mmap

The/dev/mem driver provided in the Linux kernel provides a channel for us to read and write memory physical addresses. Here are 2 ways to read and write physical addresses using MEM device files, one for device-driven and the other for system calls. First we look at the mem this device file,/dev/mem is a character device under Linux, the source file is ~/DRIVERS/CHAR/MEM.C, this device file is specifically used to read and write physical address. The contents are the address of all physical memo

php.ini join:extension=== = 100M// above parameters can be defined by themselvesStep three: Check if PHP APC apc_store Apc_fetch is supportedSee if there are APC related items in the PhpinfoInstalling APC under B.liunxFirst step: Download and installwget http://pecl.php.net/get/apc-3.1.8.tgztar-zxvf apc-3.1. 8. tgz CD apc-3.1. 8/usr/local/php/bin/phpize. /configure--ENABLE-APC--enable-mmap--enable-apc-spinlocks--disable-apc-pthreadmutex--with-php-con

. Perform a tracing test on the above program: $ strace./A. Out Execve ("./A. Out", ["./A. Out"], [/* 50 vars */]) = 0 BRK (0) = 0x1033000 Access ("/etc/lD. So. nohwcap", f_ OK) =-1 enoent (no such file or directory) MMAP (null, 8192, prot_read | prot_write, map_private | map_anonymous,-1, 0) = 0x7f64fa550000 Access ("/etc/lD. So. preload", r_ OK) =-1 enoent (no such file or directory) Open ("/etc/lD. So. cache", o_rdonly | o_cloexec) = 3 Fstat (3, {s

. As shown below, an empty process consumes approximately 1.4MB of memory.adb shell Dumpsys meminfo com.example.android.apis:empty** meminfo in PID 10172 [com.example.android.apis:empty] * * PSS PSS shared private Shared private heap heap total clean Dirty Dirty Clean clean Size Alloc free------------------------------------------------------ Native Heap 0 0 0 0 0 0 1864 1800 Dalvik heap 764 0 5228 3 0 0 5584 5499 Dalvik other 619 0 3784 448 0 0 Stack 28 0 8 0 0 other dev 4 0 0 0

, performance Loss. Second, the cache for receiving data should be provided by the receiver, but the receiver does not know how much cache is required, you can only open up as much space as possible or call the API to receive the message header to obtain the message body size, and then open up an appropriate space to receive the message body. Both methods are insufficient, either a waste of space or time. The Binder adopts a new policy: the Binder driver is responsible for managing the data rece

0 0 0 0 0 0 7800 7637(6) 126 Dalvik Heap 5110(3) 0 4136 4988(3) 0 0 9168 8958(6) 210 Dalvik Other 2850 0 2684 2772 0 0 Stack 36 0 8 36 0 0 Cursor 136 0 0 136 0 0 Ashmem 12 0 28 0 0 0 Other dev 380 0 24 376 0 4 .so

OverviewWe usually call code injection, the main static and dynamic two ways:Static injection, for executable files, such as modify Elf,dex files, and other related tools are also many, such as Ida, Apktool and so on;Dynamic injection, can also be called process injection, for the process, such as modifying the process register, memory value, etc.;The biggest difference between dynamic and static is that dynamic does not need to change the source files, but requires high permissions (usually roo

Article title: advanced return library function Exploit code implementation (bottom ). Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source. 　　 9 attachment: README. code Prepare defective programs for compilation. $ Gcc-o vuln. omit-fomit-frame-pointer vuln. c $ Gcc-o vuln. c $ Gcc-o pax. c Ex-move.c ~~~~~~~~~~~~ The front part of the ex-move.c code predefines som

third-party storage engine vendors to join MongoDB, a change that undoubtedly references MySQL's design philosophy. At present, in addition to the early Mmap storage engine, Wiredtiger and ROCKSDB have completed the support for MongoDB, the former is the acquisition of MongoDB company is directly introduced into the MONGODB 3.0 version. The introduction of the plug-in storage engine API has made it possible for MongoDB to enrich its arsenal to handle

first character is-, no matching will be cached. -Is the default value, so it can be omitted. Apc. mmap_file_mask stringIf compiled with MMAP support by using -- enable-mmap this is the mktemp-style file_mask to pass to the mmap module for determing whether your mmap 'ed memory region is going to be file-backed or sha

. After the problem is reproduced, it is found that the statistical results of the global memory pool are as expected. Therefore, it is suspected that the operation is performed by the operating system or glibc. The memory management mechanism of glibc in Linux is roughly as follows: From the operating system perspective, the memory allocation of processes is completed by two system calls: BRK and MMAP. BRK is the highest address pointer _ edata to th

cached images, that is, the number of images in the cache queue.Enum v4l2_buf_type; // data stream type, which must always be v4l2_buf_type_video_captureEnum v4l2_memory memory; // v4l2_memory_mmap or v4l2_memory_userptr_ U32 reserved [2];}; 7. obtain and record the cached physical space With vidioc_reqbufs, we get req. count caches. Next, call the vidioc_querybuf command to obtain the cached addresses. Then, use the MMAP function to convert them to

Introduction to the MMAP function:The MMAP function is a system call under Unix/linux, to see the description of mmap in "Unix Netword Programming" Volume II 12.2:The MMAP function maps either a file or a Posix shared memory object into the address space of a process. We use the This function for three purposes:1. With

Linux Environment interprocess Communication (V): Shared memory (bottom)In the shared memory (above), mainly around the system call Mmap () for discussion, this section will discuss the System V shared memory, and through the comparison of experimental results to illustrate the similarities and differences. System V shared memory refers to the sharing of all shared data in the shared memory region (IPC), and any process that wants to access that data

addresses to user space1. Memory Mapping and VMAin general, user space is not possible and should not directly access the device, however, the device driver can be implemented The mmap () function, which allows the user space to access the physical address of the device directly. In fact, Mmap () implements A mapping process that associates a piece of memory in a user's space with device memory, which in f

#define-defined constants) data Segments : Saving global variables, static variables space Heap: Is usually said dynamic memory, malloc/new most of them from this. The position of the heap top can be dynamically adjusted by function BRK and SBRK. file Map areas : such as Dynamic Library, shared memory , such as mapping physical space memory, is generally the mmap function of the virtual address space allocated . Stacks: The context space used to

window;struct Video_channel channel[8];struct video_picture picture;struct Video_mmap mmap;struct VIDEO_MBUF mbuf;unsigned char *map;};typedef struct _V4L_STRUCT V4l_device;extern int V4l_open (char *, v4l_device *);extern int V4l_close (V4l_device *);extern int v4l_get_capability (V4l_device *);extern int V4l_set_norm (v4l_device *, int);extern int V4l_get_picture (V4l_device *);extern int V4l_grab_init (v4l_device *, int, int);extern int V4l_grab_f

as the following command error:mov[addr],raxYou need to force the Declaration as a 64-bit address or instead use a relative address:mov[qword addr],rax ;okmov[rel addr],rax ;oktooHowever, there is no such restriction under linux64.6 MAC64 and linux64 are different from the C library wrapper of the system call, especially when the return value of the system call is processed, such as Mmap call, linux64 C library does not seem to check the para

necessarily the same as the hardware paging size. return value The paging size of the memory. Additional instructions on Intel x86 the return value should be 4096bytes. Example #include Main (){printf ("Page size =%d\n", getpagesize ());} malloc (Configure memory space) Related functions Calloc,free,realloc,brk Table header File #include Defining functions void * ma

What's an APC?Alternative PHP cache (APC) is a valid open source Cache tool for PHP, and he is able to cache opcode PHP intermediate code.PHP APC provides two kinds of caching functions, namely cache opcode (target file), we call it apc_compiler_cache. It also provides interfaces for PHP developers to host user data in memory, which we call Apc_user_cache. We are here mainly to control the configuration of PHP-APC.Installing the PHP APCAs a test environment, we use CentOS5.3 (2.6.18-128.EL5PAE)