臂组件回溯PC偏移

我故意撞车调查。源代码:

int* crashPointer = nullptr;
*crashPointer = 7;

生成的程序集:

11feb8: e3005007    movw    r5, #7
11febc: e3006000    movw    r6, #0 <--- r6 is #0
11fec0: e50b0014    str r0, [fp, #-20]  ; 0xffffffec
11fec4: e50b1018    str r1, [fp, #-24]  ; 0xffffffe8
11fec8: e51b0014    ldr r0, [fp, #-20]  ; 0xffffffec
    int* crashPointer = nullptr;
11fecc: e50b601c    str r6, [fp, #-28]  ; 0xffffffe4 <--- Stores #0 to [fp, #-28] from r6
    *crashPointer = 7;
11fed0: e51b101c    ldr r1, [fp, #-28]  ; 0xffffffe4 <--- Loads #0 from [fp, #-28] to r1
11fed4: e5815000    str r5, [r1] <--- This should crash since it's trying to dereference r1 which is #0

11fed4

signal 11 (SIGSEGV), code 1 (SEGV_MAPERR), fault addr 0x0
    r0 ea408800  r1 00000000  r2 00000006  r3 ea6ccfa0
    r4 ea6d1b2a  r5 00000007  r6 00000000  r7 ea3ff904
    r8 00000001  r9 e8b22ec0  sl ea6b5be9  fp ea3ff5c0
    ip ea6d1af8  sp ea3ff550  lr ea6d09aa  pc ea696ed4  cpsr 600f0010
...
ea577000-ea6d7000 r-xp 00000000 fe:01 1556782   libSomeLib.so

结论: ea696ed4-ea577000=11fed4

总而言之:没有必要在崩溃转储中向PC值添加偏移量(至少对于Android armv7)。