读取内部flash报错：SCB_CFSR_BFSR:0x82 PRECISERR

bus fault：
SCB_CFSR_BFSR:0x82 PRECISERR SCB->BFAR:08120000。

typedef __IO uint8_t vu8;
#define MEDOL_ID_ADDR 0X08120000
u8 STMFLASH_ReadHalfWord_Byte(u32 faddr)
{
    return *(vu8 *)faddr;
}

> psr: 0x41000000
r00: 0x08120000
r01: 0x08120000
r02: 0x20004990
r03: 0x00000000
r04: 0x20001738
r05: 0x20004084
r06: 0x00000000
r07: 0x00000009
r08: 0xdeadbeef
r09: 0xdeadbeef
r10: 0xdeadbeef
r11: 0xdeadbeef
r12: 0x080187e5
 lr: 0x08018db7
 pc: 0x08004e98
hard fault on thread: at_clnt
thread   pri  status      sp     stack size max used left tick  error
-------- ---  ------- ---------- ----------  ------  ---------- ---
LED_thre  27  suspend 0x0000007c 0x00000100    48%   0x00000005 000
GPS_thre  25  suspend 0x0000007c 0x00000200    63%   0x00000001 000
at_clnt    9  running 0x000000b8 0x00000600    24%   0x00000003 000
BATERY_V  21  suspend 0x0000009c 0x00000100    60%   0x00000005 000
ShutDown  25  suspend 0x0000007c 0x00000100    48%   0x00000004 000
USB_thre  20  suspend 0x0000007c 0x00000100    48%   0x00000005 000
tshell    20  suspend 0x00000084 0x00001000    03%   0x0000000a 000
tidle0    31  ready   0x00000044 0x00000100    32%   0x00000015 000
main      10  suspend 0x00000088 0x00000800    34%   0x00000013 000
bus fault:
SCB_CFSR_BFSR:0x82 PRECISERR SCB->BFAR:08120000