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register. This step is necessary, otherwise, if the call to the function comes from another running module, X is the Got table address of the caller module , and no reinitialization of x is used to refer to global variables and functions, of course, an error. The two paragraphs mean that got is a mapping table, where the content is the address map of the external symbols that are referenced in this code, such as you used a printf function, where there is an assumption of 1000, just like this:

GOT GOT table and PLT PLT table in the program of the role is very large, the next explanation I hope you can take a closer look We use a very simple example to illustrate the following code:Figure 1 Then we compile We directly gdb./a.out gdb/a.out to perform the anti-compilation process, and then through Disasmain Disas Main, look at the anti-compilation code in main main function as follows: Figure

Android-based Elf Plt/got symbol redirection process and elf hook implementation--by Low-end code farm 2014.10.27 IntroductionThere are two main reasons for writing this technical article: One is to find that most of the articles on the Web describing the Plt/got symbol redirection process are aimed at x86, such as "redirecting functions in shared ELF libraries" is very well written. Although t

Reprint modified from http://blog.sina.com.cn/s/blog_70dd16910100r1gi.html first part process junction table PLT Because programs can use the same function multiple times in a shared library, it is useful to define all the functions with a single table. In order to use this method, a dedicated area is used in the compiler, which is called the Process junction table (PLT).The

PLT Scheme (plt-scheme.org) is a very influential scheme implementation, but in fact this name represents not only the scheme language, it should be a set of languages. Scheme's unique Program, namely, the idea of data, the programmable macro system, and the powerful module mechanism designed by PLT, make it an excellent language platform where various new langua

implemented in code to refer to each global variable indirectly through got, so that the simple data references in the code become complex and must be added to the instructions that got the appropriate contents of the table. The reference to read-only data is also based on the same principle, so adding the code compiled by the IC is much more expensive than the usual code. If an elf executable needs to invoke any function defined in a shared library, then it has its own got and

Reprint of the Wind flying articles, there is time to seriously study. Linux Dynamic Connection principle GOT PLT Table detailedAttention:The following connectors are used to refer to the LD,and the loader refers to the ld-linux.so;Each entry in the GOT (Global Offset table) table is the address of a global variable or function to be referenced by this run module. You can use the Got table to refer to global variables or functions indirectly, or you c

The got plt resembles the IAT (Import Address Table) in a Windows PE file.To make the code address irrelevant, the basic idea is to put the relevant parts of the address into the data section.The elf's approach is to create an array of pointers to these variables in the data segment, called Global offset table,got, which can be indirectly referenced by the corresponding item in the GOT when the code needs to reference the global variable.The got itsel

The role of the PLT is a springboard that preserves the offset of a symbol in the relocation table (used to find a symbol for the first time) and the corresponding address of the corresponding. Got.plt.. Rel.dyn saved the start address of the. Got segment, not proven. Rel.plt saved information for the relocation table. Got is said to be the offset of each symbol that holds the elf file itself, i.e., do not dynamically link, does not prove. GOT.PLT sav

Basic problem: the main reason why dynamic links are slower than static links is that global and static access and data access are complex under dynamic links.GotLocate and then conduct indirect addressing. There are also various dynamic relocation methods. 1>The basic idea of delayed binding: a function is bound only when it is used for the first time (symbol search, relocation, etc.). If it is not used, it is not bound. DetailsElfUsePLT. Actually used functions_ Dl_runtime_resolve () 2

The dynamic Link tool for the Android system is/system/bin/linker (the General Linux system is ld.so), although the names are different, but the basic dynamic linking process is similar. It is important to note that Linux is generally lazy, the so-called "lazy" loading mode, but the Android system is a bit different, the non-lazy way, that is, all the relocation operations, before the first execution of the process has been completed. This is probably one of the reasons why Android apps are slow

functions, and redirects the reference with independent locations to the absolute location. For the PIC code, there is no relocation item in the code segment, and the actual relocation item is only in the got table of the Data Segment. The relocation types in the shared target file include r_1__relative, r_1__glob_dat, and r_1__jmp_slot, it is used to relocate static data of pointer type, global variable symbol address, and global function symbol address when the dynamic linker loads the ing sh

Plt, got, pltgot I recently learned about linux advanced debugging technology. The following is an experiment on dynamic library connection. First, we understand that plt is procedure linkage table, and got is global offset table. The got table stores external symbol addresses. The plt table stores the function address. Next, let's take a look at the lab details.

80483cf:ff FC pushl-0x4 (%ECX) 80483d2:55 Push%ebp 80483d3:89 e5 mov%esp,%ebp 80483d5:51 Push%ecx 80483d6:83 EC $0x4,%esp Hello_world (); 80483d9:e8 d6 FF FF FF call 80483B4 return 0; 80483de:b8 xx xx $0x0,%eax}When calling Hello_world, the assembly code corresponds to the call 80483b4 When calling printf, the assembly code corresponds to the call 80482f0 080482f0 Now let's analyze it with a debugger:GDB test(GDB) B main breakpoint 1 at 0x80483d9:file test.c, line 12. (GDB

←itset Brief Introduction to the implementation of –with-abi and –with-arch in gcc → PLT Example ExplanationPosted on May, from admin by XMJ, Yao First, x86 ABI Handbook original and translation Original digest from System V application BINARY INTERFACE. Figure 5-7: Position-independent Procedure Linkage Table . PLT0:PUSHL 4 (%EBX) jmp *8 (%EBX) nop; NOP nop; NOP . PLT1:JMP *name1@got (%EBX) pushl $offset jmp. PLT0@

What is ASLR? Address Space layout randomization (ASLR) is a exploit mitigation technique that randomizes Stack address. Heap address. Shared Library address. #echo 2 >/proc/sys/kernel/randomize_va_spaceLIBC base address would get randomized.Note: Only libc base address was randomized, offset of a particular function from its base address always remains constant!! Hence If we can bypass shared library base address randomization, vulnerable programs can be successfull

__name__=="__main__": File= Input ("videos that need to be intercepted:") Start= Input ("start Time (HH:MM:SS):") End= Input ("End Time (HH:MM:SS):") Print(Cut (file, start, end))Output Result:This is the original video on the left, and this is the intercepted video on the right.4, Video pumping frameFrom the video, extract one picture at every 40 frames.ImportCv2defget_video_pic (name,zhen): Path= Name.rsplit (".", 1) [0] Cap=Cv2. Videocapture (name) forIinchRange (1,int (Cap.get (7) ), Zhe

"CorelDRAW Difficult diseases Quick Search Manual" collection of the author Mu Ping and your graphic design colleagues to discuss the questions raised and Baidu CD bar questions, the actual operation and work encountered in the collation of the problem. Some of these questions refer to the friends in the bar and the network of fellow human answers, for some unclear or questionable questions the authors have personally used CorelDRAW 9 and CorelDRAW X3 respectively verify the operability and auth

Platelet count (PLT)Platelet count refers to the number of platelets contained in blood per unit volume. Platelets are the smallest cell in the blood and can protect the integrity of the capillary. Normal Range (100 ~ 300) × 109/L check the platelet count, which refers to the number of platelets contained in blood per unit volume. Platelets are the smallest cell in the blood and can protect the integrity of the capillary. The Clinical Significance of

\VisualStudio2010\ez_ setup.py successful, the C:\Python27\Scripts\ directory will be more Easy_install.exe4. Use Easy_install.exe to install Dateutil and pyparsing。。 Anyway, according to the hint, what is missing is installed with Easy_install What, this easy_install is to follow the keyword to search the installation package. Easy_install python-dateutileasy_install pyparsingeasy_install pip 4-2, do not use Easy-install installed, just use Easy_ Install PIP and then use PIP to install WHL such