runtime: print hexdump on traceback failure
Currently, if anything goes wrong when printing a traceback, we simply
cut off the traceback without any further diagnostics. Unfortunately,
right now, we have a few issues that are difficult to debug because
the traceback simply cuts off (#21431, #23484).
This is an attempt to improve the debuggability of traceback failure
by printing a diagnostic message plus a hex dump around the failed
traceback frame when something goes wrong.
The failures look like:
goroutine 5 [running]:
runtime: unexpected return pc for main.badLR2 called from 0xbad
stack: frame={sp:0xc42004dfa8, fp:0xc42004dfc8} stack=[0xc42004d800,0xc42004e000)
000000c42004dea8:
0000000000000001 0000000000000001
000000c42004deb8:
000000c42004ded8 000000c42004ded8
000000c42004dec8:
0000000000427eea <runtime.dopanic+74>
000000c42004ded8
000000c42004ded8:
000000000044df70 <runtime.dopanic.func1+0>
000000c420001080
000000c42004dee8:
0000000000427b21 <runtime.gopanic+961>
000000c42004df08
000000c42004def8:
000000c42004df98 0000000000427b21 <runtime.gopanic+961>
000000c42004df08:
0000000000000000 0000000000000000
000000c42004df18:
0000000000000000 0000000000000000
000000c42004df28:
0000000000000000 0000000000000000
000000c42004df38:
0000000000000000 000000c420001080
000000c42004df48:
0000000000000000 0000000000000000
000000c42004df58:
0000000000000000 0000000000000000
000000c42004df68:
000000c4200010a0 0000000000000000
000000c42004df78:
00000000004c6400 00000000005031d0
000000c42004df88:
0000000000000000 0000000000000000
000000c42004df98:
000000c42004dfb8 00000000004ae7d9 <main.badLR2+73>
000000c42004dfa8: <
00000000004c6400 00000000005031d0
000000c42004dfb8:
000000c42004dfd0 !
0000000000000bad
000000c42004dfc8: >
0000000000000000 0000000000000000
000000c42004dfd8:
0000000000451821 <runtime.goexit+1>
0000000000000000
000000c42004dfe8:
0000000000000000 0000000000000000
000000c42004dff8:
0000000000000000
main.badLR2(0x0)
/go/src/runtime/testdata/testprog/badtraceback.go:42 +0x49
For #21431, #23484.
Change-Id: I8718fc76ced81adb0b4b0b4f2293f3219ca80786
Reviewed-on: https://go-review.googlesource.com/89016
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>