Merge branch 'for-linus-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml

Pull UML updates from Richard Weinberger:

 - remove hppfs ("HonePot ProcFS")

 - initial support for musl libc

 - uaccess cleanup

 - random cleanups and bug fixes all over the place

* 'for-linus-4.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/uml: (21 commits)
  um: Don't pollute kernel namespace with uapi
  um: Include sys/types.h for makedev(), major(), minor()
  um: Do not use stdin and stdout identifiers for struct members
  um: Do not use __ptr_t type for stack_t's .ss pointer
  um: Fix mconsole dependency
  um: Handle tracehook_report_syscall_entry() result
  um: Remove copy&paste code from init.h
  um: Stop abusing __KERNEL__
  um: Catch unprotected user memory access
  um: Fix warning in setup_signal_stack_si()
  um: Rework uaccess code
  um: Add uaccess.h to ldt.c
  um: Add uaccess.h to syscalls_64.c
  um: Add asm/elf.h to vma.c
  um: Cleanup mem_32/64.c headers
  um: Remove hppfs
  um: Move syscall() declaration into os.h
  um: kernel: ksyms: Export symbol syscall() for fixing modpost issue
  um/os-Linux: Use char[] for syscall_stub declarations
  um: Use char[] for linker script address declarations
  ...

28 files changed, 130 insertions, 282 deletions

diff --git a/arch/um/Kconfig.um b/arch/um/Kconfig.um
index 6e67847f5272..28a9885e3a37 100644
--- a/arch/um/Kconfig.um
+++ b/arch/um/Kconfig.um
@@ -44,23 +44,9 @@ config HOSTFS
           If you'd like to be able to work with files stored on the host,
           say Y or M here; otherwise say N.
 
-config HPPFS
-	tristate "HoneyPot ProcFS"
-	depends on PROC_FS
-	help
-	  hppfs (HoneyPot ProcFS) is a filesystem which allows UML /proc
-	  entries to be overridden, removed, or fabricated from the host.
-	  Its purpose is to allow a UML to appear to be a physical machine
-	  by removing or changing anything in /proc which gives away the
-	  identity of a UML.
-
-	  See <http://user-mode-linux.sf.net/old/hppfs.html> for more information.
-
-	  You only need this if you are setting up a UML honeypot.  Otherwise,
-	  it is safe to say 'N' here.
-
 config MCONSOLE
 	bool "Management console"
+	depends on PROC_FS
 	default y
 	help
           The user mode linux management console is a low-level interface to
diff --git a/arch/um/Makefile b/arch/um/Makefile
index 17d4460b1af3..098ab3333e7c 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -68,9 +68,10 @@ KBUILD_CFLAGS += $(CFLAGS) $(CFLAGS-y) -D__arch_um__ \
 
 KBUILD_AFLAGS += $(ARCH_INCLUDE)
 
-USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -D__KERNEL__,,\
-	$(patsubst -I%,,$(KBUILD_CFLAGS)))) $(ARCH_INCLUDE) $(MODE_INCLUDE) \
-	$(filter -I%,$(CFLAGS)) -D_FILE_OFFSET_BITS=64 -idirafter include
+USER_CFLAGS = $(patsubst $(KERNEL_DEFINES),,$(patsubst -I%,,$(KBUILD_CFLAGS))) \
+		$(ARCH_INCLUDE) $(MODE_INCLUDE) $(filter -I%,$(CFLAGS)) \
+		-D_FILE_OFFSET_BITS=64 -idirafter include \
+		-D__KERNEL__ -D__UM_HOST__
 
 #This will adjust *FLAGS accordingly to the platform.
 include $(ARCH_DIR)/Makefile-os-$(OS)
diff --git a/arch/um/drivers/harddog_user.c b/arch/um/drivers/harddog_user.c
index f99b32a4dbff..3aa8b0d52a48 100644
--- a/arch/um/drivers/harddog_user.c
+++ b/arch/um/drivers/harddog_user.c
@@ -9,8 +9,8 @@
 #include <os.h>
 
 struct dog_data {
-	int stdin;
-	int stdout;
+	int stdin_fd;
+	int stdout_fd;
 	int close_me[2];
 };
 
@@ -18,11 +18,11 @@ static void pre_exec(void *d)
 {
 	struct dog_data *data = d;
 
-	dup2(data->stdin, 0);
-	dup2(data->stdout, 1);
-	dup2(data->stdout, 2);
-	close(data->stdin);
-	close(data->stdout);
+	dup2(data->stdin_fd, 0);
+	dup2(data->stdout_fd, 1);
+	dup2(data->stdout_fd, 2);
+	close(data->stdin_fd);
+	close(data->stdout_fd);
 	close(data->close_me[0]);
 	close(data->close_me[1]);
 }
@@ -49,8 +49,8 @@ int start_watchdog(int *in_fd_ret, int *out_fd_ret, char *sock)
 		goto out_close_in;
 	}
 
-	data.stdin = out_fds[0];
-	data.stdout = in_fds[1];
+	data.stdin_fd = out_fds[0];
+	data.stdout_fd = in_fds[1];
 	data.close_me[0] = out_fds[1];
 	data.close_me[1] = in_fds[0];
 
diff --git a/arch/um/drivers/mconsole.h b/arch/um/drivers/mconsole.h
index 8b22535c62ce..44af7379ea19 100644
--- a/arch/um/drivers/mconsole.h
+++ b/arch/um/drivers/mconsole.h
@@ -7,7 +7,7 @@
 #ifndef __MCONSOLE_H__
 #define __MCONSOLE_H__
 
-#ifndef __KERNEL__
+#ifdef __UM_HOST__
 #include <stdint.h>
 #define u32 uint32_t
 #endif
diff --git a/arch/um/drivers/net_user.c b/arch/um/drivers/net_user.c
index cd14157b556d..e697a4136707 100644
--- a/arch/um/drivers/net_user.c
+++ b/arch/um/drivers/net_user.c
@@ -166,7 +166,7 @@ int net_sendto(int fd, void *buf, int len, void *to, int sock_len)
 
 struct change_pre_exec_data {
 	int close_me;
-	int stdout;
+	int stdout_fd;
 };
 
 static void change_pre_exec(void *arg)
@@ -174,7 +174,7 @@ static void change_pre_exec(void *arg)
 	struct change_pre_exec_data *data = arg;
 
 	close(data->close_me);
-	dup2(data->stdout, 1);
+	dup2(data->stdout_fd, 1);
 }
 
 static int change_tramp(char **argv, char *output, int output_len)
@@ -189,7 +189,7 @@ static int change_tramp(char **argv, char *output, int output_len)
 		return err;
 	}
 	pe_data.close_me = fds[0];
-	pe_data.stdout = fds[1];
+	pe_data.stdout_fd = fds[1];
 	pid = run_helper(change_pre_exec, &pe_data, argv);
 
 	if (pid > 0)	/* Avoid hang as we won't get data in failure case. */
diff --git a/arch/um/drivers/slip_user.c b/arch/um/drivers/slip_user.c
index 55c290d925f3..0d6b66c64a81 100644
--- a/arch/um/drivers/slip_user.c
+++ b/arch/um/drivers/slip_user.c
@@ -55,8 +55,8 @@ static int set_up_tty(int fd)
 }
 
 struct slip_pre_exec_data {
-	int stdin;
-	int stdout;
+	int stdin_fd;
+	int stdout_fd;
 	int close_me;
 };
 
@@ -64,9 +64,9 @@ static void slip_pre_exec(void *arg)
 {
 	struct slip_pre_exec_data *data = arg;
 
-	if (data->stdin >= 0)
-		dup2(data->stdin, 0);
-	dup2(data->stdout, 1);
+	if (data->stdin_fd >= 0)
+		dup2(data->stdin_fd, 0);
+	dup2(data->stdout_fd, 1);
 	if (data->close_me >= 0)
 		close(data->close_me);
 }
@@ -85,8 +85,8 @@ static int slip_tramp(char **argv, int fd)
 	}
 
 	err = 0;
-	pe_data.stdin = fd;
-	pe_data.stdout = fds[1];
+	pe_data.stdin_fd = fd;
+	pe_data.stdout_fd = fds[1];
 	pe_data.close_me = fds[0];
 	err = run_helper(slip_pre_exec, &pe_data, argv);
 	if (err < 0)
diff --git a/arch/um/drivers/slirp_user.c b/arch/um/drivers/slirp_user.c
index c999d187abb9..98b6a41a254e 100644
--- a/arch/um/drivers/slirp_user.c
+++ b/arch/um/drivers/slirp_user.c
@@ -20,18 +20,18 @@ static int slirp_user_init(void *data, void *dev)
 }
 
 struct slirp_pre_exec_data {
-	int stdin;
-	int stdout;
+	int stdin_fd;
+	int stdout_fd;
 };
 
 static void slirp_pre_exec(void *arg)
 {
 	struct slirp_pre_exec_data *data = arg;
 
-	if (data->stdin != -1)
-		dup2(data->stdin, 0);
-	if (data->stdout != -1)
-		dup2(data->stdout, 1);
+	if (data->stdin_fd != -1)
+		dup2(data->stdin_fd, 0);
+	if (data->stdout_fd != -1)
+		dup2(data->stdout_fd, 1);
 }
 
 static int slirp_tramp(char **argv, int fd)
@@ -39,8 +39,8 @@ static int slirp_tramp(char **argv, int fd)
 	struct slirp_pre_exec_data pe_data;
 	int pid;
 
-	pe_data.stdin = fd;
-	pe_data.stdout = fd;
+	pe_data.stdin_fd = fd;
+	pe_data.stdout_fd = fd;
 	pid = run_helper(slirp_pre_exec, &pe_data, argv);
 
 	return pid;
diff --git a/arch/um/include/asm/Kbuild b/arch/um/include/asm/Kbuild
index b7df3ae9be51..3d63ff6f583f 100644
--- a/arch/um/include/asm/Kbuild
+++ b/arch/um/include/asm/Kbuild
@@ -21,7 +21,6 @@ generic-y += param.h
 generic-y += pci.h
 generic-y += percpu.h
 generic-y += preempt.h
-generic-y += sections.h
 generic-y += switch_to.h
 generic-y += topology.h
 generic-y += trace_clock.h
diff --git a/arch/um/include/asm/ptrace-generic.h b/arch/um/include/asm/ptrace-generic.h
index cb9b3c47ca8e..2966adbbdf6c 100644
--- a/arch/um/include/asm/ptrace-generic.h
+++ b/arch/um/include/asm/ptrace-generic.h
@@ -8,7 +8,6 @@
 
 #ifndef __ASSEMBLY__
 
-#include <asm/ptrace-abi.h>
 #include <sysdep/ptrace.h>
 
 struct pt_regs {
@@ -37,7 +36,7 @@ extern int putreg(struct task_struct *child, int regno, unsigned long value);
 
 extern int arch_copy_tls(struct task_struct *new);
 extern void clear_flushed_tls(struct task_struct *task);
-extern void syscall_trace_enter(struct pt_regs *regs);
+extern int syscall_trace_enter(struct pt_regs *regs);
 extern void syscall_trace_leave(struct pt_regs *regs);
 
 #endif
diff --git a/arch/um/include/asm/sections.h b/arch/um/include/asm/sections.h
new file mode 100644
index 000000000000..cafcf684d947
--- /dev/null
+++ b/arch/um/include/asm/sections.h
@@ -0,0 +1,9 @@
+#ifndef __UM_SECTIONS_H
+#define __UM_SECTIONS_H
+
+#include <asm-generic/sections.h>
+
+extern char __binary_start[];
+extern char __syscall_stub_start[], __syscall_stub_end[];
+
+#endif
diff --git a/arch/um/include/asm/thread_info.h b/arch/um/include/asm/thread_info.h
index b30c85b141d9..53968aaf76f9 100644
--- a/arch/um/include/asm/thread_info.h
+++ b/arch/um/include/asm/thread_info.h
@@ -10,7 +10,7 @@
 
 #include <asm/types.h>
 #include <asm/page.h>
-#include <asm/uaccess.h>
+#include <asm/segment.h>
 
 struct thread_info {
 	struct task_struct	*task;		/* main task structure */
diff --git a/arch/um/include/asm/uaccess.h b/arch/um/include/asm/uaccess.h
index 3f22fbf7ca1d..3705620ca298 100644
--- a/arch/um/include/asm/uaccess.h
+++ b/arch/um/include/asm/uaccess.h
@@ -1,178 +1,52 @@
 /* 
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ * Copyright (C) 2015 Richard Weinberger (richard@nod.at)
  * Licensed under the GPL
  */
 
 #ifndef __UM_UACCESS_H
 #define __UM_UACCESS_H
 
-/* thread_info has a mm_segment_t in it, so put the definition up here */
-typedef struct {
-	unsigned long seg;
-} mm_segment_t;
-
-#include <linux/thread_info.h>
-#include <linux/errno.h>
-#include <asm/processor.h>
+#include <asm/thread_info.h>
 #include <asm/elf.h>
 
-#define VERIFY_READ 0
-#define VERIFY_WRITE 1
-
-/*
- * The fs value determines whether argument validity checking should be
- * performed or not.  If get_fs() == USER_DS, checking is performed, with
- * get_fs() == KERNEL_DS, checking is bypassed.
- *
- * For historical reasons, these macros are grossly misnamed.
- */
-
-#define MAKE_MM_SEG(s)	((mm_segment_t) { (s) })
-
-#define KERNEL_DS	MAKE_MM_SEG(0xFFFFFFFF)
-#define USER_DS		MAKE_MM_SEG(TASK_SIZE)
-
-#define get_ds()	(KERNEL_DS)
-#define get_fs()	(current_thread_info()->addr_limit)
-#define set_fs(x)	(current_thread_info()->addr_limit = (x))
-
-#define segment_eq(a, b) ((a).seg == (b).seg)
-
 #define __under_task_size(addr, size) \
 	(((unsigned long) (addr) < TASK_SIZE) && \
 	 (((unsigned long) (addr) + (size)) < TASK_SIZE))
 
-#define __access_ok_vsyscall(type, addr, size) \
-	 ((type == VERIFY_READ) && \
-	  ((unsigned long) (addr) >= FIXADDR_USER_START) && \
+#define __access_ok_vsyscall(addr, size) \
+	  (((unsigned long) (addr) >= FIXADDR_USER_START) && \
 	  ((unsigned long) (addr) + (size) <= FIXADDR_USER_END) && \
 	  ((unsigned long) (addr) + (size) >= (unsigned long)(addr)))
 
 #define __addr_range_nowrap(addr, size) \
 	((unsigned long) (addr) <= ((unsigned long) (addr) + (size)))
 
-#define access_ok(type, addr, size) \
-	(__addr_range_nowrap(addr, size) && \
-	 (__under_task_size(addr, size) || \
-	  __access_ok_vsyscall(type, addr, size) || \
-	  segment_eq(get_fs(), KERNEL_DS)))
-
-extern int copy_from_user(void *to, const void __user *from, int n);
-extern int copy_to_user(void __user *to, const void *from, int n);
-
-/*
- * strncpy_from_user: - Copy a NUL terminated string from userspace.
- * @dst:   Destination address, in kernel space.  This buffer must be at
- *         least @count bytes long.
- * @src:   Source address, in user space.
- * @count: Maximum number of bytes to copy, including the trailing NUL.
- *
- * Copies a NUL-terminated string from userspace to kernel space.
- *
- * On success, returns the length of the string (not including the trailing
- * NUL).
- *
- * If access to userspace fails, returns -EFAULT (some data may have been
- * copied).
- *
- * If @count is smaller than the length of the string, copies @count bytes
- * and returns @count.
- */
-
-extern int strncpy_from_user(char *dst, const char __user *src, int count);
-
-/*
- * __clear_user: - Zero a block of memory in user space, with less checking.
- * @to:   Destination address, in user space.
- * @n:    Number of bytes to zero.
- *
- * Zero a block of memory in user space.  Caller must check
- * the specified block with access_ok() before calling this function.
- *
- * Returns number of bytes that could not be cleared.
- * On success, this will be zero.
- */
-extern int __clear_user(void __user *mem, int len);
-
-/*
- * clear_user: - Zero a block of memory in user space.
- * @to:   Destination address, in user space.
- * @n:    Number of bytes to zero.
- *
- * Zero a block of memory in user space.
- *
- * Returns number of bytes that could not be cleared.
- * On success, this will be zero.
- */
-extern int clear_user(void __user *mem, int len);
-
-/*
- * strlen_user: - Get the size of a string in user space.
- * @str: The string to measure.
- * @n:   The maximum valid length
- *
- * Get the size of a NUL-terminated string in user space.
- *
- * Returns the size of the string INCLUDING the terminating NUL.
- * On exception, returns 0.
- * If the string is too long, returns a value greater than @n.
- */
-extern int strnlen_user(const void __user *str, int len);
-
-#define __copy_from_user(to, from, n) copy_from_user(to, from, n)
-
-#define __copy_to_user(to, from, n) copy_to_user(to, from, n)
-
+extern long __copy_from_user(void *to, const void __user *from, unsigned long n);
+extern long __copy_to_user(void __user *to, const void *from, unsigned long n);
+extern long __strncpy_from_user(char *dst, const char __user *src, long count);
+extern long __strnlen_user(const void __user *str, long len);
+extern unsigned long __clear_user(void __user *mem, unsigned long len);
+static inline int __access_ok(unsigned long addr, unsigned long size);
+
+/* Teach asm-generic/uaccess.h that we have C functions for these. */
+#define __access_ok __access_ok
+#define __clear_user __clear_user
+#define __copy_to_user __copy_to_user
+#define __copy_from_user __copy_from_user
+#define __strnlen_user __strnlen_user
+#define __strncpy_from_user __strncpy_from_user
 #define __copy_to_user_inatomic __copy_to_user
 #define __copy_from_user_inatomic __copy_from_user
 
-#define __get_user(x, ptr) \
-({ \
-	const __typeof__(*(ptr)) __user *__private_ptr = (ptr);	\
-	__typeof__(x) __private_val;			\
-	int __private_ret = -EFAULT;			\
-	(x) = (__typeof__(*(__private_ptr)))0;				\
-	if (__copy_from_user((__force void *)&__private_val, (__private_ptr),\
-			     sizeof(*(__private_ptr))) == 0) {		\
-		(x) = (__typeof__(*(__private_ptr))) __private_val;	\
-		__private_ret = 0;					\
-	}								\
-	__private_ret;							\
-}) 
-
-#define get_user(x, ptr) \
-({ \
-        const __typeof__((*(ptr))) __user *private_ptr = (ptr); \
-        (access_ok(VERIFY_READ, private_ptr, sizeof(*private_ptr)) ? \
-	 __get_user(x, private_ptr) : ((x) = (__typeof__(*ptr))0, -EFAULT)); \
-})
-
-#define __put_user(x, ptr) \
-({ \
-        __typeof__(*(ptr)) __user *__private_ptr = ptr; \
-        __typeof__(*(__private_ptr)) __private_val; \
-        int __private_ret = -EFAULT; \
-        __private_val = (__typeof__(*(__private_ptr))) (x); \
-        if (__copy_to_user((__private_ptr), &__private_val, \
-			   sizeof(*(__private_ptr))) == 0) { \
-		__private_ret = 0; \
-	} \
-        __private_ret; \
-})
-
-#define put_user(x, ptr) \
-({ \
-        __typeof__(*(ptr)) __user *private_ptr = (ptr); \
-        (access_ok(VERIFY_WRITE, private_ptr, sizeof(*private_ptr)) ? \
-	 __put_user(x, private_ptr) : -EFAULT); \
-})
-
-#define strlen_user(str) strnlen_user(str, ~0U >> 1)
+#include <asm-generic/uaccess.h>
 
-struct exception_table_entry
+static inline int __access_ok(unsigned long addr, unsigned long size)
 {
-        unsigned long insn;
-	unsigned long fixup;
-};
+	return __addr_range_nowrap(addr, size) &&
+		(__under_task_size(addr, size) ||
+		__access_ok_vsyscall(addr, size) ||
+		segment_eq(get_fs(), KERNEL_DS));
+}
 
 #endif
diff --git a/arch/um/include/shared/init.h b/arch/um/include/shared/init.h
index b3906f860a87..233e2593eee0 100644
--- a/arch/um/include/shared/init.h
+++ b/arch/um/include/shared/init.h
@@ -40,28 +40,8 @@
 typedef int (*initcall_t)(void);
 typedef void (*exitcall_t)(void);
 
-#ifndef __KERNEL__
-#ifndef __section
-# define __section(S) __attribute__ ((__section__(#S)))
-#endif
-
-#if __GNUC__ == 3
-
-#if __GNUC_MINOR__ >= 3
-# define __used			__attribute__((__used__))
-#else
-# define __used			__attribute__((__unused__))
-#endif
-
-#else
-#if __GNUC__ == 4
-# define __used			__attribute__((__used__))
-#endif
-#endif
-
-#else
 #include <linux/compiler.h>
-#endif
+
 /* These are for everybody (although not all archs will actually
    discard it in modules) */
 #define __init		__section(.init.text)
@@ -131,7 +111,7 @@ extern struct uml_param __uml_setup_start, __uml_setup_end;
 #define __uml_postsetup_call	__used __section(.uml.postsetup.init)
 #define __uml_exit_call		__used __section(.uml.exitcall.exit)
 
-#ifndef __KERNEL__
+#ifdef __UM_HOST__
 
 #define __define_initcall(level,fn) \
 	static initcall_t __initcall_##fn __used \
diff --git a/arch/um/include/shared/os.h b/arch/um/include/shared/os.h
index d824528f6f62..ad3fa3ae6d34 100644
--- a/arch/um/include/shared/os.h
+++ b/arch/um/include/shared/os.h
@@ -301,4 +301,6 @@ extern int get_pty(void);
 /* sys-$ARCH/task_size.c */
 extern unsigned long os_get_top_address(void);
 
+long syscall(long number, ...);
+
 #endif
diff --git a/arch/um/include/shared/user.h b/arch/um/include/shared/user.h
index cef068563336..4cff19f6207a 100644
--- a/arch/um/include/shared/user.h
+++ b/arch/um/include/shared/user.h
@@ -17,7 +17,7 @@
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
 /* This is to get size_t */
-#ifdef __KERNEL__
+#ifndef __UM_HOST__
 #include <linux/types.h>
 #else
 #include <stddef.h>
diff --git a/arch/um/kernel/ksyms.c b/arch/um/kernel/ksyms.c
index 543c04756939..232b22307fdd 100644
--- a/arch/um/kernel/ksyms.c
+++ b/arch/um/kernel/ksyms.c
@@ -42,3 +42,5 @@ EXPORT_SYMBOL(os_makedev);
 EXPORT_SYMBOL(add_sigio_fd);
 EXPORT_SYMBOL(ignore_sigio_fd);
 EXPORT_SYMBOL(sigio_broken);
+
+EXPORT_SYMBOL(syscall);
diff --git a/arch/um/kernel/physmem.c b/arch/um/kernel/physmem.c
index 9034fc8056b4..4c9861b421fd 100644
--- a/arch/um/kernel/physmem.c
+++ b/arch/um/kernel/physmem.c
@@ -8,6 +8,7 @@
 #include <linux/mm.h>
 #include <linux/pfn.h>
 #include <asm/page.h>
+#include <asm/sections.h>
 #include <as-layout.h>
 #include <init.h>
 #include <kern.h>
@@ -55,8 +56,6 @@ void map_memory(unsigned long virt, unsigned long phys, unsigned long len,
 	}
 }
 
-extern int __syscall_stub_start;
-
 /**
  * setup_physmem() - Setup physical memory for UML
  * @start:	Start address of the physical kernel memory,
@@ -110,8 +109,8 @@ void __init setup_physmem(unsigned long start, unsigned long reserve_end,
 	 * Special kludge - This page will be mapped in to userspace processes
 	 * from physmem_fd, so it needs to be written out there.
 	 */
-	os_seek_file(physmem_fd, __pa(&__syscall_stub_start));
-	os_write_file(physmem_fd, &__syscall_stub_start, PAGE_SIZE);
+	os_seek_file(physmem_fd, __pa(__syscall_stub_start));
+	os_write_file(physmem_fd, __syscall_stub_start, PAGE_SIZE);
 	os_fsync_file(physmem_fd);
 
 	bootmap_size = init_bootmem(pfn, pfn + delta);
diff --git a/arch/um/kernel/ptrace.c b/arch/um/kernel/ptrace.c
index 174ee5017264..6a826cbb15c4 100644
--- a/arch/um/kernel/ptrace.c
+++ b/arch/um/kernel/ptrace.c
@@ -8,6 +8,7 @@
 #include <linux/sched.h>
 #include <linux/tracehook.h>
 #include <asm/uaccess.h>
+#include <asm/ptrace-abi.h>
 
 void user_enable_single_step(struct task_struct *child)
 {
@@ -131,7 +132,7 @@ static void send_sigtrap(struct task_struct *tsk, struct uml_pt_regs *regs,
  * XXX Check PT_DTRACE vs TIF_SINGLESTEP for singlestepping check and
  * PT_PTRACED vs TIF_SYSCALL_TRACE for syscall tracing check
  */
-void syscall_trace_enter(struct pt_regs *regs)
+int syscall_trace_enter(struct pt_regs *regs)
 {
 	audit_syscall_entry(UPT_SYSCALL_NR(&regs->regs),
 			    UPT_SYSCALL_ARG1(&regs->regs),
@@ -140,9 +141,9 @@ void syscall_trace_enter(struct pt_regs *regs)
 			    UPT_SYSCALL_ARG4(&regs->regs));
 
 	if (!test_thread_flag(TIF_SYSCALL_TRACE))
-		return;
+		return 0;
 
-	tracehook_report_syscall_entry(regs);
+	return tracehook_report_syscall_entry(regs);
 }
 
 void syscall_trace_leave(struct pt_regs *regs)
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 94abdcc1d6ad..fda1deba1757 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -8,12 +8,11 @@
 #include <linux/slab.h>
 #include <asm/pgalloc.h>
 #include <asm/pgtable.h>
+#include <asm/sections.h>
 #include <as-layout.h>
 #include <os.h>
 #include <skas.h>
 
-extern int __syscall_stub_start;
-
 static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
 			 unsigned long kernel)
 {
@@ -93,7 +92,7 @@ void uml_setup_stubs(struct mm_struct *mm)
 	int err, ret;
 
 	ret = init_stub_pte(mm, STUB_CODE,
-			    (unsigned long) &__syscall_stub_start);
+			    (unsigned long) __syscall_stub_start);
 	if (ret)
 		goto out;
 
@@ -101,7 +100,7 @@ void uml_setup_stubs(struct mm_struct *mm)
 	if (ret)
 		goto out;
 
-	mm->context.stub_pages[0] = virt_to_page(&__syscall_stub_start);
+	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 */
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index c0681e097432..d9ec0068b623 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -18,7 +18,10 @@ void handle_syscall(struct uml_pt_regs *r)
 	long result;
 	int syscall;
 
-	syscall_trace_enter(regs);
+	if (syscall_trace_enter(regs)) {
+		result = -ENOSYS;
+		goto out;
+	}
 
 	/*
 	 * This should go in the declaration of syscall, but when I do that,
@@ -34,6 +37,7 @@ void handle_syscall(struct uml_pt_regs *r)
 		result = -ENOSYS;
 	else result = EXECUTE_SYSCALL(syscall, regs);
 
+out:
 	PT_REGS_SET_SYSCALL_RETURN(regs, result);
 
 	syscall_trace_leave(regs);
diff --git a/arch/um/kernel/skas/uaccess.c b/arch/um/kernel/skas/uaccess.c
index 4ffb644d6c07..85ac8adb069b 100644
--- a/arch/um/kernel/skas/uaccess.c
+++ b/arch/um/kernel/skas/uaccess.c
@@ -87,10 +87,10 @@ static int do_op_one_page(unsigned long addr, int len, int is_write,
 	return n;
 }
 
-static int buffer_op(unsigned long addr, int len, int is_write,
-		     int (*op)(unsigned long, int, void *), void *arg)
+static long buffer_op(unsigned long addr, int len, int is_write,
+		      int (*op)(unsigned long, int, void *), void *arg)
 {
-	int size, remain, n;
+	long size, remain, n;
 
 	size = min(PAGE_ALIGN(addr) - addr, (unsigned long) len);
 	remain = len;
@@ -139,18 +139,16 @@ static int copy_chunk_from_user(unsigned long from, int len, void *arg)
 	return 0;
 }
 
-int copy_from_user(void *to, const void __user *from, int n)
+long __copy_from_user(void *to, const void __user *from, unsigned long n)
 {
 	if (segment_eq(get_fs(), KERNEL_DS)) {
 		memcpy(to, (__force void*)from, n);
 		return 0;
 	}
 
-	return access_ok(VERIFY_READ, from, n) ?
-	       buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to):
-	       n;
+	return buffer_op((unsigned long) from, n, 0, copy_chunk_from_user, &to);
 }
-EXPORT_SYMBOL(copy_from_user);
+EXPORT_SYMBOL(__copy_from_user);
 
 static int copy_chunk_to_user(unsigned long to, int len, void *arg)
 {
@@ -161,18 +159,16 @@ static int copy_chunk_to_user(unsigned long to, int len, void *arg)
 	return 0;
 }
 
-int copy_to_user(void __user *to, const void *from, int n)
+long __copy_to_user(void __user *to, const void *from, unsigned long n)
 {
 	if (segment_eq(get_fs(), KERNEL_DS)) {
 		memcpy((__force void *) to, from, n);
 		return 0;
 	}
 
-	return access_ok(VERIFY_WRITE, to, n) ?
-	       buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from) :
-	       n;
+	return buffer_op((unsigned long) to, n, 1, copy_chunk_to_user, &from);
 }
-EXPORT_SYMBOL(copy_to_user);
+EXPORT_SYMBOL(__copy_to_user);
 
 static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
 {
@@ -188,9 +184,9 @@ static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
 	return 0;
 }
 
-int strncpy_from_user(char *dst, const char __user *src, int count)
+long __strncpy_from_user(char *dst, const char __user *src, long count)
 {
-	int n;
+	long n;
 	char *ptr = dst;
 
 	if (segment_eq(get_fs(), KERNEL_DS)) {
@@ -198,16 +194,13 @@ int strncpy_from_user(char *dst, const char __user *src, int count)
 		return strnlen(dst, count);
 	}
 
-	if (!access_ok(VERIFY_READ, src, 1))
-		return -EFAULT;
-
 	n = buffer_op((unsigned long) src, count, 0, strncpy_chunk_from_user,
 		      &ptr);
 	if (n != 0)
 		return -EFAULT;
 	return strnlen(dst, count);
 }
-EXPORT_SYMBOL(strncpy_from_user);
+EXPORT_SYMBOL(__strncpy_from_user);
 
 static int clear_chunk(unsigned long addr, int len, void *unused)
 {
@@ -215,22 +208,16 @@ static int clear_chunk(unsigned long addr, int len, void *unused)
 	return 0;
 }
 
-int __clear_user(void __user *mem, int len)
-{
-	return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
-}
-
-int clear_user(void __user *mem, int len)
+unsigned long __clear_user(void __user *mem, unsigned long len)
 {
 	if (segment_eq(get_fs(), KERNEL_DS)) {
 		memset((__force void*)mem, 0, len);
 		return 0;
 	}
 
-	return access_ok(VERIFY_WRITE, mem, len) ?
-	       buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL) : len;
+	return buffer_op((unsigned long) mem, len, 1, clear_chunk, NULL);
 }
-EXPORT_SYMBOL(clear_user);
+EXPORT_SYMBOL(__clear_user);
 
 static int strnlen_chunk(unsigned long str, int len, void *arg)
 {
@@ -244,7 +231,7 @@ static int strnlen_chunk(unsigned long str, int len, void *arg)
 	return 0;
 }
 
-int strnlen_user(const void __user *str, int len)
+long __strnlen_user(const void __user *str, long len)
 {
 	int count = 0, n;
 
@@ -256,4 +243,4 @@ int strnlen_user(const void __user *str, int len)
 		return count + 1;
 	return 0;
 }
-EXPORT_SYMBOL(strnlen_user);
+EXPORT_SYMBOL(__strnlen_user);
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 47ff9b7f3e5d..557232f758b6 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -220,6 +220,11 @@ unsigned long segv(struct faultinfo fi, unsigned long ip, int is_user,
 		show_regs(container_of(regs, struct pt_regs, regs));
 		panic("Segfault with no mm");
 	}
+	else if (!is_user && address < TASK_SIZE) {
+		show_regs(container_of(regs, struct pt_regs, regs));
+		panic("Kernel tried to access user memory at addr 0x%lx, ip 0x%lx",
+		       address, ip);
+	}
 
 	if (SEGV_IS_FIXABLE(&fi))
 		err = handle_page_fault(address, ip, is_write, is_user,
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index 07f798f4bcee..16630e75f056 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -248,8 +248,6 @@ EXPORT_SYMBOL(end_iomem);
 
 #define MIN_VMALLOC (32 * 1024 * 1024)
 
-extern char __binary_start;
-
 int __init linux_main(int argc, char **argv)
 {
 	unsigned long avail, diff;
@@ -294,7 +292,7 @@ int __init linux_main(int argc, char **argv)
 		physmem_size += UML_ROUND_UP(brk_start) - UML_ROUND_UP(&_end);
 	}
 
-	uml_physmem = (unsigned long) &__binary_start & PAGE_MASK;
+	uml_physmem = (unsigned long) __binary_start & PAGE_MASK;
 
 	/* Reserve up to 4M after the current brk */
 	uml_reserved = ROUND_4M(brk_start) + (1 << 22);
diff --git a/arch/um/os-Linux/drivers/tuntap_user.c b/arch/um/os-Linux/drivers/tuntap_user.c
index 14126d9176aa..c2e6e1dad876 100644
--- a/arch/um/os-Linux/drivers/tuntap_user.c
+++ b/arch/um/os-Linux/drivers/tuntap_user.c
@@ -47,7 +47,7 @@ static void tuntap_del_addr(unsigned char *addr, unsigned char *netmask,
 }
 
 struct tuntap_pre_exec_data {
-	int stdout;
+	int stdout_fd;
 	int close_me;
 };
 
@@ -55,7 +55,7 @@ static void tuntap_pre_exec(void *arg)
 {
 	struct tuntap_pre_exec_data *data = arg;
 
-	dup2(data->stdout, 1);
+	dup2(data->stdout_fd, 1);
 	close(data->close_me);
 }
 
@@ -74,7 +74,7 @@ static int tuntap_open_tramp(char *gate, int *fd_out, int me, int remote,
 
 	sprintf(version_buf, "%d", UML_NET_VERSION);
 
-	data.stdout = remote;
+	data.stdout_fd = remote;
 	data.close_me = me;
 
 	pid = run_helper(tuntap_pre_exec, &data, argv);
diff --git a/arch/um/os-Linux/file.c b/arch/um/os-Linux/file.c
index 08d90fba952c..26e0164895e4 100644
--- a/arch/um/os-Linux/file.c
+++ b/arch/um/os-Linux/file.c
@@ -13,6 +13,7 @@
 #include <sys/socket.h>
 #include <sys/stat.h>
 #include <sys/un.h>
+#include <sys/types.h>
 #include <os.h>
 
 static void copy_stat(struct uml_stat *dst, const struct stat64 *src)
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index 7b605e4dfffa..036d0dbc7b52 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -112,9 +112,11 @@ void timer_init(void)
 
 void set_sigstack(void *sig_stack, int size)
 {
-	stack_t stack = ((stack_t) { .ss_flags	= 0,
-				     .ss_sp	= (__ptr_t) sig_stack,
-				     .ss_size 	= size - sizeof(void *) });
+	stack_t stack = {
+		.ss_flags = 0,
+		.ss_sp = sig_stack,
+		.ss_size = size - sizeof(void *)
+	};
 
 	if (sigaltstack(&stack, NULL) != 0)
 		panic("enabling signal stack failed, errno = %d\n", errno);
diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index e7f8c945a573..35015e3e1e87 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -18,7 +18,7 @@
 #include <sysdep/ptrace.h>
 #include <sysdep/stub.h>
 
-extern unsigned long batch_syscall_stub, __syscall_stub_start;
+extern char batch_syscall_stub[], __syscall_stub_start[];
 
 extern void wait_stub_done(int pid);
 
@@ -38,8 +38,8 @@ static int __init init_syscall_regs(void)
 {
 	get_safe_registers(syscall_regs, NULL);
 	syscall_regs[REGS_IP_INDEX] = STUB_CODE +
-		((unsigned long) &batch_syscall_stub -
-		 (unsigned long) &__syscall_stub_start);
+		((unsigned long) batch_syscall_stub -
+		 (unsigned long) __syscall_stub_start);
 	return 0;
 }
 
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 7a9777570a62..3dddedba3a07 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -174,7 +174,7 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
 	handle_syscall(regs);
 }
 
-extern int __syscall_stub_start;
+extern char __syscall_stub_start[];
 
 static int userspace_tramp(void *stack)
 {
@@ -197,7 +197,7 @@ static int userspace_tramp(void *stack)
 	 * This has a pte, but it can't be mapped in with the usual
 	 * tlb_flush mechanism because this is part of that mechanism
 	 */
-	fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
+	fd = phys_mapping(to_phys(__syscall_stub_start), &offset);
 	addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
 		      PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
 	if (addr == MAP_FAILED) {
@@ -223,7 +223,7 @@ static int userspace_tramp(void *stack)
 
 		unsigned long v = STUB_CODE +
 				  (unsigned long) stub_segv_handler -
-				  (unsigned long) &__syscall_stub_start;
+				  (unsigned long) __syscall_stub_start;
 
 		set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
 		sigemptyset(&sa.sa_mask);
@@ -447,7 +447,7 @@ static int __init init_thread_regs(void)
 	/* Set parent's instruction pointer to start of clone-stub */
 	thread_regs[REGS_IP_INDEX] = STUB_CODE +
 				(unsigned long) stub_clone_handler -
-				(unsigned long) &__syscall_stub_start;
+				(unsigned long) __syscall_stub_start;
 	thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
 		sizeof(void *);
 #ifdef __SIGNAL_FRAMESIZE