thread: Remove kernel stack swapping support, part 4

- Remove the IS_SWAPPED thread inhibitor state.
- Remove all uses of TD_IS_SWAPPED() in the kernel.
- Remove the TDF_CANSWAP flag.
- Remove the P

thread: Remove kernel stack swapping support, part 4

- Remove the IS_SWAPPED thread inhibitor state.
- Remove all uses of TD_IS_SWAPPED() in the kernel.
- Remove the TDF_CANSWAP flag.
- Remove the P_SWAPPINGOUT and P_SWAPPINGIN flags.

Tested by: pho
Reviewed by: alc, imp, kib
Differential Revision: https://reviews.freebsd.org/D46115

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sys/gdb: Support hardware breakpoints

Support the use of hardware breakpoints in the kernel gdb stub.

Reviewed by: jhb (earlier version)
Sponsored by: Arm Ltd
Differential Revision: https://reviews

sys/gdb: Support hardware breakpoints

Support the use of hardware breakpoints in the kernel gdb stub.

Reviewed by: jhb (earlier version)
Sponsored by: Arm Ltd
Differential Revision: https://reviews.freebsd.org/D44354

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sys: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remov

sys: Automated cleanup of cdefs and other formatting

Apply the following automated changes to try to eliminate
no-longer-needed sys/cdefs.h includes as well as now-empty
blank lines in a row.

Remove /^#if.*\n#endif.*\n#include\s+<sys/cdefs.h>.*\n/
Remove /\n+#include\s+<sys/cdefs.h>.*\n+#if.*\n#endif.*\n+/
Remove /\n+#if.*\n#endif.*\n+/
Remove /^#if.*\n#endif.*\n/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/types.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/param.h>/
Remove /\n+#include\s+<sys/cdefs.h>\n#include\s+<sys/capsicum.h>/

Sponsored by: Netflix

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sys: Remove $FreeBSD$: one-line .c pattern

Remove /^[\s*]*__FBSDID\("\$FreeBSD\$"\);?\s*\n/

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of

spdx: The BSD-2-Clause-FreeBSD identifier is obsolete, drop -FreeBSD

The SPDX folks have obsoleted the BSD-2-Clause-FreeBSD identifier. Catch
up to that fact and revert to their recommended match of BSD-2-Clause.

Discussed with: pfg
MFC After: 3 days
Sponsored by: Netflix

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gdb: report specific stop reason for watchpoints

The remote protocol allows for implementations to report more specific
reasons for the break in execution back to the client [1]. This is
entirely op

gdb: report specific stop reason for watchpoints

The remote protocol allows for implementations to report more specific
reasons for the break in execution back to the client [1]. This is
entirely optional, so it is only implemented for amd64, arm64, and i386
at the moment.

[1] https://sourceware.org/gdb/current/onlinedocs/gdb/Stop-Reply-Packets.html

Reviewed by: jhb
MFC after: 3 weeks
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
NetApp PR: 51
Differential Revision: https://reviews.freebsd.org/D29174

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gdb: allow setting/removing hardware watchpoints

Handle the 'z' and 'Z' remote packets for manipulating hardware
watchpoints.

This could be expanded quite easily to support hardware or software
bre

gdb: allow setting/removing hardware watchpoints

Handle the 'z' and 'Z' remote packets for manipulating hardware
watchpoints.

This could be expanded quite easily to support hardware or software
breakpoints as well.

https://sourceware.org/gdb/onlinedocs/gdb/Packets.html

Reviewed by: cem, markj
MFC after: 3 weeks
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
NetApp PR: 51
Differential Revision: https://reviews.freebsd.org/D29173

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Use atomic loads/stores when updating td->td_state

KCSAN complains about racy accesses in the locking code. Those races are
fine since they are inside a TD_SET_RUNNING() loop that expects the value

Use atomic loads/stores when updating td->td_state

KCSAN complains about racy accesses in the locking code. Those races are
fine since they are inside a TD_SET_RUNNING() loop that expects the value
to be changed by another CPU.

Use relaxed atomic stores/loads to indicate that this variable can be
written/read by multiple CPUs at the same time. This will also prevent
the compiler from doing unexpected re-ordering.

Reported by: GENERIC-KCSAN
Test Plan: KCSAN no longer complains, kernel still runs fine.
Reviewed By: markj, mjg (earlier version)
Differential Revision: https://reviews.freebsd.org/D28569

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gdb(4): allow bulk write of registers

Add support for the remote 'G' packet. This is not widely used by gdb
when 'P' is supported, but is technically required by any remote gdb
stub implementation [

gdb(4): allow bulk write of registers

Add support for the remote 'G' packet. This is not widely used by gdb
when 'P' is supported, but is technically required by any remote gdb
stub implementation [1].

[1] https://sourceware.org/gdb/current/onlinedocs/gdb/Overview.html

Reviewed by: cem
MFC after: 1 week
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
NetApp PR: 44
Differential Revision: https://reviews.freebsd.org/D27644

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gdb(4): handle single register read packets

We support bulk reads of the register set, but not reading specific
registers via the 'p' packet. This is useful at least for the 'call'
command in gdb.

gdb(4): handle single register read packets

We support bulk reads of the register set, but not reading specific
registers via the 'p' packet. This is useful at least for the 'call'
command in gdb.

Reviewed by: cem
MFC after: 1 week
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
NetApp PR: 44
Differential Revision: https://reviews.freebsd.org/D27644

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gdb(4): Don't escape GDB special characters at application layer

In r351368, we introduced this XML- and GDB-encoded data. The protocol
'offset' should reflex the logical XML data offset, but unfor

gdb(4): Don't escape GDB special characters at application layer

In r351368, we introduced this XML- and GDB-encoded data. The protocol
'offset' should reflex the logical XML data offset, but unfortunately we
counted the GDB escapes as well.

In fact, we cannot safely do GDB character escaping at this layer at
all, because we don't know what will be flushed in a packet. It is
bogus to send only the first character of a two-character escape
sequence.

This patch "corrects" the problem by squashing these characters in the
transmitted XML document. It would be nice to transmit the characters
faithfully, but that is a more complicated change. Thread names are a
nice convenience feature for the GDB client, but one can always inspect
td_name or p_comm directly to find the true name.

Reported by: Ka Ho Ng <khng300 AT gmail.com>
Tested by: Ka Ho Ng
Reviewed by: emaste, markj, rlibby
Differential Revision: https://reviews.freebsd.org/D26599

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MFH

Sponsored by: Rubicon Communications, LLC (netgate.com)

gdb(4): Support empty qSupported queries

Technically a client may send a qSupported query without specifying any
client features. We should respond with our supported list in that case
instead of b

gdb(4): Support empty qSupported queries

Technically a client may send a qSupported query without specifying any
client features. We should respond with our supported list in that case
instead of bailing with error.

Reported by: rlibby
Reviewed by: emaste, rlibby, vangyzen
Sponsored by: Isilon
Differential Revision: https://reviews.freebsd.org/D26115

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Merge ^/head r358269 through r358399.

Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (17 of many)

r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly mark

Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (17 of many)

r357614 added CTLFLAG_NEEDGIANT to make it easier to find nodes that are
still not MPSAFE (or already are but aren’t properly marked).
Use it in preparation for a general review of all nodes.

This is non-functional change that adds annotations to SYSCTL_NODE and
SYSCTL_PROC nodes using one of the soon-to-be-required flags.

Mark all obvious cases as MPSAFE. All entries that haven't been marked
as MPSAFE before are by default marked as NEEDGIANT

Approved by: kib (mentor, blanket)
Commented by: kib, gallatin, melifaro
Differential Revision: https://reviews.freebsd.org/D23718

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[PPC] Handle qOffsets packet

On PowerPC, this is needed in order for the debugger to find out
the memory offset where the kernel image was loaded on the remote
target.

This fixes symbol resolution

[PPC] Handle qOffsets packet

On PowerPC, this is needed in order for the debugger to find out
the memory offset where the kernel image was loaded on the remote
target.

This fixes symbol resolution when remote debugging a PowerPC kernel.

Reviewed by: cem
Differential Revision: https://reviews.freebsd.org/D22767

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gdb(4): Implement support for NoAckMode

When the underlying debugport transport is reliable, GDB's additional
checksums and acknowledgements are redundant. NoAckMode eliminates the
the acks and all

gdb(4): Implement support for NoAckMode

When the underlying debugport transport is reliable, GDB's additional
checksums and acknowledgements are redundant. NoAckMode eliminates the
the acks and allows us to skip checking RX checksums. The GDB packet
framing does not change, so unfortunately (valid) checksums are still
included as message trailers.

The gdb(4) stub in FreeBSD advertises support for the feature in response to
the client's 'qSupported' request IFF the current debugport has the
gdb_dbfeatures flag GDB_DBGP_FEAT_RELIABLE set. Currently, only netgdb(4)
supports this feature.

If the remote GDB client supports the feature and does not have it disabled
via a GDB configuration knob, it may instruct our gdb(4) stub to enter
NoAckMode. Unless and until it issues that command, we must continue to
transmit acks as usual (and for now, we continue to wait until we receive
them as well, even if we know the debugport is on a reliable transport).

In the kernel sources, the sense of the flag representing the state of the
feature is reversed from that of the GDB command. (I.e., it is
'gdb_ackmode', not 'gdb_noackmode.') This is to avoid confusing double-
negative conditions.

For reference, see:
* https://sourceware.org/gdb/onlinedocs/gdb/Packet-Acknowledgment.html
* https://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html#QStartNoAckMode

Reviewed by: jhb, markj (both earlier version)
Differential Revision: https://reviews.freebsd.org/D21761

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Implement NetGDB(4)

NetGDB(4) is a component of a system using a panic-time network stack to
remotely debug crashed FreeBSD kernels over the network, instead of
traditional serial interfaces.

There

Implement NetGDB(4)

NetGDB(4) is a component of a system using a panic-time network stack to
remotely debug crashed FreeBSD kernels over the network, instead of
traditional serial interfaces.

There are three pieces in the complete NetGDB system.

First, a dedicated proxy server must be running to accept connections from
both NetGDB and gdb(1), and pass bidirectional traffic between the two
protocols.

Second, the NetGDB client is activated much like ordinary 'gdb' and
similarly to 'netdump' in ddb(4) after a panic. Like other debugnet(4)
clients (netdump(4)), the network interface on the route to the proxy server
must be online and support debugnet(4).

Finally, the remote (k)gdb(1) uses 'target remote <proxy>:<port>' (like any
other TCP remote) to connect to the proxy server.

The NetGDB v1 protocol speaks the literal GDB remote serial protocol, and
uses a 1:1 relationship between GDB packets and sequences of debugnet
packets (fragmented by MTU). There is no encryption utilized to keep
debugging sessions private, so this is only appropriate for local
segments or trusted networks.

Submitted by: John Reimer <john.reimer AT emc.com> (earlier version)
Discussed some with: emaste, markj
Relnotes: sure
Differential Revision: https://reviews.freebsd.org/D21568

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Merge ^/head r351732 through r352104.

gdb(4): Root a sysctl tree at 'debug.gdb.'

Like debug.ddb and debug.kdb. Rename 'debug.gdbcons' to 'debug.gdb.cons,'
but leave the old name as a compatibility alias.

Merge ^/head r351317 through r351731.

Fix i386 build after r351368

Reported by: cy
Submitted by: cy

gdb(4): Style

No functional change.

I was surprised to find that no sys/ header already defines the -1 EOF
convention anywhere, so defined one locally.

gdb(4): Implement qXfer:threads:read

This streams out an XML document over several GDB packets describing all
threads in the system; their ids, name, and any loosely defined "extra info"
we feel lik

gdb(4): Implement qXfer:threads:read

This streams out an XML document over several GDB packets describing all
threads in the system; their ids, name, and any loosely defined "extra info"
we feel like including. For now, I have included a string version of the run
state, similar to some of the DDB logic to stringify thread state.

The benefit of supporting this in addition to the qfThreadInfo/qsThreadInfo
packing is that in this mode, the host gdb does not ask for every thread's
"qThreadExtraInfo," saving per-thread round-trips on "info threads."

To use this feature, (k)gdb needs to be built with the --with-expat option.
I would encourage enabling this option by default in our GDB port, if it is
not already.

Finally, there is another optional attribute you can specify per-thread
called a "handle." Handles are arbitrarily long sequences of bytes,
represented in the XML as hexadecimal. It is unclear to me how or if GDB
actually uses handles for anything. So I have left them out.

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gdb(4): Add basic 'qSupported' support

This is where the host GDB tells us what features it supports, and we
respond with the list we support. For now, just report PacketSize.