linux-support 0.0.25

Comprehensive Linux support for namespaces, cgroups, processes, scheduling, parsing /proc, parsing /sys, signals, hyper threads, CPUS, NUMA nodes, unusual file descriptors, PCI devices and much, much more
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// This file is part of linux-support. It is subject to the license terms in the COPYRIGHT file found in the top-level directory of this distribution and at https://raw.githubusercontent.com/lemonrock/linux-support/master/COPYRIGHT. No part of linux-support, including this file, may be copied, modified, propagated, or distributed except according to the terms contained in the COPYRIGHT file.
// Copyright © 2020 The developers of linux-support. See the COPYRIGHT file in the top-level directory of this distribution and at https://raw.githubusercontent.com/lemonrock/linux-support/master/COPYRIGHT.


/// Bits 57-60 (zero-based) should be set to zero and currently do not have any meaning.
#[derive(Default, Debug, Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash)]
pub struct PageMapEntry(u64);

impl PageMapEntry
{
	/// Physical Page Frame Number (PFN).
	///
	/// May be zero if an user lacks the capability `CAP_SYS_ADMIN`.
	///
	/// This data is not valid if the page can be swapped out; to prevent that, lock the page using `mlock()`.
	/// (If swapped, the bottom 5 bits are the swap type and the bits 5 (zero-based, ie this is the 6th bit) to 54 inclusive are the swap offset; we panic if this is the case in debug).
	///
	/// The top 9 bits are unset (ie always zero).
	#[inline(always)]
	pub fn physical_page_frame_number(self) -> PhysicalPageFrameNumber
	{
		debug_assert!(!self.is_swapped(), "page is swapped");
		
		PhysicalPageFrameNumber(self.0 & 0x7FFFFFFFFFFFFF)
	}
	
	/// Page is swapped.
	///
	/// Bit 62 (zero-based).
	#[inline(always)]
	pub fn is_swapped(self) -> bool
	{
		self.0 & 0x4000000000000000 != 0
	}
	
	/// Page is present.
	///
	/// Bit 63 (zero-based).
	#[inline(always)]
	pub fn is_present(self) -> bool
	{
		self.0 & 0x8000000000000000 != 0
	}
	
	/// Page is exclusively mapped.
	///
	/// Introduced in Linux 4.2.
	///
	/// Bit 56 (zero-based).
	#[inline(always)]
	pub fn is_exclusively_mapped(self) -> bool
	{
		self.0 & 0x100000000000000 != 0
	}
	
	/// Page is exclusively mapped.
	///
	/// Introduced in Linux 3.5.
	///
	/// Bit 61 (zero-based).
	#[inline(always)]
	pub fn is_file_page_or_shared_anonymous(self) -> bool
	{
		self.0 & 0x2000000000000000 != 0
	}
	
	/// Page Table Entry (PTE) is 'soft dirty'.
	///
	/// For more information, see the Linux documentation at `Documentation/vm/soft-dirty.txt`.
	///
	/// Bit 55 (zero-based).
	#[inline(always)]
	pub fn page_table_entry_is_soft_dirty(self) -> bool
	{
		self.0 & 0x80000000000000 != 0
	}
	
	#[inline(always)]
	fn read_from_pagemap_file(file: &mut File, virtual_address: VirtualAddress) -> io::Result<Self>
	{
		let virtual_page_frame_number: VirtualPageFrameNumber = virtual_address.into();
		
		file.seek(virtual_page_frame_number.into())?;

		let mut buffer: [u8; 8] = unsafe_uninitialized();
		file.read_exact(&mut buffer)?;
		
		Ok(PageMapEntry(u64::from_ne_bytes(buffer)))
	}
}