1444096 - Spurious segfault when debugging Fennec/GeckoView

Status: NEW

(GeckoView :: General, enhancement, P3)

Description

[James Willcox (:snorp) ([e-mail]) (he/him)]

When you try to debug a GeckoView or Fennec app with lldb, you always get an initial spurious SEGV. This is because SEGVHandler in mozglue (which ElfLoader inherits from) intentionally triggers one to test if the signal handling is working as expected. This is apparently only needed for on-demand compression, which we aren't using anymore. We should either:

1) See if we still run on devices that have this problem. We've raised the minimum SDK version a few times since the on-demand decompression was written, so things may be better now.

2) Not install the SEGV handler at all unless on-demand decompression is required.

Comment 1

[James Willcox (:snorp) ([e-mail]) (he/him)]

glandium, do you have any opinion on the two possible solutions above, are have other options?

Comment 2

[Mike Hommey [:glandium]]

Bug 1376704 removed the code handling on-demand decompression, so it's fine to skip the part that triggers a voluntary segfault in order to find out if the handler provides what's needed for on-demand decompression. I'd still leave the segfault handler, though, because of "system" libraries calling signal(), which break the asmjs handler and/or the crash reporter. (see the comment around sigaction/sys_sigaction)

Comment 3

[Chris Peterson [:cpeterson]]

Tasks and enhancements should have severity N/A.