The callers of dump_savectx() (i.e., doadump() and livedump_start())
subsequently call dumpsys()/minidumpsys(), which dump the calling
thread's stack when writing the dump. If dump_savectx() gets its own
stack frame, that frame might be clobbered when its caller later calls
dumpsys()/minidumpsys(), making it difficult for debuggers to unwind the
stack.
Fix this by making dump_savectx() a macro, so that savectx() is always
called directly by the function which subsequently calls
dumpsys()/minidumpsys().
This fixes stack unwinding for the panicking thread from arm64
minidumps. The same happened to work on amd64, but kgdb reports the
dump_savectx() calls as coming from dumpsys(), so in that case it
appears to work by accident.
Fixes: c9114f9f86 ("Add new vnode dumper to support live minidumps")
Reviewed by: mhorne, jhb
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D39151
The physical address argument is essentially ignored by every dumper
method. In addition, the dump routines don't actually pass a real
address; every call to dump_append() passes a value of zero for
physical.
Reviewed by: markj
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D35173
Add three hooks to the livedump process: before, after, and for each
block of dumped data. This allows, for example, quiescing the system
before the dump begins or protecting data of interest to ensure its
consistency in the final output.
Reviewed by: markj, kib (previous version)
Reviewed by: debdrup (manpages)
Reviewed by: Pau Amma <pauamma@gundo.com> (manpages)
MFC after: 3 weeks
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D34067
This dumper can instantiate and write the dump's contents to a
file-backed vnode.
Unlike existing disk or network dumpers, the vnode dumper should not be
invoked during a system panic, and therefore is not added to the global
dumper_configs list. Instead, the vnode dumper is constructed ad-hoc
when a live dump is requested using the new ioctl on /dev/mem. This is
similar in spirit to a kgdb session against the live system via
/dev/mem.
As described briefly in the mem(4) man page, live dumps are not
guaranteed to result in a usuable output file, but offer some debugging
value where forcefully panicing a system to dump its memory is not
desirable/feasible.
A future change to savecore(8) will add an option to save a live dump.
Reviewed by: markj, Pau Amma <pauamma@gundo.com> (manpages)
Discussed with: kib
MFC after: 3 weeks
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D33813
