Merge changes that enable DTrace-using ports to link correctly with lld
10, avoiding "unknown relocation 8" and other errors.

MFC r312658 (by markj):

Remove the DTRACEHIOC_ADD ioctl.

This ioctl has been considered legacy by upstream since the DTrace code
was first imported, and is unused. The removal also allows some
simplification of dtrace_helper_slurp().

Also remove a bogus copyout in the DTRACEHIOC_ADDDOF handler. Due to a
bug, it would overwrite an in-memory copy of the DOF header rather than
the passed-in DOF helper. Moreover, DTRACEHIOC_ADDDOF already copies the
helper back out automatically since its argument has the IOC_OUT attribute.

MFC r313262 (by markj):

Use PC-relative relocations for USDT probe sites on i386 and amd64.

When recording probe site addresses in the output DOF file, dtrace -G
needs to emit relocations for the .SUNW_dof section in order to obtain
the addresses of functions containing probe sites. DTrace expects the
addresses to be relative to the base address of the final ELF file,
and the amd64 USDT implementation was relying on some unspecified and
incorrect behaviour in the base system GNU ld to achieve this.

This change reimplements the probe site relocation handling to allow
USDT to be used with lld and newer GNU binutils. Specifically, it
makes use of R_X86_64_PC64/R_386_PC32 relocations to obtain the
probe site address relative to the DOF file address, and adds and uses a
new DOF relocation type which computes the final probe site address using
these relative offsets.

Reported by and discussed with: Rafael Esp?ndola
Differential Revision: https://reviews.freebsd.org/D9374

MFC r345359, r345384:
Don't attempt to measure TSC skew when running as a VM guest.

PR: 218452

MFC r333570:
DTrace aarch64: Avoid calling unwind_frame() in the probe context.

MFC r332364:
Assert that dtrace_probe() doesn't re-enter itself.

MFC r323206: Enable dtrace support for mips64 and the ERL kernel config

Turn on the required options in the ERL config file, and ensure
that the fbt module is listed as a dependency for mips in
the modules/dtrace/dtraceall/dtraceall.c file.

MFC r316648:

Corrected misspelled versions of rendezvous.

The MFC maintains smp_no_rendevous_barrier() as a symbol alias of
smp_no_rendezvous_barrier().

__FreeBSD_version bumped to indicate presence of the new name
smp_no_rendezvous_barrier().

Reviewed by: gnn, jhb (email), kib
Differential Revision: https://reviews.freebsd.org/D10313

MFC r326935:
Avoid CPU migration in dtrace_gethrtime() on x86.

MFC r326286:
Don't use pcpu_find() to determine if a CPU ID is valid.

MFC r314370,r318130,r318167:

DTrace related fixes for PowerPC.

r314370:
Unbreak kernel breakpoints, broken for ~4 years now
r318130:
Fix the encoded instruction for FBT traps on powerpc
r318167:
Fix stack tracing in dtrace for powerpc

MFC r315208:
Fix a backwards comparison in the code to dump a DTrace debug buffer.

MFC r313841, r313850:
Prevent CPU migration when checking the DTrace nofault flag on x86.

MFC r313133:
Sync the x86 dis_tables.c with upstream.

MFC r303796:

Two fixups for dtrace

* Use the right incantation to get the next stack pointer.
* Clear EE using the correct instruction sequence.

MFC: 309069

Add tunable to disable destructive dtrace

Submitted by: Joerg Pernfuss <code.jpe@gmail.com>
Reviewed by: rstone, markj

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Set oldfp so the check for fp == oldfp works as expected.

Obtained from: ABT Systems Ltd
Sponsored by: The FreeBSD Foundation

Correct the implementation of dtrace_interrupt_disable/enable.

Pointed out by: andrew
Sponsored by: DARPA, AFRL
Sponsored by: HEIF5

Fix dtrace_interrupt_disable and dtrace_interrupt_enable by having the
former return the current status for the latter to use. Without this we
could enable interrupts when they shouldn't be.

It's still not quite right as it should only update the bits we care about,
bit should be good enough until the correct fix can be tested.

PR: 204270
Obtained from: ABT Systems Ltd
Sponsored by: The FreeBSD Foundation

Try to unbreak the build after r300611 by including the header
defining VM_MIN_KERNEL_ADDRESS.

Sponsored by: DARPA/AFRL

Add initial DTrace support for RISC-V.

Sponsored by: DARPA, AFRL
Sponsored by: HEIF5

Mark all memory before the kernel as toxic to DTrace.

Obtained from: ABT Systems Ltd
Sponsored by: The FreeBSD Foundation

Add an EARLY_AP_STARTUP option to start APs earlier during boot.

Currently, Application Processors (non-boot CPUs) are started by
MD code at SI_SUB_CPU, but they are kept waiting in a "pen" until
SI_SUB_SMP at which point they are released to run kernel threads.
SI_SUB_SMP is one of the last SYSINIT levels, so APs don't enter
the scheduler and start running threads until fairly late in the
boot.

This change moves SI_SUB_SMP up to just before software interrupt
threads are created allowing the APs to start executing kernel
threads much sooner (before any devices are probed). This allows
several initialization routines that need to perform initialization
on all CPUs to now perform that initialization in one step rather
than having to defer the AP initialization to a second SYSINIT run
at SI_SUB_SMP. It also permits all CPUs to be available for
handling interrupts before any devices are probed.

This last feature fixes a problem on with interrupt vector exhaustion.
Specifically, in the old model all device interrupts were routed
onto the boot CPU during boot. Later after the APs were released at
SI_SUB_SMP, interrupts were redistributed across all CPUs.

However, several drivers for multiqueue hardware allocate N interrupts
per CPU in the system. In a system with many CPUs, just a few drivers
doing this could exhaust the available pool of interrupt vectors on
the boot CPU as each driver was allocating N * mp_ncpu vectors on the
boot CPU. Now, drivers will allocate interrupts on their desired CPUs
during boot meaning that only N interrupts are allocated from the boot
CPU instead of N * mp_ncpu.

Some other bits of code can also be simplified as smp_started is
now true much earlier and will now always be true for these bits of
code. This removes the need to treat the single-CPU boot environment
as a special case.

As a transition aid, the new behavior is available under a new kernel
option (EARLY_AP_STARTUP). This will allow the option to be turned off
if need be during initial testing. I plan to enable this on x86 by
default in a followup commit in the next few days and to have all
platforms moved over before 11.0. Once the transition is complete,
the option will be removed along with the !EARLY_AP_STARTUP code.

These changes have only been tested on x86. Other platform maintainers
are encouraged to port their architectures over as well. The main
things to check for are any uses of smp_started in MD code that can be
simplified and SI_SUB_SMP SYSINITs in MD code that can be removed in
the EARLY_AP_STARTUP case (e.g. the interrupt shuffling).

PR: kern/199321
Reviewed by: markj, gnn, kib
Sponsored by: Netflix

Implement FBT provider (MD part) for DTrace on MIPS.
Tested on MIPS64.

Sponsored by: DARPA, AFRL
Sponsored by: HEIF5

add invpcid instruction to i386 dtrace disassembler tables

MFC after: 2 weeks

Add a kern.dtrace.err_verbose sysctl to control dtrace_err_verbose.

When this flag is turned on, DOF and DIF validation errors are printed to
the kernel message buffer. This is useful for debugging.

Also remove the debug.dtrace.debug sysctl, which has no effect.

lahf/sahf are supported on some amd64 processors

While the instructions were not included into the original instruction
set, their support can be indicated by a special feature bit.
For example:
CPU: AMD Phenom(tm) II X4 955 Processor (3214.71-MHz K8-class CPU)
...
AMD Features2=0x37ff<LAHF, ...>

Clang 3.8 uses lahf/sahf as a faster alternative to pushf/popf where
possible.

MFC after: 2 weeks

Make the second argument of dtrace_invop() a trapframe pointer.

Currently this argument is a pointer into the stack which is used by FBT
to fetch the first five probe arguments. On all non-x86 architectures it's
simply the trapframe address, so this change has no functional impact. On
amd64 it's a pointer into the trapframe such that stack[1 .. 5] gives the
first five argument registers, which are deliberately grouped together in
the amd64 trapframe definition.

A trapframe argument simplifies the invop handlers on !x86 and makes the
x86 FBT invop handler easier to understand. Moreover, it allows for invop
handlers that may want to modify the register set of the interrupted thread.

Initialize DTrace hrtimer frequency during SI_SUB_CPU on i386 and amd64.

This allows the hrtimer to be used earlier during boot. This is required
for boot-time DTrace: anonymous enablings are created during
SI_SUB_DTRACE_ANON, which runs before APs are started. In particular,
the DTrace deadman timer requires that the hrtimer be functional.

MFC after: 2 weeks

Implement dtrace_getupcstack in ARM64

Allow using DTRACE for performance analysis of userspace
applications - the function call stack can be captured.
This is almost an exact copy of AMD64 solution.

Obtained from: Semihalf
Sponsored by: Cavium
Reviewed by: emaste, gnn, jhibbits
Differential Revision: https://reviews.freebsd.org/D5779

Remove unused variables dtrace_in_probe and dtrace_in_probe_addr.

Fix a couple of silly mistakes in r291962.

- Handle the case where no DOF helper is provided. This occurs with the
currently-unused DTRACEHIOC_ADD ioctl.
- Fix some checks that prevented the loading DOF in the (non-default)
lazyload mode.

As <machine/vmparam.h> is included from <vm/vm_param.h>, there is no
need to include it explicitly when <vm/vm_param.h> is already included.

Suggested by: alc
Reviewed by: alc
Differential Revision: https://reviews.freebsd.org/D5379

Support an arbitrary number of arguments to DTrace syscall probes.

Rather than pushing all eight possible arguments into dtrace_probe()'s
stack frame, make the syscall_args struct for the current syscall available
via the current thread. Using a custom getargval method for the systrace
provider, this allows any syscall argument to be fetched, even in kernels
that have modified the maximum number of system call arguments.

Sponsored by: EMC / Isilon Storage Division

Modify DTRACEHIOC_ADDDOF to copy the DOF section from the target process.

r281257 added support for lazyload mode by allowing dtrace(1) to register
a DOF section on behalf of a traced process. This was implemented by
having libdtrace copy the DOF section into a heap-allocated buffer and
passing its address to the ioctl handler. However, DTrace uses the DOF
section address as a lookup key in certain cases, so the ioctl handler
should be given the target process' DOF section address instead. This
change modifies the ADDDOF handler to copy the DOF section in from the
target process, rather than from dtrace(1).

Fix a bug in the amd64 dtrace_getarg() implementation: when unwinding the
stack, take into account the copy of rsi pushed between the breakpoint
trapframe and the dtrace_invop frame. Prior to r287644, this was covered
by the fact that sizeof(struct amd64_frame) was 24 rather than 16.

Reported by: smh

dtrace_getarg: remove stray return statement on amd64, powerpc

MFC after: 10 days

Remove the arg0 field from struct amd64_frame. Its existence was a bug,
since on amd64 the first argument to a function is generally not on the
stack.

Revert an old DTrace bug fix to some code that assumed that
sizeof(struct amd64_frame) == 16.

Reviewed by: jhb, kib
Sponsored by: EMC / Isilon Storage Division
Differential Revision: https://reviews.freebsd.org/D3255

When checking for the valid value of the frame pointer, verify that it
belongs to the kernel stack address range for the thread. Right now,
code checks that new frame is not farther then KSTACK_PAGES pages from
the current frame, which allows the address to point past the top of
the stack.

Reviewed by: andrew, emaste, markj
Differential revision: https://reviews.freebsd.org/D3108
Sponsored by: The FreeBSD Foundation
MFC after: 2 weeks

Use single instance of the identical INKERNEL() and PMC_IN_KERNEL()
macros on amd64 and i386. Move the definition to machine/param.h.
kgdb defines INKERNEL() too, the conflict is resolved by renaming kgdb
version to PINKERNEL().

On i386, correct the lowest kernel address. After the shared page was
introduced, USRSTACK no longer points to the last user address + 1 [*]

Submitted by: Oliver Pinter [*]
Sponsored by: The FreeBSD Foundation
MFC after: 1 week

First cut of DTrace for AArch64.

Reviewed by: andrew, emaste
Sponsored by: ARM Limited
Differential Revision: https://reviews.freebsd.org/D2738

Don't re-define LOCORE when dtrace is built-in to the kernel.

Remove unused references to calltrap.

MFC after: 3 days

Remove some commented-out upstream code for handling traps from usermode
DTrace probes. This handling is already done in trap() on i386 and amd64.

Fix DTrace's panic() action.

It would previously call into some unfinished Solaris compatibility code and
return without actually calling panic(9). The compatibility code is
unneeded, however, so just remove it and have dtrace_panic() call vpanic(9)
directly.

Differential Revision: https://reviews.freebsd.org/D2349
Reviewed by: avg
MFC after: 2 weeks
Sponsored by: EMC / Isilon Storage Division

libdtrace: add support for lazyload mode.

Passing "-x lazyload" to dtrace -G during compilation causes dtrace(1) to
not link drti.o into the output object file, so the USDT probes are not created
during process startup. Instead, dtrace(1) will automatically discover and
create probes on the process' behalf when attaching.

Differential Revision: https://reviews.freebsd.org/D2203
Reviewed by: rpaulo
MFC after: 1 month

Import a missing piece of commit b8fac8e162eda7e98d from illumos-gate.

This adds an upper bound, dtrace_ustackdepth_max, to the number of frames
traversed when computing the userland stack depth. Some programs - notably
firefox - are otherwise able to trigger an infinite loop in
dtrace_getustack_common(), causing a panic.

MFC after: 1 week

On ARM, unlike some other architectures, saved $pc values from in-kernel
traps do appear in the regular call stack, rather than only in a special
trap frame, so we don't need to inject the trap-frame $pc into a returned
stack trace in DTrace.

MFC after: 3 days
Sponsored by: DARPA, AFRL

Add support for walltimestamp to DTrace on ARM.

dtrace_cas32 and dtrace_casptr should retrn the data loaded from target
not the new value.

Sponsored by: ABT Systems Ltd

Add the MD parts of dtrace needed to use fbt on ARM. For this we need to
emulate the instructions used in function entry and exit.

For function entry ARM will use a push instruction to push up to 16
registers to the stack. While we don't expect all 16 to be used we need to
handle any combination the compiler may generate, even if it doesn't make
sense (e.g. pushing the program counter).

On function return we will either have a pop or branch instruction. The
former is similar to the push instruction, but with care to make sure we
update the stack pointer and program counter correctly in the cases they
are either in the list of registers or not. For branch we need to take the
24-bit offset, sign-extend it, and add that number of 4-byte words to the
program counter. Care needs to be taken as, due to historical reasons, the
address the branch is relative to is not the current instruction, but 8
bytes later.

This allows us to use the following probes on ARM boards:
dtrace -n 'fbt::malloc:entry { stack() }'
and
dtrace -n 'fbt::free:return { stack() }'

Differential Revision: https://reviews.freebsd.org/D2007
Reviewed by: gnn, rpaulo
Sponsored by: ABT Systems Ltd

Fix build after unifying DAR/DEAR storage in trap frame.

Fix the dtrace ARM atomic compare-and-set functions. These functions are
expected to return the data in the memory location pointed at by target
after the operation. The FreeBSD atomic functions previously used return
either 0 or 1 to indicate if the comparison succeeded or not respectively.

With this change these functions only support ARMv6 and later are supported
by these functions.

Sponsored by: ABT Systems Ltd

Use the ARM unwinder with dtrace to extract the stack when asked. With this
dtrace is able to display a stack trace similar to the one below.

# dtrace -p 603 -n 'tcp:kernel::receive { stack(); }'
0 70 :receive
kernel`ip_input+0x140
kernel`netisr_dispatch_src+0xb8
kernel`ether_demux+0x1c4
kernel`ether_nh_input+0x3a8
kernel`netisr_dispatch_src+0xb8
kernel`ether_input+0x60
kernel`cpsw_intr_rx+0xac
kernel`intr_event_execute_handlers+0x128
kernel`ithread_loop+0xb4
kernel`fork_exit+0x84
kernel`swi_exit
kernel`swi_exit

Tested by: gnn
Sponsored by: ABT Systems Ltd

Initial version of DTrace on ARM32.

Submitted by: Howard Su based on work by Oleksandr Tymoshenko
Reviewed by: ian, andrew, rpaulo, markj

MFV r266993:

4469 DTrace helper tracing should be dynamic

Reference:
https://illumos.org/issues/4469

Obtained from: Illumos
Phabric: D1551
Reviewed by: markj
MFC after: 2 weeks

Mechanically convert cddl sun #ifdef's to illumos

Since the upstream for cddl code is now illumos not sun, mechanically
convert all sun #ifdef's to illumos #ifdef's which have been used in all
newer code for some time.

Also do a manual pass to correct the use if #ifdef comments as per style(9)
as well as few uses of #if defined(__FreeBSD__) vs #ifndef illumos.

MFC after: 1 month
Sponsored by: Multiplay

Restore the trap type argument to the DTrace trap hook, removed in r268600.
It's redundant at the moment since it can be obtained from the trapframe
on the architectures where DTrace is supported, but this won't be the case
with ARM.

Fix multiple incorrect SYSCTL arguments in the kernel:

- Wrong integer type was specified.

- Wrong or missing "access" specifier. The "access" specifier
sometimes included the SYSCTL type, which it should not, except for
procedural SYSCTL nodes.

- Logical OR where binary OR was expected.

- Properly assert the "access" argument passed to all SYSCTL macros,
using the CTASSERT macro. This applies to both static- and dynamically
created SYSCTLs.

- Properly assert the the data type for both static and dynamic
SYSCTLs. In the case of static SYSCTLs we only assert that the data
pointed to by the SYSCTL data pointer has the correct size, hence
there is no easy way to assert types in the C language outside a
C-function.

- Rewrote some code which doesn't pass a constant "access" specifier
when creating dynamic SYSCTL nodes, which is now a requirement.

- Updated "EXAMPLES" section in SYSCTL manual page.

MFC after: 3 days
Sponsored by: Mellanox Technologies

Fix the stack tracing for dtrace/powerpc.

Summary:
Fix the stack tracing for dtrace/powerpc by using the trapexit/asttrapexit
return address sentinels instead of checking within the kernel address space.

As part of this, I had to add new inline functions. FBT traces the kernel, so
we have to have special case handling for this, since a trap will create a full
new trap frame, and there's no way to pass around the 'real' stack. I handle
this by special-casing 'aframes == 0' with the trap frame. If aframes counts
out to the trap frame, then assume we're looking for the full kernel trap frame,
so switch to the real stack pointer.

Test Plan: Tested on powerpc64

Reviewers: rpaulo, markj, nwhitehorn

Reviewed By: markj, nwhitehorn

Differential Revision: https://reviews.freebsd.org/D788

MFC after: 3 week
Relnotes: Yes

Use a C wrapper for trap() instead of checking and calling the DTrace trap
hook in assembly.

Suggested by: kib
Reviewed by: kib (original version)
X-MFC-With: r268600

Invoke the DTrace trap handler before calling trap() on amd64. This matches
the upstream implementation and helps ensure that a trap induced by tracing
fbt::trap:entry is handled without recursively generating another trap.

This makes it possible to run most (but not all) of the DTrace tests under
common/safety/ without triggering a kernel panic.

Submitted by: Anton Rang <anton.rang@isilon.com> (original version)
Phabric: D95

Pull in r267961 and r267973 again. Fix for issues reported will follow.

Revert r267961, r267973:

These changes prevent sysctl(8) from returning proper output,
such as:

1) no output from sysctl(8)
2) erroneously returning ENOMEM with tools like truss(1)
or uname(1)
truss: can not get etype: Cannot allocate memory

Extend the meaning of the CTLFLAG_TUN flag to automatically check if
there is an environment variable which shall initialize the SYSCTL
during early boot. This works for all SYSCTL types both statically and
dynamically created ones, except for the SYSCTL NODE type and SYSCTLs
which belong to VNETs. A new flag, CTLFLAG_NOFETCH, has been added to
be used in the case a tunable sysctl has a custom initialisation
function allowing the sysctl to still be marked as a tunable. The
kernel SYSCTL API is mostly the same, with a few exceptions for some
special operations like iterating childrens of a static/extern SYSCTL
node. This operation should probably be made into a factored out
common macro, hence some device drivers use this. The reason for
changing the SYSCTL API was the need for a SYSCTL parent OID pointer
and not only the SYSCTL parent OID list pointer in order to quickly
generate the sysctl path. The motivation behind this patch is to avoid
parameter loading cludges inside the OFED driver subsystem. Instead of
adding special code to the OFED driver subsystem to post-load tunables
into dynamically created sysctls, we generalize this in the kernel.

Other changes:
- Corrected a possibly incorrect sysctl name from "hw.cbb.intr_mask"
to "hw.pcic.intr_mask".
- Removed redundant TUNABLE statements throughout the kernel.
- Some minor code rewrites in connection to removing not needed
TUNABLE statements.
- Added a missing SYSCTL_DECL().
- Wrapped two very long lines.
- Avoid malloc()/free() inside sysctl string handling, in case it is
called to initialize a sysctl from a tunable, hence malloc()/free() is
not ready when sysctls from the sysctl dataset are registered.
- Bumped FreeBSD version to indicate SYSCTL API change.

MFC after: 2 weeks
Sponsored by: Mellanox Technologies

MFV illumos r266986:

2915 DTrace in a zone should see "cpu", "curpsinfo", et al
2916 DTrace in a zone should be able to access fds[]
2917 DTrace in a zone should have limited provider access

MFC after: 2 weeks

Continue the crusade towards a dev_clone()-free kernel, removing its
usage from dtrace. The dtrace code already uses cdevpriv(9) since FreeBSD
8, so this change should be quite harmless.

Reviewed by: markj
Approved by: markj
MFC after: never

Fix some bugs when fetching probe arguments in i386. Firstly ensure that
the 4 byte-aligned dtrace_invop_callsite can be found and that it
immediately follows the call to dtrace_invop(). Secondly, fix some pointer
arithmetic to account for differences between struct i386_frame and illumos'
struct frame. Finally, ensure that dtrace_getarg() isn't inlined. It works
by following a fixed number of frame pointers to the probe site, so inlining
breaks it.

MFC after: 3 weeks

Fix a couple of bugs on amd64 when fetching probe arguments beyond the
first five for probes entered through a UD fault (i.e. FBT probes).

Specifically, handle the fact that dtrace_invop_callsite must be
16 byte-aligned and thus may not immediately follow the call to
dtrace_invop() in dtrace_invop_start(). Also fetch register arguments and
the stack pointer through a struct trapframe instead of a struct reg.

PR: 191260
Submitted by: luke.tw@gmail.com
MFC after: 3 weeks

Update dis_tables.c to the latest Illumos version.

This includes decodes of recent Intel instructions, in particular
VT-x and related instructions. This allows the FBT provider to
locate the exit points of routines that include these new
instructions.

Illumos issues:
3414 Need a new word of AT_SUN_HWCAP bits
3415 Add isainfo support for f16c and rdrand
3416 Need disassembler support for rdrand and f16c
3413 isainfo -v overflows 80 columns
3417 mdb disassembler confuses rdtscp for invlpg
1518 dis should support AMD SVM/AMD-V/Pacifica instructions
1096 i386 disassembler should understand complex nops
1362 add kvmstat for monitoring of KVM statistics
1363 add vmregs[] variable to DTrace
1364 need disassembler support for VMX instructions
1365 mdb needs 16-bit disassembler support

This corresponds to Illumos-gate (github) version
eb23829ff08a873c612ac45d191d559394b4b408

Reviewed by: markj
MFC after: 1 week

DTrace's pid provider works by inserting breakpoint instructions at probe
sites and installing a hook at the kernel's trap handler. The fasttrap code
will emulate the overwritten instruction in some common cases, but otherwise
copies it out into some scratch space in the traced process' address space
and ensures that it's executed after returning from the trap.

In Solaris and illumos, this (per-thread) scratch space comes from some
reserved space in TLS, accessible via the fs segment register. This
approach is somewhat unappealing on FreeBSD since it would require some
modifications to rtld and jemalloc (for static TLS) to ensure that TLS is
executable, and would thus introduce dependencies on their implementation
details. I think it would also be impossible to safely trace static binaries
compiled without these modifications.

This change implements the functionality in a different way, by having
fasttrap map pages into the target process' address space on demand. Each
page is divided into 64-byte chunks for use by individual threads, and
fasttrap's process descriptor struct has been extended to keep track of
any scratch space allocated for the corresponding process.

With this change it's possible to trace all libc functions in a program,
e.g. with

pid$target:libc.so.*::entry {@[probefunc] = count();}

Previously this would generally cause the victim process to crash, as
tracing memcpy on amd64 requires the functionality described above.

Tested by: Prashanth Kumar <pra_udupi@yahoo.co.in> (earlier version)
MFC after: 6 weeks

Expose a few DTrace parameters as sysctls under kern.dtrace and add
descriptions for several existing sysctls.

PR: 187027
Submitted by: Fedor Indutny <fedor@indutny.com> (original version)
MFC after: 2 weeks

Fix the struct reg mappings for i386 and amd64, which differ between illumos
and FreeBSD.

Submitted by: Prashanth Kumar <pra_udupi@yahoo.co.in>
MFC after: 2 weeks

Move some files that are identical on i386 and amd64 to an x86 subdirectory
rather than keeping duplicate copies.

Discussed with: avg
MFC after: 1 week

Allocate the probe ID unrhdr before the DTrace kld_* event handlers are
registered. Otherwise there is a small window during which probe IDs may be
allocated before the unrhdr is allocated.

MFC after: 2 weeks

Revert r260091. The vmem calls seem to be slower than the *_unr() calls that
they replaced, which is important considering that probe IDs are allocated
during process startup for USDT probes.

Now that vmem(9) is available, use vmem arenas to allocate probe and
aggregation IDs, as is done in the upstream illumos code. This still
requires some FreeBSD-specific code, as our vmem API is not identical to the
one in illumos.

Submitted by: Mike Ma <mikemandarine@gmail.com>

dtrace sdt: remove the ugly sname parameter of SDT_PROBE_DEFINE

In its stead use the Solaris / illumos approach of emulating '-' (dash)
in probe names with '__' (two consecutive underscores).

Reviewed by: markj
MFC after: 3 weeks

- For kernel compiled only with KDTRACE_HOOKS and not any lock debugging
option, unbreak the lock tracing release semantic by embedding
calls to LOCKSTAT_PROFILE_RELEASE_LOCK() direclty in the inlined
version of the releasing functions for mutex, rwlock and sxlock.
Failing to do so skips the lockstat_probe_func invokation for
unlocking.
- As part of the LOCKSTAT support is inlined in mutex operation, for
kernel compiled without lock debugging options, potentially every
consumer must be compiled including opt_kdtrace.h.
Fix this by moving KDTRACE_HOOKS into opt_global.h and remove the
dependency by opt_kdtrace.h for all files, as now only KDTRACE_FRAMES
is linked there and it is only used as a compile-time stub [0].

[0] immediately shows some new bug as DTRACE-derived support for debug
in sfxge is broken and it was never really tested. As it was not
including correctly opt_kdtrace.h before it was never enabled so it
was kept broken for a while. Fix this by using a protection stub,
leaving sfxge driver authors the responsibility for fixing it
appropriately [1].

Sponsored by: EMC / Isilon storage division
Discussed with: rstone
[0] Reported by: rstone
[1] Discussed with: philip

Remove references to an unused fasttrap probe hook, and remove the
corresponding x86 trap type. Userland DTrace probes are currently handled
by the other fasttrap hooks (dtrace_pid_probe_ptr and
dtrace_return_probe_ptr).

Discussed with: rpaulo

ELF PowerPC64 ABI puts the LR save word at 16 byte offset, not 8.

When fetching function arguments out of a frame on amd64, explicitly select
the register based on the argument index rather than relying on the fields
in struct reg to be in the right order. This assumption is incorrect on
FreeBSD and generally led to bogus argument values for the sixth argument
of PID and USDT probes; the first five are passed directly to dtrace_probe()
via the fasttrap trap handler and so were correctly handled.

MFC after: 2 weeks

Add a function, memstr, which can be used to convert a buffer of
null-separated strings to a single string. This can be used to print the
full arguments of a process using execsnoop (from the DTrace toolkit) or
with the following one-liner:

dtrace -n 'syscall::execve:return {trace(curpsinfo->pr_psargs);}'

Note that this relies on the process arguments being cached via the struct
proc, which means that it will not work for argvs longer than
kern.ps_arg_cache_limit. However, the following rather non-portable
script can be used to extract any argv at exec time:

fbt::kern_execve:entry
{
printf("%s", memstr(args[1]->begin_argv, ' ',
args[1]->begin_envv - args[1]->begin_argv));
}

The debug.dtrace.memstr_max sysctl limits the maximum argument size to
memstr(). Thanks to Brendan Gregg for helpful comments on freebsd-dtrace.

Tested by: Fabian Keil (earlier version)
MFC after: 2 weeks

Initialize and free the DTrace taskqueue in the dtrace module load/unload
handlers rather than in the dtrace device open/close methods. The current
approach can cause a panic if the device is closed which the taskqueue
thread is active, or if a kernel module containing a provider is unloaded
while retained enablings are present and the dtrace device isn't opened.

Submitted by: gibbs (original version)
Reviewed by: gibbs
Approved by: re (glebius)
MFC after: 2 weeks

- Use make_dev_credf(MAKEDEV_REF) instead of the race-prone make_dev()+
dev_ref() in the clone handlers that still use it.
- Don't set SI_CHEAPCLONE flag, it's not used anywhere neither in devfs
(for anything real)

Reviewed by: kib

Whitespace cleanup.

Fixes for DTrace on PowerPC:

- Implement dtrace_getarg()
- Sync fbt with x86, and fix a typo.
- Pull in the time synchronization code from amd64.

Rename the kld_unload event handler to kld_unload_try, and add a new
kld_unload event handler which gets invoked after a linker file has been
successfully unloaded. The kld_unload and kld_load event handlers are now
invoked with the shared linker lock held, while kld_unload_try is invoked
with the lock exclusively held.

Convert hwpmc(4) to use these event handlers instead of having
kern_kldload() and kern_kldunload() invoke hwpmc(4) hooks whenever files are
loaded or unloaded. This has no functional effect, but simplifes the linker
code somewhat.

Reviewed by: jhb

Make dtrace_copy() actually work on PowerPC. Although unused currently,
it may be used in the future by dtrace.

Fix some ppc64 dtrace bugs, and enable systrace_freebsd32 for ppc64.

Use kld_{load,unload} instead of mod_{load,unload} for the linker file load
and unload event handlers added in r254266.

Reported by: jhb
X-MFC with: r254266

FreeBSD's DTrace implementation has a few problems with respect to handling
probes declared in a kernel module when that module is unloaded. In
particular,

* Unloading a module with active SDT probes will cause a panic. [1]
* A module's (FBT/SDT) probes aren't destroyed when the module is unloaded;
trying to use them after the fact will generally cause a panic.

This change fixes both problems by porting the DTrace module load/unload
handlers from illumos and registering them with the corresponding
EVENTHANDLER(9) handlers. This allows the DTrace framework to destroy all
probes defined in a module when that module is unloaded, and to prevent a
module unload from proceeding if some of its probes are active. The latter
problem has already been fixed for FBT probes by checking lf->nenabled in
kern_kldunload(), but moving the check into the DTrace framework generalizes
it to all kernel providers and also fixes a race in the current
implementation (since a probe may be activated between the check and the
call to linker_file_unload()).

Additionally, the SDT implementation has been reworked to define SDT
providers/probes/argtypes in linker sets rather than using SYSINIT/SYSUNINIT
to create and destroy SDT probes when a module is loaded or unloaded. This
simplifies things quite a bit since it means that pretty much all of the SDT
code can live in sdt.ko, and since it becomes easier to integrate SDT with
the DTrace framework. Furthermore, this allows FreeBSD to be quite flexible
in that SDT providers spanning multiple modules can be created on the fly
when a module is loaded; at the moment it looks like illumos' SDT
implementation requires all SDT probes to be statically defined in a single
kernel table.

PR: 166927, 166926, 166928
Reported by: davide [1]
Reviewed by: avg, trociny (earlier version)
MFC after: 1 month

opensolaris code: translate INVARIANTS to DEBUG and ZFS_DEBUG

Do this by forcing inclusion of
sys/cddl/compat/opensolaris/sys/debug_compat.h
via -include option into all source files from OpenSolaris.
Note that this -include option must always be after -include opt_global.h.

Additionally, remove forced definition of DEBUG for some modules and fix
their build without DEBUG.

Also, meaning of DEBUG was overloaded to enable WITNESS support for some
OpenSolaris (primarily ZFS) locks. Now this overloading is removed and
that use of DEBUG is replaced with a new option OPENSOLARIS_WITNESS.

MFC after: 17 days

dtrace disassembler: take the latest/last CDDL code from OpenSolaris

OpenSolaris version is:
13108:33bb8a0301ab
6762020 Disassembly support for Intel Advanced Vector Extensions (AVX)

This corresponds to Illumos-gate (github) version
ab47273fedff893c8ae22ec39ffc666d4fa6fc8b

MFC after: 3 weeks

Hide references to mod_lock. In FreeBSD it is always acquired with the
provider lock held, so its use has no effect.

SDT probes can directly pass up to five arguments as arguments to
dtrace_probe(). Arguments beyond these five must be obtained in an
architecture-specific way; this can be done through the getargval provider
method, and through dtrace_getarg() if getargval isn't overridden.

This change fixes two off-by-one bugs in the way these arguments are fetched
in FreeBSD's DTrace implementation. First, the SDT provider must set the
aframes parameter to 1 when creating a probe. The aframes parameter controls
the number of frames that dtrace_getarg() will step over in order to find
the frame containing the extra arguments. On FreeBSD, dtrace_getarg() is
called in SDT probe context via

dtrace_probe()->dtrace_dif_emulate()->dtrace_dif_variable->dtrace_getarg()

so aframes must be 3 since the arguments are in dtrace_probe()'s frame; it
was previously being called with a value of 2 instead. illumos uses a
different aframes value for SDT probes, but this is because illumos SDT
probes fire by triggering the #UD fault handler rather than calling
dtrace_probe() directly.

The second bug has to do with the way arguments are grabbed out
dtrace_probe()'s frame on amd64. The code currently jumps over the first
stack argument and retrieves the rest of them using a pointer into the
stack. This works on i386 because all of dtrace_probe()'s arguments will be
on the stack and the first argument is the probe ID, which should be
ignored. However, it is incorrect to ignore the first stack argument on
amd64, so we correct the pointer used to access the arguments.

MFC after: 2 weeks

Port the SDT test now that it's possible to create SDT probes that take
seven arguments.

The original test uses Solaris' uadmin system call to trigger the test
probe; this change adds a sysctl to the dtrace_test module and gets the test
program to trigger the test probe via the sysctl handler.

The test is currently failing on amd64 because of some bugs in the way that
probe arguments beyond the first five are obtained - these bugs will be
fixed in a separate change.

Bring back part of r249367 by adding DTrace's temporal option, which allows
users to guarantee that the output of DTrace scripts will be time-ordered.
This option is enabled by adding the line

#pragma D option temporal

to the beginning of a script, or by adding '-x temporal' to the arguments of
dtrace(1).

This change fixes a bug in the original port of the temporal option. This
bug was causing some assertions to fail, so they had been disabled; in this
revision the assertions are working properly and are enabled.

The DTrace version number has been bumped from 1.9.0 to 1.9.1 to reflect
the language change that's being introduced.

This change corresponds to part of illumos-gate commit e5803b76927480:
3021 option for time-ordered output from dtrace(1M)

Reviewed by: pfg
Obtained from: illumos
MFC after: 1 month

Add FBT for PowerPC DTrace. Also, clean up the DTrace assembly code,
much of which is not necessary for PowerPC.

The FBT module can likely be factored into 3 separate files: common,
intel, and powerpc, rather than duplicating most of the code between
the x86 and PowerPC flavors.

All DTrace modules for PowerPC will be MFC'd together once Fasttrap is
completed.

Fix warning: comparison of unsigned expression < 0 is always false.

Reported by: clang

Fix the PowerPC DTrace copy functions. The kernel doesn't hold the same view to
the user map, so use the md copy in/out functions provided by the kernel.

MFC with: r242723

Correct a series of errors in the hand-rolled locking for drace_debug.c:

- Use spinlock_enter()/spinlock_exit() to prevent a thread holding a
debug lock from being preempted to prevent other threads waiting
on that lock from starvation.

- Handle the possibility of CPU migration in between the fetch of curcpu
and the call to spinlock_enter() by saving curcpu in a local variable.

- Use memory barriers to prevent reordering of loads and stores of the
data protected by the lock outside of the critical section

- Eliminate false sharing of the locks by moving them into the structures
that they protect and aligning them to a cacheline boundary.

- Record the owning thread in the lock to make debugging future problems
easier.

Reviewed by: rpaulo (initial version)
MFC after: 2 weeks

Implement DTrace for PowerPC. This includes both 32-bit and 64-bit.

There is one known issue: Some probes will display an error message along the
lines of: "Invalid address (0)"

I tested this with both a simple dtrace probe and dtruss on a few different
binaries on 32-bit. I only compiled 64-bit, did not run it, but I don't expect
problems without the modules loaded. Volunteers are welcome.

MFC after: 1 month

Change UL to ULL since time is 32 bits.

Pointed out by: avg@
MFC after: 2 weeks

Add support for walltimestamp in DTrace.

Submitted by: Fabian Keil
MFC after: 2 weeks

r237748 continuation: fix nopw (0f 1f) behavior with respect to modifiers

To do: proper merge with Illumos vendor area.

Reported by: emaste
Tested by: emaste
Obtained from: Illumos commit 13442:4adbe6de60c8
MFC after: 5 days

r237748 continuation: segment-override prefixes are not invalid in long mode

Update DTrace disassembler accordingly. The code to treat the prefixes
as null prefixes was already in place.
Although in practice compilers seem to generate only cs-prefix for use
in long NOPs, the same treatment is applied to all of cs, ds, es, ss for
consistency.

Reported by: emaste
Tested by: emaste
Obtained from: Illumos commit 13442:4adbe6de60c8 (+ local changes)
MFC after: 5 days

dtrace instruction decoder: add 0x0f 0x1f NOP opcode support

According to the AMD manual the whole range from 0x09 to 0x1f are NOPs.
Intel manual mentions only 0x1f. Use only Intel one for now, it seems
to be the one actually generated by compilers.
Use gdb mnemonic for the operation: "nopw".

[1] AMD64 Architecture Programmer's Manual
Volume 3: General-Purpose and System Instructions
[2] Software Optimization Guide for AMD Family 10h Processors
[3] Intel(R) 64 and IA-32 Architectures Software Developer’s Manual
Volume 2 (2A, 2B & 2C): Instruction Set Reference, A-Z

Tested by: Fabian Keil <freebsd-listen@fabiankeil.de> (earlier version)
MFC after: 3 days

Integrate a fix for a very odd signal delivery problem found
by Bryan Cantril and others in the Solaris/Illumos version of DTrace.

Obtained from: https://www.illumos.org/issues/789
MFC after: 2 weeks

Fix DTrace TSC skew calculation:

The skew calculation here is exactly backwards. We were able to repro
it on a multi-package ESX server running a FreeBSD VM, where the TSCs
can be pretty evil.

MFC after: 1 week

Submitted by: Jeff Ford <jeffrey.ford2@isilon.com>
Reviewed by: avg, gnn

- For o32 ABI get arguments from the stack
- Clear CPU_DTRACE_FAULT flag in userland backtrace routine. It just
means we hit wrong memory region and should stop.

Properly cast 64-bit dofhp_dof to pointer.

For i386 this change is no-op. For AMD64 it was tested with DTrace test
suite: results are the same from the test run before the change and after

Use macroses to load/store pointers and increase indexes instead of
hardcoded MIPS64 instructions

Add device part of DTrace/MIPS code

On i386, fbt probes are implemented by writing an invalid opcode over
certain instructions in a function prologue or epilogue. DTrace has a
hook into the invalid opcode fault handler that checks whether the fault
was due to an probe and if so, runs the DTrace magic.

Upon returning from an invalid opcode fault caused by a probe, DTrace must
emulate the instruction that was replaced with the invalid opcode and then
return control to the instruction following the invalid opcode.

There were a pair of related bugs in the emulation for the leave
instruction. The leave instruction is used to pop off a stack frame prior
to returning from a function. The emulation for this instruction must
move the trap frame for the invalid opcode fault down the stack to the
bottom of the stack frame that is being removed, and then execute an iret.

At two points in this process, the emulation code was storing values above
the current value of the stack pointer. This opened up a window in which
if we were two take an interrupt, the trap frame for the interrupt would
overwrite the values stored on the stack, causing the system to panic
later.

The first bug was that at one point the emulation code saves the new value
for $esp above the current stack pointer value. The fix is to save this
value instead inside of the original trap frame. At this point we do
not need the original trap frame so this is safe.

The second bug is that when the emulate code loads $esp from the stack, it
points part-way through the new trap frame instead of at its beginning.
The emulation code adjusts the stack pointer to the correct value
immediately afterwards, but this still leaves a one instruction window in
which an interrupt would corrupt this trap frame. Fix this by adjusting
the stack frame value before loading it into $esp.

This fixes panics in invop_leave on i386 when using fbt return probes.

Reviewed by: rpaulo, attilio
MFC after: 1 week

Define dtrace_cmpset_long in terms of atomic_cmpset_long
and not by virtue of inline assembly. Now this file
compiles on all supported architectures.

With retirement of cpumask_t and usage of cpuset_t for representing a
mask of CPUs, pc_other_cpus and pc_cpumask become highly inefficient.

Remove them and replace their usage with custom pc_cpuid magic (as,
atm, pc_cpumask can be easilly represented by (1 << pc_cpuid) and
pc_other_cpus by (all_cpus & ~(1 << pc_cpuid))).

This change is not targeted for MFC because of struct pcpu members
removal and dependency by cpumask_t retirement.

MD review by: marcel, marius, alc
Tested by: pluknet
MD testing by: marcel, marius, gonzo, andreast

etire the cpumask_t type and replace it with cpuset_t usage.

This is intended to fix the bug where cpu mask objects are
capped to 32. MAXCPU, then, can now arbitrarely bumped to whatever
value. Anyway, as long as several structures in the kernel are
statically allocated and sized as MAXCPU, it is suggested to keep it
as low as possible for the time being.

Technical notes on this commit itself:
- More functions to handle with cpuset_t objects are introduced.
The most notable are cpusetobj_ffs() (which calculates a ffs(3)
for a cpuset_t object), cpusetobj_strprint() (which prepares a string
representing a cpuset_t object) and cpusetobj_strscan() (which
creates a valid cpuset_t starting from a string representation).
- pc_cpumask and pc_other_cpus are target to be removed soon.
With the moving from cpumask_t to cpuset_t they are now inefficient
and not really useful. Anyway, for the time being, please note that
access to pcpu datas is protected by sched_pin() in order to avoid
migrating the CPU while reading more than one (possible) word
- Please note that size of cpuset_t objects may differ between kernel
and userland. While this is not directly related to the patch itself,
it is good to understand that concept and possibly use the patch
as a reference on how to deal with cpuset_t objects in userland, when
accessing kernland members.
- KTR_CPUMASK is changed and now is represented through a string, to be
set as the example reported in NOTES.

Please additively note that no MAXCPU is bumped in this patch, but
private testing has been done until to MAXCPU=128 on a real 8x8x2(htt)
machine (amd64).

Please note that the FreeBSD version is not yet bumped because of
the upcoming pcpu changes. However, note that this patch is not
targeted for MFC.

People to thank for the time spent on this patch:
- sbruno, pluknet and Nicholas Esborn (nick AT desert DOT net) tested
several revision of the patches and really helped in improving
stability of this work.
- marius fixed several bugs in the sparc64 implementation and reviewed
patches related to ktr.
- jeff and jhb discussed the basic approach followed.
- kib and marcel made targeted review on some specific part of the
patch.
- marius, art, nwhitehorn and andreast reviewed MD specific part of
the patch.
- marius, andreast, gonzo, nwhitehorn and jceel tested MD specific
implementations of the patch.
- Other people have made contributions on other patches that have been
already committed and have been listed separately.

Companies that should be mentioned for having participated at several
degrees:
- Yahoo! for having offered the machines used for testing on big
count of CPUs.
- The FreeBSD Foundation for having sponsored my devsummit attendance,
which has been instrumental.
- Sandvine for having offered offices and infrastructure during
development.

(I really hope I didn't forget anyone, if it happened I apologize in
advance).

dtrace: remove unused code

Which is also useless, IMO.

MFC after: 5 days

Use atomic load & store for TSC frequency. It may be overkill for amd64 but
safer for i386 because it can be easily over 4 GHz now. More worse, it can
be easily changed by user with 'machdep.tsc_freq' tunable (directly) or
cpufreq(4) (indirectly). Note it is intentionally not used in performance
critical paths to avoid performance regression (but we should, in theory).
Alternatively, we may add "virtual TSC" with lower frequency if maximum
frequency overflows 32 bits (and ignore possible incoherency as we do now).

Fix typos - remove duplicate "the".

PR: bin/154928
Submitted by: Eitan Adler <lists at eitanadler.com>
MFC after: 3 days

dtrace_xcall: no need for special handling of curcpu

smp_rendezvous_cpus alreadt does the right thing in a very similar
fashion, so the code was kind of duplicating that.

MFC after: 3 weeks

dtrace_gethrtime_init: pin to master while examining other CPUs

Also use pc_cpumask to be future-friendly.

Reviewed by: jhb
MFC after: 2 weeks

Make the /dev/dtrace/helper node have the mode 0660. This allows
programs that refuse to run as root (pgsql) to install probes when their
user is part of the wheel group.

Sponsored by: The FreeBSD Foundation
> Description of fields to fill in above: 76 columns --|
> PR: If a GNATS PR is affected by the change.
> Submitted by: If someone else sent in the change.
> Reviewed by: If someone else reviewed your modification.
> Approved by: If you needed approval for this commit.
> Obtained from: If the change is from a third party.
> MFC after: N [day[s]|week[s]|month[s]]. Request a reminder email.
> Security: Vulnerability reference (one per line) or description.
> Empty fields above will be automatically removed.

M dev/dtrace/dtrace_load.c

Destroy the helper device when unloading.

Sponsored by: The FreeBSD Foundation

Add more compatibility structure members needed by the upcoming fasttrap
DTrace device.

Sponsored by: The FreeBSD Foundation

Kernel DTrace support for:
o uregs (sson@)
o ustack (sson@)
o /dev/dtrace/helper device (needed for USDT probes)

The work done by me was:
Sponsored by: The FreeBSD Foundation

Add a function compatibility function dtrace_instr_size_isa() that on
FreeBSD does the same as dtrace_dis_isize().

Sponsored by: The FreeBSD Foundation

Update several places that iterate over CPUs to use CPU_FOREACH().

dtrace_gethrtime: improve scaling of TSC ticks to nanoseconds

Currently dtrace_gethrtime uses formula similar to the following for
converting TSC ticks to nanoseconds:
rdtsc() * 10^9 / tsc_freq
The dividend overflows 64-bit type and wraps-around every 2^64/10^9 =
18446744073 ticks which is just a few seconds on modern machines.

Now we instead use precalculated scaling factor of
10^9*2^N/tsc_freq < 2^32 and perform TSC value multiplication separately
for each 32-bit half. This allows to avoid overflow of the dividend
described above.
The idea is taken from OpenSolaris.
This has an added feature of always scaling TSC with invariant value
regardless of TSC frequency changes. Thus the timestamps will not be
accurate if TSC actually changes, but they are always proportional to
TSC ticks and thus monotonic. This should be much better than current
formula which produces wildly different non-monotonic results on when
tsc_freq changes.

Also drop write-only 'cp' variable from amd64 dtrace_gethrtime_init()
to make it identical to the i386 twin.

PR: kern/127441
Tested by: Thomas Backman <serenity@exscape.org>
Reviewed by: jhb
Discussed with: current@, bde, gnn
Silence from: jb
Approved by: re (gnn)
MFC after: 1 week

dtrace/amd64: fix virtual address checks

On amd64 KERNBASE/kernbase does not mean start of kernel memory.
This should fix a KASSERT panic in dtrace_copycheck when copyin*()
is used in D program.
Also make checks for user memory a bit stricter.

Reported by: Thomas Backman <serenity@exscape.org>
Submitted by: wxs (kaddr part)
Tested by: Thomas Backman (prototype), wxs
Reviewed by: alc (concept), jhb, current@
Aprroved by: jb (concept)
MFC after: 2 weeks
PR: kern/134408

Remove unused variable.

Found with: Coverity Prevent(tm)
CID: 3669,3671

Approved by: jb

Merge latest DTrace changes from Perforce.

Remove unit2minor() use from kernel code.

When I changed kern_conf.c three months ago I made device unit numbers
equal to (unneeded) device minor numbers. We used to require
bitshifting, because there were eight bits in the middle that were
reserved for a device major number. Not very long after I turned
dev2unit(), minor(), unit2minor() and minor2unit() into macro's.
The unit2minor() and minor2unit() macro's were no-ops.

We'd better not remove these four macro's from the kernel, because there
is a lot of (external) code that may still depend on them. For now it's
harmless to remove all invocations of unit2minor() and minor2unit().

Reviewed by: kib

Custom DTrace kernel module files plus FreeBSD-specific DTrace providers.