tom-seddon/b2

Crash on branch to address with breakpoint set

tommy9 opened this issue · 3 comments

tommy9 commented

Had this occur when setting a breakpoint at the start of a loop, then stepping through the code until it branched back to the initial breakpoint. b2 Debug exits without warning.

To reproduce, paste the following text in and RUN the program:

   10 FOR O=0 TO 3 STEP 3
   20 P%=&2000
   30 [OPT O
   40 .START LDA #00
   50 BEQ START
   60 ]
   70 NEXT
   80 CALL START

Then set a breakpoint on execute address $2000. Press the Step In button a couple of times to get execution back to $2000 and b2 crashes.

I've extracted some relevant looking bits from the crash log:

Process:               b2 [72104]
Path:                  /Volumes/VOLUME/*/b2 Debug.app/Contents/MacOS/b2
Identifier:            com.tom-seddon.b2
Version:               20240423-163255-0fcf3c3 (20240423-163255-0fcf3c3)
Code Type:             X86-64 (Native)
Parent Process:        launchd [1]
User ID:               502

Date/Time:             2024-05-12 09:45:50.5094 +0100
OS Version:            macOS 14.4.1 (23E224)
Report Version:        12
Anonymous UUID:        18F4F6F8-A74A-22F5-9301-22A3D5ADE52C

Sleep/Wake UUID:       B80AD04F-BC86-46C1-82AA-E18EEAD52811

Time Awake Since Boot: 260000 seconds
Time Since Wake:       7617 seconds

System Integrity Protection: enabled

Crashed Thread:        20  BeebThread

Exception Type:        EXC_BAD_ACCESS (SIGSEGV)
Exception Codes:       KERN_INVALID_ADDRESS at 0x0000000000000058
Exception Codes:       0x0000000000000001, 0x0000000000000058

Termination Reason:    Namespace SIGNAL, Code 11 Segmentation fault: 11
Terminating Process:   exc handler [72104]

VM Region Info: 0x58 is not in any region.  Bytes before following region: 4484173736
      REGION TYPE                    START - END         [ VSIZE] PRT/MAX SHRMOD  REGION DETAIL
      UNUSED SPACE AT START
--->  
      __TEXT                      10b471000-10b99d000    [ 5296K] r-x/r-x SM=COW  /var/folders/*/b2 Debug.app/Contents/MacOS/b2

Thread 0:: Main Thread Dispatch queue: com.apple.main-thread
0   libsystem_platform.dylib      	    0x7ff8104e4609 _platform_memmove$VARIANT$Haswell + 41
1   b2                            	       0x10b6fc9b8 TVOutput::CopyTexturePixels(void*, unsigned long) const + 56
2   b2                            	       0x10b49c587 BeebWindow::EndUpdateTVTexture(bool, BeebWindow::VBlankRecord*, void*, int) + 183
3   b2                            	       0x10b49ca66 BeebWindow::HandleVBlank(unsigned long long) + 534
4   b2                            	       0x10b49e910 BeebWindow::HandleVBlank(VBlankMonitor*, void*, unsigned long long) + 128
5   b2                            	       0x10b4a65a1 BeebWindows::HandleVBlank(VBlankMonitor*, void*, unsigned long long) + 225
6   b2                            	       0x10b4e429a main2(int, char**, std::__1::shared_ptr<MessageList> const&) + 11530
7   b2                            	       0x10b4e148d main + 221
8   dyld                          	    0x7ff81012c366 start + 1942
.
.
.
Thread 20 Crashed:: BeebThread
0   b2                            	       0x10b529ee5 BBCMicro::DebugHandleStep() + 21
1   b2                            	       0x10b586b3b unsigned int BBCMicro::UpdateTemplated<266u>(VideoDataUnit*, SoundDataUnit*) + 699
2   b2                            	       0x10b48d2f7 BeebThread::ThreadMain() + 4087
3   b2                            	       0x10b49207e void* std::__1::__thread_proxy<std::__1::tuple<std::__1::unique_ptr<std::__1::__thread_struct, std::__1::default_delete<std::__1::__thread_struct>>, std::__1::__bind<void (BeebThread::*)(), BeebThread*>>>(void*) + 62
4   libsystem_pthread.dylib       	    0x7ff8104b818b _pthread_start + 99
5   libsystem_pthread.dylib       	    0x7ff8104b3ae3 thread_start + 15
.
.
.

Thread 20 crashed with X86 Thread State (64-bit):
  rax: 0x0728d55a331200fd  rbx: 0x00007fcb20581580  rcx: 0x00007fcb20960018  rdx: 0x0000000000000000
  rdi: 0x00007fcb32841a00  rsi: 0x0000000000000000  rbp: 0x000070000e9c9600  rsp: 0x000070000e9c95f0
   r8: 0x000070000e9c9328   r9: 0x000070000e9c95a0  r10: 0x00000000000003e7  r11: 0x00000fcb1201be2b
  r12: 0x00007fcb20581505  r13: 0x00007fcb32841a00  r14: 0x00007fcb32841a00  r15: 0x000000003182d700
  rip: 0x000000010b529ee5  rfl: 0x0000000000010297  cr2: 0x0000000000000058
  
Logical CPU:     0
Error Code:      0x00000004 (no mapping for user data read)
Trap Number:     14

Thread 20 instruction stream:
  f9 42 00 4c 89 f7 31 c0-e8 1e e5 ff ff 41 f6 c7  .B.L..1......A..
  04 74 2b 80 7b 22 03 77-25 49 8b 14 24 41 0f b7  .t+.{".w%I..$A..
  8e b0 01 00 00 48 8d 35-6e f9 42 00 4c 89 f7 31  .....H.5n.B.L..1
  c0 5b 41 5c 41 5e 41 5f-5d e9 ed e4 ff ff 5b 41  .[A\A^A_].....[A
  5c 41 5e 41 5f 5d c3 0f-1f 40 00 55 48 89 e5 41  \A^A_]...@.UH..A
  56 53 49 89 fe 48 8b 8f-30 25 00 00 48 8b 51 08  VSI..H..0%..H.Q.
 [48]8b 42 58 8b 71 04 83-fe 02 74 26 83 fe 01 0f  H.BX.q....t&....	<==
  85 9e 00 00 00 8a 5a 22-80 fb 06 74 33 80 fb 05  ......Z"...t3...
  0f 85 8d 00 00 00 48 8b-10 48 8d 35 fb f8 42 00  ......H..H.5..B.
  eb 10 80 7a 22 05 75 7b-48 8b 10 48 8d 35 0c f9  ...z".u{H..H.5..
  42 00 4c 89 f7 31 c0 5b-41 5e 5d e9 7b e4 ff ff  B.L..1.[A^].{...
  0f b7 72 28 8b 50 08 48-85 c9 74 1d 66 85 d2 48  ..r(.P.H..t.f..H
tom-seddon commented

Thanks for the report! I've pushed a fix for this and there should be a new prerelease version on its way.

(No ETA for the macOS versions unfortunately. The CI system produce the Windows zips pretty quickly but the macOS ones often take a lot longer.)

  • 👍1
tommy9 commented

Brilliant, thanks for the super quick fix! I confirm it works for me. 🚀

  • 🎉1