[kernel] Gracefully stop secondary CPUs when shutting down

Prior to this change...

... on x64, ZX_SYSTEM_POWERCTL_SHUTDOWN would aggressively shutdown
secondary CPUs without giving them a chance to complete critical
sections and release spinlocks. This led to hangs during shutdown (see
INTK-390).

... on arm64, the shutdown of secondary CPUs was more controlled as
they were first parked by having each CPU halt itself. However,
runqueues, DPCs, and timers were not properly handled. For example, a
DPC could fire after its CPU has been offlined, resulting in an
assertion failure (ZX-2232).

This change:

- Updates x64 and arm64 to more gracefully shutdown secondary CPUs
- Unifies the graceful shutdown paths for arm64 and x64.
- Implements arch_mp_cpu_unplug, arch_mp_prep_cpu_unplug, and
arch_flush_state_and_halt on arm64
- Changes arm64 to use mp_unplug_cpu_mask_single_locked
- Removes a workaround from userboot/start.c (INTK-390)
- Renames platform_halt_helper to platform_graceful_halt
- Removes unused enum values from platform_halt_reason
- Updates comments for platform_halt and platform_halt_secondary_cpus

Tested: Manually, observed no hangs, no panics. Details below...

- Boot looped 300,000 times ('userboot=bin/ps userboot.shutdown=true')
- qemu/arm64/gicv2
- qemu/arm64/gicv3
- qemu/x64
- Flashed vim2, netbooted, ran 'dm reboot' a few times
- Flashed eve, netbooted, ran 'dm reboot' a few times

ZX-2232 #done

ZX-2228 #comment progress

Change-Id: Ib667b272f516dc2e663aa393c1ec78837535041f

[debuglog] Enable debuglog with the early gfx console

Change-Id: I05f713cf4ec9d21ecd252e9271e9f6dc9ee14fd2

[kernel][devmgr] Add "dm reboot-recovery" command

Adds support for booting into recovery partition

Change-Id: I8e7c15a6b25a878b0e722f016070ba46a1099f9b

[kernel] Use zx_ticks_t as ticks unit, rather than uint64

Change-Id: I189a45336a9c0544de6a93a50f83d9b088dec77e

[kernel][uart] Add a cmdline for overriding bootdata settings

Passing kernel.serial=none will turn serial off.
Passing kernel.serial=legacy on x64 will use the legacy COM1 port.
Not passing kernel.serial will fallback to the bootdata settings.
If no bootdata serial setting is provided, the system on x64
currently defaults to the legacy port.

This also updates the run-zircon script to take a --no-serial
argument for disabling serial. If this option is not provided,
run-zircon will pass kernel.serial=legacy to the kernel.

ZX-1901 #comment Add the cmdline argument

Change-Id: Ied0b159ce0c6ba0542f2a5087c63013f8324e9bc

[kernel][devmgr] Add "reboot-bootloader" command

On platforms that support it, "dm reboot-bootloader" or
"k reboot-bootloader" can be used to reboot into the bootloader,
similar to "adb reboot bootloader" on Android.

ZX-1506 #comment
ZX-1507 #comment

Change-Id: I1773862bf72e0ffa38fec996c7114bad95adb69a

[kernel][ktrace][arm] use the raw tick counter for ktrace on arm

-Add current_ticks() call which uses the appropriate architectural
counter.
-Switch ktrace to using that.

ZX-1387 #comment

Change-Id: I10f1f50c7b464abb241bf719026fbdca046b1226

[kernel][suspend] Define arch/platform suspend/resume hooks

These hooks give the arch and platform layers a chance to preserve state before
suspend to RAM and reinitialize after.

ZX-1184

Change-Id: I0fc1931497db7f413efe4781575e30de3dd1ece0

[kernel][time] Prefer zx_{time,duration}_t to lk_time_t

Change-Id: Ie219c61f2ba7fd073917a6738221e2dde969fc2d

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[kernel][headers] flip remaining headers to #pragma once

Mostly older LK code that wasn't using it.

Change-Id: I57464f1621f8d5b06601a90cf1d6e4124916762d

[x86][pc] Implements mexec for Intel x86 PC

Change-Id: Id257568884e91056bbaab64d8d4650ddfd49ddda

[platform] Implements halt_secondaries and thread_migrate_cpu

Implements two new APIs in the kernel:

(1) platform_halt_secondary_cpus

Halt any CPU cores that are not designated as the boot cpu
as the platform sees fit.

This call is intended to bring the system back into the state
it was in when it booted in order to fascilitate mexec.
This patch implements this call for x86.

(2) thread_migrate_cpu

Pins the current thread on a target CPU and ensures that the
migration has succeded.

In addition, this patch refactors mexec to use the new APIs

Change-Id: Ic05b76dd117e50fdb08f98ce92ccec443c870004

[platform] Define boot cpu id to be 0

Change-Id: Iea5c070f10efeea5d1cf82bb41c5b7c3ef8a4d4a

[pc][crashlog] add platform_recover_crashlog() and nvram crashlog support

- platform_recover_crashlog() provides a way to obtain the crashlog
contents in situations where it will not be located and passed in
via the bootloader
- arm gets a do-nothing implementation
- pc gets an implementation that works with the nvram crashlog
bootdata item, and its platform_stow_crashlog() now favors the
nvram crashlog over the efi variable crashlog if both are
available
- pc: change chipset level reset to a hard reset from a full reset,
to avoid multi-second system-wide reset that could impact memory
integrity

Change-Id: I6b600249e6504f14269dc2fc0f87e6c765073854

[kernel][gigaboot][devmgr] reliable last crashlog mechanism

Introduce platform_stow_crashlog(), a simple API for the panic
path to pass a textual log to the platform in hopes that it will
find its way to the system after a reboot.

For the PC platform, if there is an EFI System Table, attempt to
use EFI Runtime Services to stash this data in an EFI variable.

Gigaboot will read this EFI variable and pass the crashlog to
the booting system as BOOTDATA_LAST_CRASHLOG, erasing the contents
of the variable afterwards.

Devmgr will unpack BOOTDATA_LAST_CRASHLOG into /boot/log/last-panic.txt

Change-Id: I6cc7602a2e85156f8d3353166f4cbc22413a5ae1

[kernel][time] Rename lk_bigtime_t and current_time_hires()

Now that millisecond time is gone from the kernel, reclaim the names
used for it.

lk_bigtime_t -> lk_time_t
current_time_hires() -> current_time()

Change-Id: I7db5de01171096c04a2b12d293e047e6a08a0aef

[kernel][time] Switch kernel to nanoseconds internally

A subsequent diff will rename lk_bigtime_t to lk_time_t and
current_time_hires() to current_time().

Change-Id: Ied15e687714f784e2180aac59c8e0813c83bfcd0

[kernel][syscalls] Add mx_ticks_per_second to return ticks per second.

Together with mx_ticks_get, this can be used to calculate the amount of time
elapsed between two calls to the high-precision timer.

MG-392 #done

Change-Id: Ie1660ce546f544043e562c265f4d10c7dc0301f6

[bluescreen] show panic onscreen after we crash

- provide platform_panic_start() to request that we
prepare to show a panic message.
- call it from panic() and from x86 fatal faults
- fix up the user to kernel display handoff to not
allocate during gfxconsole-rebind-on-panic (oops!)
- for now don't try to replay the debuglog as it is slow
and potentially dangerous if the log is being updated
when we crash

Change-Id: I6b70c2c7bb9bc158f36088d5b08b82e5aaeaf617

[kernel][time] move current_time_hires() to nanoseconds

Find all the cases where it's used (mostly for benchmarking) and
make sure it's in nanoseconds.

Switch the PC time calculations to use the fixed point multiplication
routines.

Change-Id: I06ef9d705dbef3f23e20bf25b7a8c7c8f37a72b4

[kernel][x86] add an IPI vector for halting the other cpus

Hit it in platform_halt() on PC so we can stop the rest of the system.

Change-Id: I52ea88e01dbb6879318103573efacc0d047bfeca

[system] Merge kernel compiler.h with global compiler.h

Change-Id: Ia9f35fdb5321c82a3f844510ca93aada81d2f8c9

[platform] make default platform_get_ramdisk() more robust.

Update documentation.

Change-Id: I6c6b36023b849aba2d1e641a7528aac3bba9d582

[kernel][platform] API to get at the ramdisk image

If such a thing exists.

Change-Id: I65e6abadbedd58fe290b37b3d512b7c328086f03

[magenta] Initial commit