[英]Getting parameter in ASM from C call
我從C程序調用了一個asm函數,然后嘗試調用另一個C函數並提供了新參數,但是第二個函數接收了asm的參數。 這是3個文件。
main.c
#include <stdio.h>
#include <stdlib.h>
#include "ac.h"
int main (int argc,char **argv)
{
char * s = _pusher(115,9);
fprintf(stdout,"From pusher '%s'\n",s);
free(s);
return EXIT_SUCESS;
}
ac.c文件
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include "ac.h"
char * _aff(int a,int b)
{
char * s;
fprintf(stdout,"In aff(%d,%d)\n",a,b);
asprintf(&s,"v = %d - %d",a,b);
return s;
}
文件aa.asm
[CPU x64]
[BITS 64]
extern _aff
global _pusher
[SECTION .text]
_pusher:
push rbp
mov rbp,rsp
push 123 ;seems no effect
push 321 ;seems no effect
call _aff
add rsp,24
mov rsp,rbp
pop rbp
ret
[SECTION .data]
[SECTION .bss]
執行時,得到以下輸出:
In aff(115,9)
From pusher : 'v = 115 - 9'
但我期待
In aff(123,321)
From pusher : 'v = 123 - 321'
如何傳遞自己的新參數? 最終目標是接受_pusher a char **
並按如下方式調用aff
:
_aff(char *param,...) and use VA_LIST inside so pusher should be call like this
_pusher(int count,char **tbl)
OP注意到他傳遞給他的匯編語言函數的參數未得到處理。
@Olaf指出,OP沒有為他的環境使用正確的ABI(應用程序二進制接口-如何在平台上調用函數的定義)-他正在使用Wikipedia中描述的(很多)舊版本。
@邁克爾佩奇澄清指出,針對x64的發展,而不是PUSH
荷蘭國際集團的值壓入堆棧(x86的約定),他應該將它們加載到前兩個預期寄存器: RDI
和RSI
我只是意識到在六個月后,我忘記發布工作代碼。 因此,asm函數將接收char **並將其格式化以發送給redis。
希望這段代碼對其他人有用。
redisReply * _pusher(redisContext *c, int count, char **args);
然后_pusher將調用redisCommand(c,“%s%s ...”,args [0],...,args [count-1]):
[CPU x64]
[BITS
extern redisCommand
global _pusher
[SECTION.text]
_pusher:
push rbp
mov rbp,rsp
mov rax,rsi
cmp rax,1
je arg_1
cmp rax,2
je arg_2
cmp rax,3
je arg_3
cmp rax,4
je arg_4
cmp rax,5
jge arg_more
arg_1:
sub rsp,0x3
mov byte [rbp - 0x3],0x25
mov byte [rbp - 0x2],0x73
mov byte [rbp - 0x1],0x0
mov rax,rdi
mov rdi,rdx
mov rdx,[rdi]
lea rsi,[rbp - 0x3]
mov rdi,rax
jmp debut_appel
arg_2:
sub rsp,0x6
mov byte [rbp - 0x6],0x25
mov byte [rbp - 0x5],0x73
mov byte [rbp - 0x4],0x20
mov byte [rbp - 0x3],0x25
mov byte [rbp - 0x2],0x73
mov byte [rbp - 0x1],0x0
mov rax,rdi
mov rdi,rdx
mov rdx,[rdi]
mov rcx,[rdi + 0x8]
lea rsi,[rbp - 0x6]
mov rdi,rax
jmp debut_appel
arg_3:
sub rsp,0x9
mov byte [rbp - 0x9],0x25
mov byte [rbp - 0x8],0x73
mov byte [rbp - 0x7],0x20
mov byte [rbp - 0x6],0x25
mov byte [rbp - 0x5],0x73
mov byte [rbp - 0x4],0x20
mov byte [rbp - 0x3],0x25
mov byte [rbp - 0x2],0x73
mov byte [rbp - 0x1],0x0
mov rax,rdi
mov rdi,rdx
mov rdx,[rdi]
mov rcx,[rdi + 0x8]
mov r8, [rdi + 0x10]
lea rsi,[rbp - 0x9]
mov rdi,rax
jmp debut_appel
arg_4:
sub rsp,0xc
mov byte [rbp - 0xc],0x25
mov byte [rbp - 0xb],0x73
mov byte [rbp - 0xa],0x20
mov byte [rbp - 0x9],0x25
mov byte [rbp - 0x8],0x73
mov byte [rbp - 0x7],0x20
mov byte [rbp - 0x6],0x25
mov byte [rbp - 0x5],0x73
mov byte [rbp - 0x4],0x20
mov byte [rbp - 0x3],0x25
mov byte [rbp - 0x2],0x73
mov byte [rbp - 0x1],0x0
mov rax,rdi
mov rdi,rdx
mov rdx,[rdi]
mov rcx,[rdi + 0x8]
mov r8, [rdi + 0x10]
mov r9, [rdi + 0x18]
lea rsi,[rbp - 0xc]
mov rdi,rax
jmp debut_appel
arg_more:
mov r8,rdi
mov rdi,rdx
mov rcx,rax
sub rcx,5
lea rax, [rcx * 3]
add rax, 0xf
sub rsp,rax
mov rdx,rbp
sub rdx,rax
lea rsi,[rdx]
mov byte [rbp - 0xc],0x25
mov byte [rbp - 0xb],0x73
mov byte [rbp - 0xa],0x20
mov byte [rbp - 0x9],0x25
mov byte [rbp - 0x8],0x73
mov byte [rbp - 0x7],0x20
mov byte [rbp - 0x6],0x25
mov byte [rbp - 0x5],0x73
mov byte [rbp - 0x4],0x20
mov byte [rbp - 0x3],0x25
mov byte [rbp - 0x2],0x73
mov byte [rbp - 0x1],0x0
;debut de boucle
loop_start:
mov byte [rdx],0x25
mov byte [rdx + 1],0x73
mov byte [rdx + 2],0x20
add rdx,0x3
lea rax , [rcx * 0x8]
mov rbx,[rdi + rax + 0x20]
push rbx
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