Commit graph

298 commits

Author SHA1 Message Date
Ruslan Bukin
4cc8701067 Introduce IOMMU support for arm64 platform.
This adds an arm64 iommu interface and a driver for Arm System Memory
Management Unit version 3.2 (ARM SMMU v3.2) specified in ARM IHI 0070C
document.

Hardware overview is provided in the header of smmu.c file.

The support is disabled by default. To enable add 'options IOMMU' to your
kernel configuration file.

The support was developed on Arm Neoverse N1 System Development Platform
(ARM N1SDP), kindly provided by ARM Ltd.

Currently, PCI-based devices and ACPI platforms are supported only.
The support was tested on IOMMU-enabled Marvell SATA controller,
Realtek Ethernet controller and a TI xHCI USB controller with a low to
medium load only.

Many thanks to Konstantin Belousov for help forming the generic IOMMU
framework that is vital for this project; to Andrew Turner for adding
IOMMU support to MSI interrupt code; to Mark Johnston for help with SMMU
page management; to John Baldwin for explaining various IOMMU bits.

Reviewed by:	mmel
Relnotes:	yes
Sponsored by:	DARPA / AFRL
Sponsored by:	Innovate UK (Digital Security by Design programme)
Differential Revision:	https://reviews.freebsd.org/D24618
2020-11-16 21:55:52 +00:00
Andrew Turner
9815c092de Add the pmap.h changes missed in r367320
Reported by:	bz
Sponsored by:	Innovate UK
2020-11-04 11:48:08 +00:00
Ruslan Bukin
268f7e2539 Add routines for ARM System MMU (SMMU) pmap management.
Reviewed by:	markj
Discussed with:	kib
Sponsored by:	DARPA, Innovate UK
Differential Revision:	https://reviews.freebsd.org/D26877
2020-11-02 19:56:15 +00:00
Ruslan Bukin
f9067cf591 o Add the domain member to the struct bus_dma_tag_common as required by
busdma_iommu.c.
o Add tag_set_domain() pointer to the struct bus_dma_impl as well.

Sponsored by:	Innovate DSbD
2020-10-27 15:29:53 +00:00
Oleksandr Tymoshenko
f85aa85895 [hwpmc] Fix call chain capture for ARM64
Use ELR register value instead of LR for PMC_TRAPFRAME_TO_PC macro since
it's the former that indicates PC if the interrupted execution thread.

This fixes a bug where pmcstat lost the leaf function of the call chain
and started with the second function in the chain.

Although this change is an improvement over the previous logic there is still
posibility for incomplete data: if the leaf function does not have stack
variables and does not call any other functions compiler would not generate
a stack frame for it and the FP value would point to the caller's frame, so
instead of the actual "caller1 -> caller2 -> leaf" chain only
"caller1 -> leaf" would be captured.

Sponsored by:	Ampere Computing
Submitted by:	Klara, Inc.
2020-10-22 05:07:25 +00:00
Mitchell Horne
0387f2aacb Update the ID_AA64MMFR2_EL1 register definitions
This brings these definitions in sync with the ARMv8.6 version of the
architecture reference manual.

Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26706
2020-10-16 13:35:29 +00:00
D Scott Phillips
6527b9baef arm64: Increase NIRQ to 16k
Ampere Altra in a dual socket configuration has 12 ITSes for the
12 PCIe root complexes. The NIRQ interrupts are statically split
between each child of the gic bus, so here we increase that
value. 16k is enough for

  (#cpus * #its * max_pcie_bifurcation) LPIs + (#SPIs and #PPIs)

Reviewed by:	jhb
Approved by:	scottl (implicit)
MFC after:	1 week
Sponsored by:	Ampere Computing
Differential Revision:	https://reviews.freebsd.org/D26766
2020-10-15 03:12:00 +00:00
Edward Tomasz Napierala
1e2521ffae Get rid of sa->narg. It serves no purpose; use sa->callp->sy_narg instead.
Reviewed by:	kib
Sponsored by:	DARPA
Differential Revision:	https://reviews.freebsd.org/D26458
2020-09-27 18:47:06 +00:00
Mark Johnston
78257765f2 Add a vmparam.h constant indicating pmap support for large pages.
Enable SHM_LARGEPAGE support on arm64.

Reviewed by:	alc, kib
Sponsored by:	Juniper Networks, Inc., Klara, Inc.
Differential Revision:	https://reviews.freebsd.org/D26467
2020-09-23 19:34:21 +00:00
Mark Johnston
4168aedcde Add largepage support to the arm64 pmap.
Reviewed by:	alc, kib
Sponsored by:	Juniper Networks, Inc., Klara, Inc.
Differential Revision:	https://reviews.freebsd.org/D26466
2020-09-23 19:33:47 +00:00
D Scott Phillips
00e6614750 Sparsify the vm_page_dump bitmap
On Ampere Altra systems, the sparse population of RAM within the
physical address space causes the vm_page_dump bitmap to be much
larger than necessary, increasing the size from ~8 Mib to > 2 Gib
(and overflowing `int` for the size).

Changing the page dump bitmap also changes the minidump file
format, so changes are also necessary in libkvm.

Reviewed by:	jhb
Approved by:	scottl (implicit)
MFC after:	1 week
Sponsored by:	Ampere Computing, Inc.
Differential Revision:	https://reviews.freebsd.org/D26131
2020-09-21 22:21:59 +00:00
D Scott Phillips
ab041f713a Move vm_page_dump bitset array definition to MI code
These definitions were repeated by all architectures, with small
variations. Consolidate the common definitons in machine
independent code and use bitset(9) macros for manipulation. Many
opportunities for deduplication remain in the machine dependent
minidump logic. The only intended functional change is increasing
the bit index type to vm_pindex_t, allowing the indexing of pages
with address of 8 TiB and greater.

Reviewed by:	kib, markj
Approved by:	scottl (implicit)
MFC after:	1 week
Sponsored by:	Ampere Computing, Inc.
Differential Revision:	https://reviews.freebsd.org/D26129
2020-09-21 22:20:37 +00:00
Michal Meloun
95a85c125d Add NetBSD compatible bus_space_peek_N() and bus_space_poke_N() functions.
One problem with the bus_space_read_N() and bus_space_write_N() family of
functions is that they provide no protection against exceptions which can
occur when no physical hardware or device responds to the read or write
cycles. In such a situation, the system typically would panic due to a
kernel-mode bus error. The bus_space_peek_N() and bus_space_poke_N() family
of functions provide a mechanism to handle these exceptions gracefully
without the risk of crashing the system.

Typical example is access to PCI(e) configuration space in bus enumeration
function on badly implemented PCI(e) root complexes (RK3399 or Neoverse
N1 N1SDP and/or access to PCI(e) register when device is in deep sleep state.

This commit adds a real implementation for arm64 only. The remaining
architectures have bus_space_peek()/bus_space_poke() emulated by using
bus_space_read()/bus_space_write() (without exception handling).

MFC after:	1 month
Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D25371
2020-09-19 11:06:41 +00:00
Andrew Turner
15fe2adacb Move the pl061 acpi attachment earlier
As the pl061 driver can be an interrupt controller attach it earlier in the
boot so other drivers can use it.

Use a new GPIO xref to not conflict with the existing root interrupt
controller.

Sponsored by:	Innovate UK
2020-09-10 14:58:46 +00:00
Mitchell Horne
752eb6a995 arm64: export new HWCAP features
Expose some of the new HWCAP features added in r65304. This includes the
addition of elf_hwcap2 into the sysvec, and a separate function to parse
for those features.

This only exposes features which require no further configuration, e.g.
indicating the presence of certain instructions. Larger features (SVE)
will not be advertised until we actually support them. The exact list of
features/extensions this patch exposes is:
  - ARMv8.0-DGH
  - ARMv8.0-SB
  - ARMv8.2-BF16
  - ARMv8.2-DCCVADP
  - ARMv8.2-I8MM
  - ARMv8.4-LRCPC
  - ARMv8.5-CondM
  - ARMv8.5-FRINT
  - ARMv8.5-RNG
  - PSTATE.SSBS

While here, annotate elf_hwcap and elf_hwcap2 as __read_frequently, and
move the declarations to the machine/md_var.h header.

Submitted by:	mikael@ (D22314 portion)
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26031
Differential Revision:	https://reviews.freebsd.org/D22314
2020-09-08 15:36:38 +00:00
Mitchell Horne
d81d009c6c arm64: fix incorrect HWCAP definitions
FreeBSD exports CPU features as bits in the AT_HWCAP and AT_HWCAP2
vectors via elf_aux_info(3). This interface is similar to getauxval(3)
on Linux, and for simplicity to consumers we try to maintain an
identical set of feature flags on arm64.

The first batch of AT_HWCAP flags were added in r350166, corresponding
to definitions that already existed in Linux. Unfortunately, one flag
was missed, and a portion of the values are shifted one bit to the right
as a result.

Add the missing definition for HWCAP_ASIMDHP, and adjust the affected
values to match their Linux counterparts.

Although this is an ABI-breaking change, there is no plan to provide
compat code for old binaries. An audit of our ports tree and other
software via Debian code search indicates that there are not yet any
consumers of this interface for FreeBSD/arm64.

Bump __FreeBSD_version to be on the safe side, in case compat code needs
to be added in the future.

Reviewed by:	emaste, manu
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26329
2020-09-08 15:08:20 +00:00
Mitchell Horne
7ea40e1dbf arm64: update the set of HWCAP definitions
This is in sync with what is defined for Linux 5.8. Note that all bits
in HWCAP are exhausted, and HWCAP2 has been added.

This also revealed an error in some of the existing definitions. We are
missing HWCAP_ASIMDHP, and as a result a portion of the HWCAP values are
shifted right by one bit. This will be fixed in an upcoming change, but
the values being added now are compatible with what Linux defines.

Reviewed by:	emaste, markj, manu
MFC after:	1 week
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26030
2020-09-03 17:07:58 +00:00
Andrew Turner
857ab36fc2 Switch to an empty ttbr0 pagetable when the MMU is enabled
We don't need these pagetables after the early boot. Remove the chance we
write to memory we didn't expect to and remove architectural undefined
behaviour.

Reviewed by:	alc (earlier version), mmel
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D22606
2020-09-03 10:11:12 +00:00
Mark Johnston
2d838cd867 Add the MEM_EXTRACT_PADDR ioctl to /dev/mem.
This allows privileged userspace processes to find information about the
physical page backing a given mapping.  It is useful in applications
such as DPDK which perform some of their own memory management.

Reviewed by:	kib, jhb (previous version)
MFC after:	2 weeks
Sponsored by:	Juniper Networks, Inc.
Sponsored by:	Klara Inc.
Differential Revision:	https://reviews.freebsd.org/D26237
2020-09-02 18:12:47 +00:00
Mateusz Guzik
50cedfede3 arm64: clean up empty lines in .c and .h files 2020-09-01 21:18:06 +00:00
D Scott Phillips
d4d2928a3f arm64: Increase dmap size to 95 TiB
The Ampere Altra has physical memory populated sparsely within the
physical address space. Increase the size of the dmap to cover all
physical memory.

Reviewed by:	andrew
Approved by:	scottl (implicit)
MFC after:	1 week
Sponsored by:	Ampere Computing, Inc.
Differential Revision:	https://reviews.freebsd.org/D26134
2020-08-26 02:13:27 +00:00
Mitchell Horne
6194973636 arm64: update instruction set attribute register definitions
This adds definitions for the latest additions to the AA64ISAR[01] ID
registers. This brings these registers in sync with ARMv8.6 initial spec
release.

An future change will parse many of these fields for HWCAP features.

Reviewed by:	andrew, manu, markj (all previous versions)
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D26029
2020-08-15 14:57:53 +00:00
Andrew Turner
da11e1f9ee Add support for Cortex-A76/Neoverse-N1 to hwpmc
This adds support for the Cortex-A76 and Neoverse-N1 PMU counters to pmc.

While here add more PMCR_IDCODE values and check the implementers code is
correct before setting the PMU type.

Reviewed by:	bz, emaste (looks reasonable to me)
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D25959
2020-08-12 10:17:17 +00:00
Mateusz Guzik
0ef3c62577 arm64: fix uintfptr_t
Fixes compilation after r363932
2020-08-05 22:09:57 +00:00
Alexander Motin
855e49f3b0 Add initial driver for ACPI Platform Error Interfaces.
APEI allows platform to report different kinds of errors to OS in several
ways.  We've found that Supermicro X10/X11 motherboards report PCIe errors
appearing on hot-unplug via this interface using NMI.  Without respective
driver it ended up in kernel panic without any additional information.

This driver introduces support for the APEI Generic Hardware Error Source
reporting via NMI, SCI or polling.  It decodes the reported errors and
either pass them to pci(4) for processing or just logs otherwise.  Errors
marked as fatal still end up in kernel panic, but some more informative.

When somebody get to native PCIe AER support implementation both of the
reporting mechanisms should get common error recovery code.  Since in our
case errors happen when the device is already gone, there is nothing to
recover, so the code just clears the error statuses, practically ignoring
the otherwise destructive NMIs in nicer way.

MFC after:	2 weeks
Relnotes:	yes
Sponsored by:	iXsystems, Inc.
2020-07-27 21:19:41 +00:00
Andrew Turner
e4fc3b653a Read the CPU 0 arm64 ID registers early in initarm
We also update the kernel view early in the boot. This will allow the
use of the common kernel view in ifunc resolvers.

Sponsored by:	Innovate UK
2020-07-01 16:57:57 +00:00
Andrew Turner
eeada9221b Move ID reading signatures to a better header
The functions to read the common user and kernel ID registers should be
in cpu.h rather than undefined.h as they are related to CPU details and
used by undefined instruction handlers.

Sponsored by:	Innovate UK
2020-07-01 16:17:51 +00:00
Andrew Turner
45e999d918 Create a kernel arm64 ID register view
In preparation for using ifuncs in the kernel is is useful to have a common
view of the arm64 ID registers across all CPUs. Add this and extract the
logic for finding the lower value of two fields to a new helper function.

Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D25463
2020-06-29 09:08:36 +00:00
Andrew Turner
23e42a83c1 Use EFI memory map to determine attributes for Acpi mappings on arm64.
AcpiOsMapMemory is used for device memory when e.g. an _INI method wants
to access physical memory, however, aarch64 pmap_mapbios is hardcoded to
writeback. Search for the correct memory type to use in pmap_mapbios.

Submitted by:	Greg V <greg_unrelenting.technology>
Differential Revision:	https://reviews.freebsd.org/D25201
2020-06-28 15:03:07 +00:00
Ed Maste
e46cf959d6 arm64 armreg.h: fix TCR_TBI1 definition
Submitted by:	Greg V <greg@unrelenting.technology>
Differential Revision:	https://reviews.freebsd.org/D25411
2020-06-23 15:32:05 +00:00
Andrew Turner
f3e9395d0c Add all the TCR_EL1 fields
These will be used when adding support for new Armv8 extensions.

Sponsored by:	Innovate UK
2020-06-17 11:56:10 +00:00
Andrew Turner
400c0119a7 Teach the arm64 vfp.h about struct thread.
Ensure struct thread is defined in vfp.h. In some cases it is not and stops
the kernel from building.

Sponsored by:	Innovate UK
2020-06-12 10:43:21 +00:00
Andrew Turner
2cb0e95f48 Support creating and using arm64 pmap at stage 2
Add minimal support for creating stage 2 IPA -> PA mappings. For this we
need to:

 - Create a new vmid set to allocate a vmid for each Virtual Machine
 - Add the missing stage 2 attributes
 - Use these in pmap_enter to create a new mapping
 - Handle stage 2 faults

The vmid set is based on the current asid set that was generalised in
r358328. It adds a function pointer for bhyve to use when the kernel needs
to reset the vmid set. This will need to call into EL2 and invalidate the
TLB.

The stage 2 attributes have been added. To simplify setting these fields
two new functions are added to get the memory type and protection fields.
These are slightly different on stage 1 and stage 2 tables. We then use
them in pmap_enter to set the new level 3 entry to be stored.

The D-cache on all entries is cleaned to the point of coherency. This is
to allow the data to be visible to the VM. To allow for userspace to load
code when creating a new executable entry an invalid entry is created. When
the VM tried to use it the I-cache is invalidated. As the D-cache has
already been cleaned this will ensure the I-cache is synchronised with the
D-cache.

When the hardware implements a VPIPT I-cache we need to either have the
correct VMID set or invalidate it from EL2. As the host kernel will have
the wrong VMID set we need to call into EL2 to clean it. For this a second
function pointer is added that is called when this invalidation is needed.

Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D23875
2020-05-27 08:00:38 +00:00
Andrew Turner
ad020198ff Stop performing a full icache sync when the DIC and IDC flags are set
The DIC and IDC bits in the CTR_EL0 register signal to the kernel when it
can relax the instruction cache synchronisation operations. The IDC bit
means we can relax cleaning the data cache to the point of unification
while the DIC bit means we don't need to invalidate the instruction cache
for data coherence. In both cases an appropriate barrier is still needed.

For now only implement the case where both bits are set, as is the case
on the Neoverse-N1 as used in the Amazon AWS Graviton 2 CPU. Note that
this behaviour is a optional on the N1 so we may later need to implement
only one or the other bit being set.

There is a tunable to disable each flag on boot.

Testing on a 4 core Graviton 2 instance found a significant improvement
in sys and real time when running "make buildkernel -j4", with no
significant difference in user time.

Reviewed by:	markj
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D24853
2020-05-19 16:04:27 +00:00
Andrew Turner
fd1f4df2be Remove arm64_idcache_wbinv_range as it's unused.
Sponsored by:	Innovate UK
2020-05-15 13:33:48 +00:00
Mike Karels
2cd0c52978 Add genet driver for Raspberry Pi 4B Ethernet
Add driver for Broadcom "GENET" version 5, as found in BCM-2711 on
Raspberry Pi 4B. The driver is derived in part from the bcmgenet.c
driver in NetBSD, along with bcmgenetreg.h.

Reviewed by:	manu
Obtained from:	in part from NetBSD
Relnotes:	yes, note addition
Differential Revision:	https://reviews.freebsd.org/D24436
2020-04-22 00:42:10 +00:00
Conrad Meyer
ca0ec73c11 Expand generic subword atomic primitives
The goal of this change is to make the atomic_load_acq_{8,16},
atomic_testandset{,_acq}_long, and atomic_testandclear_long primitives
available in MI-namespace.

The second goal is to get this draft out of my local tree, as anything that
requires a full tinderbox is a big burden out of tree.  MD specifics can be
refined individually afterwards.

The generic implementations may not be ideal for your architecture; feel
free to implement better versions.  If no subword_atomic definitions are
needed, the include can be removed from your arch's machine/atomic.h.
Generic definitions are guarded by defined macros of the same name.  To
avoid picking up conflicting generic definitions, some macro defines are
added to various MD machine/atomic.h to register an existing implementation.

Include _atomic_subword.h in arm and arm64 machine/atomic.h.

For some odd reason, KCSAN only generates some versions of primitives.
Generate the _acq variants of atomic_load.*_8, atomic_load.*_16, and
atomic_testandset.*_long.  There are other questionably disabled primitives,
but I didn't run into them, so I left them alone.  KCSAN is only built for
amd64 in tinderbox for now.

Add atomic_subword implementations of atomic_load_acq_{8,16} implemented
using masking and atomic_load_acq_32.

Add generic atomic_subword implementations of atomic_testandset_long(),
atomic_testandclear_long(), and atomic_testandset_acq_long(), using
atomic_fcmpset_long() and atomic_fcmpset_acq_long().

On x86, add atomic_testandset_acq_long as an alias for
atomic_testandset_long.

Reviewed by:	kevans, rlibby (previous versions both)
Differential Revision:	https://reviews.freebsd.org/D22963
2020-03-25 23:12:43 +00:00
Andrew Turner
3a1c1a303e Add more are64 special register fields
Obtained from:	https://github.com/FreeBSD-UPB/freebsd
2020-03-06 16:00:35 +00:00
Andrew Turner
db724d9005 Update the hypervisor registers
- Add more registers needed by bhyve [1]
 - Move EL2 registers from armreg.h to hypervisor.h
 - Add the register name to hypervisor.h

Obtained from:	https://github.com/FreeBSD-UPB/freebsd [1]
2020-03-06 14:46:50 +00:00
Andrew Turner
0c4be71a59 Mark the arm64 machdep.h as kernel only
None of this is useful for userspace.

Sponsored by:	Innovate UK
2020-03-05 10:52:16 +00:00
Andrew Turner
0e6627350e Fix the spelling of aliasing.
Sponsored by:	Innovate UK
2020-03-03 15:31:40 +00:00
Andrew Turner
411531cf30 Move the arm64 cache identification to identcpu.c
This allows us to call it on a per-CPU basis and to warn if the details
are different across CPUs.

While here read the L1 I-Cache type and store this for use later by pmap.

Sponsored by:	Innovate UK
2020-03-03 15:25:01 +00:00
Andrew Turner
2923027c15 Fix the spelling of the VIPT cache type field
Sponsored by:	Innovate UK
2020-03-03 12:50:45 +00:00
Andrew Turner
228b87bc31 Store the boot exception level on arm64 so it can be queried later
A hypervisor, e.g. bhyve, will need to know what exception levelthe kernel
was in when it started booting. If it was EL2 we can then enable said
hypervisor.

Store the boot exception level and allow the kernel to later query it.

Obtained from:	https://github.com/FreeBSD-UPB/freebsd (earlier version)
Sponsored by:	Innovate UK
2020-03-03 08:28:16 +00:00
Andrew Turner
249ecb6338 Generalise the arm64 ASID allocator.
The requirements of an Address Space ID allocator and a Virtual Machine ID
allocator are similar. Generalise the former code so it can be used with
the latter.

Reviewed by:	alc (previous version)
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D23831
2020-02-26 11:50:24 +00:00
Andrew Turner
23982ffd47 Start to support multiple stages in the arm64 pmap.
On arm64 the stage 1 and stage 2 pte formats are similar enough we can
reuse the pmap code for both. As they are only similar and not identical
we need to know if we are managing stage 1 or stage 2 tables.

Add an enum to store this information and a check to make sure it is
set to stage 1 when we manage stage 1 pte fields.

Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D23830
2020-02-26 11:47:24 +00:00
Andrew Turner
c32e28d5e7 Add more arm64 CTR_EL0 register fields
While here make the _SIZE macros return the size in bytes, not the log2
of the size

Sponsored by:	Innovate UK
2020-02-26 11:29:03 +00:00
Andrew Turner
d153d023f5 Split out the stage 1 pte bits and add the stage 2 bits
In preperation for adding bhyve support to arm64 we need to split the
stage 1 and stage 2 pte fields to allow future changes to create stage 2
page tables.

MFC after:	1 month
Sponsored by:	Innovate UK
Differential Revision:	https://reviews.freebsd.org/D23669
2020-02-24 16:45:31 +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
Mark Johnston
a83c682b36 Dynamically select LSE-based atomic(9)s on arm64.
Once all CPUs are online, determine if they all support LSE atomics and
set lse_supported to indicate this.  For now the atomic(9)
implementations are still always inlined, though it would be preferable
to create out-of-line functions to avoid text bloat.  This was not done
here since big.little systems exist in which some CPUs implement LSE
while others do not, and ifunc resolution must occur well before this
scenario can be detected.  It does seem unlikely that FreeBSD will
ever run on such platforms, however, so converting atomic(9) to use
ifuncs is probably a good next step.

Add a LSE_ATOMICS arm64 kernel configuration option to unconditionally
select LSE-based atomic(9) implementations when the target system is
known.

Reviewed by:	andrew, kib
MFC after:	1 month
Sponsored by:	The FreeBSD Foundation, Amazon (hardware)
Differential Revision:	https://reviews.freebsd.org/D23325
2020-02-03 18:23:50 +00:00