runtime: improve hardfault handler and stack reporting on Cortex-M#5380
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runtime: improve hardfault handler and stack reporting on Cortex-M#5380digitalentity wants to merge 1 commit into
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- Add reference to the current goroutine stack (PSP) when showing the hardfault info on Cortex-M.
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aykevl
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May 27, 2026
| // goroutine (thread mode, PSP active). The MSP-based sp above is the | ||
| // scheduler's stack and its PC is garbage in that case. | ||
| pspVal := task.GoroutineStack() | ||
| if pspVal >= 0x20000000 && pspVal < 0x20040000 { |
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Assuming 256kB of RAM seems kind of arbitrary?
I would suggest either using the range according to the Cortex-M memory map (0x2000_0000..0x3fff_ffff) or using the actual chip RAM (currently exposed as _heap_end).
| // reading PSP+0x18 gives the actual faulting PC. | ||
| // | ||
| //export GoroutineStack | ||
| func GoroutineStack() uintptr |
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I suspect you'll also need a declaration of this for -scheduler=cores (try tinygo build -scheduler=cores -target=pico examples/blinky1).
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Add reference to the current goroutine stack (PSP) when showing the hardfault info on Cortex-M. The stack where the hardfault happens is usually the scheduler's stack (MSP), which provides no information about the goroutine that actually caused the fault.
This was required to debug random crashes (#5375). The reason was stack overflow, which trigered the
udfinstruction. The MSP only pointed to the HardFault handler and the PC initially suggested stack corruption and nil dereference, while in reality the stack canary was overwritten which triggered a panic.