Murilo Opsfelder Araujo <muri...@linux.ibm.com> writes: > On Wed, Jul 25, 2018 at 05:00:21PM +1000, Michael Neuling wrote: >> On Tue, 2018-07-24 at 16:27 -0300, Murilo Opsfelder Araujo wrote: >> > This series was inspired by the need to modernize and display more >> > informative messages about unhandled signals. ... >> >> Nice.. the instruction dump would have been very handy when debugging the PCR >> init issue I had a month or so back.
These things may be related :) >> What happens if we get a sudden flood of these from different processes that >> overlap their output? Are we going to be able to match up the process with >> instruction dump? > > As to the flood of messages, ___ratelimit() makes me think that we'll > likely see some warn messages informing how many show_signal_msg() > callbacks were suppressed, instead of interleaved messages and > instruction dumps. > > As to matching process with instruction dump, I believe we'd need more > information to glue them together. > > What if we modify show_instructions() to accept a string prefix to be > printed along with each line? > >> Should we prefix every line with the PID to avoid this? > > That's possible. An alternative would be prefixing each line with the > process name and its PID, as in the first line. For example: > > pandafault[10758]: segfault (11) at 00000000100007d0 nip 000000001000061c > lr 00007fffabc85100 code 2 in pandafault[10000000+10000] > pandafault[10758]: Instruction dump: > pandafault[10758]: 4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 > 7c3f0b78 3d22fffe > pandafault[10758]: 392988d0 f93f0020 e93f0020 39400048 <99490000> > 39200000 7d234b78 383f0040 > > The above can be interleaved with other messages and we'll still be able > to match process and its corresponding instruction dump. Yeah prefixing with the comm and pid is nice. Also the "Instruction dump:" line is a waste of space. I prefer the x86 format, where it's prefixed with "code:", eg: pandafault[10758]: segfault (11) at 00000000100007d0 nip 000000001000061c lr 00007fffabc85100 code 2 in pandafault[10000000+10000] pandafault[10758]: code: 4bfffeec 4bfffee8 3c401002 38427f00 fbe1fff8 f821ffc1 7c3f0b78 3d22fffe pandafault[10758]: code: 392988d0 f93f0020 e93f0020 39400048 <99490000> 39200000 7d234b78 383f0040 cheers
