iOS裸函数应用实战

getLR

//
//  main.c
//  iOS_ARM
//
//  Created by piao on 15/7/21.
//  Copyright (c) 2015年 __MyCompanyName__. All rights reserved.
//
 
#if defined (__arm64__) /*|| defined (__aarch64__)*/
 
static __attribute__((naked)) long getLR(){
    long lr = 0;
    __asm__ volatile("mov       x0, lr\n\r"
                     "mov       %[_lr], x0\n\r"
                     "ret"
                     :[_lr]"=r"(lr));
    return lr;
}
 
static __attribute__((naked)) long getSP(){
    long sp = 0;
    __asm__ volatile("mov       x0, sp\n\r"
                     "mov       %[_sp], x0\n\r"
                     "ret"
                     :[_sp]"=r"(sp));
    return sp;
}
#else
static __attribute__((naked)) int getLR(){
    int lr = 0;
    __asm__ volatile("mov        r0, lr\n\r"
                     "mov        %[_lr], r0\n\r"
                     "bx         lr"  // 别偷懒，自己返回
                     :[_lr]"=r"(lr));
     
    return lr;
}
 
static __attribute__((naked)) int getSP(){
    int sp = 0;
    __asm__ volatile("mov        r0, sp\n\r"
                     "mov        %[_sp], r0\n\r"
                     "bx         lr"
                     :[_sp]"=r"(sp));
     
    return sp;
}
 
#endif
 
 
static void piaoyun(char *s)
{
#if defined (__arm64__)
    long lr = getLR();
    printf("[++++][arm64]return = %lx\n", lr);
#else
    int lr = getLR();
    printf("[++++][arm]return = %x\n", lr);
#endif
     
    char ss[10] = {0};
    strncpy(ss, s, sizeof(ss));
    printf("[++++]ss = %s\n\n", ss);
}
 
int main( int argc, char ** argv )
{
    piaoyun("piaoyun");
 
}