ESP8266 ROM XTOS

1 逆向工程

• http://dflund.se/~kongo/esp8266.bin/iram0.txt
• http://esp8266-re.foogod.com/wiki/Boot_ROM

2 探索

2.1 SYSTEM_RTC_MEM_READ

uint32 system_rtc_mem_read(int32 addr, void *buff, int32 length)
{
    int32 blocks;
     
    // validate reading a user block
    //if (addr < 64) return 0;
    if (buff == 0) return 0;
    // validate 4 byte aligned
    if (((uint32)buff & 0x3) != 0) return 0;
    // validate length is multiple of 4
    if ((length & 0x3) != 0) return 0;
     
    // check valid length from specified starting point
    if (length > (0x300 - (addr * 4))) return 0;
 
    // copy the data
    for (blocks = (length >> 2) - 1; blocks >= 0; blocks--) {
        volatile uint32 *ram = ((uint32*)buff) + blocks;
        volatile uint32 *rtc = ((uint32*)0x60001100) + addr + blocks;
        *ram = *rtc;
    }
 
    return 1;
}

2.2 SYSTEM_RTC_MEM_WRITE

uint32 system_rtc_mem_write(int32 addr, void *buff, int32 length)
{
    int32 blocks;
     
    // validate reading a user block
    if (addr < 64) return 0;
    if (buff == 0) return 0;
    // validate 4 byte aligned
    if (((uint32)buff & 0x3) != 0) return 0;
    // validate length is multiple of 4
    if ((length & 0x3) != 0) return 0;
     
    // check valid length from specified starting point
    if (length > (0x300 - (addr * 4))) return 0;
 
    // copy the data
    for (blocks = (length >> 2) - 1; blocks >= 0; blocks--) {
        volatile uint32 *ram = ((uint32*)buff) + blocks;
        volatile uint32 *rtc = ((uint32*)0x60001100) + addr + blocks;
        *rtc = *ram;
    }
 
    return 1;
}

2.3 SYSTEM_GET_RST_INFO

struct rst_info {
    uint32 reason;
    uint32 exccause;
    uint32 epc1;
    uint32 epc2;
    uint32 epc3;
    uint32 excvaddr;
    uint32 depc;
};
 
struct rst_info system_get_rst_info()
{
    struct rst_info rst;
    system_rtc_mem_read(0, &rst, sizeof(struct rst_info);
    if (rst.reason >= 7) {
        ets_memset(&rst, 0, sizeof(struct rst_info));
    }
    if (rtc_get_reset_reason() == 2) {
        ets_memset(&rst, 0, sizeof(struct rst_info));
        rst.reason = 6;
    }
    return rst;
}