Program terminated with signal SIGSEGV, Segmentation fault

var1: .word 3
var2: .word 4

.text
.global _start

_start:
    ldr r0, adr_var1  @ load the memory address of var1 via label adr_var1 into R0
    ldr r1, adr_var2  @ load the memory address of var2 via label adr_var2 into R1
    ldr r2, [r0]      @ load the value (0x03) at memory address found in R0 to register R2 
    str r2, [r1, #2]  @ address mode: offset. Store the value found in R2 (0x03) to the memory address found in R1 plus 2. Base register (R1) unmodified. 
    str r2, [r1, #4]! @ address mode: pre-indexed. Store the value found in R2 (0x03) to the memory address found in R1 plus 4. Base register (R1) modified: R1 = R1+4 
    ldr r3, [r1], #4  @ address mode: post-indexed. Load the value at memory address found in R1 to register R3. Base register (R1) modified: R1 = R1+4 
    bkpt

adr_var1: .word var1
adr_var2: .word var2

这是因为忘记标记var1，var2为数据段，如下，就可以对这些数据段附近的地址写入

.data
var1: .word 3
var2: .word 4

.text
.global _start

_start:
    ldr r0, adr_var1  @ load the memory address of var1 via label adr_var1 into R0
    ldr r1, adr_var2  @ load the memory address of var2 via label adr_var2 into R1
    ldr r2, [r0]      @ load the value (0x03) at memory address found in R0 to register R2 
    str r2, [r1, #2]  @ address mode: offset. Store the value found in R2 (0x03) to the memory address found in R1 plus 2. Base register (R1) unmodified. 
    str r2, [r1, #4]! @ address mode: pre-indexed. Store the value found in R2 (0x03) to the memory address found in R1 plus 4. Base register (R1) modified: R1 = R1+4 
    ldr r3, [r1], #4  @ address mode: post-indexed. Load the value at memory address found in R1 to register R3. Base register (R1) modified: R1 = R1+4 
    bkpt

adr_var1: .word var1  /* var1的地址助记符 */
adr_var2: .word var2  /* var2的地址助记符 */