- Add new DB_DEFINE_TABLE and DB_DECLARE_TABLE macros to define new
command tables. DB_DECLARE_TABLE is intended for use in headers
similar to MALLOC_DECLARE and SYSCTL_DECL.
DB_DEFINE_TABLE takes three arguments, the name of the parent table,
the command name, and the name of the table itself, e.g.
DB_DEFINE_TABLE(show, foo, show_foo) defines a new "show foo" table.
- DB_TABLE_COMMAND, DB_TABLE_COMMAND_FLAGS, DB_TABLE_ALIAS, and
DB_ALIAS_FLAGS allow new commands and aliases to be defined. These
are similar to the existing DB_COMMAND, etc. except that they take
an initial argument giving the name of the parent table, e.g.:
DB_TABLE_COMMAND(show_foo, bar, db_show_foo_bar)
defines a new "show foo bar" command.
This provides a cleaner interface than the ad-hoc use of internal
macros like _DB_SET that was required previously (e.g. in cxgbe(4)).
This retires DB_FUNC macro as well as the internal _DB_FUNC macro.
Reviewed by: melifaro, kib, markj
Differential Revision: https://reviews.freebsd.org/D40819
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
This conditionally gives all registered shutdown handlers a chance to
perform the reboot, with cpu_reset() being the fallback. The '\s'
modifier can be used with the command to get the previous behaviour.
The motivation is that some platforms may not be able do anything
meaningful via cpu_reset(), due to a lack of standardized reset
mechanism and/or firmware shortcomings. However, they may have a
separate device driver attached that normally performs the reboot. Such
is the case for some versions of the Raspberry Pi, where reset via PSCI
fails, but the BCM2835 watchdog driver has a shutdown hook.
Reported by: bz
Reviewed by: markj (slightly earlier version)
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D37981
They could potentially be abused to overwrite kernel memory, so
shouldn't be accessible when mac_ddb is loaded.
Reviewed by: mhorne
Fixes: bc4ea61d55cb ("ddb: tag core commands with DB_CMD_MEMSAFE")
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D37105
Some architectures will pretty-print a system call trap in the
backtrace. Rather than printing the symbol, use the syscallname()
function to pull the string from the sv_syscallnames array corresponding
to the process. This simplifies the function somewhat.
Mostly, this will result in dropping the "sys" prefix, e.g. "sys_exit"
will now be printed simply as "exit".
Make two minor tweaks to the function signature: use a u_int for the
syscall number since this is a more correct type (see the 'code' member
of struct syscall_args), and make the thread pointer the first argument.
The latter is more natural and conventional.
Suggested by: jrtc27
Reviewed by: jrtc27, markj, jhb
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D37200
Only i386 and amd64 print the decoded syscall name in the backtrace.
This de-duplication facilitates further changes and adoption by other
platforms.
Reviewed by: jrtc27, markj, jhb
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D36565
With clang 15, the following -Werror warnings is produced:
sys/ddb/db_lex.c:94:14: error: a function declaration without a prototype is deprecated in all versions of C [-Werror,-Wstrict-prototypes]
db_flush_line()
^
void
This is because db_flush_line() is declared with a (void) argument
list, but defined with an empty argument list. Make the definition match
the declaration.
MFC after: 3 days
Generally, access to the kernel debugger is considered to be unsafe from
a security perspective since it presents an unrestricted interface to
inspect or modify the system state, including sensitive data such as
signing keys.
However, having some access to debugger functionality on production
systems may be useful in determining the cause of a panic or hang.
Therefore, it is desirable to have an optional policy which allows
limited use of ddb(4) while disabling the functionality which could
reveal system secrets.
This loadable MAC module allows for the use of some ddb(4) commands
while preventing the execution of others. The commands have been broadly
grouped into three categories:
- Those which are 'safe' and will not emit sensitive data (e.g. trace).
Generally, these commands are deterministic and don't accept
arguments.
- Those which are definitively unsafe (e.g. examine <addr>, search
<addr> <value>)
- Commands which may be safe to execute depending on the arguments
provided (e.g. show thread <addr>).
Safe commands have been flagged as such with the DB_CMD_MEMSAFE flag.
Commands requiring extra validation can provide a function to do so.
For example, 'show thread <addr>' can be used as long as addr can be
checked against the system's list of process structures.
The policy also prevents debugger backends other than ddb(4) from
executing, for example gdb(4).
Reviewed by: markj, pauamma_gundo.com (manpages)
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35371
Add three simple hooks to the debugger allowing for a loaded MAC policy
to intervene if desired:
1. Before invoking the kdb backend
2. Before ddb command registration
3. Before ddb command execution
We extend struct db_command with a private pointer and two flag bits
reserved for policy use.
Reviewed by: markj
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35370
Those which are statically defined in db_command.c.
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35584
This is not completely exhaustive, but covers a large majority of
commands in the tree.
Reviewed by: markj
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35583
This flag value can be used to indicate if a command has the property of
being "memory safe". In this instance, memory safe means that the
command does not allow/enable reads or writes of arbitrary memory,
regardless of the arguments passed to it. For example, 'backtrace' is
considered a memory-safe command since its output is deterministic,
while 'show vnode' is not, since it requires a memory address as an
argument and will print the contents beginning at that location.
Apply the flag to the "show all" command macros. It is expected that
commands added to this table will always exhibit this property.
Reviewed by: markj
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35581
Provide _FLAGS variants of the various command definition macros, in
anticipation of adding a new flag. This can also be used for some
existing commands which require special flag values.
Reviewed by: markj
MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35581
Provide separate helper macros for regular commands and next-level table
commands as they are mutually exclusive. This ensures proper
initialization of each element and allows us to exclude some redundant
fields, such as specifying .more = NULL for every regular command.
Reviewed by: markj, jhb
MFC after: 3 days
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35580
'command' is too generic for something specific to the kernel debugger;
change this so it is less likely to collide with local variable names.
Also rename struct command_table to struct db_command_table.
Reviewed by: markj
MFC after: 1 week
Sponsored by: Juniper Networks, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D35367
It is unused, especially now that the underlying d_dumper methods do not
accept the argument.
Reviewed by: markj
MFC after: 2 weeks
Differential Revision: https://reviews.freebsd.org/D35174
It was needed for mips only, and only kinda sorta worked for mips. It
can be brought back if we grow another architecture that need it.
Sponsored by: Netflix
Move the common kernel function signatures from machine/reg.h to a new
sys/reg.h. This is in preperation for adding PT_GETREGSET to ptrace(2).
Reviewed by: imp, markj
Sponsored by: DARPA, AFRL (original work)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D19830
Use the new kdb variants. Print more specific error messages.
Reviewed by: jhb, markj
MFC after: 3 weeks
Sponsored by: NetApp, Inc.
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D29156
This lets one interrupt DDB's output, which is useful if paging is
disabled and the output device is slow.
This follows a previous implementation in svn r311952 / git
5fddef7999 which was reverted because it
broke DDB type-ahead.
Now, try this again, but with a 512-byte type-ahead buffer. While there
is buffer space, control input is handled and non-control input is
buffered. When the buffer is exhausted, the default is to print a
warning and drop further non-control input in order to continue handling
control input. sysctl debug.ddb.prioritize_control_input can be set to
0 to instead preserve all input but lose immediate handling of control
input. This could for example effect pasting of a large script into the
ddb console.
Suggested by: Anton Rang <rang@acm.org>
Reviewed by: markj
Discussed with: imp
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D28676
Get rid of db_look_char because it's not compatible with db_get_line().
This fixes the following issue:
db> script lockinfo=show alllocks
db> run lockinfo
db:0:lockinfo> how alllocks
No such command; use "help" to list available commands
Reported by: markj
Reviewed by: markj
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D28725
db_cmd_match had an even/odd bug, where if a third command was partially
matched (or any odd number greater than one) the search result would be
set back from CMD_AMBIGUOUS to CMD_FOUND, causing the last command in
the list to be executed instead of failing the match.
Reported by: mlaier
Reviewed by: markj, mlaier, vangyzen
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D28659
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
The debugger is always entered after some kind of kernel trap, often a
breakpoint in kdb_enter(). This means that the most recent trapframe
will include kernel state at the time of the trap, when often it is
desirable to the developer to view the contents of the previous
trapframe. This trapframe often corresponds to the entry from userspace.
The ddb(4) man page claims the ability to display user register state
via the 'u' modifier to `show registers`, but this appears untrue. It is
not obvious from a quick search of the history when this feature was
added, or when it was removed. (Re)implement this feature in
db_show_regs, noting that it is not necessarily populated with userspace
state.
Reviewed by: jhb (earlier version), markj, bcr (manpages)
MFC after: 2 weeks
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D27705
The "findstack", "show all trace", and "show active trace" commands
were iterating over allproc to enumerate threads. This missed threads
executing in exit1() after being removed from allproc.
Reviewed by: kib
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D27829
Not all debugger operations that enumerate threads require thread
stacks to be resident in memory to be useful. Instead, push P_INMEM
checks (if needed) into callers.
Reviewed by: kib
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D27827
Exiting processes that have been removed from allproc but are still
executing are not yet marked PRS_ZOMBIE, so they were not listed (for
example, if a thread panics during exit1()). To detect these
processes, clear p_list.le_prev to NULL explicitly after removing a
process from the allproc list and check for this sentinel rather than
PRS_ZOMBIE when walking the pidhash.
While here, simplify the pidhash walk to use a single outer loop.
Reviewed by: kib
Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D27824
This is useful for stack unwinders which need to avoid out-of-bounds
reads of a kernel stack which can trigger kernel faults.
Reviewed by: kib, markj
Obtained from: CheriBSD
Sponsored by: DARPA
Differential Revision: https://reviews.freebsd.org/D27356
The kernel will never map the first page, so any symbols in that
range cannot refer to addresses. Some third-party assembly files
define internal constants which appear in their symbol table.
Avoiding the lookup for those symbols avoids replacing small offsets
with those symbols during disassembly.
Reported by: Anton Rang <rang%acm.org>
Reviewed by: Anton Rang <rang%acm.org>, markj
MFC after: 2 weeks
Sponsored by: Dell EMC Isilon
Differential Revision: https://reviews.freebsd.org/D26895
It turns out relocating the symbol table itself can cause issues, like fbt
crashing because it applies the offsets to the kernel twice.
This had been previously brought up in rS333447 when the stoffs hack was
added, but I had been unaware of this and reimplemented symtab relocation.
Instead of relocating the symbol table, keep track of the relocation base
in ddb, so the ddb symbols behave like the kernel linker-provided symbols.
This is intended to be NFC on platforms other than PowerPC, which do not
use fully relocatable kernels. (The relbase will always be 0)
* Remove the rest of the stoffs hack.
* Remove my half-baked displace_symbol_table() function.
* Extend ddb initialization to cope with having a relocation offset on the
kernel symbol table.
* Fix my kernel-as-initrd hack to work with booke64 by using a temporary
mapping to access the data.
* Fix another instance of __powerpc__ that is actually RELOCATABLE_KERNEL.
* Change the behavior or X_db_symbol_values to apply the relocation base
when updating valp, to match link_elf_symbol_values() behavior.
Reviewed by: jhibbits
Sponsored by: Tag1 Consulting, Inc.
Differential Revision: https://reviews.freebsd.org/D25223
__builtin_unreachable doesn't raise any compile-time warnings/errors on its
own, so problems with its usage can't be easily detected. While it would be
nice for this situation to change and compilers to at least add a warning
for trivial cases where local state means the instruction can't be reached,
this isn't the case at the moment and likely will not happen.
This commit adds an __assert_unreachable, whose intent is incredibly clear:
it asserts that this instruction is unreachable. On INVARIANTS builds, it's
a panic(), and on non-INVARIANTS it expands to __unreachable().
Existing users of __unreachable() are converted to __assert_unreachable,
to improve debuggability if this assumption is violated.
Reviewed by: mjg
Differential Revision: https://reviews.freebsd.org/D23793
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
_sleep(9), wakeup(9), sleepqueue(9), et al do not dereference or modify the
channel pointers provided in any way; they are merely used as intptrs into a
dictionary structure to match waiters with wakers. Correctly annotate this
such that _sleep() and wakeup() may be used on const pointers without
invoking ugly patterns like __DECONST(). Plumb const through all of the
underlying sleepqueue bits.
No functional change.
Reviewed by: rlibby
Discussed with: kib, markj
Differential Revision: https://reviews.freebsd.org/D22914
Allow commands to specify that (hex) numbers may start with A-F, by adding
the DRT_HEX flag for db_read_token_flags(). As before, numbers containing
invalid digits for the current radix are rejected.
Also, lex ':' and '::' tokens as tCOLON and tCOLONCOLON respectively.
There is a mild conflict here with lexed "identifiers" (tIDENT): ddb
identifiers may contain arbitrary colons, and the ddb lexer is greedy. So
the identifier lex will swallow any colons it finds inside identifiers, and
consumers are still unable to expect the token sequence 'tIDENT tCOLON'.
That limitation does not matter for IPv6 addresses, because the lexer always
attempts to lex numbers before identifiers.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D21509
Add a db_read_token_flags() variant of db_read_token() with configurable
parameters.
Allow specifying an explicit radix for tNUMBER lexing. It overrides the
default inference and db_radix setting.
Also provide the option of yielding any lexed whitespace (tWSPACE) (instead
of ignoring it). This is useful for whitespace-sensitive CS_OWN commands.
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D21459
It is not needed by anything in the kernel and it slightly drives up contention
on both proctree and allproc locks.
Reviewed by: kib
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D21447
