MFC r309676

Export the whole thread name in kinfo_proc

kinfo_proc::ki_tdname is three characters shorter than
thread::td_name. Add a ki_moretdname field for these three
extra characters. Add the new field to kinfo_proc32, as well.
Update all in-tree consumers to read the new field and assemble
the full name, except for lldb's HostThreadFreeBSD.cpp, which
I will handle separately. Bump __FreeBSD_version.

Sponsored by: Dell EMC

MFC r298931, r298981, r299375:

Minor spelling fixes in:
sys/dev, sys/sys

Many of these have user-visible strings.

MFC 287442,287537,288944:
Fix corruption of coredumps due to procstat notes changing size during
coredump generation. The changes in r287442 required some reworking
since the 'fo_fill_kinfo' file op does not exist in stable/10.

287442:
Detect badly behaved coredump note helpers

Coredump notes depend on being able to invoke dump routines twice; once
in a dry-run mode to get the size of the note, and another to actually
emit the note to the corefile.

When a note helper emits a different length section the second time
around than the length it requested the first time, the kernel produces
a corrupt coredump.

NT_PROCSTAT_FILES output length, when packing kinfo structs, is tied to
the length of filenames corresponding to vnodes in the process' fd table
via vn_fullpath. As vnodes may move around during dump, this is racy.

So:

- Detect badly behaved notes in putnote() and pad underfilled notes.

- Add a fail point, debug.fail_point.fill_kinfo_vnode__random_path to
exercise the NT_PROCSTAT_FILES corruption. It simply picks random
lengths to expand or truncate paths to in fo_fill_kinfo_vnode().

- Add a sysctl, kern.coredump_pack_fileinfo, to allow users to
disable kinfo packing for PROCSTAT_FILES notes. This should avoid
both FILES note corruption and truncation, even if filenames change,
at the cost of about 1 kiB in padding bloat per open fd. Document
the new sysctl in core.5.

- Fix note_procstat_files to self-limit in the 2nd pass. Since
sometimes this will result in a short write, pad up to our advertised
size. This addresses note corruption, at the risk of sometimes
truncating the last several fd info entries.

- Fix NT_PROCSTAT_FILES consumers libutil and libprocstat to grok the
zero padding.

287537:
Follow-up to r287442: Move sysctl to compiled-once file

Avoid duplicate sysctl nodes.

288944:
Fix core corruption caused by race in note_procstat_vmmap

This fix is spiritually similar to r287442 and was discovered thanks to
the KASSERT added in that revision.

NT_PROCSTAT_VMMAP output length, when packing kinfo structs, is tied to
the length of filenames corresponding to vnodes in the process' vm map
via vn_fullpath. As vnodes may move during coredump, this is racy.

We do not remove the race, only prevent it from causing coredump
corruption.

- Add a sysctl, kern.coredump_pack_vmmapinfo, to allow users to disable
kinfo packing for PROCSTAT_VMMAP notes. This avoids VMMAP corruption
and truncation, even if names change, at the cost of up to PATH_MAX
bytes per mapped object. The new sysctl is documented in core.5.

- Fix note_procstat_vmmap to self-limit in the second pass. This
addresses corruption, at the cost of sometimes producing a truncated
result.

- Fix PROCSTAT_VMMAP consumers libutil (and libprocstat, via copy-paste)
to grok the new zero padding.

Approved by: re (gjb)

MFC 283624,283630:
Export a list of VM objects in the system via a sysctl. The list can be
examined via 'vmstat -o'. It can be used to determine which files are
using physical pages of memory and how much each is using.

MFC 261780:
Expose OBJT_MGTDEVICE VM objects used for GEM/TTM with drm2 as an
explicit object type.

MFC r260290:

Bring back the old size of the kinfo_file structure to preserve ABI.
Keep only one uint64_t spare for further cap_rights_t expension.

Add a comment clarifying that if the size of this structure changes,
a new sysctl MIB has to be allocate for it and the old structure has
to be returned by the old sysctl MIB.

Requested by: re

MFC r258661:
Add sysctl KERN_PROC_SIGTRAMP to retrieve signal trampoline location for the
given process.

Approved by: re (gjb)

MFC 283624,283630:
Export a list of VM objects in the system via a sysctl. The list can be
examined via 'vmstat -o'. It can be used to determine which files are
using physical pages of memory and how much each is using.

MFC 261780:
Expose OBJT_MGTDEVICE VM objects used for GEM/TTM with drm2 as an
explicit object type.

MFC r260290:

Bring back the old size of the kinfo_file structure to preserve ABI.
Keep only one uint64_t spare for further cap_rights_t expension.

Add a comment clarifying that if the size of this structure changes,
a new sysctl MIB has to be allocate for it and the old structure has
to be returned by the old sysctl MIB.

Requested by: re

MFC r258661:
Add sysctl KERN_PROC_SIGTRAMP to retrieve signal trampoline location for the
given process.

Approved by: re (gjb)