✨ Print stack trace to brain screen on data abort

[ion098]

Summary:

This pr prints the stack addresses to the brain screen during a data abort exception

Motivation:

This change makes it easier to debug data abort exceptions if the user is not connected to the terminal.

References (optional):

N/A

Test Plan:

• Check that it compiles
• Trigger some data abort exceptions and check that the output is correct

[noam987]

Idea behind this PR looks good but there are a few major issues, both stylistically and content wise. I would like the trace to not be global and instead passed into the trace function via __gnu_unwind_Backtrace (source for that can be found here if you want to look at it for your reference: https://github.com/gcc-mirror/gcc/blob/master/libgcc/unwind-arm-common.inc). Feel free to ask follow up questions here or ping me on discord in our beta server or in a help post on VTOW.

[noam987]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[noam987]

Your code also does not compile. Here is a list of the compile errors generated by the pipeline:

src/system/unwind.c:100:10: error: expected identifier or '(' before '[' token
  100 |  uint32_t[12] pcs;
      |          ^
src/system/unwind.c: In function 'trace_fn':
src/system/unwind.c:107:31: error: 'struct <anonymous>' has no member named 'pcs'
  107 |  if (trace.size < sizeof(trace.pcs) / sizeof(trace.pcs[0]))
      |                               ^
src/system/unwind.c:107:51: error: 'struct <anonymous>' has no member named 'pcs'
  107 |  if (trace.size < sizeof(trace.pcs) / sizeof(trace.pcs[0]))
      |                                                   ^
src/system/unwind.c:108:8: error: 'struct <anonymous>' has no member named 'pcs'
  108 |   trace.pcs[trace.size++] = pc;
      |        ^
src/system/unwind.c: In function 'report_data_abort':
src/system/unwind.c:172:64: error: 'struct <anonymous>' has no member named 'pcs'
  172 |   vexDisplayString(brain_line_no++, "%p %p %p %p", (void*)trace.pcs[4*i], (void*)trace.pcs[4*i+1], (void*)trace.pcs[4*i+2], (void*)trace.pcs[4*i+3]);
      |                                                                ^
src/system/unwind.c:172:87: error: 'struct <anonymous>' has no member named 'pcs'
  172 |   vexDisplayString(brain_line_no++, "%p %p %p %p", (void*)trace.pcs[4*i], (void*)trace.pcs[4*i+1], (void*)trace.pcs[4*i+2], (void*)trace.pcs[4*i+3]);
      |                                                                                       ^
src/system/unwind.c:172:112: error: 'struct <anonymous>' has no member named 'pcs'
  172 |   vexDisplayString(brain_line_no++, "%p %p %p %p", (void*)trace.pcs[4*i], (void*)trace.pcs[4*i+1], (void*)trace.pcs[4*i+2], (void*)trace.pcs[4*i+3]);
      |                                                                                                                ^
src/system/unwind.c:172:137: error: 'struct <anonymous>' has no member named 'pcs'
  172 |   vexDisplayString(brain_line_no++, "%p %p %p %p", (void*)trace.pcs[4*i], (void*)trace.pcs[4*i+1], (void*)trace.pcs[4*i+2], (void*)trace.pcs[4*i+3]);
      |                                                                                                                                         ^
src/system/unwind.c:176:62: error: 'struct <anonymous>' has no member named 'pcs'
  176 |    vexDisplayString(brain_line_no++, "%p %p %p", (void*)trace.pcs[trace.size-2], (void*)trace.pcs[trace.size-1], (void*)trace.pcs[trace.size]);
      |                                                              ^
src/system/unwind.c:176:94: error: 'struct <anonymous>' has no member named 'pcs'
  176 |    vexDisplayString(brain_line_no++, "%p %p %p", (void*)trace.pcs[trace.size-2], (void*)trace.pcs[trace.size-1], (void*)trace.pcs[trace.size]);
      |                                                                                              ^
src/system/unwind.c:176:126: error: 'struct <anonymous>' has no member named 'pcs'
  176 |    vexDisplayString(brain_line_no++, "%p %p %p", (void*)trace.pcs[trace.size-2], (void*)trace.pcs[trace.size-1], (void*)trace.pcs[trace.size]);
      |                                                                                                                              ^
src/system/unwind.c:179:59: error: 'struct <anonymous>' has no member named 'pcs'
  179 |    vexDisplayString(brain_line_no++, "%p %p", (void*)trace.pcs[trace.size-1], (void*)trace.pcs[trace.size]);
      |                                                           ^
src/system/unwind.c:179:91: error: 'struct <anonymous>' has no member named 'pcs'
  179 |    vexDisplayString(brain_line_no++, "%p %p", (void*)trace.pcs[trace.size-1], (void*)trace.pcs[trace.size]);
      |                                                                                           ^
src/system/unwind.c:182:56: error: 'struct <anonymous>' has no member named 'pcs'
  182 |    vexDisplayString(brain_line_no++, "%p", (void*)trace.pcs[trace.size]);
      |                                                        ^
make: *** [common.mk:273: bin/system/unwind.c.o] Error 1

[noam987]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[ion098]

@noam987 Do you think that the registers and the heap used and stack remaining should also be printed to the brain screen? Is there enough space to print those? If not, should they be written to a log file on the SD card, if present?

[ion098]

Also, does the stacktrace contain the PC? If so, then that should save a line on the brain screen.

Issues were addressed

[noam987]

Looks much better. Waiting to test this in the lab before I approve it

[noam987]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[noam987]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[noam987]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[noam987]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).