皮层从RAM执行

Question

我需要在一个皮质-M1处理器上的RAM执行固件擦除和重写闪存。我正在使用eclipse和launchpad的工具链。MDK-ARM也有一个类似的问题：How do I execute a function from RAM on a Cortex-M3 (STM32)?。

要从flash运行固件，我配置链接器脚本：

MEMORY
{
    FLASH (rx) : ORIGIN = 0x00000000, LENGTH = 8K
    RAM (rw)   : ORIGIN = 0x20004000, LENGTH = 16K
}

然后使用JLink.exe实用程序获得：

J-Link>r
Reset delay: 0 ms
Reset type NORMAL: Resets core & peripherals via SYSRESETREQ & VECTRESET bit.
J-Link>mem32 0x00,2
00000000 = 20008000 00000101
J-Link>SetPC 0x0101
Info: Cortex-M: Debugger tries to set PC to odd value. Corrected register value from 0x00000101 to 0x00000100
J-Link>wreg MSP 0x20008000
MSP = 0x20008000
J-Link>halt
PC = 00000100, CycleCnt = 00000000
R0 = 00000300, R1 = 00000300, R2 = 00000010, R3 = 400A8000
R4 = 00001000, R5 = 2010108C, R6 = 00002040, R7 = 00000021
R8 = 00000000, R9 = 00000000, R10= 00000008, R11= 00000000
R12= 00000000
SP(R13)= 20008000, MSP= 20008000, PSP= 00000000, R14(LR) = FFFFFFFF
XPSR = 01000000: APSR = nzcvq, EPSR = 01000000, IPSR = 000 (NoException)
CFBP = 00000000, CONTROL = 00, FAULTMASK = 00, BASEPRI = 00, PRIMASK = 00
J-Link>s
00000100:  09 49              LDR     R1, [PC, #+0x24]
J-Link>s
00000102:  0A 4A              LDR     R2, [PC, #+0x28]
J-Link>s
00000104:  0A 4B              LDR     R3, [PC, #+0x28]
J-Link>s
00000106:  00 F0 07 F8        BL      #+0x0E
J-Link>s
00000118:  9B 1A              SUB     R3, R3, R2
J-Link>

然后我想从RAM中运行固件。为此，我配置链接器脚本：

MEMORY
{
    FLASH (rx) : ORIGIN = 0x20001000, LENGTH = 8K
    RAM (rw)   : ORIGIN = 0x20004000, LENGTH = 16K
}

下面是我在执行该操作时遇到的错误：

 J-Link>r
Reset delay: 0 ms
Reset type NORMAL: Resets core & peripherals via SYSRESETREQ & VECTRESET bit.
J-Link>loadbin milandr-template.bin 0x20001000
Downloading file [milandr-template.bin]...O.K.
J-Link>mem32 0x20001000,2
20001000 = 20008000 20001101
J-Link>SetPC 0x20001101
Info: Cortex-M: Debugger tries to set PC to odd value. Corrected register value from 0x20001101 to 0x20001100
J-Link>wreg MSP 0x20008000
MSP = 0x20008000
J-Link>halt
PC = 20001100, CycleCnt = 00000000
R0 = 00000300, R1 = 00000300, R2 = 00000010, R3 = 400A8000
R4 = 00000648, R5 = 00000001, R6 = 00000648, R7 = 00000064
R8 = 00000800, R9 = 00000000, R10= 01000008, R11= 00000000
R12= 00000000
SP(R13)= 20008000, MSP= 20008000, PSP= 00000000, R14(LR) = FFFFFFFF
XPSR = 01000000: APSR = nzcvq, EPSR = 01000000, IPSR = 000 (NoException)
CFBP = 00000000, CONTROL = 00, FAULTMASK = 00, BASEPRI = 00, PRIMASK = 00
J-Link>s
20001100:  09 49              LDR     R1, [PC, #+0x24]
J-Link>s
00000140:  FE E7              B       #-0x04
J-Link>

这里是处理器跳转到位于闪存区域的地址- 0x00000140。在0x20000102并不像预期的那样。这两种情况下的十六进制文件是一一对应的。看起来，我需要检查执行第一条指令的结果有什么不同：

00000100:  09 49              LDR     R1, [PC, #+0x24]

也许已经有人面对了，并说出了一个错误。

Answer 1

LDR指令在从RAM执行时产生故障。大多数默认故障处理程序如下所示：

B .

您需要查看故障寄存器以获得更多信息。但是由于您的原始内存似乎是从0x20004000开始的，所以在address 0x20001000上可能没有内存。

您可以尝试这样的链接器文件：

MEMORY
{
    FLASH (rx) : ORIGIN = 0x20004000, LENGTH = 8K
    RAM (rw)   : ORIGIN = 0x20006000, LENGTH = 8K
}