x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

23 files changed, 1188 insertions, 0 deletions

diff --git a/arch/um/include/shared/arch.h b/arch/um/include/shared/arch.h
new file mode 100644
index 000000000..cc398a21a
--- /dev/null
+++ b/arch/um/include/shared/arch.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __ARCH_H__
+#define __ARCH_H__
+
+#include <sysdep/ptrace.h>
+
+extern void arch_check_bugs(void);
+extern int arch_fixup(unsigned long address, struct uml_pt_regs *regs);
+extern void arch_examine_signal(int sig, struct uml_pt_regs *regs);
+
+void mc_set_rip(void *_mc, void *target);
+
+#endif
diff --git a/arch/um/include/shared/as-layout.h b/arch/um/include/shared/as-layout.h
new file mode 100644
index 000000000..02ef258e3
--- /dev/null
+++ b/arch/um/include/shared/as-layout.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __START_H__
+#define __START_H__
+
+#include <generated/asm-offsets.h>
+
+/*
+ * Stolen from linux/const.h, which can't be directly included since
+ * this is used in userspace code, which has no access to the kernel
+ * headers.  Changed to be suitable for adding casts to the start,
+ * rather than "UL" to the end.
+ */
+
+/* Some constant macros are used in both assembler and
+ * C code.  Therefore we cannot annotate them always with
+ * 'UL' and other type specifiers unilaterally.  We
+ * use the following macros to deal with this.
+ */
+#define STUB_START stub_start
+#define STUB_CODE STUB_START
+#define STUB_DATA (STUB_CODE + UM_KERN_PAGE_SIZE)
+#define STUB_DATA_PAGES 2
+#define STUB_SIZE ((1 + STUB_DATA_PAGES) * UM_KERN_PAGE_SIZE)
+#define STUB_END (STUB_START + STUB_SIZE)
+
+#ifndef __ASSEMBLER__
+
+#include <sysdep/ptrace.h>
+
+struct task_struct;
+extern struct task_struct *cpu_tasks[];
+
+extern unsigned long long physmem_size;
+
+extern unsigned long high_physmem;
+extern unsigned long uml_physmem;
+extern unsigned long uml_reserved;
+extern unsigned long end_vm;
+extern unsigned long start_vm;
+
+extern unsigned long brk_start;
+
+extern unsigned long stub_start;
+
+extern int linux_main(int argc, char **argv, char **envp);
+extern void uml_finishsetup(void);
+
+struct siginfo;
+extern void (*sig_info[])(int, struct siginfo *si, struct uml_pt_regs *, void *);
+
+#endif
+
+#endif
diff --git a/arch/um/include/shared/elf_user.h b/arch/um/include/shared/elf_user.h
new file mode 100644
index 000000000..fd461ee40
--- /dev/null
+++ b/arch/um/include/shared/elf_user.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2004 Fujitsu Siemens Computers GmbH
+ * Author: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
+ */
+
+#ifndef __ELF_USER_H__
+#define __ELF_USER_H__
+
+/* For compilation on a host that doesn't support AT_SYSINFO (Linux 2.4)  */
+
+#ifndef AT_SYSINFO
+#define AT_SYSINFO 32
+#endif
+#ifndef AT_SYSINFO_EHDR
+#define AT_SYSINFO_EHDR 33
+#endif
+
+#endif
diff --git a/arch/um/include/shared/frame_kern.h b/arch/um/include/shared/frame_kern.h
new file mode 100644
index 000000000..ed952ac66
--- /dev/null
+++ b/arch/um/include/shared/frame_kern.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* 
+ * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ */
+
+#ifndef __FRAME_KERN_H_
+#define __FRAME_KERN_H_
+
+extern int setup_signal_stack_sc(unsigned long stack_top, struct ksignal *ksig,
+				 struct pt_regs *regs, sigset_t *mask);
+extern int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
+				 struct pt_regs *regs, sigset_t *mask);
+
+#endif
+
diff --git a/arch/um/include/shared/init.h b/arch/um/include/shared/init.h
new file mode 100644
index 000000000..1a659e2e8
--- /dev/null
+++ b/arch/um/include/shared/init.h
@@ -0,0 +1,127 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_UML_INIT_H
+#define _LINUX_UML_INIT_H
+
+/* These macros are used to mark some functions or
+ * initialized data (doesn't apply to uninitialized data)
+ * as `initialization' functions. The kernel can take this
+ * as hint that the function is used only during the initialization
+ * phase and free up used memory resources after
+ *
+ * Usage:
+ * For functions:
+ *
+ * You should add __init immediately before the function name, like:
+ *
+ * static void __init initme(int x, int y)
+ * {
+ *    extern int z; z = x * y;
+ * }
+ *
+ * If the function has a prototype somewhere, you can also add
+ * __init between closing brace of the prototype and semicolon:
+ *
+ * extern int initialize_foobar_device(int, int, int) __init;
+ *
+ * For initialized data:
+ * You should insert __initdata between the variable name and equal
+ * sign followed by value, e.g.:
+ *
+ * static int init_variable __initdata = 0;
+ * static const char linux_logo[] __initconst = { 0x32, 0x36, ... };
+ *
+ * Don't forget to initialize data not at file scope, i.e. within a function,
+ * as gcc otherwise puts the data into the bss section and not into the init
+ * section.
+ *
+ * Also note, that this data cannot be "const".
+ */
+
+#ifndef _LINUX_INIT_H
+typedef int (*initcall_t)(void);
+typedef void (*exitcall_t)(void);
+
+#include <linux/compiler_types.h>
+
+/* These are for everybody (although not all archs will actually
+   discard it in modules) */
+#define __init		__section(".init.text")
+#define __initdata	__section(".init.data")
+#define __exitdata	__section(".exit.data")
+#define __exit_call	__used __section(".exitcall.exit")
+
+#ifdef MODULE
+#define __exit		__section(".exit.text")
+#else
+#define __exit		__used __section(".exit.text")
+#endif
+
+#endif
+
+#ifndef MODULE
+struct uml_param {
+        const char *str;
+        int (*setup_func)(char *, int *);
+};
+
+extern initcall_t __uml_postsetup_start, __uml_postsetup_end;
+extern const char *__uml_help_start, *__uml_help_end;
+#endif
+
+#define __uml_exitcall(fn)						\
+	static exitcall_t __uml_exitcall_##fn __uml_exit_call = fn
+
+extern struct uml_param __uml_setup_start, __uml_setup_end;
+
+#define __uml_postsetup(fn)						\
+	static initcall_t __uml_postsetup_##fn __uml_postsetup_call = fn
+
+#define __non_empty_string(dummyname,string)				\
+	struct __uml_non_empty_string_struct_##dummyname		\
+	{								\
+		char _string[sizeof(string)-2];				\
+	}
+
+#ifndef MODULE
+#define __uml_setup(str, fn, help...)					\
+	__non_empty_string(fn ##_setup, str);				\
+	__uml_help(fn, help);						\
+	static char __uml_setup_str_##fn[] __initdata = str;		\
+	static struct uml_param __uml_setup_##fn __uml_init_setup = { __uml_setup_str_##fn, fn }
+#else
+#define __uml_setup(str, fn, help...)					\
+
+#endif
+
+#define __uml_help(fn, help...)						\
+	__non_empty_string(fn ##__help, help);				\
+	static char __uml_help_str_##fn[] __initdata = help;		\
+	static const char *__uml_help_##fn __uml_setup_help = __uml_help_str_##fn
+
+/*
+ * Mark functions and data as being only used at initialization
+ * or exit time.
+ */
+#define __uml_init_setup	__used __section(".uml.setup.init")
+#define __uml_setup_help	__used __section(".uml.help.init")
+#define __uml_postsetup_call	__used __section(".uml.postsetup.init")
+#define __uml_exit_call		__used __section(".uml.exitcall.exit")
+
+#ifdef __UM_HOST__
+
+#define __define_initcall(level,fn) \
+	static initcall_t __initcall_##fn __used \
+	__attribute__((__section__(".initcall" level ".init"))) = fn
+
+/* Userspace initcalls shouldn't depend on anything in the kernel, so we'll
+ * make them run first.
+ */
+#define __initcall(fn) __define_initcall("1", fn)
+
+#define __exitcall(fn) static exitcall_t __exitcall_##fn __exit_call = fn
+
+#define __init_call	__used __section(".initcall.init")
+
+#endif
+
+#endif /* _LINUX_UML_INIT_H */
diff --git a/arch/um/include/shared/irq_kern.h b/arch/um/include/shared/irq_kern.h
new file mode 100644
index 000000000..44357fa6e
--- /dev/null
+++ b/arch/um/include/shared/irq_kern.h
@@ -0,0 +1,80 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2001, 2002 Jeff Dike (jdike@karaya.com)
+ */
+
+#ifndef __IRQ_KERN_H__
+#define __IRQ_KERN_H__
+
+#include <linux/interrupt.h>
+#include <linux/time-internal.h>
+#include <asm/ptrace.h>
+#include "irq_user.h"
+
+#define UM_IRQ_ALLOC	-1
+
+int um_request_irq(int irq, int fd, enum um_irq_type type,
+		   irq_handler_t handler, unsigned long irqflags,
+		   const char *devname, void *dev_id);
+
+#ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
+/**
+ * um_request_irq_tt - request an IRQ with timetravel handler
+ *
+ * @irq: the IRQ number, or %UM_IRQ_ALLOC
+ * @fd: The file descriptor to request an IRQ for
+ * @type: read or write
+ * @handler: the (generic style) IRQ handler
+ * @irqflags: Linux IRQ flags
+ * @devname: name for this to show
+ * @dev_id: data pointer to pass to the IRQ handler
+ * @timetravel_handler: the timetravel interrupt handler, invoked with the IRQ
+ *	number, fd, dev_id and time-travel event pointer.
+ *
+ * Returns: The interrupt number assigned or a negative error.
+ *
+ * Note that the timetravel handler is invoked only if the time_travel_mode is
+ * %TT_MODE_EXTERNAL, and then it is invoked even while the system is suspended!
+ * This function must call time_travel_add_irq_event() for the event passed with
+ * an appropriate delay, before sending an ACK on the socket it was invoked for.
+ *
+ * If this was called while the system is suspended, then adding the event will
+ * cause the system to resume.
+ *
+ * Since this function will almost certainly have to handle the FD's condition,
+ * a read will consume the message, and after that it is up to the code using
+ * it to pass such a message to the @handler in whichever way it can.
+ *
+ * If time_travel_mode is not %TT_MODE_EXTERNAL the @timetravel_handler will
+ * not be invoked at all and the @handler must handle the FD becoming
+ * readable (or writable) instead. Use um_irq_timetravel_handler_used() to
+ * distinguish these cases.
+ *
+ * See virtio_uml.c for an example.
+ */
+int um_request_irq_tt(int irq, int fd, enum um_irq_type type,
+		      irq_handler_t handler, unsigned long irqflags,
+		      const char *devname, void *dev_id,
+		      void (*timetravel_handler)(int, int, void *,
+						 struct time_travel_event *));
+#else
+static inline
+int um_request_irq_tt(int irq, int fd, enum um_irq_type type,
+		      irq_handler_t handler, unsigned long irqflags,
+		      const char *devname, void *dev_id,
+		      void (*timetravel_handler)(int, int, void *,
+						 struct time_travel_event *))
+{
+	return um_request_irq(irq, fd, type, handler, irqflags,
+			      devname, dev_id);
+}
+#endif
+
+static inline bool um_irq_timetravel_handler_used(void)
+{
+	return time_travel_mode == TT_MODE_EXTERNAL;
+}
+
+void um_free_irq(int irq, void *dev_id);
+void free_irqs(void);
+#endif
diff --git a/arch/um/include/shared/irq_user.h b/arch/um/include/shared/irq_user.h
new file mode 100644
index 000000000..746abc24a
--- /dev/null
+++ b/arch/um/include/shared/irq_user.h
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2001 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __IRQ_USER_H__
+#define __IRQ_USER_H__
+
+#include <sysdep/ptrace.h>
+
+enum um_irq_type {
+	IRQ_READ,
+	IRQ_WRITE,
+	NUM_IRQ_TYPES,
+};
+
+struct siginfo;
+extern void sigio_handler(int sig, struct siginfo *unused_si,
+			  struct uml_pt_regs *regs, void *mc);
+extern void sigchld_handler(int sig, struct siginfo *unused_si,
+			   struct uml_pt_regs *regs, void *mc);
+void sigio_run_timetravel_handlers(void);
+extern void free_irq_by_fd(int fd);
+extern void deactivate_fd(int fd, int irqnum);
+extern int deactivate_all_fds(void);
+
+#endif
diff --git a/arch/um/include/shared/kern.h b/arch/um/include/shared/kern.h
new file mode 100644
index 000000000..3a9c75a84
--- /dev/null
+++ b/arch/um/include/shared/kern.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* 
+ * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
+ */
+
+#ifndef __KERN_H__
+#define __KERN_H__
+
+/* These are all user-mode things which are convenient to call directly
+ * from kernel code and for which writing a wrapper is too much of a pain.
+ * The regular include files can't be included because this file is included
+ * only into kernel code, and user-space includes conflict with kernel
+ * includes.
+ */
+
+extern int printf(const char *fmt, ...);
+extern void *sbrk(int increment);
+extern int pause(void);
+extern void exit(int);
+
+#endif
+
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h
new file mode 100644
index 000000000..9812efd14
--- /dev/null
+++ b/arch/um/include/shared/kern_util.h
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __KERN_UTIL_H__
+#define __KERN_UTIL_H__
+
+#include <sysdep/ptrace.h>
+#include <sysdep/faultinfo.h>
+
+struct siginfo;
+
+extern int uml_exitcode;
+
+extern int kmalloc_ok;
+
+extern unsigned long alloc_stack(int order, int atomic);
+extern void free_stack(unsigned long stack, int order);
+
+struct pt_regs;
+extern void do_signal(struct pt_regs *regs);
+extern void interrupt_end(void);
+extern void relay_signal(int sig, struct siginfo *si, struct uml_pt_regs *regs,
+			 void *mc);
+
+extern unsigned long segv(struct faultinfo fi, unsigned long ip,
+			  int is_user, struct uml_pt_regs *regs,
+			  void *mc);
+extern int handle_page_fault(unsigned long address, unsigned long ip,
+			     int is_write, int is_user, int *code_out);
+
+extern unsigned int do_IRQ(int irq, struct uml_pt_regs *regs);
+extern void initial_thread_cb(void (*proc)(void *), void *arg);
+
+extern void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs);
+
+extern void uml_pm_wake(void);
+
+extern int start_uml(void);
+
+extern void uml_cleanup(void);
+extern void do_uml_exitcalls(void);
+
+/*
+ * Are we disallowed to sleep? Used to choose between GFP_KERNEL and
+ * GFP_ATOMIC.
+ */
+extern int __uml_cant_sleep(void);
+extern int get_current_pid(void);
+extern int copy_from_user_proc(void *to, void *from, int size);
+extern char *uml_strdup(const char *string);
+int uml_need_resched(void);
+
+extern unsigned long to_irq_stack(unsigned long *mask_out);
+extern unsigned long from_irq_stack(int nested);
+
+extern int singlestepping(void);
+
+extern void segv_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs,
+			 void *mc);
+extern void winch(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs,
+		  void *mc);
+extern void fatal_sigsegv(void) __attribute__ ((noreturn));
+
+void um_idle_sleep(void);
+
+void kasan_map_memory(void *start, size_t len);
+
+#endif
diff --git a/arch/um/include/shared/longjmp.h b/arch/um/include/shared/longjmp.h
new file mode 100644
index 000000000..c53e43d98
--- /dev/null
+++ b/arch/um/include/shared/longjmp.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __UML_LONGJMP_H
+#define __UML_LONGJMP_H
+
+#include <sysdep/archsetjmp.h>
+#include <os.h>
+
+extern int setjmp(jmp_buf);
+extern void longjmp(jmp_buf, int);
+
+#define UML_LONGJMP(buf, val) do { \
+	longjmp(*buf, val);	\
+} while(0)
+
+#define UML_SETJMP(buf) ({				\
+	int n, enable;					\
+	enable = um_get_signals();			\
+	n = setjmp(*buf);				\
+	if(n != 0)					\
+		um_set_signals_trace(enable);		\
+	n; })
+
+#endif
diff --git a/arch/um/include/shared/mem.h b/arch/um/include/shared/mem.h
new file mode 100644
index 000000000..98aacd544
--- /dev/null
+++ b/arch/um/include/shared/mem.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* 
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __MEM_H__
+#define __MEM_H__
+
+extern int phys_mapping(unsigned long phys, unsigned long long *offset_out);
+
+extern unsigned long uml_physmem;
+static inline unsigned long uml_to_phys(void *virt)
+{
+	return(((unsigned long) virt) - uml_physmem);
+}
+
+static inline void *uml_to_virt(unsigned long phys)
+{
+	return((void *) uml_physmem + phys);
+}
+
+#endif
diff --git a/arch/um/include/shared/mem_user.h b/arch/um/include/shared/mem_user.h
new file mode 100644
index 000000000..8a5b72872
--- /dev/null
+++ b/arch/um/include/shared/mem_user.h
@@ -0,0 +1,42 @@
+/*
+ * arch/um/include/mem_user.h
+ *
+ * BRIEF MODULE DESCRIPTION
+ * user side memory interface for support IO memory inside user mode linux
+ *
+ * Copyright (C) 2001 RidgeRun, Inc.
+ * Author: RidgeRun, Inc.
+ *         Greg Lonnon glonnon@ridgerun.com or info@ridgerun.com
+ *
+ *  This program is free software; you can redistribute  it and/or modify it
+ *  under  the terms of  the GNU General  Public License as published by the
+ *  Free Software Foundation;  either version 2 of the  License, or (at your
+ *  option) any later version.
+ *
+ *  THIS  SOFTWARE  IS PROVIDED   ``AS  IS'' AND   ANY  EXPRESS OR IMPLIED
+ *  WARRANTIES,   INCLUDING, BUT NOT  LIMITED  TO, THE IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN
+ *  NO  EVENT  SHALL   THE AUTHOR  BE    LIABLE FOR ANY   DIRECT, INDIRECT,
+ *  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ *  NOT LIMITED   TO, PROCUREMENT OF  SUBSTITUTE GOODS  OR SERVICES; LOSS OF
+ *  USE, DATA,  OR PROFITS; OR  BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
+ *  ANY THEORY OF LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT
+ *  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ *  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ *  You should have received a copy of the  GNU General Public License along
+ *  with this program; if not, write  to the Free Software Foundation, Inc.,
+ *  675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#ifndef _MEM_USER_H
+#define _MEM_USER_H
+
+#define ROUND_4M(n) ((((unsigned long) (n)) + (1 << 22)) & ~((1 << 22) - 1))
+
+extern void setup_physmem(unsigned long start, unsigned long usable,
+			  unsigned long len);
+extern void map_memory(unsigned long virt, unsigned long phys,
+		       unsigned long len, int r, int w, int x);
+
+#endif
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
new file mode 100644
index 000000000..b26e94292
--- /dev/null
+++ b/arch/um/include/shared/os.h
@@ -0,0 +1,359 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2015 Anton Ivanov (aivanov@{brocade.com,kot-begemot.co.uk})
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __OS_H__
+#define __OS_H__
+
+#include <irq_user.h>
+#include <longjmp.h>
+#include <mm_id.h>
+/* This is to get size_t */
+#ifndef __UM_HOST__
+#include <linux/types.h>
+#else
+#include <sys/types.h>
+#endif
+
+#define CATCH_EINTR(expr) while ((errno = 0, ((expr) < 0)) && (errno == EINTR))
+
+#define OS_TYPE_FILE 1
+#define OS_TYPE_DIR 2
+#define OS_TYPE_SYMLINK 3
+#define OS_TYPE_CHARDEV 4
+#define OS_TYPE_BLOCKDEV 5
+#define OS_TYPE_FIFO 6
+#define OS_TYPE_SOCK 7
+
+/* os_access() flags */
+#define OS_ACC_F_OK    0       /* Test for existence.  */
+#define OS_ACC_X_OK    1       /* Test for execute permission.  */
+#define OS_ACC_W_OK    2       /* Test for write permission.  */
+#define OS_ACC_R_OK    4       /* Test for read permission.  */
+#define OS_ACC_RW_OK   (OS_ACC_W_OK | OS_ACC_R_OK) /* Test for RW permission */
+
+#ifdef CONFIG_64BIT
+#define OS_LIB_PATH	"/usr/lib64/"
+#else
+#define OS_LIB_PATH	"/usr/lib/"
+#endif
+
+#define OS_SENDMSG_MAX_FDS 8
+
+/*
+ * types taken from stat_file() in hostfs_user.c
+ * (if they are wrong here, they are wrong there...).
+ */
+struct uml_stat {
+	int                ust_dev;        /* device */
+	unsigned long long ust_ino;        /* inode */
+	int                ust_mode;       /* protection */
+	int                ust_nlink;      /* number of hard links */
+	int                ust_uid;        /* user ID of owner */
+	int                ust_gid;        /* group ID of owner */
+	unsigned long long ust_size;       /* total size, in bytes */
+	int                ust_blksize;    /* blocksize for filesystem I/O */
+	unsigned long long ust_blocks;     /* number of blocks allocated */
+	unsigned long      ust_atime;      /* time of last access */
+	unsigned long      ust_mtime;      /* time of last modification */
+	unsigned long      ust_ctime;      /* time of last change */
+};
+
+struct openflags {
+	unsigned int r : 1;
+	unsigned int w : 1;
+	unsigned int s : 1;	/* O_SYNC */
+	unsigned int c : 1;	/* O_CREAT */
+	unsigned int t : 1;	/* O_TRUNC */
+	unsigned int a : 1;	/* O_APPEND */
+	unsigned int e : 1;	/* O_EXCL */
+	unsigned int cl : 1;    /* FD_CLOEXEC */
+};
+
+#define OPENFLAGS() ((struct openflags) { .r = 0, .w = 0, .s = 0, .c = 0, \
+					  .t = 0, .a = 0, .e = 0, .cl = 0 })
+
+static inline struct openflags of_read(struct openflags flags)
+{
+	flags.r = 1;
+	return flags;
+}
+
+static inline struct openflags of_write(struct openflags flags)
+{
+	flags.w = 1;
+	return flags;
+}
+
+static inline struct openflags of_rdwr(struct openflags flags)
+{
+	return of_read(of_write(flags));
+}
+
+static inline struct openflags of_set_rw(struct openflags flags, int r, int w)
+{
+	flags.r = r;
+	flags.w = w;
+	return flags;
+}
+
+static inline struct openflags of_sync(struct openflags flags)
+{
+	flags.s = 1;
+	return flags;
+}
+
+static inline struct openflags of_create(struct openflags flags)
+{
+	flags.c = 1;
+	return flags;
+}
+
+static inline struct openflags of_trunc(struct openflags flags)
+{
+	flags.t = 1;
+	return flags;
+}
+
+static inline struct openflags of_append(struct openflags flags)
+{
+	flags.a = 1;
+	return flags;
+}
+
+static inline struct openflags of_excl(struct openflags flags)
+{
+	flags.e = 1;
+	return flags;
+}
+
+static inline struct openflags of_cloexec(struct openflags flags)
+{
+	flags.cl = 1;
+	return flags;
+}
+
+/* file.c */
+extern int os_stat_file(const char *file_name, struct uml_stat *buf);
+extern int os_stat_fd(const int fd, struct uml_stat *buf);
+extern int os_access(const char *file, int mode);
+extern int os_set_exec_close(int fd);
+extern int os_ioctl_generic(int fd, unsigned int cmd, unsigned long arg);
+extern int os_get_ifname(int fd, char *namebuf);
+extern int os_mode_fd(int fd, int mode);
+
+extern int os_seek_file(int fd, unsigned long long offset);
+extern int os_open_file(const char *file, struct openflags flags, int mode);
+extern int os_read_file(int fd, void *buf, int len);
+extern int os_write_file(int fd, const void *buf, int count);
+extern int os_sync_file(int fd);
+extern int os_file_size(const char *file, unsigned long long *size_out);
+extern int os_pread_file(int fd, void *buf, int len, unsigned long long offset);
+extern int os_pwrite_file(int fd, const void *buf, int count, unsigned long long offset);
+extern int os_file_modtime(const char *file, long long *modtime);
+extern int os_pipe(int *fd, int stream, int close_on_exec);
+extern int os_set_fd_async(int fd);
+extern int os_clear_fd_async(int fd);
+extern int os_set_fd_block(int fd, int blocking);
+extern int os_accept_connection(int fd);
+extern int os_create_unix_socket(const char *file, int len, int close_on_exec);
+extern int os_shutdown_socket(int fd, int r, int w);
+extern int os_dup_file(int fd);
+extern void os_close_file(int fd);
+ssize_t os_rcv_fd_msg(int fd, int *fds, unsigned int n_fds,
+		      void *data, size_t data_len);
+extern int os_connect_socket(const char *name);
+extern int os_file_type(char *file);
+extern int os_file_mode(const char *file, struct openflags *mode_out);
+extern int os_lock_file(int fd, int excl);
+extern void os_flush_stdout(void);
+extern unsigned os_major(unsigned long long dev);
+extern unsigned os_minor(unsigned long long dev);
+extern unsigned long long os_makedev(unsigned major, unsigned minor);
+extern int os_falloc_punch(int fd, unsigned long long offset, int count);
+extern int os_falloc_zeroes(int fd, unsigned long long offset, int count);
+extern int os_eventfd(unsigned int initval, int flags);
+extern int os_sendmsg_fds(int fd, const void *buf, unsigned int len,
+			  const int *fds, unsigned int fds_num);
+int os_poll(unsigned int n, const int *fds);
+void *os_mmap_rw_shared(int fd, size_t size);
+void *os_mremap_rw_shared(void *old_addr, size_t old_size, size_t new_size);
+
+/* start_up.c */
+extern void os_early_checks(void);
+extern void os_check_bugs(void);
+extern void check_host_supports_tls(int *supports_tls, int *tls_min);
+extern void get_host_cpu_features(
+	void (*flags_helper_func)(char *line),
+	void (*cache_helper_func)(char *line));
+
+/* mem.c */
+extern int create_mem_file(unsigned long long len);
+
+/* tlb.c */
+extern void report_enomem(void);
+
+/* process.c */
+pid_t os_reap_child(void);
+extern void os_alarm_process(int pid);
+extern void os_kill_process(int pid, int reap_child);
+extern void os_kill_ptraced_process(int pid, int reap_child);
+
+extern int os_getpid(void);
+
+extern void init_new_thread_signals(void);
+
+extern int os_map_memory(void *virt, int fd, unsigned long long off,
+			 unsigned long len, int r, int w, int x);
+extern int os_protect_memory(void *addr, unsigned long len,
+			     int r, int w, int x);
+extern int os_unmap_memory(void *addr, int len);
+extern int os_drop_memory(void *addr, int length);
+extern int can_drop_memory(void);
+
+void os_set_pdeathsig(void);
+
+int os_futex_wait(void *uaddr, unsigned int val);
+int os_futex_wake(void *uaddr);
+
+/* execvp.c */
+extern int execvp_noalloc(char *buf, const char *file, char *const argv[]);
+/* helper.c */
+extern int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv);
+extern int run_helper_thread(int (*proc)(void *), void *arg,
+			     unsigned int flags, unsigned long *stack_out);
+extern int helper_wait(int pid);
+
+struct os_helper_thread;
+int os_run_helper_thread(struct os_helper_thread **td_out,
+			 void *(*routine)(void *), void *arg);
+void os_kill_helper_thread(struct os_helper_thread *td);
+void os_fix_helper_thread_signals(void);
+
+/* umid.c */
+extern int umid_file_name(char *name, char *buf, int len);
+extern int set_umid(char *name);
+extern char *get_umid(void);
+
+/* signal.c */
+extern void timer_set_signal_handler(void);
+extern void set_sigstack(void *sig_stack, int size);
+extern void set_handler(int sig);
+extern void send_sigio_to_self(void);
+extern int change_sig(int signal, int on);
+extern void block_signals(void);
+extern void unblock_signals(void);
+extern int um_get_signals(void);
+extern int um_set_signals(int enable);
+extern int um_set_signals_trace(int enable);
+extern void deliver_alarm(void);
+extern void register_pm_wake_signal(void);
+extern void block_signals_hard(void);
+extern void unblock_signals_hard(void);
+extern void mark_sigio_pending(void);
+
+/* util.c */
+extern void stack_protections(unsigned long address);
+extern int raw(int fd);
+extern void setup_machinename(char *machine_out);
+extern void setup_hostinfo(char *buf, int len);
+extern ssize_t os_getrandom(void *buf, size_t len, unsigned int flags);
+extern void os_dump_core(void) __attribute__ ((noreturn));
+extern void um_early_printk(const char *s, unsigned int n);
+extern void os_fix_helper_signals(void);
+extern void os_info(const char *fmt, ...)
+	__attribute__ ((format (printf, 1, 2)));
+extern void os_warn(const char *fmt, ...)
+	__attribute__ ((format (printf, 1, 2)));
+
+/* time.c */
+void os_idle_prepare(void);
+extern void os_idle_sleep(void);
+extern int os_timer_create(void);
+extern int os_timer_set_interval(int cpu, unsigned long long nsecs);
+extern int os_timer_one_shot(int cpu, unsigned long long nsecs);
+extern void os_timer_disable(int cpu);
+extern long long os_persistent_clock_emulation(void);
+extern long long os_nsecs(void);
+
+/* skas/mem.c */
+int syscall_stub_flush(struct mm_id *mm_idp);
+struct stub_syscall *syscall_stub_alloc(struct mm_id *mm_idp);
+void syscall_stub_dump_error(struct mm_id *mm_idp);
+
+int map(struct mm_id *mm_idp, unsigned long virt,
+	unsigned long len, int prot, int phys_fd,
+	unsigned long long offset);
+int unmap(struct mm_id *mm_idp, unsigned long addr, unsigned long len);
+
+/* skas/process.c */
+extern int is_skas_winch(int pid, int fd, void *data);
+extern int start_userspace(struct mm_id *mm_id);
+extern void userspace(struct uml_pt_regs *regs);
+extern void new_thread(void *stack, jmp_buf *buf, void (*handler)(void));
+extern void switch_threads(jmp_buf *me, jmp_buf *you);
+extern int start_idle_thread(void *stack, jmp_buf *switch_buf);
+extern void initial_thread_cb_skas(void (*proc)(void *),
+				 void *arg);
+extern void halt_skas(void);
+extern void reboot_skas(void);
+
+/* irq.c */
+extern int os_waiting_for_events_epoll(void);
+extern void *os_epoll_get_data_pointer(int index);
+extern int os_epoll_triggered(int index, int events);
+extern int os_event_mask(enum um_irq_type irq_type);
+extern int os_setup_epoll(void);
+extern int os_add_epoll_fd(int events, int fd, void *data);
+extern int os_mod_epoll_fd(int events, int fd, void *data);
+extern int os_del_epoll_fd(int fd);
+extern void os_set_ioignore(void);
+extern void os_close_epoll_fd(void);
+extern void um_irqs_suspend(void);
+extern void um_irqs_resume(void);
+
+/* sigio.c */
+extern int add_sigio_fd(int fd);
+extern int ignore_sigio_fd(int fd);
+extern void maybe_sigio_broken(int fd);
+extern void sigio_broken(void);
+/*
+ * unlocked versions for IRQ controller code.
+ *
+ * This is safe because it's used at suspend/resume and nothing
+ * else is running.
+ */
+extern int __add_sigio_fd(int fd);
+extern int __ignore_sigio_fd(int fd);
+
+/* tty.c */
+extern int get_pty(void);
+
+long syscall(long number, ...);
+
+/* irqflags tracing */
+extern void block_signals_trace(void);
+extern void unblock_signals_trace(void);
+extern void um_trace_signals_on(void);
+extern void um_trace_signals_off(void);
+
+/* time-travel */
+extern void deliver_time_travel_irqs(void);
+
+/* smp.c */
+#if IS_ENABLED(CONFIG_SMP)
+void os_init_smp(void);
+int os_start_cpu_thread(int cpu);
+void os_start_secondary(void *arg, jmp_buf *switch_buf);
+int os_send_ipi(int cpu, int vector);
+void os_local_ipi_enable(void);
+void os_local_ipi_disable(void);
+#else /* !CONFIG_SMP */
+static inline void os_local_ipi_enable(void) { }
+static inline void os_local_ipi_disable(void) { }
+#endif /* CONFIG_SMP */
+
+#endif
diff --git a/arch/um/include/shared/ptrace_user.h b/arch/um/include/shared/ptrace_user.h
new file mode 100644
index 000000000..8a705d8f9
--- /dev/null
+++ b/arch/um/include/shared/ptrace_user.h
@@ -0,0 +1,15 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* 
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __PTRACE_USER_H__
+#define __PTRACE_USER_H__
+
+#include <sys/ptrace.h>
+#include <sysdep/ptrace_user.h>
+
+extern int ptrace_getregs(long pid, unsigned long *regs_out);
+extern int ptrace_setregs(long pid, unsigned long *regs_in);
+
+#endif
diff --git a/arch/um/include/shared/registers.h b/arch/um/include/shared/registers.h
new file mode 100644
index 000000000..7d81b2339
--- /dev/null
+++ b/arch/um/include/shared/registers.h
@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2004 PathScale, Inc
+ */
+
+#ifndef __REGISTERS_H
+#define __REGISTERS_H
+
+#include <sysdep/ptrace.h>
+
+extern int init_pid_registers(int pid);
+extern void get_safe_registers(unsigned long *regs, unsigned long *fp_regs);
+extern int get_fp_registers(int pid, unsigned long *regs);
+extern int put_fp_registers(int pid, unsigned long *regs);
+
+#endif
diff --git a/arch/um/include/shared/sigio.h b/arch/um/include/shared/sigio.h
new file mode 100644
index 000000000..c6c2edce1
--- /dev/null
+++ b/arch/um/include/shared/sigio.h
@@ -0,0 +1,12 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* 
+ * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ */
+
+#ifndef __SIGIO_H__
+#define __SIGIO_H__
+
+extern void sigio_lock(void);
+extern void sigio_unlock(void);
+
+#endif
diff --git a/arch/um/include/shared/skas/mm_id.h b/arch/um/include/shared/skas/mm_id.h
new file mode 100644
index 000000000..18c062143
--- /dev/null
+++ b/arch/um/include/shared/skas/mm_id.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2005 Jeff Dike (jdike@karaya.com)
+ */
+
+#ifndef __MM_ID_H
+#define __MM_ID_H
+
+#include <linux/compiler_types.h>
+
+#define STUB_MAX_FDS 4
+
+struct mm_id {
+	int pid;
+	unsigned long stack;
+	int syscall_data_len;
+
+	/* Only used with SECCOMP mode */
+	int sock;
+	int syscall_fd_num;
+	int syscall_fd_map[STUB_MAX_FDS];
+};
+
+struct mutex *__get_turnstile(struct mm_id *mm_id);
+void enter_turnstile(struct mm_id *mm_id) __acquires(__get_turnstile(mm_id));
+void exit_turnstile(struct mm_id *mm_id) __releases(__get_turnstile(mm_id));
+
+void notify_mm_kill(int pid);
+
+#endif
diff --git a/arch/um/include/shared/skas/skas.h b/arch/um/include/shared/skas/skas.h
new file mode 100644
index 000000000..2237ffede
--- /dev/null
+++ b/arch/um/include/shared/skas/skas.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __SKAS_H
+#define __SKAS_H
+
+#include <sysdep/ptrace.h>
+
+extern int using_seccomp;
+
+extern void new_thread_handler(void);
+extern void handle_syscall(struct uml_pt_regs *regs);
+extern unsigned long current_stub_stack(void);
+extern struct mm_id *current_mm_id(void);
+extern void current_mm_sync(void);
+void initial_jmpbuf_lock(void);
+void initial_jmpbuf_unlock(void);
+
+#endif
diff --git a/arch/um/include/shared/skas/stub-data.h b/arch/um/include/shared/skas/stub-data.h
new file mode 100644
index 000000000..27db38e95
--- /dev/null
+++ b/arch/um/include/shared/skas/stub-data.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+
+ * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
+ * Copyright (C) 2005 Jeff Dike (jdike@karaya.com)
+ */
+
+#ifndef __STUB_DATA_H
+#define __STUB_DATA_H
+
+#include <linux/compiler_types.h>
+#include <as-layout.h>
+#include <sysdep/tls.h>
+#include <sysdep/stub-data.h>
+#include <mm_id.h>
+
+#define FUTEX_IN_CHILD 0
+#define FUTEX_IN_KERN 1
+
+struct stub_init_data {
+	int seccomp;
+
+	unsigned long stub_start;
+
+	int stub_code_fd;
+	unsigned long stub_code_offset;
+	int stub_data_fd;
+	unsigned long stub_data_offset;
+
+	unsigned long signal_handler;
+	unsigned long signal_restorer;
+};
+
+#define STUB_NEXT_SYSCALL(s) \
+	((struct stub_syscall *) (((unsigned long) s) + (s)->cmd_len))
+
+enum stub_syscall_type {
+	STUB_SYSCALL_UNSET = 0,
+	STUB_SYSCALL_MMAP,
+	STUB_SYSCALL_MUNMAP,
+};
+
+struct stub_syscall {
+	struct {
+		unsigned long addr;
+		unsigned long length;
+		unsigned long offset;
+		int fd;
+		int prot;
+	} mem;
+
+	enum stub_syscall_type syscall;
+};
+
+struct stub_data {
+	long err;
+
+	int syscall_data_len;
+	/* 128 leaves enough room for additional fields in the struct */
+	struct stub_syscall syscall_data[(UM_KERN_PAGE_SIZE - 128) / sizeof(struct stub_syscall)] __aligned(16);
+
+	/* data shared with signal handler (only used in seccomp mode) */
+	short restart_wait;
+	unsigned int futex;
+	int signal;
+	unsigned short si_offset;
+	unsigned short mctx_offset;
+
+	/* seccomp architecture specific state restore */
+	struct stub_data_arch arch_data;
+
+	/* Stack for our signal handlers and for calling into . */
+	unsigned char sigstack[UM_KERN_PAGE_SIZE] __aligned(UM_KERN_PAGE_SIZE);
+};
+
+#endif
diff --git a/arch/um/include/shared/smp.h b/arch/um/include/shared/smp.h
new file mode 100644
index 000000000..06e3faa95
--- /dev/null
+++ b/arch/um/include/shared/smp.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __UM_SHARED_SMP_H
+#define __UM_SHARED_SMP_H
+
+#if IS_ENABLED(CONFIG_SMP)
+
+extern int uml_ncpus;
+
+int uml_curr_cpu(void);
+void uml_start_secondary(void *opaque);
+void uml_ipi_handler(int vector);
+
+#else /* !CONFIG_SMP */
+
+#define uml_ncpus 1
+#define uml_curr_cpu() 0
+
+#endif /* CONFIG_SMP */
+
+#endif /* __UM_SHARED_SMP_H */
diff --git a/arch/um/include/shared/timetravel.h b/arch/um/include/shared/timetravel.h
new file mode 100644
index 000000000..7c2b277b7
--- /dev/null
+++ b/arch/um/include/shared/timetravel.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019-2021 Intel Corporation
+ */
+#ifndef _UM_TIME_TRAVEL_H_
+#define _UM_TIME_TRAVEL_H_
+
+enum time_travel_mode {
+	TT_MODE_OFF,
+	TT_MODE_BASIC,
+	TT_MODE_INFCPU,
+	TT_MODE_EXTERNAL,
+};
+
+#if IS_ENABLED(CONFIG_UML_TIME_TRAVEL_SUPPORT)
+extern enum time_travel_mode time_travel_mode;
+extern int time_travel_should_print_bc_msg;
+#else
+#define time_travel_mode TT_MODE_OFF
+#define time_travel_should_print_bc_msg 0
+#endif /* CONFIG_UML_TIME_TRAVEL_SUPPORT */
+
+void _time_travel_print_bc_msg(void);
+static inline void time_travel_print_bc_msg(void)
+{
+	if (time_travel_should_print_bc_msg)
+		_time_travel_print_bc_msg();
+}
+
+#endif /* _UM_TIME_TRAVEL_H_ */
diff --git a/arch/um/include/shared/um_malloc.h b/arch/um/include/shared/um_malloc.h
new file mode 100644
index 000000000..815dd03e8
--- /dev/null
+++ b/arch/um/include/shared/um_malloc.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2005 Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
+ */
+
+#ifndef __UM_MALLOC_H__
+#define __UM_MALLOC_H__
+
+#include <generated/asm-offsets.h>
+
+extern void *uml_kmalloc(int size, int flags);
+extern void kfree(const void *ptr);
+
+extern void *vmalloc_noprof(unsigned long size);
+#define vmalloc(...)		vmalloc_noprof(__VA_ARGS__)
+extern void vfree(const void *ptr);
+
+#endif /* __UM_MALLOC_H__ */
+
+
diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
new file mode 100644
index 000000000..139eb78a4
--- /dev/null
+++ b/arch/um/include/shared/user.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* 
+ * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ */
+
+#ifndef __USER_H__
+#define __USER_H__
+
+#include <generated/asm-offsets.h>
+
+/*
+ * The usual definition - copied here because the kernel provides its own,
+ * fancier, type-safe, definition.  Using that one would require
+ * copying too much infrastructure for my taste, so userspace files
+ * get less checking than kernel files.
+ */
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+/* This is to get size_t and NULL */
+#ifndef __UM_HOST__
+#include <linux/types.h>
+#else
+#include <stddef.h>
+#include <sys/types.h>
+#endif
+
+extern void panic(const char *fmt, ...)
+	__attribute__ ((format (printf, 1, 2)));
+
+/* Requires preincluding include/linux/kern_levels.h */
+#define UM_KERN_EMERG	KERN_EMERG
+#define UM_KERN_ALERT	KERN_ALERT
+#define UM_KERN_CRIT	KERN_CRIT
+#define UM_KERN_ERR	KERN_ERR
+#define UM_KERN_WARNING	KERN_WARNING
+#define UM_KERN_NOTICE	KERN_NOTICE
+#define UM_KERN_INFO	KERN_INFO
+#define UM_KERN_DEBUG	KERN_DEBUG
+#define UM_KERN_CONT	KERN_CONT
+
+#if IS_ENABLED(CONFIG_PRINTK)
+#define printk(...) _printk(__VA_ARGS__)
+extern int _printk(const char *fmt, ...)
+	__attribute__ ((format (printf, 1, 2)));
+extern void print_hex_dump(const char *level, const char *prefix_str,
+			   int prefix_type, int rowsize, int groupsize,
+			   const void *buf, size_t len, _Bool ascii);
+#else
+static inline int printk(const char *fmt, ...)
+{
+	return 0;
+}
+static inline void print_hex_dump(const char *level, const char *prefix_str,
+				  int prefix_type, int rowsize, int groupsize,
+				  const void *buf, size_t len, _Bool ascii)
+{
+}
+#endif
+
+extern int in_aton(char *str);
+extern size_t strlcat(char *, const char *, size_t);
+extern size_t sized_strscpy(char *, const char *, size_t);
+#define strscpy(dst, src)	sized_strscpy(dst, src, sizeof(dst))
+
+/* Copied from linux/compiler-gcc.h since we can't include it directly */
+#define barrier() __asm__ __volatile__("": : :"memory")
+
+#endif