Native ARM: This is not a language causes hard crash on Ctrl-BREAK

hoglet67 / PiTubeDirect

Bare-metal Raspberry Pi project that attaches to the Acorn TUBE interface and emulates many BBC Micro Co Processors

GNU General Public License v3.0

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New Copro = 15 cycle counter = 28910240960 I_CACHE_MISS = 2962008 D_CACHE_MISS = 130926 tube reset - copro 15 Raspberry Pi Direct 15 ARM Native Client emulator speed 0 Copro Memory size 0 cycle counter = 35703997312 I_CACHE_MISS = 2972473 D_CACHE_MISS = 147139 tube reset - copro 15 Undefined Instruction at A4A22FFC Registers: r[00]=00000001 r[01]=000000AA r[02]=00000000 r[03]=0D973F98 r[04]=000000AA r[05]=000000AA r[06]=AAAAAAAA r[07]=AAAAAAAA r[08]=AAAAAAAA r[09]=AAAAAAAA r[10]=AAAAAAAA r[11]=AAAAAAAA r[12]=AAAAAAAA r[14]=A4A23000 Memory: A4A22FEC=55555555 A4A22FF0=55555555 A4A22FF4=55555555 A4A22FF8=55555555 A4A22FFC=5D555555 <<<<<< A4A23000=55555555 A4A23004=55555555 A4A23008=55555555 A4A2300C=55555555 Flags: NZCV--------------------IFTMMMMM 00100000000000000000000100010011 (Supervisor Mode) Halted waiting for reset Data Abort at 0D4C3FE0 Registers: r[00]=00001000 r[01]=0D974490 r[02]=0D97448F r[03]=00000000 r[04]=20000113 r[05]=A4A23010 r[06]=0D50FB5C r[07]=0D4F3AA0 r[08]=00000000 r[09]=0D4F3A98 r[10]=00000005 r[11]=00000000 r[12]=00000000 r[14]=0D4C3FEC Memory: 0D4C3FD0=EBFD37E6 0D4C3FD4=E2001004 0D4C3FD8=E1880501 0D4C3FDC=EBFF0651 0D4C3FE0=E8FD800F <<<<<< 0D4C3FE4=E92D5FFF 0D4C3FE8=E1A0100D 0D4C3FEC=E14F0000 0D4C3FF0=E92D0009 Flags: NZCV--------------------IFTMMMMM 00000000000000000000000111010011 (Supervisor Mode) Halted waiting for reset

Here's a trace with DEBUG_ARM 1

New Copro = 15
             cycle counter = 33520808960
              I_CACHE_MISS = 3279139
              D_CACHE_MISS = 131018
tube reset - copro 15
Raspberry Pi Direct 15 ARM Native Client
emulator speed 0
Copro Memory size 0
             cycle counter = 39112425024
              I_CACHE_MISS = 3279782
              D_CACHE_MISS = 132409
tube reset - copro 15
Sending banner
Banner sent, awaiting response
Error = 0 00 This is not a language
SWI 00000002 called from 0d4764d0 cpsr=40000113
SWI 00000002 complete cpsr=60000113
SWI 00000000 called from 0d4764d8 cpsr=40000113
SWI 00000000 complete cpsr=80000113
SWI 00000000 called from 0d4764e0 cpsr=40000113
SWI 00000000 complete cpsr=60000113
SWI 00000011 called from 0d4764e4 cpsr=40000113
Calling exit handler at 0d478fb8 with r12 aaaaaaaa
Invoking default exit handler
SWI 00000016 called from 0d478fd0 cpsr=40000113
SWI 00000016 complete cpsr=20000113
Undefined Instruction at 000000F0
Registers:
Registers:
  r[00]=55555555
  r[01]=00000001
  r[02]=00000000
  r[03]=0D8C82AC
  r[04]=000000AA
  r[05]=700000AA
  r[06]=9D1E27FE
  r[07]=AAAAAA00
  r[08]=AAAAAAAA
  r[09]=AAAAAAAA
  r[10]=AAAAAAAA
  r[11]=AAAAAAAA
  r[12]=0D973018
  r[14]=000000F4
Memory:
  000000E0=00000000
  000000E4=00000000
  000000E8=00000000
  000000EC=00000000
  000000F0=F8000000 <<<<<< 
  000000F4=00000000
  000000F8=F87BF95D
  000000FC=00023700
  00000100=58FEF8AD
Flags: 
  NZCV--------------------IFTMMMMM
  00000000000000000000000100010011 (Supervisor Mode)
Halted waiting for reset

It looks like the default exit handler is crashing after SWI_OS_EnterOS (SWI 16):

// This should be called in USR mode whenever OS_Exit or OS_ExitAndDie is called.
static void defaultExitHandler() {
  if (DEBUG_ARM) {
    printf("Invoking default exit handler\r\n");
  }
  // Avoid re-entering ARM Basic
  armbasic = 0;
  // Move back to supervisor mode
  swi(SWI_OS_EnterOS);
  // Jump back to the command prompt
  longjmp(enterOS, 1);
}

I think the bug is the "This is not a language" error is received asynchronously and early in the first invocation of the reset handler, before setjmp(enterOS); has ever been called.

hoglet67 / PiTubeDirect

Native ARM: This is not a language causes hard crash on Ctrl-BREAK #205