virt2phys.c File Reference

Mapping of virtual to physical memory. More...

#include <stdio.h>
#include <sys/stat.h>
#include <fcntl.h>
#include "virt2phys.h"

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Macros
#define	_LARGEFILE64_SOURCE
#define	BIT(i)   ((unsigned long long) 1 << i)
#define	FILENAME_SIZE   30
#define	PAGE_SHIFT   12
#define	PAGE_SIZE   (1<<PAGE_SHIFT)
#define	PAGE_MASK   (((unsigned long long)1<< PAGE_SHIFT) -1)
#define	PAGE_PRESENT   BIT(63)
#define	PAGE_SWAPPED   BIT(62)
#define	PAGE_PFN_MASK   (((unsigned long long)1<< 55) -1)

Functions
static int	open_pagemap (pid_t pid)
static int	virt2phys (int fd, unsigned long vaddr, unsigned long *paddr)
int	check_contiguity (unsigned long vaddr, pid_t pid, struct physmem *pmem, size_t size)

Detailed Description

Mapping of virtual to physical memory.

Source : See the linux kernel documentation at -> https://www.kernel.org/doc/Documentation/vm/pagemap.txt

The file /proc/pid/pagemap contains 8 bytes for each virtual PFN describing the page status. First we check the bits indicating if page is present and not swapped. Then we can get the physical PFN.

Contiguity check consist to verify of contiguous virtual memory correspond to present, not swapped and contiguous physical pages.

Definition in file virt2phys.c.

Macro Definition Documentation

_LARGEFILE64_SOURCE

#define _LARGEFILE64_SOURCE

Definition at line 37 of file virt2phys.c.

BIT

#define BIT

(

i

)

((unsigned long long) 1 << i)

Definition at line 44 of file virt2phys.c.

FILENAME_SIZE

#define FILENAME_SIZE   30

Definition at line 45 of file virt2phys.c.

PAGE_MASK

#define PAGE_MASK   (((unsigned long long)1<< PAGE_SHIFT) -1)

Definition at line 48 of file virt2phys.c.

PAGE_PFN_MASK

#define PAGE_PFN_MASK   (((unsigned long long)1<< 55) -1)

Definition at line 52 of file virt2phys.c.

PAGE_PRESENT

#define PAGE_PRESENT   BIT(63)

Definition at line 50 of file virt2phys.c.

PAGE_SHIFT

#define PAGE_SHIFT   12

Definition at line 46 of file virt2phys.c.

PAGE_SIZE

#define PAGE_SIZE   (1<<PAGE_SHIFT)

Definition at line 47 of file virt2phys.c.

PAGE_SWAPPED

#define PAGE_SWAPPED   BIT(62)

Definition at line 51 of file virt2phys.c.

Function Documentation

check_contiguity()

int check_contiguity	(	unsigned long	vaddr,
		pid_t	pid,
		struct physmem *	pmem,
		size_t	size
	)

Definition at line 111 of file virt2phys.c.

References fd, open_pagemap(), physmem::paddr, PAGE_MASK, PAGE_SIZE, physmem::size, and virt2phys().

Referenced by v4l2_init().

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open_pagemap()

static int open_pagemap ( pid_t  pid )

static

Definition at line 59 of file virt2phys.c.

References FILENAME_SIZE.

Referenced by check_contiguity().

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virt2phys()

static int virt2phys ( int  fd, unsigned long  vaddr, unsigned long *  paddr  )

static

Definition at line 78 of file virt2phys.c.

References fd, PAGE_MASK, PAGE_PFN_MASK, PAGE_PRESENT, PAGE_SHIFT, and PAGE_SWAPPED.

Referenced by check_contiguity().

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