Skip to main content

Browse the archive

https://github.com/torvalds/linux
05 April 2024, 19:05:47 UTC
Revision 925cf0457d7e62ce08878ffb789189ac08ca8677 authored by Linus Torvalds on 19 February 2023, 01:57:16 UTC, committed by Linus Torvalds on 19 February 2023, 01:57:16 UTC 
Merge tag 'x86-urgent-2023-02-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
 
Pull x86 fix from Thomas Gleixner:
 "A single fix for x86.

  Revert the recent change to the MTRR code which aimed to support
  SEV-SNP guests on Hyper-V. It caused a regression on XEN Dom0 kernels.

  The underlying issue of MTTR (mis)handling in the x86 code needs some
  deeper investigation and is definitely not 6.2 material"

* tag 'x86-urgent-2023-02-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/mtrr: Revert 90b926e68f50 ("x86/pat: Fix pat_x_mtrr_type() for MTRR disabled case")
2 parent s 0097c18 + f9f57da
Raw File
Tip revision: 925cf0457d7e62ce08878ffb789189ac08ca8677 authored by Linus Torvalds on 19 February 2023, 01:57:16 UTC
Merge tag 'x86-urgent-2023-02-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Tip revision: 925cf04
memweight.c 
// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/bitmap.h>

/**
 * memweight - count the total number of bits set in memory area
 * @ptr: pointer to the start of the area
 * @bytes: the size of the area
 */
size_t memweight(const void *ptr, size_t bytes)
{
	size_t ret = 0;
	size_t longs;
	const unsigned char *bitmap = ptr;

	for (; bytes > 0 && ((unsigned long)bitmap) % sizeof(long);
			bytes--, bitmap++)
		ret += hweight8(*bitmap);

	longs = bytes / sizeof(long);
	if (longs) {
		BUG_ON(longs >= INT_MAX / BITS_PER_LONG);
		ret += bitmap_weight((unsigned long *)bitmap,
				longs * BITS_PER_LONG);
		bytes -= longs * sizeof(long);
		bitmap += longs * sizeof(long);
	}
	/*
	 * The reason that this last loop is distinct from the preceding
	 * bitmap_weight() call is to compute 1-bits in the last region smaller
	 * than sizeof(long) properly on big-endian systems.
	 */
	for (; bytes > 0; bytes--, bitmap++)
		ret += hweight8(*bitmap);

	return ret;
}
EXPORT_SYMBOL(memweight);
back to top