Merge tag 'uml-for-linus-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

Pull UML updates from Richard Weinberger:

 - Fixes for -Wmissing-prototypes warnings and further cleanup

 - Remove callback returning void from rtc and virtio drivers

 - Fix bash location

* tag 'uml-for-linus-6.10-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux: (26 commits)
  um: virtio_uml: Convert to platform remove callback returning void
  um: rtc: Convert to platform remove callback returning void
  um: Remove unused do_get_thread_area function
  um: Fix -Wmissing-prototypes warnings for __vdso_*
  um: Add an internal header shared among the user code
  um: Fix the declaration of kasan_map_memory
  um: Fix the -Wmissing-prototypes warning for get_thread_reg
  um: Fix the -Wmissing-prototypes warning for __switch_mm
  um: Fix -Wmissing-prototypes warnings for (rt_)sigreturn
  um: Stop tracking host PID in cpu_tasks
  um: process: remove unused 'n' variable
  um: vector: remove unused len variable/calculation
  um: vector: fix bpfflash parameter evaluation
  um: slirp: remove set but unused variable 'pid'
  um: signal: move pid variable where needed
  um: Makefile: use bash from the environment
  um: Add winch to winch_handlers before registering winch IRQ
  um: Fix -Wmissing-prototypes warnings for __warp_* and foo
  um: Fix -Wmissing-prototypes warnings for text_poke*
  um: Move declarations to proper headers
  ...

54 files changed, 136 insertions, 129 deletions

diff --git a/arch/um/Makefile b/arch/um/Makefile
index 34957dcb88b9..00b63bac5eff 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -20,7 +20,7 @@ endif
 ARCH_DIR := arch/um
 # We require bash because the vmlinux link and loader script cpp use bash
 # features.
-SHELL := /bin/bash
+SHELL := bash
 
 MODE_INCLUDE	+= -I$(srctree)/$(ARCH_DIR)/include/shared/skas
 
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index ffc5cb92fa36..d82bc3fdb86e 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -676,24 +676,26 @@ void register_winch_irq(int fd, int tty_fd, int pid, struct tty_port *port,
 		goto cleanup;
 	}
 
-	*winch = ((struct winch) { .list  	= LIST_HEAD_INIT(winch->list),
-				   .fd  	= fd,
+	*winch = ((struct winch) { .fd  	= fd,
 				   .tty_fd 	= tty_fd,
 				   .pid  	= pid,
 				   .port 	= port,
 				   .stack	= stack });
 
+	spin_lock(&winch_handler_lock);
+	list_add(&winch->list, &winch_handlers);
+	spin_unlock(&winch_handler_lock);
+
 	if (um_request_irq(WINCH_IRQ, fd, IRQ_READ, winch_interrupt,
 			   IRQF_SHARED, "winch", winch) < 0) {
 		printk(KERN_ERR "register_winch_irq - failed to register "
 		       "IRQ\n");
+		spin_lock(&winch_handler_lock);
+		list_del(&winch->list);
+		spin_unlock(&winch_handler_lock);
 		goto out_free;
 	}
 
-	spin_lock(&winch_handler_lock);
-	list_add(&winch->list, &winch_handlers);
-	spin_unlock(&winch_handler_lock);
-
 	return;
 
  out_free:
diff --git a/arch/um/drivers/pcap_kern.c b/arch/um/drivers/pcap_kern.c
index 25ee2c97ca21..d9bf95d7867b 100644
--- a/arch/um/drivers/pcap_kern.c
+++ b/arch/um/drivers/pcap_kern.c
@@ -15,7 +15,7 @@ struct pcap_init {
 	char *filter;
 };
 
-void pcap_init_kern(struct net_device *dev, void *data)
+static void pcap_init_kern(struct net_device *dev, void *data)
 {
 	struct uml_net_private *pri;
 	struct pcap_data *ppri;
@@ -50,7 +50,7 @@ static const struct net_kern_info pcap_kern_info = {
 	.write			= pcap_write,
 };
 
-int pcap_setup(char *str, char **mac_out, void *data)
+static int pcap_setup(char *str, char **mac_out, void *data)
 {
 	struct pcap_init *init = data;
 	char *remain, *host_if = NULL, *options[2] = { NULL, NULL };
diff --git a/arch/um/drivers/rtc_kern.c b/arch/um/drivers/rtc_kern.c
index 97ceb205cfe6..3a1582219c4b 100644
--- a/arch/um/drivers/rtc_kern.c
+++ b/arch/um/drivers/rtc_kern.c
@@ -168,16 +168,15 @@ cleanup:
 	return err;
 }
 
-static int uml_rtc_remove(struct platform_device *pdev)
+static void uml_rtc_remove(struct platform_device *pdev)
 {
 	device_init_wakeup(&pdev->dev, 0);
 	uml_rtc_cleanup();
-	return 0;
 }
 
 static struct platform_driver uml_rtc_driver = {
 	.probe = uml_rtc_probe,
-	.remove = uml_rtc_remove,
+	.remove_new = uml_rtc_remove,
 	.driver = {
 		.name = "uml-rtc",
 	},
diff --git a/arch/um/drivers/slirp_user.c b/arch/um/drivers/slirp_user.c
index 8f633e2e5f3d..97228aa080cb 100644
--- a/arch/um/drivers/slirp_user.c
+++ b/arch/um/drivers/slirp_user.c
@@ -49,7 +49,7 @@ static int slirp_tramp(char **argv, int fd)
 static int slirp_open(void *data)
 {
 	struct slirp_data *pri = data;
-	int fds[2], pid, err;
+	int fds[2], err;
 
 	err = os_pipe(fds, 1, 1);
 	if (err)
@@ -60,7 +60,6 @@ static int slirp_open(void *data)
 		printk(UM_KERN_ERR "slirp_tramp failed - errno = %d\n", -err);
 		goto out;
 	}
-	pid = err;
 
 	pri->slave = fds[1];
 	pri->slip.pos = 0;
diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c
index 63fc062add70..ef805eaa9e01 100644
--- a/arch/um/drivers/ubd_kern.c
+++ b/arch/um/drivers/ubd_kern.c
@@ -1092,7 +1092,7 @@ static int __init ubd_init(void)
 
 	if (irq_req_buffer == NULL) {
 		printk(KERN_ERR "Failed to initialize ubd buffering\n");
-		return -1;
+		return -ENOMEM;
 	}
 	io_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
 				      sizeof(struct io_thread_req *),
@@ -1103,7 +1103,7 @@ static int __init ubd_init(void)
 
 	if (io_req_buffer == NULL) {
 		printk(KERN_ERR "Failed to initialize ubd buffering\n");
-		return -1;
+		return -ENOMEM;
 	}
 	platform_driver_register(&ubd_driver);
 	mutex_lock(&ubd_lock);
diff --git a/arch/um/drivers/ubd_user.c b/arch/um/drivers/ubd_user.c
index a1afe414ce48..b4f8b8e60564 100644
--- a/arch/um/drivers/ubd_user.c
+++ b/arch/um/drivers/ubd_user.c
@@ -23,7 +23,7 @@
 #include <os.h>
 #include <poll.h>
 
-struct pollfd kernel_pollfd;
+static struct pollfd kernel_pollfd;
 
 int start_io_thread(unsigned long sp, int *fd_out)
 {
diff --git a/arch/um/drivers/vector_kern.c b/arch/um/drivers/vector_kern.c
index dc2feae789cb..4279793b11b7 100644
--- a/arch/um/drivers/vector_kern.c
+++ b/arch/um/drivers/vector_kern.c
@@ -141,7 +141,7 @@ static bool get_bpf_flash(struct arglist *def)
 
 	if (allow != NULL) {
 		if (kstrtoul(allow, 10, &result) == 0)
-			return (allow > 0);
+			return result > 0;
 	}
 	return false;
 }
@@ -712,11 +712,9 @@ static struct vector_device *find_device(int n)
 static int vector_parse(char *str, int *index_out, char **str_out,
 			char **error_out)
 {
-	int n, len, err;
+	int n, err;
 	char *start = str;
 
-	len = strlen(str);
-
 	while ((*str != ':') && (strlen(str) > 1))
 		str++;
 	if (*str != ':') {
diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
index 8adca2000e51..77faa2cf3a13 100644
--- a/arch/um/drivers/virtio_uml.c
+++ b/arch/um/drivers/virtio_uml.c
@@ -1241,12 +1241,11 @@ error_free:
 	return rc;
 }
 
-static int virtio_uml_remove(struct platform_device *pdev)
+static void virtio_uml_remove(struct platform_device *pdev)
 {
 	struct virtio_uml_device *vu_dev = platform_get_drvdata(pdev);
 
 	unregister_virtio_device(&vu_dev->vdev);
-	return 0;
 }
 
 /* Command line device list */
@@ -1445,7 +1444,7 @@ static int virtio_uml_resume(struct platform_device *pdev)
 
 static struct platform_driver virtio_uml_driver = {
 	.probe = virtio_uml_probe,
-	.remove = virtio_uml_remove,
+	.remove_new = virtio_uml_remove,
 	.driver = {
 		.name = "virtio-uml",
 		.of_match_table = virtio_uml_match,
diff --git a/arch/um/include/asm/kasan.h b/arch/um/include/asm/kasan.h
index 0d6547f4ec85..f97bb1f7b851 100644
--- a/arch/um/include/asm/kasan.h
+++ b/arch/um/include/asm/kasan.h
@@ -24,7 +24,6 @@
 
 #ifdef CONFIG_KASAN
 void kasan_init(void);
-void kasan_map_memory(void *start, unsigned long len);
 extern int kasan_um_is_ready;
 
 #ifdef CONFIG_STATIC_LINK
diff --git a/arch/um/include/asm/mmu.h b/arch/um/include/asm/mmu.h
index a7555e43ed14..f2923c767bb9 100644
--- a/arch/um/include/asm/mmu.h
+++ b/arch/um/include/asm/mmu.h
@@ -14,8 +14,6 @@ typedef struct mm_context {
 	struct uml_arch_mm_context arch;
 } mm_context_t;
 
-extern void __switch_mm(struct mm_id * mm_idp);
-
 /* Avoid tangled inclusion with asm/ldt.h */
 extern long init_new_ldt(struct mm_context *to_mm, struct mm_context *from_mm);
 extern void free_ldt(struct mm_context *mm);
diff --git a/arch/um/include/asm/processor-generic.h b/arch/um/include/asm/processor-generic.h
index 6c3779541845..5a7c05275aa7 100644
--- a/arch/um/include/asm/processor-generic.h
+++ b/arch/um/include/asm/processor-generic.h
@@ -94,7 +94,6 @@ extern struct cpuinfo_um boot_cpu_data;
 #define current_cpu_data boot_cpu_data
 #define cache_line_size()	(boot_cpu_data.cache_alignment)
 
-extern unsigned long get_thread_reg(int reg, jmp_buf *buf);
 #define KSTK_REG(tsk, reg) get_thread_reg(reg, &tsk->thread.switch_buf)
 extern unsigned long __get_wchan(struct task_struct *p);
 
diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h
index adf91ef553ae..4696f24d1492 100644
--- a/arch/um/include/asm/ptrace-generic.h
+++ b/arch/um/include/asm/ptrace-generic.h
@@ -36,6 +36,9 @@ extern long subarch_ptrace(struct task_struct *child, long request,
 extern unsigned long getreg(struct task_struct *child, int regno);
 extern int putreg(struct task_struct *child, int regno, unsigned long value);
 
+extern int poke_user(struct task_struct *child, long addr, long data);
+extern int peek_user(struct task_struct *child, long addr, long data);
+
 extern int arch_set_tls(struct task_struct *new, unsigned long tls);
 extern void clear_flushed_tls(struct task_struct *task);
 extern int syscall_trace_enter(struct pt_regs *regs);
diff --git a/arch/um/include/shared/as-layout.h b/arch/um/include/shared/as-layout.h
index 9ec3015bc5e2..c22f46a757dc 100644
--- a/arch/um/include/shared/as-layout.h
+++ b/arch/um/include/shared/as-layout.h
@@ -31,7 +31,6 @@
 #include <sysdep/ptrace.h>
 
 struct cpu_task {
-	int pid;
 	void *task;
 };
 
diff --git a/arch/um/include/shared/kern_util.h b/arch/um/include/shared/kern_util.h
index 789b83013f35..95521b1f5b20 100644
--- a/arch/um/include/shared/kern_util.h
+++ b/arch/um/include/shared/kern_util.h
@@ -41,6 +41,7 @@ extern void uml_pm_wake(void);
 
 extern int start_uml(void);
 extern void paging_init(void);
+extern int parse_iomem(char *str, int *add);
 
 extern void uml_cleanup(void);
 extern void do_uml_exitcalls(void);
@@ -66,4 +67,6 @@ 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/skas/mm_id.h b/arch/um/include/shared/skas/mm_id.h
index e82e203f5f41..92dbf727e384 100644
--- a/arch/um/include/shared/skas/mm_id.h
+++ b/arch/um/include/shared/skas/mm_id.h
@@ -15,4 +15,6 @@ struct mm_id {
 	int kill;
 };
 
+void __switch_mm(struct mm_id *mm_idp);
+
 #endif
diff --git a/arch/um/include/shared/um_malloc.h b/arch/um/include/shared/um_malloc.h
index bf503658f08e..815dd03e8707 100644
--- a/arch/um/include/shared/um_malloc.h
+++ b/arch/um/include/shared/um_malloc.h
@@ -13,7 +13,7 @@ extern void kfree(const void *ptr);
 
 extern void *vmalloc_noprof(unsigned long size);
 #define vmalloc(...)		vmalloc_noprof(__VA_ARGS__)
-extern void vfree(void *ptr);
+extern void vfree(const void *ptr);
 
 #endif /* __UM_MALLOC_H__ */
 
diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
index 427dd5a61a38..4382cf02a6d1 100644
--- a/arch/um/kernel/kmsg_dump.c
+++ b/arch/um/kernel/kmsg_dump.c
@@ -57,7 +57,7 @@ static struct kmsg_dumper kmsg_dumper = {
 	.dump = kmsg_dumper_stdout
 };
 
-int __init kmsg_dumper_stdout_init(void)
+static int __init kmsg_dumper_stdout_init(void)
 {
 	return kmsg_dump_register(&kmsg_dumper);
 }
diff --git a/arch/um/kernel/mem.c b/arch/um/kernel/mem.c
index 38d5a71a579b..ca91accd64fc 100644
--- a/arch/um/kernel/mem.c
+++ b/arch/um/kernel/mem.c
@@ -12,12 +12,14 @@
 #include <linux/slab.h>
 #include <asm/fixmap.h>
 #include <asm/page.h>
+#include <asm/pgalloc.h>
 #include <as-layout.h>
 #include <init.h>
 #include <kern.h>
 #include <kern_util.h>
 #include <mem_user.h>
 #include <os.h>
+#include <um_malloc.h>
 #include <linux/sched/task.h>
 
 #ifdef CONFIG_KASAN
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index 91485119ae67..fb2adfb49945 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -12,6 +12,7 @@
 #include <as-layout.h>
 #include <init.h>
 #include <kern.h>
+#include <kern_util.h>
 #include <mem_user.h>
 #include <os.h>
 
@@ -161,8 +162,6 @@ __uml_setup("mem=", uml_mem_setup,
 "	Example: mem=64M\n\n"
 );
 
-extern int __init parse_iomem(char *str, int *add);
-
 __uml_setup("iomem=", parse_iomem,
 "iomem=<name>,<file>\n"
 "    Configure <file> as an IO memory region named <name>.\n\n"
diff --git a/arch/um/kernel/process.c b/arch/um/kernel/process.c
index ab95648e93e1..d2134802f6a8 100644
--- a/arch/um/kernel/process.c
+++ b/arch/um/kernel/process.c
@@ -15,6 +15,7 @@
 #include <linux/proc_fs.h>
 #include <linux/ptrace.h>
 #include <linux/random.h>
+#include <linux/cpu.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
 #include <linux/sched/debug.h>
@@ -26,6 +27,8 @@
 #include <linux/resume_user_mode.h>
 #include <asm/current.h>
 #include <asm/mmu_context.h>
+#include <asm/switch_to.h>
+#include <asm/exec.h>
 #include <linux/uaccess.h>
 #include <as-layout.h>
 #include <kern_util.h>
@@ -40,24 +43,7 @@
  * cares about its entry, so it's OK if another processor is modifying its
  * entry.
  */
-struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { -1, NULL } };
-
-static inline int external_pid(void)
-{
-	/* FIXME: Need to look up userspace_pid by cpu */
-	return userspace_pid[0];
-}
-
-int pid_to_processor_id(int pid)
-{
-	int i;
-
-	for (i = 0; i < ncpus; i++) {
-		if (cpu_tasks[i].pid == pid)
-			return i;
-	}
-	return -1;
-}
+struct cpu_task cpu_tasks[NR_CPUS] = { [0 ... NR_CPUS - 1] = { NULL } };
 
 void free_stack(unsigned long stack, int order)
 {
@@ -78,13 +64,10 @@ unsigned long alloc_stack(int order, int atomic)
 
 static inline void set_current(struct task_struct *task)
 {
-	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task)
-		{ external_pid(), task });
+	cpu_tasks[task_thread_info(task)->cpu] = ((struct cpu_task) { task });
 }
 
-extern void arch_switch_to(struct task_struct *to);
-
-void *__switch_to(struct task_struct *from, struct task_struct *to)
+struct task_struct *__switch_to(struct task_struct *from, struct task_struct *to)
 {
 	to->thread.prev_sched = from;
 	set_current(to);
@@ -119,7 +102,7 @@ int get_current_pid(void)
  */
 void new_thread_handler(void)
 {
-	int (*fn)(void *), n;
+	int (*fn)(void *);
 	void *arg;
 
 	if (current->thread.prev_sched != NULL)
@@ -132,12 +115,12 @@ void new_thread_handler(void)
 	/*
 	 * callback returns only if the kernel thread execs a process
 	 */
-	n = fn(arg);
+	fn(arg);
 	userspace(&current->thread.regs.regs, current_thread_info()->aux_fp_regs);
 }
 
 /* Called magically, see new_thread_handler above */
-void fork_handler(void)
+static void fork_handler(void)
 {
 	force_flush_all();
 
@@ -216,7 +199,6 @@ void um_idle_sleep(void)
 
 void arch_cpu_idle(void)
 {
-	cpu_tasks[current_thread_info()->cpu].pid = os_getpid();
 	um_idle_sleep();
 }
 
@@ -250,32 +232,22 @@ char *uml_strdup(const char *string)
 }
 EXPORT_SYMBOL(uml_strdup);
 
-int copy_to_user_proc(void __user *to, void *from, int size)
-{
-	return copy_to_user(to, from, size);
-}
-
 int copy_from_user_proc(void *to, void __user *from, int size)
 {
 	return copy_from_user(to, from, size);
 }
 
-int clear_user_proc(void __user *buf, int size)
-{
-	return clear_user(buf, size);
-}
-
 static atomic_t using_sysemu = ATOMIC_INIT(0);
 int sysemu_supported;
 
-void set_using_sysemu(int value)
+static void set_using_sysemu(int value)
 {
 	if (value > sysemu_supported)
 		return;
 	atomic_set(&using_sysemu, value);
 }
 
-int get_using_sysemu(void)
+static int get_using_sysemu(void)
 {
 	return atomic_read(&using_sysemu);
 }
@@ -313,7 +285,7 @@ static const struct proc_ops sysemu_proc_ops = {
 	.proc_write	= sysemu_proc_write,
 };
 
-int __init make_proc_sysemu(void)
+static int __init make_proc_sysemu(void)
 {
 	struct proc_dir_entry *ent;
 	if (!sysemu_supported)
diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index 6600a2782796..2124624b7817 100644
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -35,9 +35,6 @@ void ptrace_disable(struct task_struct *child)
 	user_disable_single_step(child);
 }
 
-extern int peek_user(struct task_struct * child, long addr, long data);
-extern int poke_user(struct task_struct * child, long addr, long data);
-
 long arch_ptrace(struct task_struct *child, long request,
 		 unsigned long addr, unsigned long data)
 {
diff --git a/arch/um/kernel/reboot.c b/arch/um/kernel/reboot.c
index 48c0610d506e..25840eee1068 100644
--- a/arch/um/kernel/reboot.c
+++ b/arch/um/kernel/reboot.c
@@ -9,6 +9,7 @@
 #include <linux/spinlock.h>
 #include <linux/slab.h>
 #include <linux/oom.h>
+#include <linux/reboot.h>
 #include <kern_util.h>
 #include <os.h>
 #include <skas.h>
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 656fe16c9b63..aeed1c2aaf3c 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -10,6 +10,7 @@
 
 #include <asm/pgalloc.h>
 #include <asm/sections.h>
+#include <asm/mmu_context.h>
 #include <as-layout.h>
 #include <os.h>
 #include <skas.h>
diff --git a/arch/um/kernel/skas/process.c b/arch/um/kernel/skas/process.c
index f2ac134c9752..99a5cbb36083 100644
--- a/arch/um/kernel/skas/process.c
+++ b/arch/um/kernel/skas/process.c
@@ -12,17 +12,14 @@
 #include <kern.h>
 #include <os.h>
 #include <skas.h>
+#include <kern_util.h>
 
 extern void start_kernel(void);
 
 static int __init start_kernel_proc(void *unused)
 {
-	int pid;
-
 	block_signals_trace();
-	pid = os_getpid();
 
-	cpu_tasks[0].pid = pid;
 	cpu_tasks[0].task = current;
 
 	start_kernel();
diff --git a/arch/um/kernel/time.c b/arch/um/kernel/time.c
index 3e270da6b6f6..a8bfe8be1526 100644
--- a/arch/um/kernel/time.c
+++ b/arch/um/kernel/time.c
@@ -19,6 +19,7 @@
 #include <asm/param.h>
 #include <kern_util.h>
 #include <os.h>
+#include <linux/delay.h>
 #include <linux/time-internal.h>
 #include <linux/um_timetravel.h>
 #include <shared/init.h>
@@ -319,7 +320,7 @@ void time_travel_add_event_rel(struct time_travel_event *e,
 	time_travel_add_event(e, time_travel_time + delay_ns);
 }
 
-void time_travel_periodic_timer(struct time_travel_event *e)
+static 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);
@@ -812,7 +813,7 @@ unsigned long calibrate_delay_is_known(void)
 	return 0;
 }
 
-int setup_time_travel(char *str)
+static int setup_time_travel(char *str)
 {
 	if (strcmp(str, "=inf-cpu") == 0) {
 		time_travel_mode = TT_MODE_INFCPU;
@@ -862,7 +863,7 @@ __uml_help(setup_time_travel,
 "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)
+static int setup_time_travel_start(char *str)
 {
 	int err;
 
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 7d050ab0f78a..8784f03fa4a6 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -8,6 +8,7 @@
 #include <linux/sched/signal.h>
 
 #include <asm/tlbflush.h>
+#include <asm/mmu_context.h>
 #include <as-layout.h>
 #include <mem_user.h>
 #include <os.h>
@@ -576,12 +577,6 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
 }
 EXPORT_SYMBOL(flush_tlb_range);
 
-void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
-			unsigned long end)
-{
-	fix_range(mm, start, end, 0);
-}
-
 void flush_tlb_mm(struct mm_struct *mm)
 {
 	struct vm_area_struct *vma;
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 7a9820797eae..e95f805e5004 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -23,6 +23,7 @@
 #include <asm/cpufeature.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
+#include <asm/text-patching.h>
 #include <as-layout.h>
 #include <arch.h>
 #include <init.h>
diff --git a/arch/um/kernel/um_arch.h b/arch/um/kernel/um_arch.h
index 1e07fb7ee35e..46e731ab9dfc 100644
--- a/arch/um/kernel/um_arch.h
+++ b/arch/um/kernel/um_arch.h
@@ -11,4 +11,6 @@ extern void __init uml_dtb_init(void);
 static inline void uml_dtb_init(void) { }
 #endif
 
+extern int __init read_initrd(void);
+
 #endif
diff --git a/arch/um/os-Linux/drivers/ethertap_kern.c b/arch/um/os-Linux/drivers/ethertap_kern.c
index 3182e759d8de..5e5ee40680ce 100644
--- a/arch/um/os-Linux/drivers/ethertap_kern.c
+++ b/arch/um/os-Linux/drivers/ethertap_kern.c
@@ -63,7 +63,7 @@ const struct net_kern_info ethertap_kern_info = {
 	.write 			= etap_write,
 };
 
-int ethertap_setup(char *str, char **mac_out, void *data)
+static int ethertap_setup(char *str, char **mac_out, void *data)
 {
 	struct ethertap_init *init = data;
 
diff --git a/arch/um/os-Linux/drivers/tuntap_kern.c b/arch/um/os-Linux/drivers/tuntap_kern.c
index adcb6717be6f..ff022d9cf0dd 100644
--- a/arch/um/os-Linux/drivers/tuntap_kern.c
+++ b/arch/um/os-Linux/drivers/tuntap_kern.c
@@ -53,7 +53,7 @@ const struct net_kern_info tuntap_kern_info = {
 	.write 			= tuntap_write,
 };
 
-int tuntap_setup(char *str, char **mac_out, void *data)
+static int tuntap_setup(char *str, char **mac_out, void *data)
 {
 	struct tuntap_init *init = data;
 
diff --git a/arch/um/os-Linux/elf_aux.c b/arch/um/os-Linux/elf_aux.c
index 344ac403fb5d..0a0f91cf4d6d 100644
--- a/arch/um/os-Linux/elf_aux.c
+++ b/arch/um/os-Linux/elf_aux.c
@@ -13,6 +13,7 @@
 #include <init.h>
 #include <elf_user.h>
 #include <mem_user.h>
+#include "internal.h"
 
 typedef Elf32_auxv_t elf_auxv_t;
 
diff --git a/arch/um/os-Linux/internal.h b/arch/um/os-Linux/internal.h
new file mode 100644
index 000000000000..317fca190c2b
--- /dev/null
+++ b/arch/um/os-Linux/internal.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __UM_OS_LINUX_INTERNAL_H
+#define __UM_OS_LINUX_INTERNAL_H
+
+/*
+ * elf_aux.c
+ */
+void scan_elf_aux(char **envp);
+
+/*
+ * mem.c
+ */
+void check_tmpexec(void);
+
+/*
+ * skas/process.c
+ */
+void wait_stub_done(int pid);
+
+#endif /* __UM_OS_LINUX_INTERNAL_H */
diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
index c8a42ecbd7a2..f98ff79cdbf7 100644
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -16,6 +16,7 @@
 #include <kern_util.h>
 #include <os.h>
 #include <um_malloc.h>
+#include "internal.h"
 
 #define PGD_BOUND (4 * 1024 * 1024)
 #define STACKSIZE (8 * 1024 * 1024)
@@ -102,8 +103,6 @@ static void setup_env_path(void)
 	}
 }
 
-extern void scan_elf_aux( char **envp);
-
 int __init main(int argc, char **argv, char **envp)
 {
 	char **new_argv;
@@ -184,6 +183,11 @@ int __init main(int argc, char **argv, char **envp)
 
 extern void *__real_malloc(int);
 
+/* workaround for -Wmissing-prototypes warnings */
+void *__wrap_malloc(int size);
+void *__wrap_calloc(int n, int size);
+void __wrap_free(void *ptr);
+
 void *__wrap_malloc(int size)
 {
 	void *ret;
diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 8530b2e08604..cf44d386f23c 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -15,7 +15,9 @@
 #include <sys/vfs.h>
 #include <linux/magic.h>
 #include <init.h>
+#include <kern_util.h>
 #include <os.h>
+#include "internal.h"
 
 /*
  * kasan_map_memory - maps memory from @start with a size of @len.
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 24a403a70a02..787cfb9a0308 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -72,7 +72,7 @@ static int signals_blocked;
 static unsigned int signals_pending;
 static unsigned int signals_active = 0;
 
-void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
+static void sig_handler(int sig, struct siginfo *si, mcontext_t *mc)
 {
 	int enabled = signals_enabled;
 
@@ -108,7 +108,7 @@ static void timer_real_alarm_handler(mcontext_t *mc)
 	timer_handler(SIGALRM, NULL, &regs);
 }
 
-void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
+static void timer_alarm_handler(int sig, struct siginfo *unused_si, mcontext_t *mc)
 {
 	int enabled;
 
diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index 953fb10f3f93..1f9c1bffc3a6 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -17,11 +17,10 @@
 #include <skas.h>
 #include <sysdep/ptrace.h>
 #include <sysdep/stub.h>
+#include "../internal.h"
 
 extern char batch_syscall_stub[], __syscall_stub_start[];
 
-extern void wait_stub_done(int pid);
-
 static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
 					      unsigned long *stack)
 {
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 1f5c3f2523d1..41a288dcfc34 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -23,6 +23,7 @@
 #include <skas.h>
 #include <sysdep/stub.h>
 #include <linux/threads.h>
+#include "../internal.h"
 
 int is_skas_winch(int pid, int fd, void *data)
 {
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 8b0e98ab842c..89ad9f4f865c 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -20,10 +20,12 @@
 #include <asm/unistd.h>
 #include <init.h>
 #include <os.h>
+#include <kern_util.h>
 #include <mem_user.h>
 #include <ptrace_user.h>
 #include <registers.h>
 #include <skas.h>
+#include "internal.h"
 
 static void ptrace_child(void)
 {
@@ -221,8 +223,6 @@ static void __init check_ptrace(void)
 	check_sysemu();
 }
 
-extern void check_tmpexec(void);
-
 static void __init check_coredump_limit(void)
 {
 	struct rlimit lim;
diff --git a/arch/x86/um/asm/ptrace.h b/arch/x86/um/asm/ptrace.h
index 83822fd42204..2fef3da55533 100644
--- a/arch/x86/um/asm/ptrace.h
+++ b/arch/x86/um/asm/ptrace.h
@@ -54,6 +54,8 @@ extern int ptrace_get_thread_area(struct task_struct *child, int idx,
 extern int ptrace_set_thread_area(struct task_struct *child, int idx,
                                   struct user_desc __user *user_desc);
 
+extern int arch_switch_tls(struct task_struct *to);
+
 #else
 
 #define PT_REGS_R8(r) UPT_R8(&(r)->regs)
@@ -83,5 +85,9 @@ extern long arch_prctl(struct task_struct *task, int option,
 		       unsigned long __user *addr);
 
 #endif
+
 #define user_stack_pointer(regs) PT_REGS_SP(regs)
+
+extern void arch_switch_to(struct task_struct *to);
+
 #endif /* __UM_X86_PTRACE_H */
diff --git a/arch/x86/um/bugs_32.c b/arch/x86/um/bugs_32.c
index 33daff4dade4..d29929efcc07 100644
--- a/arch/x86/um/bugs_32.c
+++ b/arch/x86/um/bugs_32.c
@@ -3,6 +3,7 @@
  * Licensed under the GPL
  */
 
+#include <arch.h>
 #include <signal.h>
 #include <kern_util.h>
 #include <longjmp.h>
diff --git a/arch/x86/um/bugs_64.c b/arch/x86/um/bugs_64.c
index 8cc8256c698d..b01295e8a676 100644
--- a/arch/x86/um/bugs_64.c
+++ b/arch/x86/um/bugs_64.c
@@ -4,6 +4,7 @@
  * Licensed under the GPL
  */
 
+#include <arch.h>
 #include <sysdep/ptrace.h>
 
 void arch_check_bugs(void)
diff --git a/arch/x86/um/elfcore.c b/arch/x86/um/elfcore.c
index 650cdbbdaf45..ef50662fc40d 100644
--- a/arch/x86/um/elfcore.c
+++ b/arch/x86/um/elfcore.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/elf.h>
+#include <linux/elfcore.h>
 #include <linux/coredump.h>
 #include <linux/fs.h>
 #include <linux/mm.h>
diff --git a/arch/x86/um/fault.c b/arch/x86/um/fault.c
index 84ac7f7b0257..0dde4d613a87 100644
--- a/arch/x86/um/fault.c
+++ b/arch/x86/um/fault.c
@@ -3,6 +3,7 @@
  * Licensed under the GPL
  */
 
+#include <arch.h>
 #include <sysdep/ptrace.h>
 
 /* These two are from asm-um/uaccess.h and linux/module.h, check them. */
diff --git a/arch/x86/um/os-Linux/mcontext.c b/arch/x86/um/os-Linux/mcontext.c
index 49c3744cac37..e80ab7d28117 100644
--- a/arch/x86/um/os-Linux/mcontext.c
+++ b/arch/x86/um/os-Linux/mcontext.c
@@ -3,6 +3,7 @@
 #define __FRAME_OFFSETS
 #include <asm/ptrace.h>
 #include <sysdep/ptrace.h>
+#include <sysdep/mcontext.h>
 
 void get_regs_from_mc(struct uml_pt_regs *regs, mcontext_t *mc)
 {
diff --git a/arch/x86/um/os-Linux/registers.c b/arch/x86/um/os-Linux/registers.c
index df8f4b4bf98b..f3638dd09cec 100644
--- a/arch/x86/um/os-Linux/registers.c
+++ b/arch/x86/um/os-Linux/registers.c
@@ -17,7 +17,7 @@
 #include <linux/elf.h>
 #include <registers.h>
 
-int have_xstate_support;
+static int have_xstate_support;
 
 int save_i387_registers(int pid, unsigned long *fp_regs)
 {
diff --git a/arch/x86/um/os-Linux/tls.c b/arch/x86/um/os-Linux/tls.c
index 3e1b1bf6acbc..eed9efe29ade 100644
--- a/arch/x86/um/os-Linux/tls.c
+++ b/arch/x86/um/os-Linux/tls.c
@@ -6,6 +6,7 @@
 #include <sys/syscall.h>
 #include <unistd.h>
 
+#include <os.h>
 #include <sysdep/tls.h>
 
 #ifndef PTRACE_GET_THREAD_AREA
diff --git a/arch/x86/um/ptrace_32.c b/arch/x86/um/ptrace_32.c
index 7f1abde2c84b..b0a71c6cdc6e 100644
--- a/arch/x86/um/ptrace_32.c
+++ b/arch/x86/um/ptrace_32.c
@@ -10,8 +10,6 @@
 #include <registers.h>
 #include <skas.h>
 
-extern int arch_switch_tls(struct task_struct *to);
-
 void arch_switch_to(struct task_struct *to)
 {
 	int err = arch_switch_tls(to);
diff --git a/arch/x86/um/shared/sysdep/archsetjmp.h b/arch/x86/um/shared/sysdep/archsetjmp.h
index 166cedbab926..8c81d1a604a9 100644
--- a/arch/x86/um/shared/sysdep/archsetjmp.h
+++ b/arch/x86/um/shared/sysdep/archsetjmp.h
@@ -1,6 +1,13 @@
 /* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __X86_UM_SYSDEP_ARCHSETJMP_H
+#define __X86_UM_SYSDEP_ARCHSETJMP_H
+
 #ifdef __i386__
 #include "archsetjmp_32.h"
 #else
 #include "archsetjmp_64.h"
 #endif
+
+unsigned long get_thread_reg(int reg, jmp_buf *buf);
+
+#endif /* __X86_UM_SYSDEP_ARCHSETJMP_H */
diff --git a/arch/x86/um/shared/sysdep/kernel-offsets.h b/arch/x86/um/shared/sysdep/kernel-offsets.h
index a004bffb7b8d..48de3a71f845 100644
--- a/arch/x86/um/shared/sysdep/kernel-offsets.h
+++ b/arch/x86/um/shared/sysdep/kernel-offsets.h
@@ -6,6 +6,9 @@
 #include <linux/kbuild.h>
 #include <asm/mman.h>
 
+/* workaround for a warning with -Wmissing-prototypes */
+void foo(void);
+
 void foo(void)
 {
 #include <common-offsets.h>
diff --git a/arch/x86/um/signal.c b/arch/x86/um/signal.c
index 263e1d08f216..2cc8c2309022 100644
--- a/arch/x86/um/signal.c
+++ b/arch/x86/um/signal.c
@@ -8,6 +8,7 @@
 #include <linux/personality.h>
 #include <linux/ptrace.h>
 #include <linux/kernel.h>
+#include <linux/syscalls.h>
 #include <asm/unistd.h>
 #include <linux/uaccess.h>
 #include <asm/ucontext.h>
@@ -155,7 +156,7 @@ static int copy_sc_from_user(struct pt_regs *regs,
 			     struct sigcontext __user *from)
 {
 	struct sigcontext sc;
-	int err, pid;
+	int err;
 
 	/* Always make any pending restarted system calls return -EINTR */
 	current->restart_block.fn = do_no_restart_syscall;
@@ -201,10 +202,10 @@ static int copy_sc_from_user(struct pt_regs *regs,
 
 #undef GETREG
 
-	pid = userspace_pid[current_thread_info()->cpu];
 #ifdef CONFIG_X86_32
 	if (have_fpx_regs) {
 		struct user_fxsr_struct fpx;
+		int pid = userspace_pid[current_thread_info()->cpu];
 
 		err = copy_from_user(&fpx,
 			&((struct _fpstate __user *)sc.fpstate)->_fxsr_env[0],
@@ -240,7 +241,7 @@ static int copy_sc_to_user(struct sigcontext __user *to,
 {
 	struct sigcontext sc;
 	struct faultinfo * fi = &current->thread.arch.faultinfo;
-	int err, pid;
+	int err;
 	memset(&sc, 0, sizeof(struct sigcontext));
 
 #define PUTREG(regno, regname) sc.regname = regs->regs.gp[HOST_##regno]
@@ -288,10 +289,9 @@ static int copy_sc_to_user(struct sigcontext __user *to,
 	if (err)
 		return 1;
 
-	pid = userspace_pid[current_thread_info()->cpu];
-
 #ifdef CONFIG_X86_32
 	if (have_fpx_regs) {
+		int pid = userspace_pid[current_thread_info()->cpu];
 		struct user_fxsr_struct fpx;
 
 		err = save_fpx_registers(pid, (unsigned long *) &fpx);
@@ -450,7 +450,7 @@ int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
 	return 0;
 }
 
-long sys_sigreturn(void)
+SYSCALL_DEFINE0(sigreturn)
 {
 	unsigned long sp = PT_REGS_SP(&current->thread.regs);
 	struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
@@ -557,7 +557,7 @@ int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig,
 }
 #endif
 
-long sys_rt_sigreturn(void)
+SYSCALL_DEFINE0(rt_sigreturn)
 {
 	unsigned long sp = PT_REGS_SP(&current->thread.regs);
 	struct rt_sigframe __user *frame =
diff --git a/arch/x86/um/tls_32.c b/arch/x86/um/tls_32.c
index 66162eafd8e8..d301deee041f 100644
--- a/arch/x86/um/tls_32.c
+++ b/arch/x86/um/tls_32.c
@@ -20,7 +20,7 @@
 static int host_supports_tls = -1;
 int host_gdt_entry_tls_min;
 
-int do_set_thread_area(struct user_desc *info)
+static int do_set_thread_area(struct user_desc *info)
 {
 	int ret;
 	u32 cpu;
@@ -36,22 +36,6 @@ int do_set_thread_area(struct user_desc *info)
 	return ret;
 }
 
-int do_get_thread_area(struct user_desc *info)
-{
-	int ret;
-	u32 cpu;
-
-	cpu = get_cpu();
-	ret = os_get_thread_area(info, userspace_pid[cpu]);
-	put_cpu();
-
-	if (ret)
-		printk(KERN_ERR "PTRACE_GET_THREAD_AREA failed, err = %d, "
-		       "index = %d\n", ret, info->entry_number);
-
-	return ret;
-}
-
 /*
  * sys_get_thread_area: get a yet unused TLS descriptor index.
  * XXX: Consider leaving one free slot for glibc usage at first place. This must
@@ -231,7 +215,6 @@ out:
 	return ret;
 }
 
-/* XXX: use do_get_thread_area to read the host value? I'm not at all sure! */
 static int get_tls_entry(struct task_struct *task, struct user_desc *info,
 			 int idx)
 {
diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index e54a9814ccf1..1c77d9946199 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -14,6 +14,9 @@
 	COMMENT(#val " / sizeof(unsigned long)");	\
 	DEFINE(sym, val / sizeof(unsigned long))
 
+/* workaround for a warning with -Wmissing-prototypes */
+void foo(void);
+
 void foo(void)
 {
 #ifdef __i386__
diff --git a/arch/x86/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c
index ff0f3b4b6c45..cbae2584124f 100644
--- a/arch/x86/um/vdso/um_vdso.c
+++ b/arch/x86/um/vdso/um_vdso.c
@@ -13,6 +13,12 @@
 #include <linux/getcpu.h>
 #include <asm/unistd.h>
 
+/* workaround for -Wmissing-prototypes warnings */
+int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts);
+int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz);
+__kernel_old_time_t __vdso_time(__kernel_old_time_t *t);
+long __vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused);
+
 int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts)
 {
 	long ret;
@@ -54,7 +60,7 @@ __kernel_old_time_t __vdso_time(__kernel_old_time_t *t)
 __kernel_old_time_t time(__kernel_old_time_t *t) __attribute__((weak, alias("__vdso_time")));
 
 long
-__vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
+__vdso_getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *unused)
 {
 	/*
 	 * UML does not support SMP, we can cheat here. :)
@@ -68,5 +74,5 @@ __vdso_getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *unused)
 	return 0;
 }
 
-long getcpu(unsigned *cpu, unsigned *node, struct getcpu_cache *tcache)
+long getcpu(unsigned int *cpu, unsigned int *node, struct getcpu_cache *tcache)
 	__attribute__((weak, alias("__vdso_getcpu")));