[task] Add a zx_task_suspend with the same behavior as zx_task_suspend_token

ZX-2184 #comment
Test: cq

Change-Id: I9de6de21acb57eea5f4d0f515d087cd92dce271e

[debug] add thread states for fs/gs registers

also delete previously introduced "extra regs" state

ZX-2258 # step 1

TESTED=None (these states are not used at the moment)

Change-Id: I80cf642b82187c209a0f43aeb10052d3ed87016f

[thread] clang-format on fs/gs register related files

ran zircon/scripts/clang-fmt on all the files I am about to edit

ZX-2258 # initial re-formatting

TESTED=None

Change-Id: Id963c5415469078558035c6f28ed39ceff3affce

[thread] Allow, but do not require, ZX_RIGHT_MANAGE_THREAD to allow starting a thread

Change-Id: I6b1cafdffa1158e2b398dba24c4eeee2f08c596e

[syscalls] Add ZX_POL_NEW_PROCESS

Previously, we lacked a policy bit for controlling process creation.
We'll use this policy bit in the future to force clients through
fuchsia.process.Launcher.

Also, hide ZX_POL_MAX from userspace so we can add more policy bits in
the future.

TEST=spawn_launcher_test

Change-Id: Idcba7c7db595774bd10b227da41e4c7249bb83ea

[job] Remove unused zx_job_set_relative_importance

Change-Id: If267a668c17da073fd8c52cff57a51235366a7ad

[syscalls] zx_proces_start should always consume arg_handle

After this CL, zx_process_start always consumes the startup handle
passed to the started process, even in error cases.

ZX-2204 #comment

Change-Id: I10d35a12dec160a3da86df70e3246fd08bcffc64

[debugger] Add thread state for FP regs and FS/GS

Adds FPU, vector, and "extra" states to the CPU states that can be
queried and set via zx_thread_read/write_state.

ZX-2101

Change-Id: Ic809077a62d963bab578ee76379deb0c1e0362c1

[job] Revert "[job][right] Only use ZX_RIGHT_MANAGE_JOB for creating jobs"

This reverts commit 14012b9c9c39c1cccc61193ebd0472fdb2a59862.

Change-Id: If076d0ab32c3898250ab315d634c5d085d4f8e7c

[job][right] Only use ZX_RIGHT_MANAGE_JOB for creating jobs

Change-Id: Ie6674a11f3a2323de03c5d76790a5204a6371e54

[syscalls] Update parameter types and names

This CL updates the parameter types and names for a number of syscalls
to match the Zircon System API rubric. There's more work to do to make
all the syscalls conform to the rubric, but this change is a start.

Change-Id: I218ac5e7e0cbd80a8c69fef7891ad40b78b6b407

[zircon][clean-api] process return code

To have explicit size, in this case int64_t

Change-Id: I9d5bc3d5564787bd5a6146ae952126f6f856db7b

[jobs] Also check the MANAGE_JOB right for allowing job creation

Change-Id: I1933f93c8e1e7a9319e19768c5640334ff688d70

[zircon] thread priority

This is the low level part. There is an API today
but it only operates on the current thread. The
change here allows it to operate on any thread_t

Tests added via 'k thread_tests'

Change-Id: I79beafd15634bb95c69c87846c139da6caa189b8

[threads] Add a token to suspend threads.

Suspending a thread will will return a handle to a token that allows resuming
that thread exactly once. This ensures that different clients suspending and
resuming threads don't stomp on each other's state.

Currently this is implemented as a separate API call to facilitate landing.
In the future task_suspend/resume will use the new signature and the *_token
versions will be deleted.

Refcounting is added on ThreadDispatcher for suspend/resume calls. This
will affect the legacy suspend/resume calls.

ZX-1072

Change-Id: I9ecc63409e2e7dcea733f3ec58db50c1e8b0210b

[syscall][vmo] removal of zx_vmo_{read,write}() actual parameter 16/n

Plumb removal of actual further down.
Still need to plumb into sys_process_{read,write}_memory

ZX-1802

Change-Id: Ibba8ce14815f34a9ca08abf854996418a25d1a87

[zircon] enable zx_thread_set_priority by default

This (still an experiment) was disabled by default, change the
sense and the kernel cmdline flag name so people can still
experiment, but now badness is opt in. See bug for details.

ZX-940 #comment change flag sense.

Change-Id: I034100b319503ae7e810bb04289a42b2bbe117a4

[debugger][vm] Fix process_(read|write)_memory offset clamp

f509df9187 clamped read/writes to the length of the associated VMAR, but
did not take into account the mapping being offset into the VMO. Fix
this and add a test.

Change-Id: Id2dd0551b88e06d2befd7de53b4737a8aa326808

[debugger] Allow threads to be single stepped.

This adds a new thread state parameter to put the thread in single-step
mode (or not). The architecture-specific exception handlers use this
flag to enable or disable single-stepping on the thread before returning
from the exception.

On x86 this sets FLAGS.TF ("trap flag"). On ARM64, this sets
MDSCR_EL1.SS which causes the process state to be set to "single step"
upon exception return.

An alternative would be to standardize on the flags to enable
single-stepping like on X86. On ARM this would be to define bit 21 or
the saved CPSR flags bit to be "single step" and then set MDSCR_EL1
accordingly before returning from the exception. On ARM32 this bit is
defined, but on ARM64 it is always undefined and you can only control
the single step state indirectly.

While this alternate approach would have enabled us to avoid the new
bool on the thread structure, using a reserved bit on the flags seemed
like a bad idea that might bite us in the future (even if it's very
unlikely). This approach is also much cleaner from an API perspective
since there is a clear step state that is toggleable, rather than
relying on CPU-specific behavior (ARM clears the SS bit after doing a
step, x86 doesn't, for example).

Change-Id: I1ef441aca6728d7837098290106fdab07e178c4c

[debugger] Remove out param for thread_read_state

The size of data being read and written should always be known in advance by
both caller and callee.

Removes backward-compatibility definitions from debug.h since the API is
currently changing in a non-backwards-compatible-way and we need to update
callers anyway. There were many changes associated with removing some users of
these structs and defines.

Add thread_read_state and thread_write_state to the zx::thread class.

Change-Id: I6d7e428d337f2722c529b68074dff16356984d63

[debugger] Clarify thread state API

Firms up the contract for zx_read|write_thread_state and makes the state more
explicit for each platform.

The general register struct has been made for the current platform which
simplifies much fo the code.

The sizes are converted to size_t for consistency with other object calls.

Forwarding #defines and typedefs are included for downstream users until they
can be updated.

This will likely need to be revised somewhat again when we add more thread
states, which I plan to do in a followup.

Change-Id: I57e8e9979d073c8efdfaeb2683f9f83494d19abf

[kernel][vm] Make sys_process_(read|write)_memory() clamp to mapping end

Previously, process_(read|write)_memory() would read/write any amount
out of the VMO in which it was started. Instead, clamp the length to
the mapped region. This is still not a full solution, as an ideal API
would need to read from the correct VMO for each page in the region,
but it's slightly less unexpected behavior.

ZX-1631

Change-Id: I24d543fd867160479e8e59b2a4951b6a87774314

[kernel][syscalls] Remove redundant filename prefix

All of these files are already in a directory named syscalls.

Change-Id: If4945b107c2ae9787e63dfbfe3750d7dfdba739b