hujun260 opened a new pull request, #17946:
URL: https://github.com/apache/nuttx/pull/17946
## Summary
This PR includes a series of fixes and improvements for the GDB stub and
ARM64
backtrace functionality:
1. **Fix SMP call in IRQ context**: Replace synchronous SMP calls with
asynchronous
equivalents to prevent deadlocks when gdbstub debugpoint operations are
invoked
from interrupt handlers.
2. **Fix ARM64 backtrace register access**: Correct register access in
arm64_backtrace
to use TCB context directly instead of running_regs(), ensuring accurate
stack
traces for non-running tasks.
3. **Improve conditional compilation**: Add proper architecture guards to
prevent
compilation errors in builds without debug support.
## Changes
The following modifications have been made:
1. **libs/libc/gdbstub/lib_gdbstub.c**:
- Add static `smp_call_data_s` structure for SMP communication
- Replace `nxsched_smp_call()` with `nxsched_smp_call_async()` in
`gdb_debugpoint_add()`
- Replace `nxsched_smp_call()` with `nxsched_smp_call_async()` in
`gdb_debugpoint_remove()`
- Initialize async call data using `nxsched_smp_call_init()`
- Add `CONFIG_ARCH_HAVE_DEBUG` guard to prevent undefined references
2. **arch/arm64/src/common/arm64_backtrace.c**:
- Fix `up_backtrace()` to access registers from `tcb->xcp.regs` directly
- Replace `running_regs()[REG_X29]` with `(void
*)(tcb->xcp.regs)[REG_X29]`
- Replace `running_regs()[REG_ELR]` with `(void
*)(tcb->xcp.regs)[REG_ELR]`
- Ensures backtrace works correctly for any task, not just the running
task
## Testing
Tested on:
- **Platform**: NuttX simulator with SMP and debug support enabled
- **Target**: GDB stub debug operations and ARM64 task backtrace
- **Method**:
- Verified SMP debugpoint operations work correctly when called from IRQ
handlers
- Verified backtrace generation for ARM64 tasks with accurate register
values
- Tested with CONFIG_DEBUG_SYMBOLS and CONFIG_GDBSTUB enabled
- **Result**:
- No deadlocks observed when setting/removing debug points from interrupt
context
- Backtrace output correctly reflects TCB register state rather than
current CPU state
## Impact
- **Stability**: Prevents potential deadlocks in debugger operations on SMP
systems
- **Correctness**: Improves accuracy of stack traces for all ARM64 tasks
- **Compatibility**: No breaking changes; all existing APIs remain unchanged
- **Code Quality**: Improves robustness of debug infrastructure
- **Performance**: Negligible impact; async calls are more efficient than
sync in IRQ context
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