hos_basic_mprotect.cpp

int mprotect(void *addr, void *base, size_t len, int prot)
{
    Result rc=0;
    static bool isMapped=false;
    Handle hProc = envGetOwnProcessHandle();
    if (isMapped) {        
        rc=svcUnmapProcessCodeMemory(hProc, (u64)addr, (u64)base, len);
        if (R_FAILED(rc)) {
            printf(" Error, svcUnmapProcessCodeMemory() failed w. rc: %X\n", rc);
            return (int)rc;
        }
        isMapped=false;
    }
    
    rc=svcMapProcessCodeMemory(hProc, (u64)addr, (u64)base, len);
    if (R_FAILED(rc)) {
        printf(" Error, svcMapProcessCodeMemory() failed w. rc: %X\n", rc);
        return (int)rc;
    }
    else isMapped=true;
    
    rc = svcSetProcessMemoryPermission(hProc, (u64)addr, len, prot);
    if (R_FAILED(rc)) {
        printf(" Error, svcSetProcessMemoryPermission() failed w. rc: %X\n", rc);
        return (int)rc;
    }
    return 0;
}

void test()
{
    u64 vmBase=(u64)virtmemReserve(PAGE_SIZE);

    u8 *ptext = (u8*)memalign(PAGE_SIZE, PAGE_SIZE);  // single page , aligned 

    int res = 0;
    
    if(0 != (res = mprotect((void*)vmBase, ptext, PAGE_SIZE, Perm_Rw)))
        printf("mprotect Rw failed! res: %X\n",(u64)res);

    memcpy((void*)vmBase, testcode, sizeof(testcode));

    if(0 != (res = mprotect((void*)vmBase, ptext, PAGE_SIZE, Perm_Rx)))
        printf("mprotect Rx failed! res: %X\n",(u64)res);
    else {
        funcptr = (fp_t)vmBase;
        printf("Test code returned: 0x%lx\n", funcptr());//This should return 0x7 (see above).
    }
}