Update Linux to v5.10.109

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.10.109.tar.xz

Change-Id: I19bca9fc6762d4e63bcf3e4cba88bbe560d9c76c
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/arch/um/kernel/dyn.lds.S b/arch/um/kernel/dyn.lds.S
index a82ec01..2f2a8ce 100644
--- a/arch/um/kernel/dyn.lds.S
+++ b/arch/um/kernel/dyn.lds.S
@@ -170,8 +170,8 @@
   PROVIDE (end = .);
 
   STABS_DEBUG
-
   DWARF_DEBUG
+  ELF_DETAILS
 
   DISCARDS
 }
diff --git a/arch/um/kernel/exitcode.c b/arch/um/kernel/exitcode.c
index 369fd84..43edc2a 100644
--- a/arch/um/kernel/exitcode.c
+++ b/arch/um/kernel/exitcode.c
@@ -55,20 +55,19 @@
 	return count;
 }
 
-static const struct file_operations exitcode_proc_fops = {
-	.owner		= THIS_MODULE,
-	.open		= exitcode_proc_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-	.write		= exitcode_proc_write,
+static const struct proc_ops exitcode_proc_ops = {
+	.proc_open	= exitcode_proc_open,
+	.proc_read	= seq_read,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= single_release,
+	.proc_write	= exitcode_proc_write,
 };
 
 static int make_proc_exitcode(void)
 {
 	struct proc_dir_entry *ent;
 
-	ent = proc_create("exitcode", 0600, NULL, &exitcode_proc_fops);
+	ent = proc_create("exitcode", 0600, NULL, &exitcode_proc_ops);
 	if (ent == NULL) {
 		printk(KERN_WARNING "make_proc_exitcode : Failed to register "
 		       "/proc/exitcode\n");
diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
index 98bdf69..e4abac6 100644
--- a/arch/um/kernel/kmsg_dump.c
+++ b/arch/um/kernel/kmsg_dump.c
@@ -9,20 +9,19 @@
 				enum kmsg_dump_reason reason)
 {
 	static char line[1024];
-
+	struct console *con;
 	size_t len = 0;
-	bool con_available = false;
 
 	/* only dump kmsg when no console is available */
 	if (!console_trylock())
 		return;
 
-	if (console_drivers != NULL)
-		con_available = true;
+	for_each_console(con)
+		break;
 
 	console_unlock();
 
-	if (con_available == true)
+	if (con)
 		return;
 
 	printf("kmsg_dump:\n");
diff --git a/arch/um/kernel/maccess.c b/arch/um/kernel/maccess.c
index 67b2e0f..8ccd568 100644
--- a/arch/um/kernel/maccess.c
+++ b/arch/um/kernel/maccess.c
@@ -7,15 +7,13 @@
 #include <linux/kernel.h>
 #include <os.h>
 
-long probe_kernel_read(void *dst, const void *src, size_t size)
+bool copy_from_kernel_nofault_allowed(const void *src, size_t size)
 {
 	void *psrc = (void *)rounddown((unsigned long)src, PAGE_SIZE);
 
 	if ((unsigned long)src < PAGE_SIZE || size <= 0)
-		return -EFAULT;
-
+		return false;
 	if (os_mincore(psrc, size + src - psrc) <= 0)
-		return -EFAULT;
-
-	return __probe_kernel_read(dst, src, size);
+		return false;
+	return true;
 }
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 417ff64..9242dc9 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -96,6 +96,7 @@
 				 pgd_t *pgd_base)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	int i, j;
@@ -107,7 +108,8 @@
 	pgd = pgd_base + i;
 
 	for ( ; (i < PTRS_PER_PGD) && (vaddr < end); pgd++, i++) {
-		pud = pud_offset(pgd, vaddr);
+		p4d = p4d_offset(pgd, vaddr);
+		pud = pud_offset(p4d, vaddr);
 		if (pud_none(*pud))
 			one_md_table_init(pud);
 		pmd = pmd_offset(pud, vaddr);
@@ -123,9 +125,6 @@
 {
 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 	long size = FIXADDR_USER_END - FIXADDR_USER_START;
-	pgd_t *pgd;
-	pud_t *pud;
-	pmd_t *pmd;
 	pte_t *pte;
 	phys_t p;
 	unsigned long v, vaddr = FIXADDR_USER_START;
@@ -143,10 +142,7 @@
 	p = __pa(v);
 	for ( ; size > 0; size -= PAGE_SIZE, vaddr += PAGE_SIZE,
 		      p += PAGE_SIZE) {
-		pgd = swapper_pg_dir + pgd_index(vaddr);
-		pud = pud_offset(pgd, vaddr);
-		pmd = pmd_offset(pud, vaddr);
-		pte = pte_offset_kernel(pmd, vaddr);
+		pte = virt_to_kpte(vaddr);
 		pte_set_val(*pte, p, PAGE_READONLY);
 	}
 #endif
@@ -154,8 +150,8 @@
 
 void __init paging_init(void)
 {
-	unsigned long zones_size[MAX_NR_ZONES], vaddr;
-	int i;
+	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0 };
+	unsigned long vaddr;
 
 	empty_zero_page = (unsigned long *) memblock_alloc_low(PAGE_SIZE,
 							       PAGE_SIZE);
@@ -163,12 +159,8 @@
 		panic("%s: Failed to allocate %lu bytes align=%lx\n",
 		      __func__, PAGE_SIZE, PAGE_SIZE);
 
-	for (i = 0; i < ARRAY_SIZE(zones_size); i++)
-		zones_size[i] = 0;
-
-	zones_size[ZONE_NORMAL] = (end_iomem >> PAGE_SHIFT) -
-		(uml_physmem >> PAGE_SHIFT);
-	free_area_init(zones_size);
+	max_zone_pfn[ZONE_NORMAL] = end_iomem >> PAGE_SHIFT;
+	free_area_init(max_zone_pfn);
 
 	/*
 	 * Fixed mappings, only the page table structure has to be
@@ -204,23 +196,6 @@
 	return pgd;
 }
 
-void pgd_free(struct mm_struct *mm, pgd_t *pgd)
-{
-	free_page((unsigned long) pgd);
-}
-
-#ifdef CONFIG_3_LEVEL_PGTABLES
-pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
-{
-	pmd_t *pmd = (pmd_t *) __get_free_page(GFP_KERNEL);
-
-	if (pmd)
-		memset(pmd, 0, PAGE_SIZE);
-
-	return pmd;
-}
-#endif
-
 void *uml_kmalloc(int size, int flags)
 {
 	return kmalloc(size, flags);
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index 17045e7..9505a7e 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -25,14 +25,13 @@
 #include <linux/threads.h>
 #include <linux/tracehook.h>
 #include <asm/current.h>
-#include <asm/pgtable.h>
 #include <asm/mmu_context.h>
 #include <linux/uaccess.h>
 #include <as-layout.h>
 #include <kern_util.h>
 #include <os.h>
 #include <skas.h>
-#include <timer-internal.h>
+#include <linux/time-internal.h>
 
 /*
  * This is a per-cpu array.  A processor only modifies its entry and it only
@@ -102,7 +101,7 @@
 		schedule();
 	if (test_thread_flag(TIF_SIGPENDING))
 		do_signal(regs);
-	if (test_and_clear_thread_flag(TIF_NOTIFY_RESUME))
+	if (test_thread_flag(TIF_NOTIFY_RESUME))
 		tracehook_notify_resume(regs);
 }
 
@@ -153,7 +152,7 @@
 	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
 }
 
-int copy_thread_tls(unsigned long clone_flags, unsigned long sp,
+int copy_thread(unsigned long clone_flags, unsigned long sp,
 		unsigned long arg, struct task_struct * p, unsigned long tls)
 {
 	void (*handler)(void);
@@ -203,43 +202,6 @@
 	kmalloc_ok = save_kmalloc_ok;
 }
 
-static void time_travel_sleep(unsigned long long duration)
-{
-	unsigned long long next = time_travel_time + duration;
-
-	if (time_travel_mode != TT_MODE_INFCPU)
-		os_timer_disable();
-
-	while (time_travel_timer_mode == TT_TMR_PERIODIC &&
-	       time_travel_timer_expiry < time_travel_time)
-		time_travel_set_timer_expiry(time_travel_timer_expiry +
-					     time_travel_timer_interval);
-
-	if (time_travel_timer_mode != TT_TMR_DISABLED &&
-	    time_travel_timer_expiry < next) {
-		if (time_travel_timer_mode == TT_TMR_ONESHOT)
-			time_travel_set_timer_mode(TT_TMR_DISABLED);
-		/*
-		 * In basic mode, time_travel_time will be adjusted in
-		 * the timer IRQ handler so it works even when the signal
-		 * comes from the OS timer, see there.
-		 */
-		if (time_travel_mode != TT_MODE_BASIC)
-			time_travel_set_time(time_travel_timer_expiry);
-
-		deliver_alarm();
-	} else {
-		time_travel_set_time(next);
-	}
-
-	if (time_travel_mode != TT_MODE_INFCPU) {
-		if (time_travel_timer_mode == TT_TMR_PERIODIC)
-			os_timer_set_interval(time_travel_timer_interval);
-		else if (time_travel_timer_mode == TT_TMR_ONESHOT)
-			os_timer_one_shot(time_travel_timer_expiry - next);
-	}
-}
-
 static void um_idle_sleep(void)
 {
 	unsigned long long duration = UM_NSEC_PER_SEC;
@@ -255,7 +217,7 @@
 {
 	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 	um_idle_sleep();
-	local_irq_enable();
+	raw_local_irq_enable();
 }
 
 int __cant_sleep(void) {
@@ -348,13 +310,12 @@
 	return count;
 }
 
-static const struct file_operations sysemu_proc_fops = {
-	.owner		= THIS_MODULE,
-	.open		= sysemu_proc_open,
-	.read		= seq_read,
-	.llseek		= seq_lseek,
-	.release	= single_release,
-	.write		= sysemu_proc_write,
+static const struct proc_ops sysemu_proc_ops = {
+	.proc_open	= sysemu_proc_open,
+	.proc_read	= seq_read,
+	.proc_lseek	= seq_lseek,
+	.proc_release	= single_release,
+	.proc_write	= sysemu_proc_write,
 };
 
 int __init make_proc_sysemu(void)
@@ -363,7 +324,7 @@
 	if (!sysemu_supported)
 		return 0;
 
-	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_fops);
+	ent = proc_create("sysemu", 0600, NULL, &sysemu_proc_ops);
 
 	if (ent == NULL)
 	{
diff --git a/arch/um/kernel/signal.c b/arch/um/kernel/signal.c
index 3d57c71..88cd9b5 100644
--- a/arch/um/kernel/signal.c
+++ b/arch/um/kernel/signal.c
@@ -70,7 +70,7 @@
 				PT_REGS_SYSCALL_RET(regs) = -EINTR;
 				break;
 			}
-		/* fallthrough */
+			fallthrough;
 		case -ERESTARTNOINTR:
 			PT_REGS_RESTART_SYSCALL(regs);
 			PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index b5e3d91..d996116 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -9,7 +9,6 @@
 #include <linux/slab.h>
 
 #include <asm/pgalloc.h>
-#include <asm/pgtable.h>
 #include <asm/sections.h>
 #include <as-layout.h>
 #include <os.h>
@@ -19,15 +18,21 @@
 			 unsigned long kernel)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
 
 	pgd = pgd_offset(mm, proc);
-	pud = pud_alloc(mm, pgd, proc);
-	if (!pud)
+
+	p4d = p4d_alloc(mm, pgd, proc);
+	if (!p4d)
 		goto out;
 
+	pud = pud_alloc(mm, p4d, proc);
+	if (!pud)
+		goto out_pud;
+
 	pmd = pmd_alloc(mm, pud, proc);
 	if (!pmd)
 		goto out_pmd;
@@ -44,6 +49,8 @@
 	pmd_free(mm, pmd);
  out_pmd:
 	pud_free(mm, pud);
+ out_pud:
+	p4d_free(mm, p4d);
  out:
 	return -ENOMEM;
 }
@@ -107,7 +114,7 @@
 	mm->context.stub_pages[0] = virt_to_page(__syscall_stub_start);
 	mm->context.stub_pages[1] = virt_to_page(mm->context.id.stack);
 
-	/* dup_mmap already holds mmap_sem */
+	/* dup_mmap already holds mmap_lock */
 	err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
 				      VM_READ | VM_MAYREAD | VM_EXEC |
 				      VM_MAYEXEC | VM_DONTCOPY | VM_PFNMAP,
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index f574b18..3d91f89 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -10,7 +10,8 @@
 #include <sysdep/ptrace.h>
 #include <sysdep/ptrace_user.h>
 #include <sysdep/syscalls.h>
-#include <shared/timer-internal.h>
+#include <linux/time-internal.h>
+#include <asm/unistd.h>
 
 void handle_syscall(struct uml_pt_regs *r)
 {
@@ -24,7 +25,8 @@
 	 * went to sleep, even if said userspace interacts with the kernel in
 	 * various ways.
 	 */
-	if (time_travel_mode == TT_MODE_INFCPU)
+	if (time_travel_mode == TT_MODE_INFCPU ||
+	    time_travel_mode == TT_MODE_EXTERNAL)
 		schedule();
 
 	/* Initialize the syscall number and default return value. */
@@ -35,7 +37,7 @@
 		goto out;
 
 	/* Do the seccomp check after ptrace; failures should be fast. */
-	if (secure_computing(NULL) == -1)
+	if (secure_computing() == -1)
 		goto out;
 
 	syscall = UPT_SYSCALL_NR(r);
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index 3236052..2dec915 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -10,13 +10,13 @@
 #include <linux/sched.h>
 #include <asm/current.h>
 #include <asm/page.h>
-#include <asm/pgtable.h>
 #include <kern_util.h>
 #include <os.h>
 
 pte_t *virt_to_pte(struct mm_struct *mm, unsigned long addr)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 
@@ -27,7 +27,11 @@
 	if (!pgd_present(*pgd))
 		return NULL;
 
-	pud = pud_offset(pgd, addr);
+	p4d = p4d_offset(pgd, addr);
+	if (!p4d_present(*p4d))
+		return NULL;
+
+	pud = pud_offset(p4d, addr);
 	if (!pud_present(*pud))
 		return NULL;
 
diff --git a/arch/um/kernel/sysrq.c b/arch/um/kernel/sysrq.c
index c71b5ef..7452f70 100644
--- a/arch/um/kernel/sysrq.c
+++ b/arch/um/kernel/sysrq.c
@@ -17,7 +17,9 @@
 
 static void _print_addr(void *data, unsigned long address, int reliable)
 {
-	pr_info(" [<%08lx>] %s%pS\n", address, reliable ? "" : "? ",
+	const char *loglvl = data;
+
+	printk("%s [<%08lx>] %s%pS\n", loglvl, address, reliable ? "" : "? ",
 		(void *)address);
 }
 
@@ -25,9 +27,9 @@
 	.address = _print_addr
 };
 
-void show_stack(struct task_struct *task, unsigned long *stack)
+void show_stack(struct task_struct *task, unsigned long *stack,
+		       const char *loglvl)
 {
-	unsigned long *sp = stack;
 	struct pt_regs *segv_regs = current->thread.segv_regs;
 	int i;
 
@@ -38,10 +40,9 @@
 	}
 
 	if (!stack)
-		sp = get_stack_pointer(task, segv_regs);
+		stack = get_stack_pointer(task, segv_regs);
 
-	pr_info("Stack:\n");
-	stack = sp;
+	printk("%sStack:\n", loglvl);
 	for (i = 0; i < 3 * STACKSLOTS_PER_LINE; i++) {
 		if (kstack_end(stack))
 			break;
@@ -49,9 +50,7 @@
 			pr_cont("\n");
 		pr_cont(" %08lx", *stack++);
 	}
-	pr_cont("\n");
 
-	pr_info("Call Trace:\n");
-	dump_trace(current, &stackops, NULL);
-	pr_info("\n");
+	printk("%sCall Trace:\n", loglvl);
+	dump_trace(current, &stackops, (void *)loglvl);
 }
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index 94ea87b..8dafc3f 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -4,6 +4,7 @@
  * Copyright (C) 2015 Thomas Meyer (thomas@m3y3r.de)
  * Copyright (C) 2012-2014 Cisco Systems
  * Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+ * Copyright (C) 2019 Intel Corporation
  */
 
 #include <linux/clockchips.h>
@@ -18,21 +19,484 @@
 #include <asm/param.h>
 #include <kern_util.h>
 #include <os.h>
-#include <timer-internal.h>
+#include <linux/time-internal.h>
+#include <linux/um_timetravel.h>
 #include <shared/init.h>
 
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
 enum time_travel_mode time_travel_mode;
-unsigned long long time_travel_time;
-enum time_travel_timer_mode time_travel_timer_mode;
-unsigned long long time_travel_timer_expiry;
-unsigned long long time_travel_timer_interval;
+EXPORT_SYMBOL_GPL(time_travel_mode);
 
 static bool time_travel_start_set;
 static unsigned long long time_travel_start;
-#else
+static unsigned long long time_travel_time;
+static LIST_HEAD(time_travel_events);
+static unsigned long long time_travel_timer_interval;
+static unsigned long long time_travel_next_event;
+static struct time_travel_event time_travel_timer_event;
+static int time_travel_ext_fd = -1;
+static unsigned int time_travel_ext_waiting;
+static bool time_travel_ext_prev_request_valid;
+static unsigned long long time_travel_ext_prev_request;
+static bool time_travel_ext_free_until_valid;
+static unsigned long long time_travel_ext_free_until;
+
+static void time_travel_set_time(unsigned long long ns)
+{
+	if (unlikely(ns < time_travel_time))
+		panic("time-travel: time goes backwards %lld -> %lld\n",
+		      time_travel_time, ns);
+	time_travel_time = ns;
+}
+
+enum time_travel_message_handling {
+	TTMH_IDLE,
+	TTMH_POLL,
+	TTMH_READ,
+};
+
+static void time_travel_handle_message(struct um_timetravel_msg *msg,
+				       enum time_travel_message_handling mode)
+{
+	struct um_timetravel_msg resp = {
+		.op = UM_TIMETRAVEL_ACK,
+	};
+	int ret;
+
+	/*
+	 * Poll outside the locked section (if we're not called to only read
+	 * the response) so we can get interrupts for e.g. virtio while we're
+	 * here, but then we need to lock to not get interrupted between the
+	 * read of the message and write of the ACK.
+	 */
+	if (mode != TTMH_READ) {
+		bool disabled = irqs_disabled();
+
+		BUG_ON(mode == TTMH_IDLE && !disabled);
+
+		if (disabled)
+			local_irq_enable();
+		while (os_poll(1, &time_travel_ext_fd) != 0) {
+			/* nothing */
+		}
+		if (disabled)
+			local_irq_disable();
+	}
+
+	ret = os_read_file(time_travel_ext_fd, msg, sizeof(*msg));
+
+	if (ret == 0)
+		panic("time-travel external link is broken\n");
+	if (ret != sizeof(*msg))
+		panic("invalid time-travel message - %d bytes\n", ret);
+
+	switch (msg->op) {
+	default:
+		WARN_ONCE(1, "time-travel: unexpected message %lld\n",
+			  (unsigned long long)msg->op);
+		break;
+	case UM_TIMETRAVEL_ACK:
+		return;
+	case UM_TIMETRAVEL_RUN:
+		time_travel_set_time(msg->time);
+		break;
+	case UM_TIMETRAVEL_FREE_UNTIL:
+		time_travel_ext_free_until_valid = true;
+		time_travel_ext_free_until = msg->time;
+		break;
+	}
+
+	resp.seq = msg->seq;
+	os_write_file(time_travel_ext_fd, &resp, sizeof(resp));
+}
+
+static u64 time_travel_ext_req(u32 op, u64 time)
+{
+	static int seq;
+	int mseq = ++seq;
+	struct um_timetravel_msg msg = {
+		.op = op,
+		.time = time,
+		.seq = mseq,
+	};
+	unsigned long flags;
+
+	/*
+	 * We need to save interrupts here and only restore when we
+	 * got the ACK - otherwise we can get interrupted and send
+	 * another request while we're still waiting for an ACK, but
+	 * the peer doesn't know we got interrupted and will send
+	 * the ACKs in the same order as the message, but we'd need
+	 * to see them in the opposite order ...
+	 *
+	 * This wouldn't matter *too* much, but some ACKs carry the
+	 * current time (for UM_TIMETRAVEL_GET) and getting another
+	 * ACK without a time would confuse us a lot!
+	 *
+	 * The sequence number assignment that happens here lets us
+	 * debug such message handling issues more easily.
+	 */
+	local_irq_save(flags);
+	os_write_file(time_travel_ext_fd, &msg, sizeof(msg));
+
+	while (msg.op != UM_TIMETRAVEL_ACK)
+		time_travel_handle_message(&msg, TTMH_READ);
+
+	if (msg.seq != mseq)
+		panic("time-travel: ACK message has different seqno! op=%d, seq=%d != %d time=%lld\n",
+		      msg.op, msg.seq, mseq, msg.time);
+
+	if (op == UM_TIMETRAVEL_GET)
+		time_travel_set_time(msg.time);
+	local_irq_restore(flags);
+
+	return msg.time;
+}
+
+void __time_travel_wait_readable(int fd)
+{
+	int fds[2] = { fd, time_travel_ext_fd };
+	int ret;
+
+	if (time_travel_mode != TT_MODE_EXTERNAL)
+		return;
+
+	while ((ret = os_poll(2, fds))) {
+		struct um_timetravel_msg msg;
+
+		if (ret == 1)
+			time_travel_handle_message(&msg, TTMH_READ);
+	}
+}
+EXPORT_SYMBOL_GPL(__time_travel_wait_readable);
+
+static void time_travel_ext_update_request(unsigned long long time)
+{
+	if (time_travel_mode != TT_MODE_EXTERNAL)
+		return;
+
+	/* asked for exactly this time previously */
+	if (time_travel_ext_prev_request_valid &&
+	    time == time_travel_ext_prev_request)
+		return;
+
+	time_travel_ext_prev_request = time;
+	time_travel_ext_prev_request_valid = true;
+	time_travel_ext_req(UM_TIMETRAVEL_REQUEST, time);
+}
+
+void __time_travel_propagate_time(void)
+{
+	time_travel_ext_req(UM_TIMETRAVEL_UPDATE, time_travel_time);
+}
+EXPORT_SYMBOL_GPL(__time_travel_propagate_time);
+
+/* returns true if we must do a wait to the simtime device */
+static bool time_travel_ext_request(unsigned long long time)
+{
+	/*
+	 * If we received an external sync point ("free until") then we
+	 * don't have to request/wait for anything until then, unless
+	 * we're already waiting.
+	 */
+	if (!time_travel_ext_waiting && time_travel_ext_free_until_valid &&
+	    time < time_travel_ext_free_until)
+		return false;
+
+	time_travel_ext_update_request(time);
+	return true;
+}
+
+static void time_travel_ext_wait(bool idle)
+{
+	struct um_timetravel_msg msg = {
+		.op = UM_TIMETRAVEL_ACK,
+	};
+
+	time_travel_ext_prev_request_valid = false;
+	time_travel_ext_waiting++;
+
+	time_travel_ext_req(UM_TIMETRAVEL_WAIT, -1);
+
+	/*
+	 * Here we are deep in the idle loop, so we have to break out of the
+	 * kernel abstraction in a sense and implement this in terms of the
+	 * UML system waiting on the VQ interrupt while sleeping, when we get
+	 * the signal it'll call time_travel_ext_vq_notify_done() completing the
+	 * call.
+	 */
+	while (msg.op != UM_TIMETRAVEL_RUN)
+		time_travel_handle_message(&msg, idle ? TTMH_IDLE : TTMH_POLL);
+
+	time_travel_ext_waiting--;
+
+	/* we might request more stuff while polling - reset when we run */
+	time_travel_ext_prev_request_valid = false;
+}
+
+static void time_travel_ext_get_time(void)
+{
+	time_travel_ext_req(UM_TIMETRAVEL_GET, -1);
+}
+
+static void __time_travel_update_time(unsigned long long ns, bool idle)
+{
+	if (time_travel_mode == TT_MODE_EXTERNAL && time_travel_ext_request(ns))
+		time_travel_ext_wait(idle);
+	else
+		time_travel_set_time(ns);
+}
+
+static struct time_travel_event *time_travel_first_event(void)
+{
+	return list_first_entry_or_null(&time_travel_events,
+					struct time_travel_event,
+					list);
+}
+
+static void __time_travel_add_event(struct time_travel_event *e,
+				    unsigned long long time)
+{
+	struct time_travel_event *tmp;
+	bool inserted = false;
+
+	if (e->pending)
+		return;
+
+	e->pending = true;
+	e->time = time;
+
+	list_for_each_entry(tmp, &time_travel_events, list) {
+		/*
+		 * Add the new entry before one with higher time,
+		 * or if they're equal and both on stack, because
+		 * in that case we need to unwind the stack in the
+		 * right order, and the later event (timer sleep
+		 * or such) must be dequeued first.
+		 */
+		if ((tmp->time > e->time) ||
+		    (tmp->time == e->time && tmp->onstack && e->onstack)) {
+			list_add_tail(&e->list, &tmp->list);
+			inserted = true;
+			break;
+		}
+	}
+
+	if (!inserted)
+		list_add_tail(&e->list, &time_travel_events);
+
+	tmp = time_travel_first_event();
+	time_travel_ext_update_request(tmp->time);
+	time_travel_next_event = tmp->time;
+}
+
+static void time_travel_add_event(struct time_travel_event *e,
+				  unsigned long long time)
+{
+	if (WARN_ON(!e->fn))
+		return;
+
+	__time_travel_add_event(e, time);
+}
+
+void time_travel_periodic_timer(struct time_travel_event *e)
+{
+	time_travel_add_event(&time_travel_timer_event,
+			      time_travel_time + time_travel_timer_interval);
+	deliver_alarm();
+}
+
+static void time_travel_deliver_event(struct time_travel_event *e)
+{
+	if (e == &time_travel_timer_event) {
+		/*
+		 * deliver_alarm() does the irq_enter/irq_exit
+		 * by itself, so must handle it specially here
+		 */
+		e->fn(e);
+	} else {
+		unsigned long flags;
+
+		local_irq_save(flags);
+		irq_enter();
+		e->fn(e);
+		irq_exit();
+		local_irq_restore(flags);
+	}
+}
+
+static bool time_travel_del_event(struct time_travel_event *e)
+{
+	if (!e->pending)
+		return false;
+	list_del(&e->list);
+	e->pending = false;
+	return true;
+}
+
+static void time_travel_update_time(unsigned long long next, bool idle)
+{
+	struct time_travel_event ne = {
+		.onstack = true,
+	};
+	struct time_travel_event *e;
+	bool finished = idle;
+
+	/* add it without a handler - we deal with that specifically below */
+	__time_travel_add_event(&ne, next);
+
+	do {
+		e = time_travel_first_event();
+
+		BUG_ON(!e);
+		__time_travel_update_time(e->time, idle);
+
+		/* new events may have been inserted while we were waiting */
+		if (e == time_travel_first_event()) {
+			BUG_ON(!time_travel_del_event(e));
+			BUG_ON(time_travel_time != e->time);
+
+			if (e == &ne) {
+				finished = true;
+			} else {
+				if (e->onstack)
+					panic("On-stack event dequeued outside of the stack! time=%lld, event time=%lld, event=%pS\n",
+					      time_travel_time, e->time, e);
+				time_travel_deliver_event(e);
+			}
+		}
+
+		e = time_travel_first_event();
+		if (e)
+			time_travel_ext_update_request(e->time);
+	} while (ne.pending && !finished);
+
+	time_travel_del_event(&ne);
+}
+
+void time_travel_ndelay(unsigned long nsec)
+{
+	time_travel_update_time(time_travel_time + nsec, false);
+}
+EXPORT_SYMBOL(time_travel_ndelay);
+
+void time_travel_add_irq_event(struct time_travel_event *e)
+{
+	BUG_ON(time_travel_mode != TT_MODE_EXTERNAL);
+
+	time_travel_ext_get_time();
+	/*
+	 * We could model interrupt latency here, for now just
+	 * don't have any latency at all and request the exact
+	 * same time (again) to run the interrupt...
+	 */
+	time_travel_add_event(e, time_travel_time);
+}
+EXPORT_SYMBOL_GPL(time_travel_add_irq_event);
+
+static void time_travel_oneshot_timer(struct time_travel_event *e)
+{
+	deliver_alarm();
+}
+
+void time_travel_sleep(unsigned long long duration)
+{
+	unsigned long long next = time_travel_time + duration;
+
+	if (time_travel_mode == TT_MODE_BASIC)
+		os_timer_disable();
+
+	time_travel_update_time(next, true);
+
+	if (time_travel_mode == TT_MODE_BASIC &&
+	    time_travel_timer_event.pending) {
+		if (time_travel_timer_event.fn == time_travel_periodic_timer) {
+			/*
+			 * This is somewhat wrong - we should get the first
+			 * one sooner like the os_timer_one_shot() below...
+			 */
+			os_timer_set_interval(time_travel_timer_interval);
+		} else {
+			os_timer_one_shot(time_travel_timer_event.time - next);
+		}
+	}
+}
+
+static void time_travel_handle_real_alarm(void)
+{
+	time_travel_set_time(time_travel_next_event);
+
+	time_travel_del_event(&time_travel_timer_event);
+
+	if (time_travel_timer_event.fn == time_travel_periodic_timer)
+		time_travel_add_event(&time_travel_timer_event,
+				      time_travel_time +
+				      time_travel_timer_interval);
+}
+
+static void time_travel_set_interval(unsigned long long interval)
+{
+	time_travel_timer_interval = interval;
+}
+
+static int time_travel_connect_external(const char *socket)
+{
+	const char *sep;
+	unsigned long long id = (unsigned long long)-1;
+	int rc;
+
+	if ((sep = strchr(socket, ':'))) {
+		char buf[25] = {};
+		if (sep - socket > sizeof(buf) - 1)
+			goto invalid_number;
+
+		memcpy(buf, socket, sep - socket);
+		if (kstrtoull(buf, 0, &id)) {
+invalid_number:
+			panic("time-travel: invalid external ID in string '%s'\n",
+			      socket);
+			return -EINVAL;
+		}
+
+		socket = sep + 1;
+	}
+
+	rc = os_connect_socket(socket);
+	if (rc < 0) {
+		panic("time-travel: failed to connect to external socket %s\n",
+		      socket);
+		return rc;
+	}
+
+	time_travel_ext_fd = rc;
+
+	time_travel_ext_req(UM_TIMETRAVEL_START, id);
+
+	return 1;
+}
+#else /* CONFIG_UML_TIME_TRAVEL_SUPPORT */
 #define time_travel_start_set 0
 #define time_travel_start 0
+#define time_travel_time 0
+
+static inline void time_travel_update_time(unsigned long long ns, bool retearly)
+{
+}
+
+static inline void time_travel_handle_real_alarm(void)
+{
+}
+
+static void time_travel_set_interval(unsigned long long interval)
+{
+}
+
+/* fail link if this actually gets used */
+extern u64 time_travel_ext_req(u32 op, u64 time);
+
+/* these are empty macros so the struct/fn need not exist */
+#define time_travel_add_event(e, time) do { } while (0)
+#define time_travel_del_event(e) do { } while (0)
 #endif
 
 void timer_handler(int sig, struct siginfo *unused_si, struct uml_pt_regs *regs)
@@ -48,7 +512,7 @@
 	 * never get any real signals from the OS.
 	 */
 	if (time_travel_mode == TT_MODE_BASIC)
-		time_travel_set_time(time_travel_timer_expiry);
+		time_travel_handle_real_alarm();
 
 	local_irq_save(flags);
 	do_IRQ(TIMER_IRQ, regs);
@@ -58,9 +522,10 @@
 static int itimer_shutdown(struct clock_event_device *evt)
 {
 	if (time_travel_mode != TT_MODE_OFF)
-		time_travel_set_timer_mode(TT_TMR_DISABLED);
+		time_travel_del_event(&time_travel_timer_event);
 
-	if (time_travel_mode != TT_MODE_INFCPU)
+	if (time_travel_mode != TT_MODE_INFCPU &&
+	    time_travel_mode != TT_MODE_EXTERNAL)
 		os_timer_disable();
 
 	return 0;
@@ -71,12 +536,16 @@
 	unsigned long long interval = NSEC_PER_SEC / HZ;
 
 	if (time_travel_mode != TT_MODE_OFF) {
-		time_travel_set_timer_mode(TT_TMR_PERIODIC);
-		time_travel_set_timer_expiry(time_travel_time + interval);
-		time_travel_set_timer_interval(interval);
+		time_travel_del_event(&time_travel_timer_event);
+		time_travel_set_event_fn(&time_travel_timer_event,
+					 time_travel_periodic_timer);
+		time_travel_set_interval(interval);
+		time_travel_add_event(&time_travel_timer_event,
+				      time_travel_time + interval);
 	}
 
-	if (time_travel_mode != TT_MODE_INFCPU)
+	if (time_travel_mode != TT_MODE_INFCPU &&
+	    time_travel_mode != TT_MODE_EXTERNAL)
 		os_timer_set_interval(interval);
 
 	return 0;
@@ -88,11 +557,15 @@
 	delta += 1;
 
 	if (time_travel_mode != TT_MODE_OFF) {
-		time_travel_set_timer_mode(TT_TMR_ONESHOT);
-		time_travel_set_timer_expiry(time_travel_time + delta);
+		time_travel_del_event(&time_travel_timer_event);
+		time_travel_set_event_fn(&time_travel_timer_event,
+					 time_travel_oneshot_timer);
+		time_travel_add_event(&time_travel_timer_event,
+				      time_travel_time + delta);
 	}
 
-	if (time_travel_mode != TT_MODE_INFCPU)
+	if (time_travel_mode != TT_MODE_INFCPU &&
+	    time_travel_mode != TT_MODE_EXTERNAL)
 		return os_timer_one_shot(delta);
 
 	return 0;
@@ -143,8 +616,17 @@
 		 * stuck in loops that expect time to move more than the
 		 * exact requested sleep amount, e.g. python's socket server,
 		 * see https://bugs.python.org/issue37026.
+		 *
+		 * However, don't do that when we're in interrupt or such as
+		 * then we might recurse into our own processing, and get to
+		 * even more waiting, and that's not good - it messes up the
+		 * "what do I do next" and onstack event we use to know when
+		 * to return from time_travel_update_time().
 		 */
-		time_travel_set_time(time_travel_time + TIMER_MULTIPLIER);
+		if (!irqs_disabled() && !in_interrupt() && !in_softirq())
+			time_travel_update_time(time_travel_time +
+						TIMER_MULTIPLIER,
+						false);
 		return time_travel_time / TIMER_MULTIPLIER;
 	}
 
@@ -188,6 +670,8 @@
 
 	if (time_travel_start_set)
 		nsecs = time_travel_start + time_travel_time;
+	else if (time_travel_mode == TT_MODE_EXTERNAL)
+		nsecs = time_travel_ext_req(UM_TIMETRAVEL_GET_TOD, -1);
 	else
 		nsecs = os_persistent_clock_emulation();
 
@@ -204,7 +688,8 @@
 #ifdef CONFIG_UML_TIME_TRAVEL_SUPPORT
 unsigned long calibrate_delay_is_known(void)
 {
-	if (time_travel_mode == TT_MODE_INFCPU)
+	if (time_travel_mode == TT_MODE_INFCPU ||
+	    time_travel_mode == TT_MODE_EXTERNAL)
 		return 1;
 	return 0;
 }
@@ -218,6 +703,13 @@
 		return 1;
 	}
 
+	if (strncmp(str, "=ext:", 5) == 0) {
+		time_travel_mode = TT_MODE_EXTERNAL;
+		timer_clockevent.name = "time-travel-timer-external";
+		timer_clocksource.name = "time-travel-clock-external";
+		return time_travel_connect_external(str + 5);
+	}
+
 	if (!*str) {
 		time_travel_mode = TT_MODE_BASIC;
 		timer_clockevent.name = "time-travel-timer";
@@ -242,7 +734,15 @@
 "are no wall clock timers, and any CPU processing happens - as seen from the\n"
 "guest - instantly. This can be useful for accurate simulation regardless of\n"
 "debug overhead, physical CPU speed, etc. but is somewhat dangerous as it can\n"
-"easily lead to getting stuck (e.g. if anything in the system busy loops).\n");
+"easily lead to getting stuck (e.g. if anything in the system busy loops).\n"
+"\n"
+"time-travel=ext:[ID:]/path/to/socket\n"
+"This enables time travel mode similar to =inf-cpu, except the system will\n"
+"use the given socket to coordinate with a central scheduler, in order to\n"
+"have more than one system simultaneously be on simulated time. The virtio\n"
+"driver code in UML knows about this so you can also simulate networks and\n"
+"devices using it, assuming the device has the right capabilities.\n"
+"The optional ID is a 64-bit integer that's sent to the central scheduler.\n");
 
 int setup_time_travel_start(char *str)
 {
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 1149913..5be1b0d 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -7,7 +7,6 @@
 #include <linux/module.h>
 #include <linux/sched/signal.h>
 
-#include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <as-layout.h>
 #include <mem_user.h>
@@ -283,7 +282,7 @@
 	return ret;
 }
 
-static inline int update_pud_range(pgd_t *pgd, unsigned long addr,
+static inline int update_pud_range(p4d_t *p4d, unsigned long addr,
 				   unsigned long end,
 				   struct host_vm_change *hvc)
 {
@@ -291,7 +290,7 @@
 	unsigned long next;
 	int ret = 0;
 
-	pud = pud_offset(pgd, addr);
+	pud = pud_offset(p4d, addr);
 	do {
 		next = pud_addr_end(addr, end);
 		if (!pud_present(*pud)) {
@@ -305,6 +304,28 @@
 	return ret;
 }
 
+static inline int update_p4d_range(pgd_t *pgd, unsigned long addr,
+				   unsigned long end,
+				   struct host_vm_change *hvc)
+{
+	p4d_t *p4d;
+	unsigned long next;
+	int ret = 0;
+
+	p4d = p4d_offset(pgd, addr);
+	do {
+		next = p4d_addr_end(addr, end);
+		if (!p4d_present(*p4d)) {
+			if (hvc->force || p4d_newpage(*p4d)) {
+				ret = add_munmap(addr, next - addr, hvc);
+				p4d_mkuptodate(*p4d);
+			}
+		} else
+			ret = update_pud_range(p4d, addr, next, hvc);
+	} while (p4d++, addr = next, ((addr < end) && !ret));
+	return ret;
+}
+
 void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
 		      unsigned long end_addr, int force)
 {
@@ -322,8 +343,8 @@
 				ret = add_munmap(addr, next - addr, &hvc);
 				pgd_mkuptodate(*pgd);
 			}
-		}
-		else ret = update_pud_range(pgd, addr, next, &hvc);
+		} else
+			ret = update_p4d_range(pgd, addr, next, &hvc);
 	} while (pgd++, addr = next, ((addr < end_addr) && !ret));
 
 	if (!ret)
@@ -331,12 +352,11 @@
 
 	/* This is not an else because ret is modified above */
 	if (ret) {
+		struct mm_id *mm_idp = &current->mm->context.id;
+
 		printk(KERN_ERR "fix_range_common: failed, killing current "
 		       "process: %d\n", task_tgid_vnr(current));
-		/* We are under mmap_sem, release it such that current can terminate */
-		up_write(&current->mm->mmap_sem);
-		force_sig(SIGKILL);
-		do_signal(&current->thread.regs);
+		mm_idp->kill = 1;
 	}
 }
 
@@ -344,6 +364,7 @@
 {
 	struct mm_struct *mm;
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -370,7 +391,23 @@
 			continue;
 		}
 
-		pud = pud_offset(pgd, addr);
+		p4d = p4d_offset(pgd, addr);
+		if (!p4d_present(*p4d)) {
+			last = ADD_ROUND(addr, P4D_SIZE);
+			if (last > end)
+				last = end;
+			if (p4d_newpage(*p4d)) {
+				updated = 1;
+				err = add_munmap(addr, last - addr, &hvc);
+				if (err < 0)
+					panic("munmap failed, errno = %d\n",
+					      -err);
+			}
+			addr = last;
+			continue;
+		}
+
+		pud = pud_offset(p4d, addr);
 		if (!pud_present(*pud)) {
 			last = ADD_ROUND(addr, PUD_SIZE);
 			if (last > end)
@@ -430,6 +467,7 @@
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long address)
 {
 	pgd_t *pgd;
+	p4d_t *p4d;
 	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
@@ -447,7 +485,11 @@
 	if (!pgd_present(*pgd))
 		goto kill;
 
-	pud = pud_offset(pgd, address);
+	p4d = p4d_offset(pgd, address);
+	if (!p4d_present(*p4d))
+		goto kill;
+
+	pud = pud_offset(p4d, address);
 	if (!pud_present(*pud))
 		goto kill;
 
@@ -500,35 +542,6 @@
 	force_sig(SIGKILL);
 }
 
-pgd_t *pgd_offset_proc(struct mm_struct *mm, unsigned long address)
-{
-	return pgd_offset(mm, address);
-}
-
-pud_t *pud_offset_proc(pgd_t *pgd, unsigned long address)
-{
-	return pud_offset(pgd, address);
-}
-
-pmd_t *pmd_offset_proc(pud_t *pud, unsigned long address)
-{
-	return pmd_offset(pud, address);
-}
-
-pte_t *pte_offset_proc(pmd_t *pmd, unsigned long address)
-{
-	return pte_offset_kernel(pmd, address);
-}
-
-pte_t *addr_pte(struct task_struct *task, unsigned long addr)
-{
-	pgd_t *pgd = pgd_offset(task->mm, addr);
-	pud_t *pud = pud_offset(pgd, addr);
-	pmd_t *pmd = pmd_offset(pud, addr);
-
-	return pte_offset_map(pmd, addr);
-}
-
 void flush_tlb_all(void)
 {
 	/*
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index e62296c..ad12f78 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -10,7 +10,6 @@
 #include <linux/uaccess.h>
 #include <linux/sched/debug.h>
 #include <asm/current.h>
-#include <asm/pgtable.h>
 #include <asm/tlbflush.h>
 #include <arch.h>
 #include <as-layout.h>
@@ -27,12 +26,10 @@
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
-	pgd_t *pgd;
-	pud_t *pud;
 	pmd_t *pmd;
 	pte_t *pte;
 	int err = -EFAULT;
-	unsigned int flags = FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_KILLABLE;
+	unsigned int flags = FAULT_FLAG_DEFAULT;
 
 	*code_out = SEGV_MAPERR;
 
@@ -46,7 +43,7 @@
 	if (is_user)
 		flags |= FAULT_FLAG_USER;
 retry:
-	down_read(&mm->mmap_sem);
+	mmap_read_lock(mm);
 	vma = find_vma(mm, address);
 	if (!vma)
 		goto out;
@@ -74,7 +71,7 @@
 	do {
 		vm_fault_t fault;
 
-		fault = handle_mm_fault(vma, address, flags);
+		fault = handle_mm_fault(vma, address, flags, NULL);
 
 		if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current))
 			goto out_nosemaphore;
@@ -91,21 +88,14 @@
 			BUG();
 		}
 		if (flags & FAULT_FLAG_ALLOW_RETRY) {
-			if (fault & VM_FAULT_MAJOR)
-				current->maj_flt++;
-			else
-				current->min_flt++;
 			if (fault & VM_FAULT_RETRY) {
-				flags &= ~FAULT_FLAG_ALLOW_RETRY;
 				flags |= FAULT_FLAG_TRIED;
 
 				goto retry;
 			}
 		}
 
-		pgd = pgd_offset(mm, address);
-		pud = pud_offset(pgd, address);
-		pmd = pmd_offset(pud, address);
+		pmd = pmd_off(mm, address);
 		pte = pte_offset_kernel(pmd, address);
 	} while (!pte_present(*pte));
 	err = 0;
@@ -122,7 +112,7 @@
 #endif
 	flush_tlb_page(vma, address);
 out:
-	up_read(&mm->mmap_sem);
+	mmap_read_unlock(mm);
 out_nosemaphore:
 	return err;
 
@@ -131,7 +121,7 @@
 	 * We ran out of memory, call the OOM killer, and return the userspace
 	 * (which will retry the fault, or kill us if we got oom-killed).
 	 */
-	up_read(&mm->mmap_sem);
+	mmap_read_unlock(mm);
 	if (!is_user)
 		goto out_nosemaphore;
 	pagefault_out_of_memory();
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 0f40ecc..76b3729 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -14,7 +14,6 @@
 #include <linux/sched/task.h>
 #include <linux/kmsg_dump.h>
 
-#include <asm/pgtable.h>
 #include <asm/processor.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
@@ -53,7 +52,7 @@
 };
 
 union thread_union cpu0_irqstack
-	__attribute__((__section__(".data..init_irqstack"))) =
+	__section(".data..init_irqstack") =
 		{ .thread_info = INIT_THREAD_INFO(init_task) };
 
 /* Changed in setup_arch, which is called in early boot */
@@ -362,3 +361,19 @@
 void apply_alternatives(struct alt_instr *start, struct alt_instr *end)
 {
 }
+
+void *text_poke(void *addr, const void *opcode, size_t len)
+{
+	/*
+	 * In UML, the only reference to this function is in
+	 * apply_relocate_add(), which shouldn't ever actually call this
+	 * because UML doesn't have live patching.
+	 */
+	WARN_ON(1);
+
+	return memcpy(addr, opcode, len);
+}
+
+void text_poke_sync(void)
+{
+}
diff --git a/arch/um/kernel/uml.lds.S b/arch/um/kernel/uml.lds.S
index 85b404d..7a8e2b1 100644
--- a/arch/um/kernel/uml.lds.S
+++ b/arch/um/kernel/uml.lds.S
@@ -25,10 +25,10 @@
   __binary_start = START;
 
   . = START + SIZEOF_HEADERS;
+  . = ALIGN(PAGE_SIZE);
 
   _text = .;
   INIT_TEXT_SECTION(0)
-  . = ALIGN(PAGE_SIZE);
 
   .text      :
   {
@@ -114,8 +114,8 @@
   PROVIDE (end = .);
 
   STABS_DEBUG
-
   DWARF_DEBUG
+  ELF_DETAILS
 
   DISCARDS
 }