{"id":2831,"date":"2020-10-06T22:42:38","date_gmt":"2020-10-06T19:42:38","guid":{"rendered":"http:\/\/demensdeum.com\/blog\/?p=2831"},"modified":"2024-12-16T22:32:25","modified_gmt":"2024-12-16T19:32:25","slug":"x86_64-assembler-c-one-love","status":"publish","type":"post","link":"https:\/\/demensdeum.com\/blog\/hi\/2020\/10\/06\/x86_64-assembler-c-one-love\/","title":{"rendered":"x86_64 Assembler + C = One Love"},"content":{"rendered":"

In this note I will describe the process of calling C functions from assembler.
Let’s try calling printf(\u201cHello World!\\n\u201d); and exit(0);<\/p>\n

\n
    message: db \"Hello, world!\", 10, 0\n\nsection .text\n    extern printf\n    extern exit\n    global main\n\nmain:\n    xor\trax, rax\n    mov\trdi, message    \n    call printf\n    xor rdi, rdi\n    call exit\n<\/code><\/pre>\n<\/div>\n
Everything is much simpler than it seems, in the .rodata section we will describe static data, in this case the string \u201cHello, world!\u201d, 10 is the newline character, also do not forget to zero it.<\/p>\n
In the code section, we will declare external functions printf, exit of the stdio, stdlib libraries, and also declare the entry function main:<\/p>\n
\n
    extern printf\n    extern exit\n    global main\n<\/code><\/pre>\n<\/div>\n
We pass 0 to the return register from the rax function, you can use mov rax, 0; but to speed it up, use xor rax, rax; Next, we pass a pointer to a string to the first argument:<\/p>\n
\n
\u0414\u0430\u043b\u0435\u0435 \u0432\u044b\u0437\u044b\u0432\u0430\u0435\u043c \u0432\u043d\u0435\u0448\u043d\u044e\u044e \u0444\u0443\u043d\u043a\u0446\u0438\u044e \u0421\u0438 printf:<\/p>\n
    xor\trax, rax\n    mov\trdi, message    \n    call printf\n    xor rdi, rdi\n    call exit\n<\/code><\/pre>\n<\/div>\n
By analogy, we pass 0 to the first argument and call exit:<\/p>\n
\n
    call exit\n<\/code><\/pre>\n<\/div>\n
As Americans say:
Who doesn't listen to anyone
That pilaf is eaten by @ Alexander Pelevin<\/a><\/p>\n
Sources<\/h3>\n
https:\/\/www.devdungeon. com\/content\/how-mix-c-and-assembly<\/a>
https:\/\/nekosecurity.com\/x86-64-assembly\/part-3-nasm-anatomy-syscall-passing-argument<\/a>
\nhttps:\/\/www.cs.uaf.edu\/2017\/fall\/cs301\/reference\/x86_64.html<\/a><\/p>\n
Source code<\/h3>\n
https:\/\/gitlab.com\/demensdeum\/assembly-playground<\/a <\/p>\n","protected":false},"excerpt":{"rendered":"
In this note I will describe the process of calling C functions from assembler.Let’s try calling printf(\u201cHello World!\\n\u201d); and exit(0); message: db “Hello, world!”, 10, 0 section .text extern printf extern exit global main main: xor rax, rax mov rdi, message call printf xor rdi, rdi call exit Everything is much simpler than it seems,Continue reading “x86_64 Assembler + C = One Love”<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":""},"categories":[61,52],"tags":[165,166,164],"class_list":["post-2831","post","type-post","status-publish","format-standard","hentry","category-techie","category-tutorials","tag-asm","tag-assembly","tag-nasm","entry"],"translation":{"provider":"WPGlobus","version":"3.0.2","language":"hi","enabled_languages":["en","ru","zh","de","fr","ja","pt","hi"],"languages":{"en":{"title":true,"content":true,"excerpt":false},"ru":{"title":true,"content":true,"excerpt":false},"zh":{"title":true,"content":true,"excerpt":false},"de":{"title":true,"content":true,"excerpt":false},"fr":{"title":true,"content":true,"excerpt":false},"ja":{"title":true,"content":true,"excerpt":false},"pt":{"title":true,"content":true,"excerpt":false},"hi":{"title":false,"content":false,"excerpt":false}}},"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/posts\/2831","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/comments?post=2831"}],"version-history":[{"count":16,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/posts\/2831\/revisions"}],"predecessor-version":[{"id":3905,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/posts\/2831\/revisions\/3905"}],"wp:attachment":[{"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/media?parent=2831"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/categories?post=2831"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/hi\/wp-json\/wp\/v2\/tags?post=2831"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}