Commit Graph

8190 Commits

Author SHA1 Message Date
Brandon Bergren
3069380898 [PowerPC][Book-E] Fix missing load base in elf_cpu_parse_dynamic().
When I implemented MD DYNAMIC parsing, I was originally passing a
linker_file_t so that the MD code could relocate pointers.

However, it turns out this isn't even filled in until later, so it was
always 0.

Just pass the load base (ef->address) directly, as that's really the only
thing we were interested in in the first place.

This fixes a crash on RB800 where it was trying to write to an unmapped
address when updating the GOT.

Reviewed by:	jhibbits
Sponsored by:	Tag1 Consulting, Inc.
Differential Revision:	https://reviews.freebsd.org/D24105
2020-03-18 02:58:18 +00:00
Michael Reifenberger
1bc51bad2b Untangle TPR shadowing and APIC virtualization.
This speeds up Windows guests tremendously.

The patch does:
Add a new tuneable 'hw.vmm.vmx.use_tpr_shadowing' to disable TLP shadowing.
Also add 'hw.vmm.vmx.cap.tpr_shadowing' to be able to query if TPR shadowing is used.

Detach the initialization of TPR shadowing from the initialization of APIC virtualization.
APIC virtualization still needs TPR shadowing, but not vice versa.
Any CPU that supports APIC virtualization should also support TPR shadowing.

When TPR shadowing is used, the APIC page of each vCPU is written to the VMCS_VIRTUAL_APIC field of the VMCS
so that the CPU can write directly to the page without intercept.

On vm exit, vlapic_update_ppr() is called to update the PPR.

Submitted by:	Yamagi Burmeister
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D22942
2020-03-10 16:53:49 +00:00
Leandro Lupori
d8c51c6f74 [aacraid] Port driver to big-endian
Port aacraid driver to big-endian (BE) hosts.

The immediate goal of this change is to make it possible to use the
aacraid driver on PowerPC64 machines that have Adaptec Series 8 SAS
controllers.

Adapters supported by this driver expect FIB contents in little-endian
(LE) byte order. All FIBs have a fixed header part as well as a data
part that depends on the command being issued to the controller.

In this way, on BE hosts, the FIB header and all FIB data structures
used in aacraid.c and aacraid_cam.c need to be converted to LE before
being sent to the adapter and converted to BE when coming from it.

The functions to convert each struct are on aacraid_endian.c.
For little-endian (LE) targets, they are macros that expand
to nothing.
In some cases, when only a few fields of a large structure are used,
the fields are converted inline, by the code using them.

PR:		237463
Reviewed by:	jhibbits
Sponsored by:	Eldorado Research Institute (eldorado.org.br)
Differential Revision:	https://reviews.freebsd.org/D23887
2020-03-05 20:04:41 +00:00
Ryan Libby
cd1da6ff8b amd64 pmap.c: minor codegen optimization in flag access
Following previous revision, apply the same minor optimization to
hand-rolled atomic_fcmpset_128 in pmap.c.

Reviewed by:	kib, markj
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D23870
2020-02-28 18:32:40 +00:00
Ryan Libby
6d1a70dd0a amd64 atomic.h: minor codegen optimization in flag access
Previously the pattern to extract status flags from inline assembly
blocks was to use setcc in the block to write the flag to a register.
This was suboptimal in a few ways:
 - It would lead to code like: sete %cl; test %cl; jne, i.e. a flag
   would just be loaded into a register and then reloaded to a flag.
 - The setcc would force the block to use an additional register.
 - If the client code didn't care for the flag value then the setcc
   would be entirely pointless but could not be eliminated by the
   optimizer.

A more modern inline asm construct (since gcc 6 and clang 9) allows for
"flag output operands", where a C variable can be written directly from
a flag.  The optimizer can then use this to produce direct code where
the flag does not take a trip through a register.

In practice this makes each affected operation sequence shorter by five
bytes of instructions.  It's unlikely this has a measurable performance
impact.

Reviewed by:	kib, markj, mjg
Sponsored by:	Dell EMC Isilon
Differential Revision:	https://reviews.freebsd.org/D23869
2020-02-28 18:32:36 +00:00
Brooks Davis
dfa4261db4 Remove trailing whitespace. 2020-02-27 23:06:40 +00:00
Pawel Biernacki
7029da5c36 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
2020-02-26 14:26:36 +00:00
Konstantin Belousov
a324b7f71d Fix IBRS for machines with IBRS_ALL capability.
When turning IBRS mitigation using sysctl, as opposed to loader tunable,
send IPI to tweak MSR on all cores.  Right now code only performed MSR write
onr the CPU where sysctl was run.

Properly report hw.ibrs_active for IBRS_ALL.  Split hw_ibrs_ibpb_active out
from ibrs_active, to keep the current semantic of guiding kernel entry and
exit handlers.

Reported and tested by:	mav
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
2020-02-25 17:26:10 +00:00
Chuck Silvers
2272f66379 amd64: keep PTE bitmasks in sync with target pmap during pv reclaim
in reclaim_pv_chunk_domain(), when we switch to a new target pmap from which
we are trying to reclaim a pv chunk, always update the current PTE bitmasks
to match.

Reviewed by:	kib, markj
Approved by:	imp (mentor)
Sponsored by:	Netflix
2020-02-18 00:02:20 +00:00
Pawel Biernacki
b40598c539 Mark more nodes as CTLFLAG_MPSAFE or CTLFLAG_NEEDGIANT (4 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.

Reviewed by:	kib
Approved by:	kib (mentor)
Differential Revision:	https://reviews.freebsd.org/D23625
X-Generally looks fine:	jhb
2020-02-15 18:57:49 +00:00
Mateusz Guzik
a201ef9d82 amd64: remove no longer needed atomic_load_ptr casts 2020-02-14 23:17:03 +00:00
Mateusz Guzik
082a6b2a92 Make atomic_load_ptr type-aware
Returned value has type based on the argument, meaning consumers no longer
have to cast in the commmon case.

This commit keeps the kernel compilable without patching the rest.
2020-02-14 23:15:41 +00:00
Mateusz Guzik
ed8cd4795c amd64: only check for error != 0 in the inlined part of l1d flush check
this replaces the following near the syscall exit:
cmp    $0x39,%rax
ja     0xffffffff8108f82c
movabs $0x200001800060005,%rcx
bt     %rax,%rcx
jae    0xffffffff8108f82c

with:
test   %edi,%edi
jne    0xffffffff8091a49c
2020-02-14 13:14:19 +00:00
Konstantin Belousov
caab504277 vmm: Add Hygon Dhyana support.
Submitted by:	Pu Wen <puwen@hygon.cn>
Discussed with:	grehan
Reviewed by:	jhb (previous version)
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D23553
2020-02-13 19:03:12 +00:00
Mateusz Guzik
2318ed2508 amd64: provide custom zpcpu set/add/sub routines
Note that clobbers are highly overzealous, can be cleaned up later.
2020-02-12 11:15:33 +00:00
Mateusz Guzik
fb886947d9 amd64: store per-cpu allocations subtracted by __pcpu
This eliminates a runtime subtraction from counter_u64_add.

before:
mov    0x4f00ed(%rip),%rax        # 0xffffffff80c01788 <numfullpathfail4>
sub    0x808ff6(%rip),%rax        # 0xffffffff80f1a698 <__pcpu>
addq   $0x1,%gs:(%rax)

after:
mov    0x4f02fd(%rip),%rax        # 0xffffffff80c01788 <numfullpathfail4>
addq   $0x1,%gs:(%rax)

Reviewed by:	jeff
Differential Revision:	https://reviews.freebsd.org/D23570
2020-02-12 11:12:13 +00:00
Mateusz Guzik
e7ce9c32a7 amd64: remove redundant sa->code assignment from cpu_fetch_syscall_args_fallback
It is already set in the only caller.
2020-02-11 18:15:23 +00:00
Mateusz Guzik
e2b81f518a amd64: clean up counter(9)
- stop open-coding access to per-cpu data, use common macros instead
- consistently use counter_t type where appropriate
2020-02-07 16:22:02 +00:00
Mark Johnston
c3d326fd44 Define MAXCPU consistently between the kernel and KLDs.
This reverts r177661.  The change is no longer very useful since
out-of-tree KLDs will be built to target SMP kernels anyway.  Moveover
it breaks the KBI in !SMP builds since cpuset_t's layout depends on the
value of MAXCPU, and several kernel interfaces, notably
smp_rendezvous_cpus(), take a cpuset_t as a parameter.

PR:		243711
Reviewed by:	jhb, kib
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D23512
2020-02-05 19:08:21 +00:00
Ed Maste
690a8a6acd regen linuxulator sysent after r357577 2020-02-05 16:54:16 +00:00
Ed Maste
fc7510aef7 linuxulator: implement sendfile
Submitted by:	Bora Özarslan <borako.ozarslan@gmail.com>
Submitted by:	Yang Wang <2333@outlook.jp>
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D19917
2020-02-05 16:53:02 +00:00
Mark Johnston
7c390929d9 Fix map locking in the CLEAR_PKRU sysarch(2) handler.
Reported and tested by:	pho
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
2020-02-05 16:09:02 +00:00
Edward Tomasz Napierala
eff8d99fb3 Regen after r357503.
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
2020-02-04 16:02:04 +00:00
Edward Tomasz Napierala
369c4633c1 Add missing linux(4) syscall entries. This fixes missing debug
messages for some of the unimplemented syscalls, in particular
the AIO-related ones.

MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D23231
2020-02-04 16:01:06 +00:00
Mark Johnston
1c29da0279 Reimplement stack capture of running threads on i386 and amd64.
After r355784 the td_oncpu field is no longer synchronized by the thread
lock, so the stack capture interrupt cannot be delievered precisely.
Fix this using a loop which drops the thread lock and restarts if the
wrong thread was sampled from the stack capture interrupt handler.

Change the implementation to use a regular interrupt instead of an NMI.
Now that we drop the thread lock, there is no advantage to the latter.

Simplify the KPIs.  Remove stack_save_td_running() and add a return
value to stack_save_td().  On platforms that do not support stack
capture of running threads, stack_save_td() returns EOPNOTSUPP.  If the
target thread is running in user mode, stack_save_td() returns EBUSY.

Reviewed by:	kib
Reported by:	mjg, pho
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D23355
2020-01-31 15:43:33 +00:00
Mateusz Guzik
aa88cc44f3 amd64: speed up failing case for memcmp
Instead of branching on up to 8 bytes, drop the size to 4.

Assorted clean ups while here.

Validated with glibc test suite.
2020-01-30 19:56:22 +00:00
Mateusz Guzik
f0ddecd745 amd64: revamp memcmp
Borrow the trick from memset and memmove and use the scale/index/base addressing
to avoid branches.

If a mismatch is found, the routine has to calculate the difference. Make sure
there is always up to 8 bytes to inspect. This replaces the previous loop which
would operate over up to 16 bytes with an unrolled list of 8 tests.

Speed varies a lot, but this is a net win over the previous routine with probably
a lot more to gain.

Validated with glibc test suite.
2020-01-28 17:48:17 +00:00
Mark Johnston
f01fe060e6 Regen.
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
2020-01-21 17:28:36 +00:00
Mark Johnston
149afbf3ba Fix 64-bit syscall argument fetching in 32-bit Linux syscall handlers.
The Linux32 system call argument fetcher places each argument (passed in
registers in the Linux x86 system call convention) into an entry in the
generic system call args array.  Each member of this array is 8 bytes
wide, so this approach is broken for system calls that take off_t
arguments.

Fix the problem by splitting l_loff_t arguments in the 32-bit system
call descriptions, the same as we do for FreeBSD32.  Change entry points
to handle this using the PAIR32TO64 macro.

Move linux_ftruncate64() into compat/linux.

PR:		243155
Reported by:	Alex S <iwtcex@gmail.com>
Reviewed by:	kib (previous version)
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D23210
2020-01-21 17:28:22 +00:00
Konstantin Belousov
2ee49fac82 Add support for Hygon Dhyana Family 18h processor.
As a new x86 CPU vendor, Chengdu Haiguang IC Design Co., Ltd (Hygon)
is a joint venture between AMD and Haiguang Information Technology Co.,
Ltd., aims at providing x86 processors for China server market.

The first generation Hygon processor(Dhyana) shares most architecture
with AMD's family 17h, but with different CPU vendor ID("HygonGenuine")
and PCI vendor ID(0x1d94) and family series number 18h(Hygon negotiated
with AMD to confirm that only Hygon use family 18h).

To enable Hygon Dhyana support in FreeBSD, add new definitions
HYGON_VENDOR_ID("HygonGenuine") and X86_VENDOR_HYGON(0x1d94) to identify
Hygon Dhyana CPU.

Initialize the CPU features(topology, local APIC ext, MSI, TSC, hwpstate,
MCA, DEBUG_CTL, etc) for amd64 and i386 mode by sharing the code path of
AMD family 17h.

The changes have been applied on FreeBSD 13.0-CURRENT and tested
successfully on Hygon Dhyana processor.

References:
[1] Linux kernel patches for Hygon Dhyana, merged in 4.20:

https://git.kernel.org/tip/c9661c1e80b609cd038db7c908e061f0535804ef

[2] MSR and CPUID definition:

https://www.amd.com/system/files/TechDocs/54945_PPR_Family_17h_Models_00h-0Fh.pdf

Submitted by:	Pu Wen <puwen@hygon.cn>
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D23163
2020-01-21 13:22:35 +00:00
Kyle Evans
05d7dd739c sysent targets: further cleanup and deduplication
r355473 vastly improved the readability and cleanliness of these Makefiles.
Every single one of them follows the same pattern and duplicates the exact
same logic.

Now that we have GENERATED/SRCS, split SRCS up into the two parameters we'll
use for ${MAKESYSCALLS} rather than assuming a specific ordering of SRCS and
include a common sysent.mk to handle the rest. This makes it less tedious to
make sweeping changes.

Some default values are provided for GENERATED/SYSENT_*; almost all of these
just use a 'syscalls.master' and 'syscalls.conf' in cwd, and they all use
effectively the same filenames with an arbitrary prefix. Most ABIs will be
able to get away with just setting GENERATED_PREFIX and including
^/sys/conf/sysent.mk, while others only need light additions. kern/Makefile
is the notable exception, as it doesn't take a SYSENT_CONF and the generated
files are spread out between ^/sys/kern and ^/sys/sys, but it otherwise fits
the pattern enough to use the common version.

Reviewed by:	brooks, imp
Nice!:		emaste
Differential Revision:	https://reviews.freebsd.org/D23197
2020-01-18 20:37:45 +00:00
Kyle Evans
1171c633fb Set .ORDER for makesyscalls generated files
When either makesyscalls.lua or syscalls.master changes, all of the
${GENERATED} targets are now out-of-date. With make jobs > 1, this means we
will run the makesyscalls script in parallel for the same ABI, generating
the same set of output files.

Prior to r356603 , there is a large window for interlacing output for some
of the generated files that we were generating in-place rather than staging
in a temp dir. After that, we still should't need to run the script more
than once per-ABI as the first invocation should update all of them. Add
.ORDER to do so cleanly.

Reviewed by:	brooks
Discussed with:	sjg
Differential Revision:	https://reviews.freebsd.org/D23099
2020-01-10 18:24:17 +00:00
Pawel Biernacki
a1d7296784 sysctl: mark more nodes as MPSAFE
vm.kvm_size and vm.kvm_free are read only and marked as MPSAFE on i386
already. Mark them as that on amd64 and arm64 too to avoid locking Giant.

Reviewed by:	kib (mentor)
Approved by:	kib (mentor)
Differential Revision:	https://reviews.freebsd.org/D23039
2020-01-06 10:52:13 +00:00
Mateusz Guzik
2e77cad11d locks: add default delay struct
Use it for all primitives. This makes everything fit in 8 bytes.
2020-01-05 12:48:19 +00:00
Alan Cox
1c3a241032 When a copy-on-write fault occurs, pmap_enter() is called on to replace the
mapping to the old read-only page with a mapping to the new read-write page.
To destroy the old mapping, pmap_enter() must destroy its page table and PV
entries and invalidate its TLB entry.  This change simply invalidates that
TLB entry a little earlier, specifically, on amd64 and arm64, before the PV
list lock is held.

Reviewed by:	kib, markj
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D23027
2020-01-04 19:50:25 +00:00
Konstantin Belousov
b837dadd87 bhyve: terminate waiting loops if thread suspension is requested.
PR:	242724
Reviewed by:	markj
Reported and tested by:	Aleksandr Fedorov <aleksandr.fedorov@itglobal.com>
	 (previous version)
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D22881
2020-01-02 22:37:04 +00:00
Edward Tomasz Napierala
cc50333011 Add basic getcpu(2) support to linuxulator. The purpose of this
syscall is to query the CPU number and the NUMA domain the calling
thread is currently running on.  The third argument is ignored.
It doesn't do anything regarding scheduling - it's literally
just a way to query the current state, without any guarantees
you won't get rescheduled an opcode later.

This unbreaks Java from CentOS 8
(java-11-openjdk-11.0.5.10-0.el8_0.x86_64).

Reviewed by:	kib
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D22972
2019-12-31 22:01:08 +00:00
Edward Tomasz Napierala
da7627d797 Regen after r356229.
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
2019-12-31 16:01:37 +00:00
Edward Tomasz Napierala
a8bfc7a85c Fix definitions for Linux getcpu(2).
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
2019-12-31 15:57:29 +00:00
Pawel Biernacki
54666dffa8 linux(4): implement copy_file_range(2)
copy_file_range(2) is implemented natively since r350315, make it available
for Linux binaries too.

Reviewed by:	kib (mentor), trasz (previous version)
Approved by:	kib (mentor)
Differential Revision:	https://reviews.freebsd.org/D22959
2019-12-30 18:11:06 +00:00
Edward Tomasz Napierala
ee0fe82ee2 Implement Linux syslog(2) syscall; just enough to make Linux dmesg(8)
utility work.

MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D22465
2019-12-29 15:53:55 +00:00
Brandon Bergren
38f69a619e Unbreak build. It seems that mips and amd64 still pull in link_elf.c, so
we need to have elf_cpu_parse_dynamic() everywhere after all to avoid
an undefined symbol.
2019-12-24 16:52:10 +00:00
Alan Cox
50079417a5 Micro-optimize the control flow in _pmap_unwire_ptp(), and eliminate
unnecessary parentheses.

Reviewed by:	kib, markj
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D22893
2019-12-21 22:32:24 +00:00
Alan Cox
7c237b7c3a Correct a mistakenly inverted condition in r355833.
Noticed by:	kib
X-MFC with:	r355833
2019-12-20 20:46:26 +00:00
Alan Cox
48ef33180a When pmap_enter_{l2,pde}() are called to create a kernel mapping, they are
incrementing (and decrementing) the ref_count on kernel page table pages.
They should not do this.  Kernel page table pages are expected to have a
fixed ref_count.  Address this problem by refactoring pmap_alloc{_l2,pde}()
and their callers.  This also eliminates some duplicated code from the
callers.

Correctly implement PMAP_ENTER_NOREPLACE in pmap_enter_{l2,pde}() on kernel
mappings.

Reduce code duplication by defining a function, pmap_abort_ptp(), for
handling a common error case.

Handle a possible page table page leak in pmap_copy().  Suppose that we are
determining whether to copy a superpage mapping.  If we abort because there
is already a mapping in the destination pmap at the current address, then
simply decrementing the page table page's ref_count is correct, because the
page table page must have a ref_count > 1.  However, if we abort because we
failed to allocate a PV entry, this might be a just allocated page table
page that has a ref_count = 1, so we should call pmap_abort_ptp().

Simplify error handling in pmap_enter_quick_locked().

Reviewed by:	kib, markj (an earlier)
MFC after:	2 weeks
Differential Revision:	https://reviews.freebsd.org/D22763
2019-12-18 18:21:39 +00:00
Edward Tomasz Napierala
b5f20658ee Add compat.linux.emul_path, so it can be set to something other
than "/compat/linux".  Useful when you have several compat directories
with different Linux versions and you don't want to clash with files
installed by linux-c7 packages.

Reviewed by:	bcr (manpages)
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D22574
2019-12-16 20:07:04 +00:00
Edward Tomasz Napierala
cf69fe66d4 Add sync_file_range(2) implementation to linux(4); it's a thin wrapper
over the usual fsync(2).

This silences some warnings when running "apt-get upgrade".

Reviewed by:	brooks, emaste
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D22371
2019-12-14 13:37:17 +00:00
Edward Tomasz Napierala
0cde2b3239 Regen after r355752.
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D22371
2019-12-14 13:32:37 +00:00
Edward Tomasz Napierala
0610f417a4 Fix definitions for linuxulator's sync_file_range(2).
Reviewed by:	brooks, emaste
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D22371
2019-12-14 13:30:43 +00:00
John Baldwin
cbd03a9df2 Support software breakpoints in the debug server on Intel CPUs.
- Allow the userland hypervisor to intercept breakpoint exceptions
  (BP#) in the guest.  A new capability (VM_CAP_BPT_EXIT) is used to
  enable this feature.  These exceptions are reported to userland via
  a new VM_EXITCODE_BPT that includes the length of the original
  breakpoint instruction.  If userland wishes to pass the exception
  through to the guest, it must be explicitly re-injected via
  vm_inject_exception().

- Export VMCS_ENTRY_INST_LENGTH as a VM_REG_GUEST_ENTRY_INST_LENGTH
  pseudo-register.  Injecting a BP# on Intel requires setting this to
  the length of the breakpoint instruction.  AMD SVM currently ignores
  writes to this register (but reports success) and fails to read it.

- Rework the per-vCPU state tracked by the debug server.  Rather than
  a single 'stepping_vcpu' global, add a structure for each vCPU that
  tracks state about that vCPU ('stepping', 'stepped', and
  'hit_swbreak').  A global 'stopped_vcpu' tracks which vCPU is
  currently reporting an event.  Event handlers for MTRAP and
  breakpoint exits loop until the associated event is reported to the
  debugger.

  Breakpoint events are discarded if the breakpoint is not present
  when a vCPU resumes in the breakpoint handler to retry submitting
  the breakpoint event.

- Maintain a linked-list of active breakpoints in response to the GDB
  'Z0' and 'z0' packets.

Reviewed by:	markj (earlier version)
MFC after:	2 months
Differential Revision:	https://reviews.freebsd.org/D20309
2019-12-13 19:21:58 +00:00