int test_va_arg()
{
char str[4+1] = {0};
char argv1[4+1] = {'1', '1', '1', '1', 0};
char argv2[4+1] = {'2', '2', '2', '2', 0};
char argv3[4+1] = {'3', '3', '3', '3', 0};
char argv4[4+1] = {'4', '4', '4', '4', 0};
char argv5[4+1] = {'5', '5', '5', '5', 0};
char argv6[4+1] = {'6', '6', '6', '6', 0};
char argv7[4+1] = {'7', '7', '7', '7', 0};
char argv8[4+1] = {'8', '8', '8', '8', 0};
char argv9[4+1] = {'9', '9', '9', '9', 0};
char argv10[4+1] = {'a', 'a', 'a', 'a', 0};
strcpy(str,"INFO");
//tLog( str, argv1, argv2, argv3, argv4, argv5, argv6, argv7, argv8, argv9, argv10 );
//tLog1( str, argv1, argv2, argv3, argv4, argv5, argv6, argv7, argv8, argv9, argv10 );
strcpy( (void *)0x42000200, (const char *)"xoutputx: %s.\n" );
fuck_log1( str, argv1, argv2, argv3, argv4, argv5, argv6, argv7, argv8, argv9, argv10 );
//tLog1( str, argv1, argv2, argv3, argv4, argv5, argv6, argv7, argv8, argv9, argv10 );
return 0;
}
/* SPDX-License-Identifier: GPL-2.0+ */
/*
* relocate - common relocation function for AArch64 U-Boot
*
* (C) Copyright 2013
* Albert ARIBAUD
* David Feng
*/
#include
#include
#include
#include
#include
ENTRY( fuck_code )
LDR X10, =0x42000000
STR X10, [X10, #0x00]
STP X29, X30, [SP,#-0x100]!
MOV X29, SP
STR X19, [SP,#0x10]
MOV W0, #0xFFFFFFf8
STR W0, [X29,#0x38]
LDR W1, [X29,#0x38]
LDR X0, [X29,#0x20]
STR w1, [X10, #0x08]
TBZ W1, #0x1F, loc_3718a
ADD W2, W1, #8
CMP W2, #0
STR W2, [X29,#0x38]
STR w1, [X10, #0x10]
ADD W2, W2, #3
STR w2, [X10, #0x18]
B.LE loc_3728a
loc_3718a:
LDR X4, =0x1234
B quit
loc_3728a:
LDR X4, =0x55aa
quit:
STR X4, [X10, #0xf0]
LDR X19, [SP,#0x10]
LDP X29, X30, [SP],#0x100
ret
ENDPROC(fuck_code)
ENTRY( fuck_log1 )
STP X29, X30, [SP,#-0x100]!
//变量sp+0x00 存储 X29, X30 的原始值
MOV X29, SP
LDR X10, =0x42000000
STR X10, [x10, #0x00]
ADD X0, X29, #0x100
//x0 栈顶指针 指向函数调用之前的堆栈sp
//函数的参数如果是8个以内(包含8个) 用x0-x7来传递 (param0-param7)
//超过8个的部分 从此sp开始依次先储存好 比如超过3个
//sp+0x00->param8 sp+0x08->param9 sp+0x10->param10
STR X19, [SP,#0x10]
//变量sp+0x10 存储 x19 的原始值
ldr X19, =0x42000200 //"xoutputx: %s.\n" printf的第一个参数 x0
mov X11, X0
STR X11, [x10, #0x08]
ldr X12, [X11]
STR X12, [x10, #0x10]
add X11, x11, #0x08
STR X11, [x10, #0x18]
ldr X12, [X11]
STR X12, [x10, #0x20]
add X11, x11, #0x08
STR X11, [x10, #0x28]
ldr X12, [X11]
STR X12, [x10, #0x30]
add X11, x11, #0x08
STR X11, [x10, #0x38]
ldr X12, [X11]
STR X12, [x10, #0x40]
//add X11, x11, #0x08
STR X7, [x10, #0x48]
ldr X12, [X7]
STR X12, [x10, #0x50]
STR X6, [x10, #0x58]
ldr X12, [X6]
STR X12, [x10, #0x60]
STP X0, X0, [X29, #0x20]
//变量sp+0x20 sp+0x28 存储 x0 栈顶指针
ADD X0, X29, #0xC0
STR X0, [X29,#0x30]
//变量sp+0x30 = sp+0xc0
MOV W0, #0xFFFFFFC8
STR W0, [X29,#0x38]
//变量sp+0x38 = 0xFFFFFFC8 4字节
MOV W0, #0xFFFFFF80
STR W0, [X29,#0x3C]
//变量sp+0x3C = 0xFFFFFF80 4字节
STP X1, X2, [X29,#0xC8]
STP X3, X4, [X29,#0xD8]
STP X5, X6, [X29,#0xE8]
STR X7, [X29,#0xF8]
//传递进来的参数 依次压入堆栈 x1-x7 c8-d8-e8-f8-0x100-[x0 栈顶指针的位置]
STR Q0, [X29,#0x40]
STR Q1, [X29,#0x50]
STR Q2, [X29,#0x60]
STR Q3, [X29,#0x70]
STR Q4, [X29,#0x80]
STR Q5, [X29,#0x90]
STR Q6, [X29,#0xA0]
STR Q7, [X29,#0xB0]
//0x40-0xc0 用0填充这块区域 没有用到
loc_36FC:
LDR W1, [X29,#0x38]
//变量sp+0x38 = 0xFFFFFFC8 4字节
LDR X0, [X29,#0x20]
//栈顶指针
TBZ W1, #0x1F, loc_3718
//测试 sp+0x38 0xFFFFFFC8 & 0x1F 是否等于0,等于0的话跳转到loc_3718
//否则执行下一条指令
ADD W2, W1, #8
//[sp+0x38] & 0x1f 不等于0, 自加8
CMP W2, #0
STR W2, [X29,#0x38]
B.LE loc_3728
//不等于0 跳转
loc_3718:
//等于0 说明经过7次循环 x1-x7已经用完了
ADD X1, X0, #0xF
AND X1, X1, #0xFFFFFFFFFFFFFFF8
STR X1, [X29,#0x20]
B loc_3730
loc_3728:
LDR X0, [X29,#0x28]
//sp+0x28 存储 x0 栈顶指针
ADD X0, X0, W1,SXTW
//x0+w1 w1符号扩展 此例是一个负数
//传递进来的参数 依次压入堆栈 x1-x7 c8-d8-e8-f8-0x100-[x0 栈顶指针的位置]
//栈顶指针的位置 + 负数 精确计算好了 第一次是定位到 x1
//7*8=56 0x38 0xFFFFFFC8 + 0x38 = 0x00000000 即-0x38
//下一次循环就是 -0x30 总共循环7次
loc_3730:
LDR X1, [X0]
//取得压入堆栈的x1的值 第二次是x2 ...
CBZ X1, loc_3744
//等于空退出函数
MOV X0, X19
BL printf
B loc_36FC
loc_3744:
LDR X19, [SP,#0x10]
//变量sp+0x10 恢复 x19 的原始值
LDP X29, X30, [SP],#0x100
//恢复 X29, X30 的原始值,sp堆栈平衡
RET
//程序返回
ENDPROC(fuck_log1)
IDA伪C码：
__int64 *__fastcall fuck_log1(long double a1, long double a2, long double a3, long double a4, long double a5, long double a6, long double a7, long double a8, __int64 a9, __int64 a10, __int64 a11, __int64 a12, __int64 a13, __int64 a14, _QWORD *a15, _QWORD *a16, __int64 a17, __int64 a18, __int64 a19, __int64 a20)
{
int v20; // w1
__int64 *result; // x0
__int64 *v22; // [xsp+20h] [xbp+20h]
int v23; // [xsp+38h] [xbp+38h]
MEMORY[0x42000000] = 0x42000000LL;
MEMORY[0x42000008] = &a17;
MEMORY[0x42000010] = a17;
MEMORY[0x42000018] = &a18;
MEMORY[0x42000020] = a18;
MEMORY[0x42000028] = &a19;
MEMORY[0x42000030] = a19;
MEMORY[0x42000038] = &a20;
MEMORY[0x42000040] = a20;
MEMORY[0x42000048] = a16;
MEMORY[0x42000050] = *a16;
MEMORY[0x42000058] = a15;
MEMORY[0x42000060] = *a15;
v22 = &a17;
v23 = -56;
while ( 1 )
{
v20 = v23;
result = v22;
if ( (v23 & 0x80000000) != 0 && (v23 += 8, v20 + 8 <= 0) )
result = (__int64 *)((char *)&a17 + v20);
else
v22 = (__int64 *)(((unsigned __int64)v22 + 15) & 0xFFFFFFFFFFFFFFF8LL);
if ( !*result )
break;
printf((const unsigned __int8 *)0x42000200);
}
return result;
}
原始c码：
void tLog1(char *sInfo, ...)
{
char *str = NULL;
char *str1 = NULL;
char *str2 = NULL;
va_list sArgv; // 申请参数列表变量
va_start(sArgv, sInfo); // 申明最后一个传递给函数的已知的固定参数
/* 依次读取固定参数 sInfo 后的 参数 */
while(1){
str = va_arg(sArgv, char*);
if( str ){
printf("output: %s \n", str );
}else{
break;
}
}
va_end(sArgv);
}