x86-64

问题 How fortunate it is for all of use learning the art of computer programming to have access to a community such as Stack Overflow! I have made the decision to take up the task of learning how to program computers and I am doing so by the knowledge of an e-book called 'Programming From the Ground Up', which teaches the reader how to create programs in the assembly language within the GNU/Linux environment. My progress in the book has come to the point of creating a program which computes the

问题 I am trying to install a Ubuntu container on Archlinux using LXC. I am following this guide:https://gist.github.com/manoj23/8a35849697945896cdaef77927c695a7 After I run this command: lxc-create --name=ubuntu-16 --template=ubuntu -- --release xenial --arch amd64 I get the following error: Bad template: ubuntu Error creating container ubuntu-16 Why is this happening? 回答1: It says in the error. Bad template. You can see that in the current version of lxc there is no ubuntu template. The gist is

问题 Is it required to save/push the any XMM registers to the stack before the assembly function call? Because am observing the crash issue in my code with release mode for 64-bit development(Using AVX2). In debug mode its working fine. I tried with saving the content of the XMM8 register and restoring it at end of function call then its working fine. Any idea or references? 回答1: Yes, on Microsoft Windows you are required to preserve the XMM6-XMM15 registers. See http://msdn.microsoft.com/en-us

问题 I have written a simple assembly code which I am trying to compile in 64-bit mode. Here is the code: extern printf section .rodata readinfo db `%d\n`, 0 section .text global main main: mov rbp, rsp ; for correct debugging mov rax, 5 push rax push readinfo call printf add rsp, 8 xor rax, rax mov rsp, rbp ret And here are the instructions I give to nasm and gcc (as I have read on other posts, gcc automatically links the object file with the default c libraries): nasm -f elf64 -o test.o test.asm

问题 I was going over some Assembly code and I saw this: mov r12, _read_loopr jmp _bzero _read_loopr: ... _bzero: inc r8 mov byte [r8+r15], 0x0 cmp r8, 0xff jle _bzero jmp r12 And I was wondering if there was any particular advantage to doing this (mov _read_loopr to a register jmp to the function and then jmp back) rather than the usual call _bzero and ret? 回答1: This just looks like braindead code, especially if the return-address label is always right after the jmp _bzero like you say in your

问题 I have a problem, I can't compile my strdup while calling malloc. When I don't call malloc, it compiles my shared library perfectly, so if someone could help me that would be great ! here is my code: BITS 64 DEFAULT REL global my_strdup:function extern malloc my_strdup: [...] call malloc I compile with this: $> nasm -f elf64 my_strdup.S $> gcc -shared -o libmy.so my_strdup.o /usr/lib64/gcc/x86_64-suse-linux/4.8/../../../../x86_64-suse-linux/bin/ld: my_strdup.o: relocation R_X86_64_PC32

问题 I'm trying to measure memory access timings and need to reduce the noise produced by TLB hits and misses In order to clear a specific page out of the TLB I tried to use the INVLPG instruction, following those two examples: http://wiki.osdev.org/Paging and http://wiki.osdev.org/Inline_Assembly/Examples I wrote the following code: static inline void __native_flush_tlb_single(unsigned long addr) { asm volatile("invlpg (%0)" ::"r" (addr) : "memory"); } But the resulting binary throws an SIGSEGV

问题 Want to define same local label in multiple functions: .text .globl main func: push %rbp mov %rsp, %rbp .a: leave ret main: push %rbp mov %rsp, %rbp .a: leave ret Strangely get error: $ clang -c main.s main.s:13:1: error: invalid symbol redefinition .a: ^ When I was using yasm it allowed same local labels in multiple functions. Do you have any clues? 回答1: Unlike NASM, .label isn't local to the function (actually preceding non- . label) in gas syntax. .Llabel is a "local" symbol name, meaning

问题 There is that one question that troubles me. So ... Why in x86_32 the parameters are passed in registers that I feel are in alphabetically ( eax , ecx , edx , esi ) and ranked order ( esi , edi , ebp ) +---------+------+------+------+------+------+------+ | syscall | arg0 | arg1 | arg2 | arg3 | arg4 | arg5 | +---------+------+------+------+------+------+------+ | %eax | %ebx | %ecx | %edx | %esi | %edi | %ebp | +---------+------+------+------+------+------+------+ section .text global _start

问题 I have some assembly that needs to load a C symbol in OS X (x86-64). With x86, the way you do this is: mov rax, some_symbol_name However, with x86-64, this causes a link warning: ld: warning: PIE disabled. Absolute addressing (perhaps -mdynamic-no-pic) not allowed in code signed PIE, but used in _main from Test2.o. To fix this warning, don't compile with -mdynamic-no-pic or link with -Wl,-no_pie Note: I know what PIE is, and I don't want to disable it. Here are some of my other attempts to