm64's, so that one perhaps then will want dropping as well? We
surely don't want to carry two (almost) identical copies of the same
logic.

> --- /dev/null
> +++ b/xen/arch/riscv/lib/Makefile
> @@ -0,0 +1 @@
> +obj-y += find_next_bit.o

Dashes instead of underscores please in new file's names, whenever
possible.

Jan
Oleksii K. Dec. 18, 2023, 9:56 a.m. UTC | #2 
On Thu, 2023-12-14 at 14:27 +0100, Jan Beulich wrote:
> On 24.11.2023 11:30, Oleksii Kurochko wrote:
> > Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
> 
> Did you write this code from scratch? If not, you need to at least
> point
> out the origin. But: None of this looks RISC-V specific, so shouldn't
> it
> instead be put under xen/lib/, as a fallback implementation for arch-
> es
> not having optimized implementations? Looks also at least very
> similar
> to Arm64's, so that one perhaps then will want dropping as well? We
> surely don't want to carry two (almost) identical copies of the same
> logic.
No, I took the code from Arm because as you mentioned it doesn't have
RISC-V specific things.

I think we can move it to xen/lib. Would it be better to as part of
this patch series?

> 
> > --- /dev/null
> > +++ b/xen/arch/riscv/lib/Makefile
> > @@ -0,0 +1 @@
> > +obj-y += find_next_bit.o
> 
> Dashes instead of underscores please in new file's names, whenever
> possible.
Sure. I'll update that. Thanks.

~ Oleksii
Jan Beulich Dec. 18, 2023, 10:06 a.m. UTC | #3 
On 18.12.2023 10:56, Oleksii wrote:
> On Thu, 2023-12-14 at 14:27 +0100, Jan Beulich wrote:
>> On 24.11.2023 11:30, Oleksii Kurochko wrote:
>>> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@gmail.com>
>>
>> Did you write this code from scratch? If not, you need to at least
>> point
>> out the origin. But: None of this looks RISC-V specific, so shouldn't
>> it
>> instead be put under xen/lib/, as a fallback implementation for arch-
>> es
>> not having optimized implementations? Looks also at least very
>> similar
>> to Arm64's, so that one perhaps then will want dropping as well? We
>> surely don't want to carry two (almost) identical copies of the same
>> logic.
> No, I took the code from Arm because as you mentioned it doesn't have
> RISC-V specific things.
> 
> I think we can move it to xen/lib. Would it be better to as part of
> this patch series?

Doesn't matter much whether it's separate or part of this series, I'd say.

Jan
diff mbox series

Patch

diff --git a/xen/arch/riscv/Makefile b/xen/arch/riscv/Makefile
index 2fefe14e7c..b08048948f 100644
--- a/xen/arch/riscv/Makefile
+++ b/xen/arch/riscv/Makefile
@@ -1,5 +1,6 @@ 
 obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
 obj-y += entry.o
+obj-y += lib/
 obj-y += mm.o
 obj-$(CONFIG_RISCV_64) += riscv64/
 obj-y += sbi.o
diff --git a/xen/arch/riscv/lib/Makefile b/xen/arch/riscv/lib/Makefile
new file mode 100644
index 0000000000..6fae6a1f10
--- /dev/null
+++ b/xen/arch/riscv/lib/Makefile
@@ -0,0 +1 @@ 
+obj-y += find_next_bit.o
diff --git a/xen/arch/riscv/lib/find_next_bit.c b/xen/arch/riscv/lib/find_next_bit.c
new file mode 100644
index 0000000000..ac5a4687e3
--- /dev/null
+++ b/xen/arch/riscv/lib/find_next_bit.c
@@ -0,0 +1,278 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * find_next_bit.c: fallback find next bit implementation
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+#include <xen/bitops.h>
+#include <asm/types.h>
+#include <asm/byteorder.h>
+
+#ifndef find_next_bit
+/*
+ * Find the next set bit in a memory region.
+ */
+unsigned long find_next_bit(const unsigned long *addr, unsigned long size,
+			    unsigned long offset)
+{
+	const unsigned long *p = addr + BIT_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);
+}
+EXPORT_SYMBOL(find_next_bit);
+#endif
+
+#ifndef find_next_zero_bit
+/*
+ * This implementation of find_{first,next}_zero_bit was stolen from
+ * Linus' asm-alpha/bitops.h.
+ */
+unsigned long find_next_zero_bit(const unsigned long *addr, unsigned long size,
+				 unsigned long offset)
+{
+	const unsigned long *p = addr + BIT_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);
+}
+EXPORT_SYMBOL(find_next_zero_bit);
+#endif
+
+#ifndef find_first_bit
+/*
+ * Find the first set bit in a memory region.
+ */
+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);
+}
+EXPORT_SYMBOL(find_first_bit);
+#endif
+
+#ifndef find_first_zero_bit
+/*
+ * Find the first cleared bit in a memory region.
+ */
+unsigned long find_first_zero_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 << size);
+	if (tmp == ~0UL)	/* Are any bits zero? */
+		return result + size;	/* Nope. */
+found:
+	return result + ffz(tmp);
+}
+EXPORT_SYMBOL(find_first_zero_bit);
+#endif
+
+#ifdef __BIG_ENDIAN
+
+/* include/linux/byteorder does not support "unsigned long" type */
+static inline unsigned long ext2_swabp(const unsigned long * x)
+{
+#if BITS_PER_LONG == 64
+	return (unsigned long) __swab64p((u64 *) x);
+#elif BITS_PER_LONG == 32
+	return (unsigned long) __swab32p((u32 *) x);
+#else
+#error BITS_PER_LONG not defined
+#endif
+}
+
+/* include/linux/byteorder doesn't support "unsigned long" type */
+static inline unsigned long ext2_swab(const unsigned long y)
+{
+#if BITS_PER_LONG == 64
+	return (unsigned long) __swab64((u64) y);
+#elif BITS_PER_LONG == 32
+	return (unsigned long) __swab32((u32) y);
+#else
+#error BITS_PER_LONG not defined
+#endif
+}
+
+#ifndef find_next_zero_bit_le
+unsigned long find_next_zero_bit_le(const void *addr, unsigned
+		long size, unsigned long offset)
+{
+	const unsigned long *p = addr;
+	unsigned long result = offset & ~(BITS_PER_LONG - 1);
+	unsigned long tmp;
+
+	if (offset >= size)
+		return size;
+	p += BIT_WORD(offset);
+	size -= result;
+	offset &= (BITS_PER_LONG - 1UL);
+	if (offset) {
+		tmp = ext2_swabp(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_swap;
+		result += BITS_PER_LONG;
+		size -= BITS_PER_LONG;
+	}
+	if (!size)
+		return result;
+	tmp = ext2_swabp(p);
+found_first:
+	tmp |= ~0UL << size;
+	if (tmp == ~0UL)	/* Are any bits zero? */
+		return result + size; /* Nope. Skip ffz */
+found_middle:
+	return result + ffz(tmp);
+
+found_middle_swap:
+	return result + ffz(ext2_swab(tmp));
+}
+EXPORT_SYMBOL(find_next_zero_bit_le);
+#endif
+
+#ifndef find_next_bit_le
+unsigned long find_next_bit_le(const void *addr, unsigned
+		long size, unsigned long offset)
+{
+	const unsigned long *p = addr;
+	unsigned long result = offset & ~(BITS_PER_LONG - 1);
+	unsigned long tmp;
+
+	if (offset >= size)
+		return size;
+	p += BIT_WORD(offset);
+	size -= result;
+	offset &= (BITS_PER_LONG - 1UL);
+	if (offset) {
+		tmp = ext2_swabp(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)) {
+		tmp = *(p++);
+		if (tmp)
+			goto found_middle_swap;
+		result += BITS_PER_LONG;
+		size -= BITS_PER_LONG;
+	}
+	if (!size)
+		return result;
+	tmp = ext2_swabp(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);
+
+found_middle_swap:
+	return result + __ffs(ext2_swab(tmp));
+}
+EXPORT_SYMBOL(find_next_bit_le);
+#endif
+
+#endif /* __BIG_ENDIAN */