[RFC,03/47] lkl: architecture skeleton for Linux kernel library
diff mbox series

Message ID 0b1464dd4904ee2b049fef624895ead3fe6aa555.1571798507.git.thehajime@gmail.com
State New
Headers show
Series
  • [RFC,01/47] asm-generic: atomic64: allow using generic atomic64 on 64bit platforms
Related show

Commit Message

Hajime Tazaki Oct. 23, 2019, 4:37 a.m. UTC
From: Octavian Purdila <tavi.purdila@gmail.com>

Adds the LKL Kconfig, vmlinux linker script, basic architecture
headers and miscellaneous basic functions or stubs such as
dump_stack(), show_regs() and cpuinfo proc ops.

The headers we introduce in this patch are simple wrappers to the
asm-generic headers or stubs for things we don't support, such as
ptrace, DMA, signals, ELF handling and low level processor operations.

The kernel configuration is automatically updated to reflect the
endianness of the host, 64bit support or the output format for
vmlinux's linker script. We do this by looking at the ld's default
output format.

Signed-off-by: Andreas Abel <aabel@google.com>
Signed-off-by: Conrad Meyer <cem@FreeBSD.org>
Signed-off-by: Edison M. Castro <edisonmcastro@hotmail.com>
Signed-off-by: H.K. Jerry Chu <hkchu@google.com>
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Signed-off-by: Jens Staal <staal1978@gmail.com>
Signed-off-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Levente Kurusa <levex@linux.com>
Signed-off-by: Luca Dariz <luca.dariz@gmail.com>
Signed-off-by: Mark Stillwell <mark@stillwell.me>
Signed-off-by: Matthieu Coudron <mattator@gmail.com>
Signed-off-by: Michael Zimmermann <sigmaepsilon92@gmail.com>
Signed-off-by: Motomu Utsumi <motomuman@gmail.com>
Signed-off-by: Patrick Collins <pscollins@google.com>
Signed-off-by: Petros Angelatos <petrosagg@gmail.com>
Signed-off-by: Pierre-Hugues Husson <phh@phh.me>
Signed-off-by: Xiao Jia <xiaoj@google.com>
Signed-off-by: Yuan Liu <liuyuan@google.com>
Signed-off-by: Octavian Purdila <tavi.purdila@gmail.com>
---
 MAINTAINERS                                |   8 +
 arch/um/lkl/.gitignore                     |   2 +
 arch/um/lkl/Kconfig                        |  96 ++++++
 arch/um/lkl/Kconfig.debug                  |   0
 arch/um/lkl/Makefile                       |   0
 arch/um/lkl/Makefile.um                    |  70 +++++
 arch/um/lkl/configs/lkl_defconfig          |  95 ++++++
 arch/um/lkl/include/asm/Kbuild             |  80 +++++
 arch/um/lkl/include/asm/bitsperlong.h      |  11 +
 arch/um/lkl/include/asm/byteorder.h        |   7 +
 arch/um/lkl/include/asm/cpu.h              |  14 +
 arch/um/lkl/include/asm/elf.h              |  15 +
 arch/um/lkl/include/asm/mutex.h            |   7 +
 arch/um/lkl/include/asm/processor.h        |  60 ++++
 arch/um/lkl/include/asm/ptrace.h           |  25 ++
 arch/um/lkl/include/asm/sched.h            |  23 ++
 arch/um/lkl/include/asm/syscalls.h         |  18 ++
 arch/um/lkl/include/asm/syscalls_32.h      |  43 +++
 arch/um/lkl/include/asm/tlb.h              |  12 +
 arch/um/lkl/include/asm/uaccess.h          |  64 ++++
 arch/um/lkl/include/asm/unistd_32.h        |  31 ++
 arch/um/lkl/include/asm/vmlinux.lds.h      |  14 +
 arch/um/lkl/include/asm/xor.h              |   9 +
 arch/um/lkl/include/uapi/asm/Kbuild        |   9 +
 arch/um/lkl/include/uapi/asm/bitsperlong.h |  13 +
 arch/um/lkl/include/uapi/asm/byteorder.h   |  11 +
 arch/um/lkl/include/uapi/asm/siginfo.h     |  11 +
 arch/um/lkl/include/uapi/asm/swab.h        |  11 +
 arch/um/lkl/include/uapi/asm/syscalls.h    | 348 +++++++++++++++++++++
 arch/um/lkl/kernel/asm-offsets.c           |   2 +
 arch/um/lkl/kernel/misc.c                  |  60 ++++
 arch/um/lkl/kernel/vmlinux.lds.S           |  51 +++
 32 files changed, 1220 insertions(+)
 create mode 100644 arch/um/lkl/.gitignore
 create mode 100644 arch/um/lkl/Kconfig
 create mode 100644 arch/um/lkl/Kconfig.debug
 create mode 100644 arch/um/lkl/Makefile
 create mode 100644 arch/um/lkl/Makefile.um
 create mode 100644 arch/um/lkl/configs/lkl_defconfig
 create mode 100644 arch/um/lkl/include/asm/Kbuild
 create mode 100644 arch/um/lkl/include/asm/bitsperlong.h
 create mode 100644 arch/um/lkl/include/asm/byteorder.h
 create mode 100644 arch/um/lkl/include/asm/cpu.h
 create mode 100644 arch/um/lkl/include/asm/elf.h
 create mode 100644 arch/um/lkl/include/asm/mutex.h
 create mode 100644 arch/um/lkl/include/asm/processor.h
 create mode 100644 arch/um/lkl/include/asm/ptrace.h
 create mode 100644 arch/um/lkl/include/asm/sched.h
 create mode 100644 arch/um/lkl/include/asm/syscalls.h
 create mode 100644 arch/um/lkl/include/asm/syscalls_32.h
 create mode 100644 arch/um/lkl/include/asm/tlb.h
 create mode 100644 arch/um/lkl/include/asm/uaccess.h
 create mode 100644 arch/um/lkl/include/asm/unistd_32.h
 create mode 100644 arch/um/lkl/include/asm/vmlinux.lds.h
 create mode 100644 arch/um/lkl/include/asm/xor.h
 create mode 100644 arch/um/lkl/include/uapi/asm/Kbuild
 create mode 100644 arch/um/lkl/include/uapi/asm/bitsperlong.h
 create mode 100644 arch/um/lkl/include/uapi/asm/byteorder.h
 create mode 100644 arch/um/lkl/include/uapi/asm/siginfo.h
 create mode 100644 arch/um/lkl/include/uapi/asm/swab.h
 create mode 100644 arch/um/lkl/include/uapi/asm/syscalls.h
 create mode 100644 arch/um/lkl/kernel/asm-offsets.c
 create mode 100644 arch/um/lkl/kernel/misc.c
 create mode 100644 arch/um/lkl/kernel/vmlinux.lds.S

Comments

Richard Weinberger Oct. 25, 2019, 9:40 p.m. UTC | #1
On Wed, Oct 23, 2019 at 6:39 AM Hajime Tazaki <thehajime@gmail.com> wrote:
>
> From: Octavian Purdila <tavi.purdila@gmail.com>
> +LINUX KERNEL LIBRARY
> +M:     Octavian Purdila <octavian.purdila@intel.com>
> +M:     Hajime Tazaki <thehajime@gmail.com>
> +L:     linux-kernel-library@freelists.org
> +S:     Maintained
> +F:     arch/lkl/
> +F:     tools/lkl/
> +

The arch/lkl path is outdated.
So, you and Octavian will maintain LKL?

Do you want to be sub maintainers of arch/um/lkl and send pull requests to me
or co-maintain the whole UML ecosystem together with me and Anton?

I'm perfectly fine with both variants but tend to the latter one since
it is less overhead.
In case you need your PGP keys signed, next week I'll be in Lyon at
OSS, ELCE, ...
Hajime Tazaki Oct. 27, 2019, 2:36 a.m. UTC | #2
# dropping two Cc's since those are not reachable..

On Sat, 26 Oct 2019 06:40:05 +0900,
Richard Weinberger wrote:
> 
> On Wed, Oct 23, 2019 at 6:39 AM Hajime Tazaki <thehajime@gmail.com> wrote:
> >
> > From: Octavian Purdila <tavi.purdila@gmail.com>
> > +LINUX KERNEL LIBRARY
> > +M:     Octavian Purdila <octavian.purdila@intel.com>
> > +M:     Hajime Tazaki <thehajime@gmail.com>
> > +L:     linux-kernel-library@freelists.org
> > +S:     Maintained
> > +F:     arch/lkl/
> > +F:     tools/lkl/
> > +
> 
> The arch/lkl path is outdated.

Ah, should be updated.  We will fix it.

> So, you and Octavian will maintain LKL?

Yes.

> Do you want to be sub maintainers of arch/um/lkl and send pull requests to me
> or co-maintain the whole UML ecosystem together with me and Anton?
>
> I'm perfectly fine with both variants but tend to the latter one since
> it is less overhead.

I was not thinking well enough for the maintenance procedure;
I agree that the latter case is better, but for the early
stage of this integration, I think starting with the former
(send pull-req from LKL to you/Anton) would be nice.

LKL is now on github and utilizes several useful features
(CI test at each pull request, issue tracking, wiki), and if
possible I'd also like to migrate those tools, or make them
available to UML because this makes easier maintenance for
LKL.

What do you think ?

> In case you need your PGP keys signed, next week I'll be in Lyon at
> OSS, ELCE, ...

I won't be there, unfortunately..

-- Hajime
Lai Jiangshan Oct. 29, 2019, 4:04 a.m. UTC | #3
Hello, Hajime

I can't get how UML&LKL is going to unify even I read
the cover-letter of the patchset. After quick glance, what I
understand is that the patchset just puts LKL under
arch/um/lkl rather than arch/lkl. It is still separated "arch" for me.

Could you put me in more detail of the plan to unify them please?

Thanks
Lai

On Sun, Oct 27, 2019 at 10:36 AM Hajime Tazaki <thehajime@gmail.com> wrote:
>
>
> # dropping two Cc's since those are not reachable..
>
> On Sat, 26 Oct 2019 06:40:05 +0900,
> Richard Weinberger wrote:
> >
> > On Wed, Oct 23, 2019 at 6:39 AM Hajime Tazaki <thehajime@gmail.com> wrote:
> > >
> > > From: Octavian Purdila <tavi.purdila@gmail.com>
> > > +LINUX KERNEL LIBRARY
> > > +M:     Octavian Purdila <octavian.purdila@intel.com>
> > > +M:     Hajime Tazaki <thehajime@gmail.com>
> > > +L:     linux-kernel-library@freelists.org
> > > +S:     Maintained
> > > +F:     arch/lkl/
> > > +F:     tools/lkl/
> > > +
> >
> > The arch/lkl path is outdated.
>
> Ah, should be updated.  We will fix it.
>
> > So, you and Octavian will maintain LKL?
>
> Yes.
>
> > Do you want to be sub maintainers of arch/um/lkl and send pull requests to me
> > or co-maintain the whole UML ecosystem together with me and Anton?
> >
> > I'm perfectly fine with both variants but tend to the latter one since
> > it is less overhead.
>
> I was not thinking well enough for the maintenance procedure;
> I agree that the latter case is better, but for the early
> stage of this integration, I think starting with the former
> (send pull-req from LKL to you/Anton) would be nice.
>
> LKL is now on github and utilizes several useful features
> (CI test at each pull request, issue tracking, wiki), and if
> possible I'd also like to migrate those tools, or make them
> available to UML because this makes easier maintenance for
> LKL.
>
> What do you think ?
>
> > In case you need your PGP keys signed, next week I'll be in Lyon at
> > OSS, ELCE, ...
>
> I won't be there, unfortunately..
>
> -- Hajime
Hajime Tazaki Oct. 29, 2019, 7:13 a.m. UTC | #4
Hello Lai,

On Tue, 29 Oct 2019 13:04:59 +0900,
Lai Jiangshan wrote:
> 
> Hello, Hajime
> 
> I can't get how UML&LKL is going to unify even I read
> the cover-letter of the patchset. After quick glance, what I
> understand is that the patchset just puts LKL under
> arch/um/lkl rather than arch/lkl. It is still separated "arch" for me.
> 
> Could you put me in more detail of the plan to unify them please?

Thanks for the comment.

You're right: current patchset only share Makefile(s)
between UML and LKL.  This is the first step toward the
unification in my plan, described in the milestone of the
cover letter (copy-pasted below).

> Milestone
> =========
> (snip)
> 1. Put LKL code under arch/um (arch/um/lkl), and build it in a
> separate way from UML.
> 2. Share common parts of implementation between UML and LKL.
> 3. Reimplement UML features with LKL API (if we wish)

For the step 2, [PATCH 46/47] and [47/47] are the kind of
examples for this level of unification (sorry for the very
dirty code).

For the step 3, I don't have any WIP code nor detailed plan.
Implementing ptrace-based (or similar) syscall interception
would be one of the development (I believe there are more).

Offering UML feature-sets, keeping compatibility, while
benefiting from LKL (e.g., various underlying environment
support) would be very high-level goal since there are many
users of UML (various test tool projects, including coming
Kunit).



Having similar archs in Linux kernel is not likely to
happen; that was feedback after RFC email of LKL (in 2015).
This motivates us to upstream the LKL code into arch/um.

-- Hajime
Johannes Berg Oct. 29, 2019, 7:57 a.m. UTC | #5
Hi,

> You're right: current patchset only share Makefile(s)
> between UML and LKL.  This is the first step toward the
> unification in my plan, described in the milestone of the
> cover letter (copy-pasted below).
> 
> > Milestone
> > =========
> > (snip)
> > 1. Put LKL code under arch/um (arch/um/lkl), and build it in a
> > separate way from UML.
> > 2. Share common parts of implementation between UML and LKL.
> > 3. Reimplement UML features with LKL API (if we wish)
> 
> For the step 2, [PATCH 46/47] and [47/47] are the kind of
> examples for this level of unification (sorry for the very
> dirty code).
> 
> For the step 3, I don't have any WIP code nor detailed plan.
> Implementing ptrace-based (or similar) syscall interception
> would be one of the development (I believe there are more).
> 
> Offering UML feature-sets, keeping compatibility, while
> benefiting from LKL (e.g., various underlying environment
> support) would be very high-level goal since there are many
> users of UML (various test tool projects, including coming
> Kunit).

Aren't you going about this the wrong way around?

I mean, this reads like you're proposing to start from LKL and
reimplement UML on top of it, but we currently have UML in the tree and
LKL isn't. Seems backward to me.

Also, looking at the patches, I'm not a huge fan of the whole "drop LKL
into UML". UML is already complex enough as is, with its memory model
and all, mixing in LKL makes it way more complex.

I don't think "drop LKL under UML" was what people had in mind when they
suggested that the two merge ...

johannes
Richard Weinberger Oct. 29, 2019, 8:15 a.m. UTC | #6
----- Urspr√ľngliche Mail -----
> Von: "Johannes Berg" <johannes@sipsolutions.net>
> An: "Hajime Tazaki" <thehajime@gmail.com>, jiangshanlai@gmail.com
> CC: levex@linux.com, mattator@gmail.com, cem@freebsd.org, "Richard Weinberger" <richard.weinberger@gmail.com>,
> staal1978@gmail.com, motomuman@gmail.com, "linux-um" <linux-um@lists.infradead.org>, retrage01@gmail.com,
> petrosagg@gmail.com, "tavi purdila" <tavi.purdila@gmail.com>, xiaoj@google.com, mark@stillwell.me,
> edisonmcastro@hotmail.com, pscollins@google.com, phh@phh.me, sigmaepsilon92@gmail.com, "luca dariz"
> <luca.dariz@gmail.com>, liuyuan@google.com
> Gesendet: Dienstag, 29. Oktober 2019 08:57:43
> Betreff: Re: [RFC PATCH 03/47] lkl: architecture skeleton for Linux kernel library

> Hi,
> 
>> You're right: current patchset only share Makefile(s)
>> between UML and LKL.  This is the first step toward the
>> unification in my plan, described in the milestone of the
>> cover letter (copy-pasted below).
>> 
>> > Milestone
>> > =========
>> > (snip)
>> > 1. Put LKL code under arch/um (arch/um/lkl), and build it in a
>> > separate way from UML.
>> > 2. Share common parts of implementation between UML and LKL.
>> > 3. Reimplement UML features with LKL API (if we wish)
>> 
>> For the step 2, [PATCH 46/47] and [47/47] are the kind of
>> examples for this level of unification (sorry for the very
>> dirty code).
>> 
>> For the step 3, I don't have any WIP code nor detailed plan.
>> Implementing ptrace-based (or similar) syscall interception
>> would be one of the development (I believe there are more).
>> 
>> Offering UML feature-sets, keeping compatibility, while
>> benefiting from LKL (e.g., various underlying environment
>> support) would be very high-level goal since there are many
>> users of UML (various test tool projects, including coming
>> Kunit).
> 
> Aren't you going about this the wrong way around?
> 
> I mean, this reads like you're proposing to start from LKL and
> reimplement UML on top of it, but we currently have UML in the tree and
> LKL isn't. Seems backward to me.

This is surely not intended. 
 
> Also, looking at the patches, I'm not a huge fan of the whole "drop LKL
> into UML". UML is already complex enough as is, with its memory model
> and all, mixing in LKL makes it way more complex.
> 
> I don't think "drop LKL under UML" was what people had in mind when they
> suggested that the two merge ...

Yes, just having a lkl folder under arch/um/ is for sure not the final solution.
The goal is merging as much as possible.
But having purely lkl stuff in a subfolder like arch/um/lkl/ is not a big deal.
 
This patch series is just a start not the final solution which will get merged. :-)

Thanks,
//richard
Hajime Tazaki Oct. 30, 2019, 3:19 a.m. UTC | #7
Hello,

On Tue, 29 Oct 2019 16:57:43 +0900,
Johannes Berg wrote:

> > Offering UML feature-sets, keeping compatibility, while
> > benefiting from LKL (e.g., various underlying environment
> > support) would be very high-level goal since there are many
> > users of UML (various test tool projects, including coming
> > Kunit).
> 
> Aren't you going about this the wrong way around?
> 
> I mean, this reads like you're proposing to start from LKL and
> reimplement UML on top of it, but we currently have UML in the tree and
> LKL isn't. Seems backward to me.

I see your point.

Our basic standpoint is to follow the project idea listed in
the old UML web page.

http://user-mode-linux.sourceforge.net/old/projects.html

Especially LKL should be able to contribute the following
ideas to UML.

- Architecture Ports (e.g., run on arm32)
- OS Ports (e.g., Windows host)
- UML as a normal userspace library

I wish I'm not going to break any existing facility of UML
in this introduction.  If you found any, I'm happy to fix
such problems.

> Also, looking at the patches, I'm not a huge fan of the whole "drop LKL
> into UML". UML is already complex enough as is, with its memory model
> and all, mixing in LKL makes it way more complex.
> 
> I don't think "drop LKL under UML" was what people had in mind when they
> suggested that the two merge ...

As Richard explained, putting new arch/um/lkl folder should
not be our final goal.

-- Hajime

Patch
diff mbox series

diff --git a/MAINTAINERS b/MAINTAINERS
index e7a47b5210fd..6832972ad54b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9369,6 +9369,14 @@  F:	Documentation/core-api/atomic_ops.rst
 F:	Documentation/core-api/refcount-vs-atomic.rst
 F:	Documentation/memory-barriers.txt
 
+LINUX KERNEL LIBRARY
+M:	Octavian Purdila <octavian.purdila@intel.com>
+M:	Hajime Tazaki <thehajime@gmail.com>
+L:	linux-kernel-library@freelists.org
+S:	Maintained
+F:	arch/lkl/
+F:	tools/lkl/
+
 LIS3LV02D ACCELEROMETER DRIVER
 M:	Eric Piel <eric.piel@tremplin-utc.net>
 S:	Maintained
diff --git a/arch/um/lkl/.gitignore b/arch/um/lkl/.gitignore
new file mode 100644
index 000000000000..ced1c60d8235
--- /dev/null
+++ b/arch/um/lkl/.gitignore
@@ -0,0 +1,2 @@ 
+kernel/vmlinux.lds
+include/generated
diff --git a/arch/um/lkl/Kconfig b/arch/um/lkl/Kconfig
new file mode 100644
index 000000000000..1e68e474a21b
--- /dev/null
+++ b/arch/um/lkl/Kconfig
@@ -0,0 +1,96 @@ 
+# SPDX-License-Identifier: GPL-2.0
+
+config UML_LKL
+       def_bool y
+       depends on !SMP && !MMU && !COREDUMP && !SECCOMP && !UPROBES && !COMPAT && !USER_RETURN_NOTIFIER
+       select ARCH_THREAD_STACK_ALLOCATOR
+       select RWSEM_GENERIC_SPINLOCK
+       select GENERIC_ATOMIC64
+       select GENERIC_HWEIGHT
+       select FLATMEM
+       select FLAT_NODE_MEM_MAP
+       select GENERIC_CLOCKEVENTS
+       select GENERIC_CPU_DEVICES
+       select NO_HZ_IDLE
+       select NO_PREEMPT
+       select ARCH_WANT_FRAME_POINTERS
+       select HAS_DMA
+       select DMA_DIRECT_OPS
+       select PHYS_ADDR_T_64BIT if 64BIT
+       select 64BIT if "$(OUTPUT_FORMAT)" = "elf64-x86-64"
+       select 64BIT if "$(OUTPUT_FORMAT)" = "pe-x86-64"
+       select HAVE_UNDERSCORE_SYMBOL_PREFIX if "$(OUTPUT_FORMAT)" = "pe-i386"
+       select 64BIT if "$(OUTPUT_FORMAT)" = "elf64-x86-64-freebsd"
+       select 64BIT if "$(OUTPUT_FORMAT)" = "elf64-littleaarch64"
+       select NET
+       select MULTIUSER
+       select INET
+       select IPV6
+       select IP_PNP
+       select IP_PNP_DHCP
+       select TCP_CONG_ADVANCED
+       select TCP_CONG_BBR
+       select HIGH_RES_TIMERS
+       select NET_SCHED
+       select NET_SCH_FQ
+       select IP_MULTICAST
+       select IPV6_MULTICAST
+       select IP_MULTIPLE_TABLES
+       select IPV6_MULTIPLE_TABLES
+       select IP_ROUTE_MULTIPATH
+       select IPV6_ROUTE_MULTIPATH
+       select IP_ADVANCED_ROUTER
+       select IPV6_ADVANCED_ROUTER
+       select ARCH_NO_COHERENT_DMA_MMAP
+       select HAVE_MEMBLOCK
+       select NO_BOOTMEM
+
+config OUTPUT_FORMAT
+       string "Output format"
+       default "$(OUTPUT_FORMAT)"
+
+config ARCH_DMA_ADDR_T_64BIT
+       def_bool 64BIT
+
+config 64BIT
+       def_bool n
+
+config COREDUMP
+       def_bool n
+
+config BIG_ENDIAN
+       def_bool n
+
+config GENERIC_CSUM
+       def_bool y
+
+config GENERIC_HWEIGHT
+       def_bool y
+
+config NO_IOPORT_MAP
+       def_bool y
+
+config RWSEM_GENERIC_SPINLOCK
+	bool
+	default y
+
+config HAVE_UNDERSCORE_SYMBOL_PREFIX
+       bool
+       help
+         Some architectures generate an _ in front of C symbols; things like
+         module loading and assembly files need to know about this.
+
+config HZ
+        int
+        default 100
+
+config CONSOLE_LOGLEVEL_QUIET
+	int "quiet console loglevel (1-15)"
+	range 1 15
+	default "4"
+	help
+	  loglevel to use when "quiet" is passed on the kernel commandline.
+
+	  When "quiet" is passed on the kernel commandline this loglevel
+	  will be used as the loglevel. IOW passing "quiet" will be the
+	  equivalent of passing "loglevel=<CONSOLE_LOGLEVEL_QUIET>"
diff --git a/arch/um/lkl/Kconfig.debug b/arch/um/lkl/Kconfig.debug
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/arch/um/lkl/Makefile b/arch/um/lkl/Makefile
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/arch/um/lkl/Makefile.um b/arch/um/lkl/Makefile.um
new file mode 100644
index 000000000000..612705870e82
--- /dev/null
+++ b/arch/um/lkl/Makefile.um
@@ -0,0 +1,70 @@ 
+# SPDX-License-Identifier: GPL-2.0
+
+include $(HOST_DIR)/auto.conf
+
+SRCARCH := um/$(SUBARCH)
+ARCH_INCLUDE += -I$(srctree)/$(HOST_DIR)/um/include
+LINUXINCLUDE := $(subst $(ARCH_DIR),$(HOST_DIR),$(LINUXINCLUDE)) $(ARCH_INCLUDE)
+KBUILD_CFLAGS += -fno-builtin
+
+ifneq (,$(filter $(OUTPUT_FORMAT),elf64-x86-64 elf32-i386 elf64-x86-64-freebsd elf32-littlearm elf64-littleaarch64))
+KBUILD_CFLAGS += -fPIC
+else ifneq (,$(filter $(OUTPUT_FORMAT),pe-i386 pe-x86-64 ))
+ifneq ($(OUTPUT_FORMAT),pe-x86-64)
+prefix=_
+endif
+# workaround for #include_next<stdarg.h> errors
+LINUXINCLUDE := -isystem $(HOST_DIR)/include/system $(LINUXINCLUDE)
+# workaround for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=52991
+KBUILD_CFLAGS += -mno-ms-bitfields
+else
+$(error Unrecognized platform: $(OUTPUT_FORMAT))
+endif
+
+ifeq ($(shell uname -s), Linux)
+NPROC=$(shell nproc)
+else # e.g., FreeBSD
+NPROC=$(shell sysctl -n hw.ncpu)
+endif
+
+LDFLAGS_vmlinux += -r
+LKL_ENTRY_POINTS := lkl_start_kernel lkl_sys_halt lkl_syscall lkl_trigger_irq \
+	lkl_get_free_irq lkl_put_irq lkl_is_running lkl_bug lkl_printf
+
+ifeq ($(OUTPUT_FORMAT),elf32-i386)
+LKL_ENTRY_POINTS += \
+	__x86.get_pc_thunk.bx __x86.get_pc_thunk.dx __x86.get_pc_thunk.ax \
+	__x86.get_pc_thunk.cx __x86.get_pc_thunk.si __x86.get_pc_thunk.di
+endif
+
+core-y += $(HOST_DIR)/kernel/
+core-y += $(HOST_DIR)/mm/
+
+all: lkl.o
+
+lkl.o: vmlinux
+	$(OBJCOPY) -R .eh_frame -R .syscall_defs $(foreach sym,$(LKL_ENTRY_POINTS),-G$(prefix)$(sym)) vmlinux lkl.o
+
+$(HOST_DIR)/include/generated/uapi/asm/syscall_defs.h: vmlinux
+	$(OBJCOPY) -j .syscall_defs -O binary --set-section-flags .syscall_defs=alloc $< $@
+	$(Q) export tmpfile=$(shell mktemp); \
+	sed 's/\x0//g' $@ > $$tmpfile; mv $$tmpfile $@ ; rm -f $$tmpfile
+
+install: lkl.o headers $(HOST_DIR)/include/generated/uapi/asm/syscall_defs.h
+	@echo "  INSTALL	$(INSTALL_PATH)/lib/lkl.o"
+	@mkdir -p $(INSTALL_PATH)/lib/
+	@cp lkl.o $(INSTALL_PATH)/lib/
+	@$(srctree)/$(HOST_DIR)/scripts/headers_install.py \
+		$(subst -j,-j$(NPROC),$(findstring -j,$(MAKEFLAGS))) \
+		$(INSTALL_PATH)/include
+
+archheaders:
+	$(Q)$(MAKE) -f $(srctree)/Makefile ARCH=$(SRCARCH) asm-generic archheaders
+
+archclean:
+	$(Q)rm -rf $(srctree)/$(HOST_DIR)/include/generated
+	$(Q)$(MAKE) $(clean)=$(boot)
+
+define archhelp
+  echo '  install	- Install library and headers to INSTALL_PATH/{lib,include}'
+endef
diff --git a/arch/um/lkl/configs/lkl_defconfig b/arch/um/lkl/configs/lkl_defconfig
new file mode 100644
index 000000000000..f91380beee7c
--- /dev/null
+++ b/arch/um/lkl/configs/lkl_defconfig
@@ -0,0 +1,95 @@ 
+# CONFIG_LOCALVERSION_AUTO is not set
+CONFIG_NO_HZ_IDLE=y
+# CONFIG_SYSFS_SYSCALL is not set
+CONFIG_KALLSYMS_USE_DATA_SECTION=y
+CONFIG_KALLSYMS_ALL=y
+# CONFIG_BASE_FULL is not set
+# CONFIG_FUTEX is not set
+# CONFIG_SIGNALFD is not set
+# CONFIG_TIMERFD is not set
+# CONFIG_AIO is not set
+# CONFIG_ADVISE_SYSCALLS is not set
+CONFIG_EMBEDDED=y
+# CONFIG_VM_EVENT_COUNTERS is not set
+# CONFIG_COMPAT_BRK is not set
+# CONFIG_BLK_DEV_BSG is not set
+CONFIG_NET=y
+CONFIG_INET=y
+# CONFIG_WIRELESS is not set
+# CONFIG_UEVENT_HELPER is not set
+# CONFIG_FW_LOADER is not set
+CONFIG_VIRTIO_BLK=y
+CONFIG_NETDEVICES=y
+CONFIG_VIRTIO_NET=y
+# CONFIG_ETHERNET is not set
+# CONFIG_WLAN is not set
+# CONFIG_VT is not set
+CONFIG_VIRTIO_MMIO=y
+CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES=y
+CONFIG_EXT4_FS=y
+CONFIG_EXT4_FS_POSIX_ACL=y
+CONFIG_EXT4_FS_SECURITY=y
+CONFIG_XFS_FS=y
+CONFIG_XFS_POSIX_ACL=y
+CONFIG_BTRFS_FS=y
+CONFIG_BTRFS_FS_POSIX_ACL=y
+# CONFIG_FILE_LOCKING is not set
+# CONFIG_DNOTIFY is not set
+# CONFIG_INOTIFY_USER is not set
+CONFIG_VFAT_FS=y
+CONFIG_NLS_CODEPAGE_437=y
+CONFIG_NLS_CODEPAGE_737=y
+CONFIG_NLS_CODEPAGE_775=y
+CONFIG_NLS_CODEPAGE_850=y
+CONFIG_NLS_CODEPAGE_852=y
+CONFIG_NLS_CODEPAGE_855=y
+CONFIG_NLS_CODEPAGE_857=y
+CONFIG_NLS_CODEPAGE_860=y
+CONFIG_NLS_CODEPAGE_861=y
+CONFIG_NLS_CODEPAGE_862=y
+CONFIG_NLS_CODEPAGE_863=y
+CONFIG_NLS_CODEPAGE_864=y
+CONFIG_NLS_CODEPAGE_865=y
+CONFIG_NLS_CODEPAGE_866=y
+CONFIG_NLS_CODEPAGE_869=y
+CONFIG_NLS_CODEPAGE_936=y
+CONFIG_NLS_CODEPAGE_950=y
+CONFIG_NLS_CODEPAGE_932=y
+CONFIG_NLS_CODEPAGE_949=y
+CONFIG_NLS_CODEPAGE_874=y
+CONFIG_NLS_ISO8859_8=y
+CONFIG_NLS_CODEPAGE_1250=y
+CONFIG_NLS_CODEPAGE_1251=y
+CONFIG_NLS_ASCII=y
+CONFIG_NLS_ISO8859_1=y
+CONFIG_NLS_ISO8859_2=y
+CONFIG_NLS_ISO8859_3=y
+CONFIG_NLS_ISO8859_4=y
+CONFIG_NLS_ISO8859_5=y
+CONFIG_NLS_ISO8859_6=y
+CONFIG_NLS_ISO8859_7=y
+CONFIG_NLS_ISO8859_9=y
+CONFIG_NLS_ISO8859_13=y
+CONFIG_NLS_ISO8859_14=y
+CONFIG_NLS_ISO8859_15=y
+CONFIG_NLS_KOI8_R=y
+CONFIG_NLS_KOI8_U=y
+CONFIG_NLS_MAC_ROMAN=y
+CONFIG_NLS_MAC_CELTIC=y
+CONFIG_NLS_MAC_CENTEURO=y
+CONFIG_NLS_MAC_CROATIAN=y
+CONFIG_NLS_MAC_CYRILLIC=y
+CONFIG_NLS_MAC_GAELIC=y
+CONFIG_NLS_MAC_GREEK=y
+CONFIG_NLS_MAC_ICELAND=y
+CONFIG_NLS_MAC_INUIT=y
+CONFIG_NLS_MAC_ROMANIAN=y
+CONFIG_NLS_MAC_TURKISH=y
+CONFIG_NLS_UTF8=y
+CONFIG_HZ_100=y
+CONFIG_CRYPTO_ANSI_CPRNG=y
+CONFIG_PRINTK_TIME=y
+CONFIG_DEBUG_INFO=y
+CONFIG_DEBUG_INFO_REDUCED=y
+# CONFIG_ENABLE_WARN_DEPRECATED is not set
+# CONFIG_ENABLE_MUST_CHECK is not set
diff --git a/arch/um/lkl/include/asm/Kbuild b/arch/um/lkl/include/asm/Kbuild
new file mode 100644
index 000000000000..f6308985c61c
--- /dev/null
+++ b/arch/um/lkl/include/asm/Kbuild
@@ -0,0 +1,80 @@ 
+generic-y += atomic.h
+generic-y += barrier.h
+generic-y += bitops.h
+generic-y += bug.h
+generic-y += bugs.h
+generic-y += cache.h
+generic-y += cacheflush.h
+generic-y += checksum.h
+generic-y += cmpxchg-local.h
+generic-y += cmpxchg.h
+generic-y += compat.h
+generic-y += cputime.h
+generic-y += current.h
+generic-y += delay.h
+generic-y += device.h
+generic-y += div64.h
+generic-y += dma.h
+generic-y += dma-mapping.h
+generic-y += emergency-restart.h
+generic-y += errno.h
+generic-y += extable.h
+generic-y += exec.h
+generic-y += ftrace.h
+generic-y += futex.h
+generic-y += hardirq.h
+generic-y += hw_irq.h
+generic-y += ioctl.h
+generic-y += ipcbuf.h
+generic-y += irq_regs.h
+generic-y += irqflags.h
+generic-y += irq_work.h
+generic-y += kdebug.h
+generic-y += kmap_types.h
+generic-y += linkage.h
+generic-y += local.h
+generic-y += local64.h
+generic-y += mcs_spinlock.h
+generic-y += mmiowb.h
+generic-y += mmu.h
+generic-y += mmu_context.h
+generic-y += module.h
+generic-y += msgbuf.h
+generic-y += param.h
+generic-y += parport.h
+generic-y += pci.h
+generic-y += percpu.h
+generic-y += pgalloc.h
+generic-y += poll.h
+generic-y += preempt.h
+generic-y += resource.h
+generic-y += rwsem.h
+generic-y += scatterlist.h
+generic-y += seccomp.h
+generic-y += sections.h
+generic-y += segment.h
+generic-y += sembuf.h
+generic-y += serial.h
+generic-y += shmbuf.h
+generic-y += signal.h
+generic-y += simd.h
+generic-y += sizes.h
+generic-y += socket.h
+generic-y += sockios.h
+generic-y += stat.h
+generic-y += statfs.h
+generic-y += string.h
+generic-y += swab.h
+generic-y += switch_to.h
+generic-y += syscall.h
+generic-y += termbits.h
+generic-y += termios.h
+generic-y += time.h
+generic-y += timex.h
+generic-y += tlbflush.h
+generic-y += topology.h
+generic-y += trace_clock.h
+generic-y += unaligned.h
+generic-y += user.h
+generic-y += word-at-a-time.h
+generic-y += kprobes.h
diff --git a/arch/um/lkl/include/asm/bitsperlong.h b/arch/um/lkl/include/asm/bitsperlong.h
new file mode 100644
index 000000000000..5745d5e51274
--- /dev/null
+++ b/arch/um/lkl/include/asm/bitsperlong.h
@@ -0,0 +1,11 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LKL_BITSPERLONG_H
+#define __LKL_BITSPERLONG_H
+
+#include <uapi/asm/bitsperlong.h>
+
+#define BITS_PER_LONG __BITS_PER_LONG
+
+#define BITS_PER_LONG_LONG 64
+
+#endif
diff --git a/arch/um/lkl/include/asm/byteorder.h b/arch/um/lkl/include/asm/byteorder.h
new file mode 100644
index 000000000000..5d0c4efaa44b
--- /dev/null
+++ b/arch/um/lkl/include/asm/byteorder.h
@@ -0,0 +1,7 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_BYTEORDER_H
+#define _ASM_LKL_BYTEORDER_H
+
+#include <uapi/asm/byteorder.h>
+
+#endif /* _ASM_LKL_BYTEORDER_H */
diff --git a/arch/um/lkl/include/asm/cpu.h b/arch/um/lkl/include/asm/cpu.h
new file mode 100644
index 000000000000..d2b8c501c7b1
--- /dev/null
+++ b/arch/um/lkl/include/asm/cpu.h
@@ -0,0 +1,14 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_CPU_H
+#define _ASM_LKL_CPU_H
+
+int lkl_cpu_get(void);
+void lkl_cpu_put(void);
+int lkl_cpu_try_run_irq(int irq);
+int lkl_cpu_init(void);
+void lkl_cpu_shutdown(void);
+void lkl_cpu_wait_shutdown(void);
+void lkl_cpu_change_owner(lkl_thread_t owner);
+void lkl_cpu_set_irqs_pending(void);
+
+#endif /* _ASM_LKL_CPU_H */
diff --git a/arch/um/lkl/include/asm/elf.h b/arch/um/lkl/include/asm/elf.h
new file mode 100644
index 000000000000..bb2456d638f4
--- /dev/null
+++ b/arch/um/lkl/include/asm/elf.h
@@ -0,0 +1,15 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_ELF_H
+#define _ASM_LKL_ELF_H
+
+#define elf_check_arch(x) 0
+
+#ifdef CONFIG_64BIT
+#define ELF_CLASS ELFCLASS64
+#else
+#define ELF_CLASS ELFCLASS32
+#endif
+
+#define elf_gregset_t long
+#define elf_fpregset_t double
+#endif
diff --git a/arch/um/lkl/include/asm/mutex.h b/arch/um/lkl/include/asm/mutex.h
new file mode 100644
index 000000000000..492d04183f9c
--- /dev/null
+++ b/arch/um/lkl/include/asm/mutex.h
@@ -0,0 +1,7 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_MUTEX_H
+#define _ASM_LKL_MUTEX_H
+
+#include <asm-generic/mutex-dec.h>
+
+#endif
diff --git a/arch/um/lkl/include/asm/processor.h b/arch/um/lkl/include/asm/processor.h
new file mode 100644
index 000000000000..c1aa8b3a266e
--- /dev/null
+++ b/arch/um/lkl/include/asm/processor.h
@@ -0,0 +1,60 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_PROCESSOR_H
+#define _ASM_LKL_PROCESSOR_H
+
+struct task_struct;
+
+static inline void cpu_relax(void)
+{
+	unsigned long flags;
+
+	/* since this is usually called in a tight loop waiting for some
+	 * external condition (e.g. jiffies) lets run interrupts now to allow
+	 * the external condition to propagate
+	 */
+	local_irq_save(flags);
+	local_irq_restore(flags);
+}
+
+#define current_text_addr() ({ __label__ _l; _l: &&_l; })
+
+static inline unsigned long thread_saved_pc(struct task_struct *tsk)
+{
+	return 0;
+}
+
+static inline void release_thread(struct task_struct *dead_task)
+{
+}
+
+static inline void prepare_to_copy(struct task_struct *tsk)
+{
+}
+
+static inline unsigned long get_wchan(struct task_struct *p)
+{
+	return 0;
+}
+
+static inline void flush_thread(void)
+{
+}
+
+static inline void trap_init(void)
+{
+}
+
+struct thread_struct { };
+
+#define INIT_THREAD { }
+
+#define task_pt_regs(tsk) (struct pt_regs *)(NULL)
+
+/* We don't have strict user/kernel spaces */
+#define TASK_SIZE ((unsigned long)-1)
+#define TASK_UNMAPPED_BASE 0
+
+#define KSTK_EIP(tsk) (0)
+#define KSTK_ESP(tsk) (0)
+
+#endif
diff --git a/arch/um/lkl/include/asm/ptrace.h b/arch/um/lkl/include/asm/ptrace.h
new file mode 100644
index 000000000000..28199be26dc0
--- /dev/null
+++ b/arch/um/lkl/include/asm/ptrace.h
@@ -0,0 +1,25 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_PTRACE_H
+#define _ASM_LKL_PTRACE_H
+
+#include <linux/errno.h>
+
+struct task_struct;
+
+#define user_mode(regs) 0
+#define kernel_mode(regs) 1
+#define profile_pc(regs) 0
+#define instruction_pointer(regs) 0
+#define user_stack_pointer(regs) 0
+
+static inline long arch_ptrace(struct task_struct *child, long request,
+			       unsigned long addr, unsigned long data)
+{
+	return -EINVAL;
+}
+
+static inline void ptrace_disable(struct task_struct *child)
+{
+}
+
+#endif
diff --git a/arch/um/lkl/include/asm/sched.h b/arch/um/lkl/include/asm/sched.h
new file mode 100644
index 000000000000..4c2635921ec8
--- /dev/null
+++ b/arch/um/lkl/include/asm/sched.h
@@ -0,0 +1,23 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_SCHED_H
+#define _ASM_LKL_SCHED_H
+
+#include <linux/sched.h>
+#include <uapi/asm/host_ops.h>
+
+static inline void thread_sched_jb(void)
+{
+	if (test_ti_thread_flag(current_thread_info(), TIF_HOST_THREAD)) {
+		set_ti_thread_flag(current_thread_info(), TIF_SCHED_JB);
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		lkl_ops->jmp_buf_set(&current_thread_info()->sched_jb,
+				     schedule);
+	} else {
+		lkl_bug("%s() can be used only for host task\n", __func__);
+	}
+}
+
+void switch_to_host_task(struct task_struct *);
+int host_task_stub(void *unused);
+
+#endif /*  _ASM_LKL_SCHED_H */
diff --git a/arch/um/lkl/include/asm/syscalls.h b/arch/um/lkl/include/asm/syscalls.h
new file mode 100644
index 000000000000..2eaa870a9020
--- /dev/null
+++ b/arch/um/lkl/include/asm/syscalls.h
@@ -0,0 +1,18 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_SYSCALLS_H
+#define _ASM_LKL_SYSCALLS_H
+
+int syscalls_init(void);
+void syscalls_cleanup(void);
+long lkl_syscall(long no, long *params);
+void wakeup_idle_host_task(void);
+
+#define sys_mmap sys_mmap_pgoff
+#define sys_mmap2 sys_mmap_pgoff
+#define sys_clone sys_ni_syscall
+#define sys_vfork sys_ni_syscall
+#define sys_rt_sigreturn sys_ni_syscall
+
+#include <asm-generic/syscalls.h>
+
+#endif /* _ASM_LKL_SYSCALLS_H */
diff --git a/arch/um/lkl/include/asm/syscalls_32.h b/arch/um/lkl/include/asm/syscalls_32.h
new file mode 100644
index 000000000000..0e1a7649c81b
--- /dev/null
+++ b/arch/um/lkl/include/asm/syscalls_32.h
@@ -0,0 +1,43 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_SYSCALLS_32_H
+#define _ASM_SYSCALLS_32_H
+
+#include <linux/compiler.h>
+#include <linux/linkage.h>
+#include <linux/types.h>
+#include <linux/signal.h>
+
+#if __BITS_PER_LONG == 32
+
+/* kernel/syscalls_32.c */
+asmlinkage long sys32_truncate64(const char __user *, unsigned long,
+				 unsigned long);
+asmlinkage long sys32_ftruncate64(unsigned int, unsigned long, unsigned long);
+
+#ifdef CONFIG_MMU
+struct mmap_arg_struct32;
+asmlinkage long sys32_mmap(struct mmap_arg_struct32 __user *);
+#endif
+
+asmlinkage long sys32_wait4(pid_t, unsigned int __user *, int,
+			    struct rusage __user *);
+
+asmlinkage long sys32_pread64(unsigned int, char __user *, u32, u32, u32);
+asmlinkage long sys32_pwrite64(unsigned int, const char __user *, u32, u32,
+			       u32);
+
+long sys32_fadvise64_64(int a, __u32 b, __u32 c, __u32 d, __u32 e, int f);
+
+asmlinkage ssize_t sys32_readahead(int, unsigned int, unsigned int, size_t);
+asmlinkage long sys32_sync_file_range(int, unsigned int, unsigned int,
+				      unsigned int, unsigned int, unsigned int);
+asmlinkage long sys32_sync_file_range2(int, unsigned int, unsigned int,
+				       unsigned int, unsigned int,
+				       unsigned int);
+asmlinkage long sys32_fadvise64(int, unsigned int, unsigned int, size_t, int);
+asmlinkage long sys32_fallocate(int, int, unsigned int, unsigned int,
+				unsigned int, unsigned int);
+
+#endif /* __BITS_PER_LONG */
+
+#endif /* _ASM_SYSCALLS_32_H */
diff --git a/arch/um/lkl/include/asm/tlb.h b/arch/um/lkl/include/asm/tlb.h
new file mode 100644
index 000000000000..d474890d317d
--- /dev/null
+++ b/arch/um/lkl/include/asm/tlb.h
@@ -0,0 +1,12 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_TLB_H
+#define _ASM_LKL_TLB_H
+
+#define tlb_start_vma(tlb, vma)				do { } while (0)
+#define tlb_end_vma(tlb, vma)				do { } while (0)
+#define __tlb_remove_tlb_entry(tlb, pte, address)	do { } while (0)
+#define tlb_flush(tlb)					do { } while (0)
+
+#include <asm-generic/tlb.h>
+
+#endif /* _ASM_LKL_TLB_H */
diff --git a/arch/um/lkl/include/asm/uaccess.h b/arch/um/lkl/include/asm/uaccess.h
new file mode 100644
index 000000000000..f267ac3be8b3
--- /dev/null
+++ b/arch/um/lkl/include/asm/uaccess.h
@@ -0,0 +1,64 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_UACCESS_H
+#define _ASM_LKL_UACCESS_H
+
+/* copied from old include/asm-generic/uaccess.h */
+static inline __must_check long
+raw_copy_from_user(void *to, const void __user *from, unsigned long n)
+{
+	if (__builtin_constant_p(n)) {
+		switch (n) {
+		case 1:
+			*(u8 *)to = *(u8 __force *)from;
+			return 0;
+		case 2:
+			*(u16 *)to = *(u16 __force *)from;
+			return 0;
+		case 4:
+			*(u32 *)to = *(u32 __force *)from;
+			return 0;
+#ifdef CONFIG_64BIT
+		case 8:
+			*(u64 *)to = *(u64 __force *)from;
+			return 0;
+#endif
+		default:
+			break;
+		}
+	}
+
+	memcpy(to, (const void __force *)from, n);
+	return 0;
+}
+
+static inline __must_check long
+raw_copy_to_user(void __user *to, const void *from, unsigned long n)
+{
+	if (__builtin_constant_p(n)) {
+		switch (n) {
+		case 1:
+			*(u8 __force *)to = *(u8 *)from;
+			return 0;
+		case 2:
+			*(u16 __force *)to = *(u16 *)from;
+			return 0;
+		case 4:
+			*(u32 __force *)to = *(u32 *)from;
+			return 0;
+#ifdef CONFIG_64BIT
+		case 8:
+			*(u64 __force *)to = *(u64 *)from;
+			return 0;
+#endif
+		default:
+			break;
+		}
+	}
+
+	memcpy((void __force *)to, from, n);
+	return 0;
+}
+
+#include <asm-generic/uaccess.h>
+
+#endif
diff --git a/arch/um/lkl/include/asm/unistd_32.h b/arch/um/lkl/include/asm/unistd_32.h
new file mode 100644
index 000000000000..8582a55e61e2
--- /dev/null
+++ b/arch/um/lkl/include/asm/unistd_32.h
@@ -0,0 +1,31 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <asm/bitsperlong.h>
+
+#ifndef __SYSCALL
+#define __SYSCALL(x, y)
+#endif
+
+#if __BITS_PER_LONG == 32
+__SYSCALL(__NR3264_truncate, sys32_truncate64)
+__SYSCALL(__NR3264_ftruncate, sys32_ftruncate64)
+
+#ifdef CONFIG_MMU
+__SYSCALL(__NR3264_mmap, sys32_mmap)
+#endif
+
+__SYSCALL(__NR_wait4, sys32_wait4)
+
+__SYSCALL(__NR_pread64, sys32_pread64)
+__SYSCALL(__NR_pwrite64, sys32_pwrite64)
+
+__SYSCALL(__NR_readahead, sys32_readahead)
+#ifdef __ARCH_WANT_SYNC_FILE_RANGE2
+__SYSCALL(__NR_sync_file_range2, sys32_sync_file_range2)
+#else
+__SYSCALL(__NR_sync_file_range, sys32_sync_file_range)
+#endif
+/* mm/fadvise.c */
+__SYSCALL(__NR3264_fadvise64, sys32_fadvise64_64)
+__SYSCALL(__NR_fallocate, sys32_fallocate)
+
+#endif
diff --git a/arch/um/lkl/include/asm/vmlinux.lds.h b/arch/um/lkl/include/asm/vmlinux.lds.h
new file mode 100644
index 000000000000..a3c285882dc4
--- /dev/null
+++ b/arch/um/lkl/include/asm/vmlinux.lds.h
@@ -0,0 +1,14 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LKL_VMLINUX_LDS_H
+#define _LKL_VMLINUX_LDS_H
+
+/* we encode our own __ro_after_init section */
+#define RO_AFTER_INIT_DATA
+
+#ifdef __MINGW32__
+#define RODATA_SECTION .rdata
+#endif
+
+#include <asm-generic/vmlinux.lds.h>
+
+#endif
diff --git a/arch/um/lkl/include/asm/xor.h b/arch/um/lkl/include/asm/xor.h
new file mode 100644
index 000000000000..286ce75b5d9d
--- /dev/null
+++ b/arch/um/lkl/include/asm/xor.h
@@ -0,0 +1,9 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_LKL_XOR_H
+#define _ASM_LKL_XOR_H
+
+#include <asm-generic/xor.h>
+
+#define XOR_SELECT_TEMPLATE(x) (&xor_block_8regs)
+
+#endif /* _ASM_LKL_XOR_H */
diff --git a/arch/um/lkl/include/uapi/asm/Kbuild b/arch/um/lkl/include/uapi/asm/Kbuild
new file mode 100644
index 000000000000..39d9a1f2e8f5
--- /dev/null
+++ b/arch/um/lkl/include/uapi/asm/Kbuild
@@ -0,0 +1,9 @@ 
+# UAPI Header export list
+
+generic-y += elf.h
+generic-y += kvm_para.h
+generic-y += shmparam.h
+generic-y += timex.h
+
+# no header-y since we need special user headers handling
+# see arch/lkl/script/headers.py
diff --git a/arch/um/lkl/include/uapi/asm/bitsperlong.h b/arch/um/lkl/include/uapi/asm/bitsperlong.h
new file mode 100644
index 000000000000..8b4ebf2b0264
--- /dev/null
+++ b/arch/um/lkl/include/uapi/asm/bitsperlong.h
@@ -0,0 +1,13 @@ 
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_UAPI_LKL_BITSPERLONG_H
+#define _ASM_UAPI_LKL_BITSPERLONG_H
+
+#ifdef CONFIG_64BIT
+#define __BITS_PER_LONG 64
+#else
+#define __BITS_PER_LONG 32
+#endif
+
+#define __ARCH_WANT_STAT64
+
+#endif /* _ASM_UAPI_LKL_BITSPERLONG_H */
diff --git a/arch/um/lkl/include/uapi/asm/byteorder.h b/arch/um/lkl/include/uapi/asm/byteorder.h
new file mode 100644
index 000000000000..3c4a58d2062f
--- /dev/null
+++ b/arch/um/lkl/include/uapi/asm/byteorder.h
@@ -0,0 +1,11 @@ 
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_UAPI_LKL_BYTEORDER_H
+#define _ASM_UAPI_LKL_BYTEORDER_H
+
+#if defined(CONFIG_BIG_ENDIAN)
+#include <linux/byteorder/big_endian.h>
+#else
+#include <linux/byteorder/little_endian.h>
+#endif
+
+#endif /* _ASM_UAPI_LKL_BYTEORDER_H */
diff --git a/arch/um/lkl/include/uapi/asm/siginfo.h b/arch/um/lkl/include/uapi/asm/siginfo.h
new file mode 100644
index 000000000000..811916cf42c8
--- /dev/null
+++ b/arch/um/lkl/include/uapi/asm/siginfo.h
@@ -0,0 +1,11 @@ 
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_LKL_SIGINFO_H
+#define _ASM_LKL_SIGINFO_H
+
+#ifdef CONFIG_64BIT
+#define __ARCH_SI_PREAMBLE_SIZE	(4 * sizeof(int))
+#endif
+
+#include <asm-generic/siginfo.h>
+
+#endif /* _ASM_LKL_SIGINFO_H */
diff --git a/arch/um/lkl/include/uapi/asm/swab.h b/arch/um/lkl/include/uapi/asm/swab.h
new file mode 100644
index 000000000000..1a1773e1bd35
--- /dev/null
+++ b/arch/um/lkl/include/uapi/asm/swab.h
@@ -0,0 +1,11 @@ 
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_LKL_SWAB_H
+#define _ASM_LKL_SWAB_H
+
+#ifndef __arch_swab32
+#define __arch_swab32(x) ___constant_swab32(x)
+#endif
+
+#include <asm-generic/swab.h>
+
+#endif /* _ASM_LKL_SWAB_H */
diff --git a/arch/um/lkl/include/uapi/asm/syscalls.h b/arch/um/lkl/include/uapi/asm/syscalls.h
new file mode 100644
index 000000000000..a81534ffccb7
--- /dev/null
+++ b/arch/um/lkl/include/uapi/asm/syscalls.h
@@ -0,0 +1,348 @@ 
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_UAPI_LKL_SYSCALLS_H
+#define _ASM_UAPI_LKL_SYSCALLS_H
+
+#include <autoconf.h>
+#include <linux/types.h>
+
+typedef __kernel_uid32_t	qid_t;
+typedef __kernel_fd_set		fd_set;
+typedef __kernel_mode_t		mode_t;
+typedef unsigned short		umode_t;
+typedef __u32			nlink_t;
+typedef __kernel_off_t		off_t;
+typedef __kernel_pid_t		pid_t;
+typedef __kernel_key_t		key_t;
+typedef __kernel_suseconds_t	suseconds_t;
+typedef __kernel_timer_t	timer_t;
+typedef __kernel_clockid_t	clockid_t;
+typedef __kernel_mqd_t		mqd_t;
+typedef __kernel_uid32_t	uid_t;
+typedef __kernel_gid32_t	gid_t;
+typedef __kernel_uid16_t        uid16_t;
+typedef __kernel_gid16_t        gid16_t;
+typedef unsigned long		uintptr_t;
+#ifdef CONFIG_UID16
+typedef __kernel_old_uid_t	old_uid_t;
+typedef __kernel_old_gid_t	old_gid_t;
+#endif
+typedef __kernel_loff_t		loff_t;
+typedef __kernel_size_t		size_t;
+typedef __kernel_ssize_t	ssize_t;
+typedef __kernel_time_t		time_t;
+typedef __kernel_clock_t	clock_t;
+typedef __u32			u32;
+typedef __s32			s32;
+typedef __u64			u64;
+typedef __s64			s64;
+
+#define __user
+
+#include <asm/unistd.h>
+/* Temporary undefine system calls that don't have data types defined in UAPI
+ * headers
+ */
+#undef __NR_kexec_load
+#undef __NR_getcpu
+#undef __NR_sched_getattr
+#undef __NR_sched_setattr
+#undef __NR_sched_setparam
+#undef __NR_sched_getparam
+#undef __NR_sched_setscheduler
+#undef __NR_name_to_handle_at
+#undef __NR_open_by_handle_at
+
+/* deprecated system calls */
+#undef __NR_epoll_create
+#undef __NR_epoll_wait
+#undef __NR_access
+#undef __NR_chmod
+#undef __NR_chown
+#undef __NR_lchown
+#undef __NR_open
+#undef __NR_creat
+#undef __NR_readlink
+#undef __NR_pipe
+#undef __NR_mknod
+#undef __NR_mkdir
+#undef __NR_rmdir
+#undef __NR_unlink
+#undef __NR_symlink
+#undef __NR_link
+#undef __NR_rename
+#undef __NR_getdents
+#undef __NR_select
+#undef __NR_poll
+#undef __NR_dup2
+#undef __NR_futimesat
+#undef __NR_utimes
+#undef __NR_ustat
+#undef __NR_eventfd
+#undef __NR_bdflush
+#undef __NR_send
+#undef __NR_recv
+
+#undef __NR_umount
+#define __NR_umount __NR_umount2
+
+#ifdef CONFIG_64BIT
+#define __NR_newfstat __NR3264_fstat
+#define __NR_newfstatat __NR3264_fstatat
+#endif
+
+#define __NR_mmap_pgoff __NR3264_mmap
+
+#include <linux/time.h>
+#include <linux/times.h>
+#include <linux/timex.h>
+#include <linux/capability.h>
+#define __KERNEL__ /* to pull in S_ definitions */
+#include <linux/stat.h>
+#undef __KERNEL__
+#include <linux/errno.h>
+#include <linux/fcntl.h>
+#include <linux/fs.h>
+#include <asm/statfs.h>
+#include <asm/stat.h>
+#include <linux/bpf.h>
+#include <linux/msg.h>
+#include <linux/resource.h>
+#include <linux/sysinfo.h>
+#include <linux/shm.h>
+#include <linux/aio_abi.h>
+#include <linux/socket.h>
+#include <linux/perf_event.h>
+#include <linux/sem.h>
+#include <linux/futex.h>
+#include <linux/poll.h>
+#include <linux/mqueue.h>
+#include <linux/eventpoll.h>
+#include <linux/uio.h>
+#include <asm/signal.h>
+#include <asm/siginfo.h>
+#include <linux/utime.h>
+#include <asm/socket.h>
+#include <linux/icmp.h>
+#include <linux/ip.h>
+
+/* Define data structures used in system calls that are not defined in UAPI
+ * headers
+ */
+struct sockaddr {
+	unsigned short int sa_family;
+	char sa_data[14];
+};
+
+#define __UAPI_DEF_IF_NET_DEVICE_FLAGS_LOWER_UP_DORMANT_ECHO 1
+#define __UAPI_DEF_IF_IFNAMSIZ	1
+#define __UAPI_DEF_IF_NET_DEVICE_FLAGS 1
+#define __UAPI_DEF_IF_IFREQ	1
+#define __UAPI_DEF_IF_IFMAP	1
+#include <linux/if.h>
+#define __UAPI_DEF_IN_IPPROTO	1
+#define __UAPI_DEF_IN_ADDR	1
+#define __UAPI_DEF_IN6_ADDR	1
+#define __UAPI_DEF_IP_MREQ	1
+#define __UAPI_DEF_IN_PKTINFO	1
+#define __UAPI_DEF_SOCKADDR_IN	1
+#define __UAPI_DEF_IN_CLASS	1
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/sockios.h>
+#include <linux/route.h>
+#include <linux/ipv6_route.h>
+#include <linux/ipv6.h>
+#include <linux/netlink.h>
+#include <linux/neighbour.h>
+#include <linux/rtnetlink.h>
+#include <linux/fib_rules.h>
+
+#include <linux/kdev_t.h>
+#include <asm/irq.h>
+#include <linux/virtio_blk.h>
+#include <linux/virtio_net.h>
+#include <linux/virtio_ring.h>
+#include <linux/pkt_sched.h>
+#include <linux/io_uring.h>
+
+struct user_msghdr {
+	void		__user *msg_name;
+	int		msg_namelen;
+	struct iovec	__user *msg_iov;
+	__kernel_size_t	msg_iovlen;
+	void		__user *msg_control;
+	__kernel_size_t	msg_controllen;
+	unsigned int	msg_flags;
+};
+
+typedef __u32 key_serial_t;
+
+struct mmsghdr {
+	struct user_msghdr  msg_hdr;
+	unsigned int        msg_len;
+};
+
+struct linux_dirent64 {
+	u64		d_ino;
+	s64		d_off;
+	unsigned short	d_reclen;
+	unsigned char	d_type;
+	char		d_name[0];
+};
+
+struct linux_dirent {
+	unsigned long	d_ino;
+	unsigned long	d_off;
+	unsigned short	d_reclen;
+	char		d_name[1];
+};
+
+struct ustat {
+	__kernel_daddr_t	f_tfree;
+	__kernel_ino_t		f_tinode;
+	char			f_fname[6];
+	char			f_fpack[6];
+};
+
+typedef __kernel_rwf_t		rwf_t;
+
+#define AF_UNSPEC       0
+#define AF_UNIX         1
+#define AF_LOCAL        1
+#define AF_INET         2
+#define AF_AX25         3
+#define AF_IPX          4
+#define AF_APPLETALK    5
+#define AF_NETROM       6
+#define AF_BRIDGE       7
+#define AF_ATMPVC       8
+#define AF_X25          9
+#define AF_INET6        10
+#define AF_ROSE         11
+#define AF_DECnet       12
+#define AF_NETBEUI      13
+#define AF_SECURITY     14
+#define AF_KEY          15
+#define AF_NETLINK      16
+#define AF_ROUTE        AF_NETLINK
+#define AF_PACKET       17
+#define AF_ASH          18
+#define AF_ECONET       19
+#define AF_ATMSVC       20
+#define AF_RDS          21
+#define AF_SNA          22
+#define AF_IRDA         23
+#define AF_PPPOX        24
+#define AF_WANPIPE      25
+#define AF_LLC          26
+#define AF_IB           27
+#define AF_MPLS         28
+#define AF_CAN          29
+#define AF_TIPC         30
+#define AF_BLUETOOTH    31
+#define AF_IUCV         32
+#define AF_RXRPC        33
+#define AF_ISDN         34
+#define AF_PHONET       35
+#define AF_IEEE802154   36
+#define AF_CAIF         37
+#define AF_ALG          38
+#define AF_NFC          39
+#define AF_VSOCK        40
+
+#define SOCK_STREAM		1
+#define SOCK_DGRAM		2
+#define SOCK_RAW		3
+#define SOCK_RDM		4
+#define SOCK_SEQPACKET		5
+#define SOCK_DCCP		6
+#define SOCK_PACKET		10
+
+#define MSG_TRUNC 0x20
+#define MSG_DONTWAIT 0x40
+
+/* avoid colision with system headers defines */
+#define sa_handler sa_handler
+#define st_atime st_atime
+#define st_mtime st_mtime
+#define st_ctime st_ctime
+#define s_addr s_addr
+
+long lkl_syscall(long no, long *params);
+long lkl_sys_halt(void);
+
+#define __MAP0(m, ...)
+#define __MAP1(m, t, a) m(t, a)
+#define __MAP2(m, t, a, ...) m(t, a), __MAP1(m, __VA_ARGS__)
+#define __MAP3(m, t, a, ...) m(t, a), __MAP2(m, __VA_ARGS__)
+#define __MAP4(m, t, a, ...) m(t, a), __MAP3(m, __VA_ARGS__)
+#define __MAP5(m, t, a, ...) m(t, a), __MAP4(m, __VA_ARGS__)
+#define __MAP6(m, t, a, ...) m(t, a), __MAP5(m, __VA_ARGS__)
+#define __MAP(n, ...) __MAP##n(__VA_ARGS__)
+
+#define __SC_LONG(t, a) (long)a
+#define __SC_TABLE(t, a) {sizeof(t), (long long)(a)}
+#define __SC_DECL(t, a) t a
+
+#define LKL_SYSCALL0(name)					       \
+	static inline long lkl_sys##name(void)			       \
+	{							       \
+		long params[6];					       \
+		return lkl_syscall(__lkl__NR##name, params);	       \
+	}
+
+#if __BITS_PER_LONG == 32
+#define LKL_SYSCALLx(x, name, ...)					\
+	static inline							\
+	long lkl_sys##name(__MAP(x, __SC_DECL, __VA_ARGS__))		\
+	{								\
+		struct {						\
+			unsigned int size;				\
+			long long value;				\
+		} lkl_params[x] = { __MAP(x, __SC_TABLE, __VA_ARGS__) }; \
+		long sys_params[6], i, k;				\
+		for (i = k = 0; i < x && k < 6; i++, k++) {		\
+			if (lkl_params[i].size > sizeof(long) &&	\
+			    k + 1 < 6) {				\
+				sys_params[k] =				\
+					(long)(lkl_params[i].value & (-1UL)); \
+				k++;					\
+				sys_params[k] =				\
+					(long)(lkl_params[i].value >>	\
+					       __BITS_PER_LONG);	\
+			} else {					\
+				sys_params[k] = (long)(lkl_params[i].value); \
+			}						\
+		}							\
+		return lkl_syscall(__lkl__NR##name, sys_params);	\
+	}
+#else
+#define LKL_SYSCALLx(x, name, ...)					\
+	static inline							\
+	long lkl_sys##name(__MAP(x, __SC_DECL, __VA_ARGS__))		\
+	{								\
+		long lkl_params[6] = { __MAP(x, __SC_LONG, __VA_ARGS__) }; \
+		return lkl_syscall(__lkl__NR##name, lkl_params);	\
+	}
+#endif
+
+#define SYSCALL_DEFINE0(name, ...) LKL_SYSCALL0(name)
+#define SYSCALL_DEFINE1(name, ...) LKL_SYSCALLx(1, name, __VA_ARGS__)
+#define SYSCALL_DEFINE2(name, ...) LKL_SYSCALLx(2, name, __VA_ARGS__)
+#define SYSCALL_DEFINE3(name, ...) LKL_SYSCALLx(3, name, __VA_ARGS__)
+#define SYSCALL_DEFINE4(name, ...) LKL_SYSCALLx(4, name, __VA_ARGS__)
+#define SYSCALL_DEFINE5(name, ...) LKL_SYSCALLx(5, name, __VA_ARGS__)
+#define SYSCALL_DEFINE6(name, ...) LKL_SYSCALLx(6, name, __VA_ARGS__)
+
+#if __BITS_PER_LONG == 32
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wpointer-to-int-cast"
+#endif
+
+#include <asm/syscall_defs.h>
+
+#if __BITS_PER_LONG == 32
+#pragma GCC diagnostic pop
+#endif
+
+#endif
diff --git a/arch/um/lkl/kernel/asm-offsets.c b/arch/um/lkl/kernel/asm-offsets.c
new file mode 100644
index 000000000000..6be0763698dc
--- /dev/null
+++ b/arch/um/lkl/kernel/asm-offsets.c
@@ -0,0 +1,2 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/* Dummy asm-offsets.c file. Required by kbuild and ready to be used - hint! */
diff --git a/arch/um/lkl/kernel/misc.c b/arch/um/lkl/kernel/misc.c
new file mode 100644
index 000000000000..60f048f02ae6
--- /dev/null
+++ b/arch/um/lkl/kernel/misc.c
@@ -0,0 +1,60 @@ 
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kallsyms.h>
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/seq_file.h>
+#include <asm/ptrace.h>
+#include <asm/host_ops.h>
+
+#ifdef CONFIG_PRINTK
+void dump_stack(void)
+{
+	unsigned long dummy;
+	unsigned long *stack = &dummy;
+	unsigned long addr;
+
+	pr_info("Call Trace:\n");
+	while (((long)stack & (THREAD_SIZE - 1)) != 0) {
+		addr = *stack;
+		if (__kernel_text_address(addr)) {
+			pr_info("%p:  [<%08lx>] %pS", stack, addr,
+				(void *)addr);
+			pr_cont("\n");
+		}
+		stack++;
+	}
+	pr_info("\n");
+}
+#endif
+
+void show_regs(struct pt_regs *regs)
+{
+}
+
+#ifdef CONFIG_PROC_FS
+static void *cpuinfo_start(struct seq_file *m, loff_t *pos)
+{
+	return NULL;
+}
+
+static void *cpuinfo_next(struct seq_file *m, void *v, loff_t *pos)
+{
+	return NULL;
+}
+
+static void cpuinfo_stop(struct seq_file *m, void *v)
+{
+}
+
+static int show_cpuinfo(struct seq_file *m, void *v)
+{
+	return 0;
+}
+
+const struct seq_operations cpuinfo_op = {
+	.start	= cpuinfo_start,
+	.next	= cpuinfo_next,
+	.stop	= cpuinfo_stop,
+	.show	= show_cpuinfo,
+};
+#endif
diff --git a/arch/um/lkl/kernel/vmlinux.lds.S b/arch/um/lkl/kernel/vmlinux.lds.S
new file mode 100644
index 000000000000..efe420f38110
--- /dev/null
+++ b/arch/um/lkl/kernel/vmlinux.lds.S
@@ -0,0 +1,51 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#include <asm/vmlinux.lds.h>
+#include <asm/thread_info.h>
+#include <asm/page.h>
+#include <asm/cache.h>
+#include <linux/export.h>
+
+OUTPUT_FORMAT(CONFIG_OUTPUT_FORMAT)
+
+VMLINUX_SYMBOL(jiffies) = VMLINUX_SYMBOL(jiffies_64);
+
+SECTIONS
+{
+	VMLINUX_SYMBOL(__init_begin) = .;
+	HEAD_TEXT_SECTION
+	INIT_TEXT_SECTION(PAGE_SIZE)
+	INIT_DATA_SECTION(16)
+	PERCPU_SECTION(L1_CACHE_BYTES)
+	VMLINUX_SYMBOL(__init_end) = .;
+
+	VMLINUX_SYMBOL(_stext) = .;
+	VMLINUX_SYMBOL(_text) = . ;
+	VMLINUX_SYMBOL(text) = . ;
+	.text      :
+	{
+		TEXT_TEXT
+		SCHED_TEXT
+		LOCK_TEXT
+		CPUIDLE_TEXT
+	}
+	VMLINUX_SYMBOL(_etext) = .;
+
+	VMLINUX_SYMBOL(_sdata) = .;
+	RO_DATA_SECTION(PAGE_SIZE)
+	RW_DATA_SECTION(L1_CACHE_BYTES, PAGE_SIZE, THREAD_SIZE)
+	VMLINUX_SYMBOL(_edata) = .;
+
+	VMLINUX_SYMBOL(__start_ro_after_init) = .;
+	.data..ro_after_init : { *(.data..ro_after_init)}
+	EXCEPTION_TABLE(16)
+	VMLINUX_SYMBOL(__end_ro_after_init) = .;
+	NOTES
+
+	BSS_SECTION(0, 0, 0)
+	VMLINUX_SYMBOL(_end) = .;
+
+	STABS_DEBUG
+	DWARF_DEBUG
+
+	DISCARDS
+}