{"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\/pt\/2020\/10\/06\/x86_64-assembler-c-one-love\/","title":{"rendered":"x86_64 Montador + C = Um Amor"},"content":{"rendered":"

Nesta nota descreverei o processo de chamada de fun\u00e7\u00f5es C a partir do assembler.
Vamos tentar chamar printf(\u201cHello World!\\n\u201d); e sair(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
Tudo \u00e9 muito mais simples do que parece, na se\u00e7\u00e3o .rodata iremos descrever dados est\u00e1ticos, neste caso a linha \u201cHello, world!\u201d, 10 \u00e9 um caractere de nova linha, e tamb\u00e9m n\u00e3o esquecemos de anul\u00e1-lo. <\/p>\n
Na se\u00e7\u00e3o de c\u00f3digo declararemos as fun\u00e7\u00f5es externas printf, exit das bibliotecas stdio, stdlib e tamb\u00e9m declararemos a fun\u00e7\u00e3o de entrada main:<\/p>\n
\n
    extern printf\n    extern exit\n    global main\n<\/code><\/pre>\n<\/div>\n
Passamos 0 para o registrador de retorno da fun\u00e7\u00e3o rax, voc\u00ea pode usar mov rax, 0; mas para acelerar eles usam xor rax, rax; A seguir, passamos um ponteiro para a string do primeiro argumento:<\/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
Por analogia, passamos 0 para o primeiro argumento e chamamos exit:<\/p>\n
\n
    call exit\n<\/code><\/pre>\n<\/div>\n
Como dizem os americanos:
Quem n\u00e3o escuta ningu\u00e9m
Esse pilaf est\u00e1 comendo @ Alexander Pelevin<\/a><\/p>\n
Fontes<\/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
C\u00f3digo fonte<\/h3>\n
https:\/\/gitlab.com\/demensdeum\/assembly-playground<\/a <\/p>\n","protected":false},"excerpt":{"rendered":"
Nesta nota descreverei o processo de chamada de fun\u00e7\u00f5es C a partir do assembler.Vamos tentar chamar printf(\u201cHello World!\\n\u201d); e sair(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 Tudo \u00e9 muito mais simples do queContinue reading “x86_64 Montador + C = Um Amor”<\/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":"pt","enabled_languages":["en","ru","zh","de","fr","ja","pt"],"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}}},"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/posts\/2831","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/comments?post=2831"}],"version-history":[{"count":16,"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/posts\/2831\/revisions"}],"predecessor-version":[{"id":3905,"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/posts\/2831\/revisions\/3905"}],"wp:attachment":[{"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/media?parent=2831"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/categories?post=2831"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/demensdeum.com\/blog\/pt\/wp-json\/wp\/v2\/tags?post=2831"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}