[PATCH] uml: move libc-dependent startup and signal code

The serial UML OS-abstraction layer patch (um/kernel dir).

This moves all systemcalls from process.c file under os-Linux dir and join
process.c and process_kern.c files.
Signed-off-by: NGennady Sharapov <gennady.v.sharapov@intel.com>
Signed-off-by: NJeff Dike <jdike@addtoit.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

arch/um/include/os.h

@@ -153,6 +153,11 @@ extern int os_file_type(char *file);
 extern int os_file_mode(char *file, struct openflags *mode_out);
 extern int os_lock_file(int fd, int excl);
 
+/* start_up.c */
+extern void os_early_checks(void);
+extern int can_do_skas(void);
+
+/* process.c */
 extern unsigned long os_process_pc(int pid);
 extern int os_process_parent(int pid);
 extern void os_stop_process(int pid);
@@ -161,6 +166,9 @@ extern void os_kill_ptraced_process(int pid, int reap_child);
 extern void os_usr1_process(int pid);
 extern int os_getpid(void);
 extern int os_getpgrp(void);
+extern void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int));
+extern void init_new_thread_signals(int altstack);
+extern int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr);
 
 extern int os_map_memory(void *virt, int fd, unsigned long long off,
 			 unsigned long len, int r, int w, int x);
@@ -170,6 +178,13 @@ extern int os_unmap_memory(void *addr, int len);
 extern void os_flush_stdout(void);
 extern unsigned long long os_usecs(void);
 
+/* tt.c
+ * for tt mode only (will be deleted in future...)
+ */
+extern void forward_pending_sigio(int target);
+extern int start_fork_tramp(void *arg, unsigned long temp_stack,
+			    int clone_flags, int (*tramp)(void *));
+
 #endif
 
 /*

arch/um/include/user_util.h

@@ -54,8 +54,6 @@ extern void stack_protections(unsigned long address);
 extern void task_protections(unsigned long address);
 extern int wait_for_stop(int pid, int sig, int cont_type, void *relay);
 extern void *add_signal_handler(int sig, void (*handler)(int));
-extern int start_fork_tramp(void *arg, unsigned long temp_stack, 
-			    int clone_flags, int (*tramp)(void *));
 extern int linux_main(int argc, char **argv);
 extern void set_cmdline(char *cmd);
 extern void input_cb(void (*proc)(void *), void *arg, int arg_len);
@@ -64,8 +62,6 @@ extern void *um_kmalloc(int size);
 extern int switcheroo(int fd, int prot, void *from, void *to, int size);
 extern void setup_machinename(char *machine_out);
 extern void setup_hostinfo(void);
-extern void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int));
-extern void init_new_thread_signals(int altstack);
 extern void do_exec(int old_pid, int new_pid);
 extern void tracer_panic(char *msg, ...);
 extern char *get_umid(int only_if_set);
@@ -74,16 +70,12 @@ extern int detach(int pid, int sig);
 extern int attach(int pid);
 extern void kill_child_dead(int pid);
 extern int cont(int pid);
-extern void check_ptrace(void);
 extern void check_sigio(void);
-extern int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr);
 extern void write_sigio_workaround(void);
 extern void arch_check_bugs(void);
 extern int cpu_feature(char *what, char *buf, int len);
 extern int arch_handle_signal(int sig, union uml_pt_regs *regs);
 extern int arch_fixup(unsigned long address, void *sc_ptr);
-extern void forward_pending_sigio(int target);
-extern int can_do_skas(void);
 extern void arch_init_thread(void);
 extern int setjmp_wrapper(void (*proc)(void *, void *), ...);
 extern int raw(int fd);

arch/um/kernel/Makefile

@@ -8,11 +8,10 @@ clean-files :=
 
 obj-y = config.o exec_kern.o exitcode.o \
 	helper.o init_task.o irq.o irq_user.o ksyms.o main.o mem.o mem_user.o \
-	physmem.o process.o process_kern.o ptrace.o reboot.o resource.o \
-	sigio_user.o sigio_kern.o signal_kern.o signal_user.o smp.o \
-	syscall_kern.o sysrq.o tempfile.o time.o time_kern.o \
-	tlb.o trap_kern.o trap_user.o uaccess_user.o um_arch.o umid.o \
-	user_util.o
+	physmem.o process_kern.o ptrace.o reboot.o resource.o sigio_user.o \
+	sigio_kern.o signal_kern.o signal_user.o smp.o syscall_kern.o sysrq.o \
+	tempfile.o time.o time_kern.o tlb.o trap_kern.o trap_user.o \
+	uaccess_user.o um_arch.o umid.o user_util.o
 
 obj-$(CONFIG_BLK_DEV_INITRD) += initrd.o
 obj-$(CONFIG_GPROF)	+= gprof_syms.o
@@ -25,8 +24,8 @@ obj-$(CONFIG_MODE_SKAS) += skas/
 
 user-objs-$(CONFIG_TTY_LOG) += tty_log.o
 
-USER_OBJS := $(user-objs-y) config.o helper.o main.o process.o tempfile.o \
-	time.o tty_log.o umid.o user_util.o
+USER_OBJS := $(user-objs-y) config.o helper.o main.o tempfile.o time.o \
+	tty_log.o umid.o user_util.o
 
 include arch/um/scripts/Makefile.rules
 

arch/um/kernel/um_arch.c

@@ -333,6 +333,7 @@ int linux_main(int argc, char **argv)
 	if(have_root == 0)
 		add_arg(DEFAULT_COMMAND_LINE);
 
+	os_early_checks();
 	mode_tt = force_tt ? 1 : !can_do_skas();
 #ifndef CONFIG_MODE_TT
 	if (mode_tt) {
@@ -470,7 +471,6 @@ void __init setup_arch(char **cmdline_p)
 void __init check_bugs(void)
 {
 	arch_check_bugs();
-	check_ptrace();
 	check_sigio();
 	check_devanon();
 }

arch/um/os-Linux/Makefile

@@ -3,10 +3,11 @@
 # Licensed under the GPL
 #
 
-obj-y = aio.o elf_aux.o file.o process.o signal.o time.o tty.o user_syms.o \
-	drivers/ sys-$(SUBARCH)/
+obj-y = aio.o elf_aux.o file.o process.o signal.o start_up.o time.o tt.o \
+	tty.o user_syms.o drivers/ sys-$(SUBARCH)/
 
-USER_OBJS := aio.o elf_aux.o file.o process.o signal.o time.o tty.o
+USER_OBJS := aio.o elf_aux.o file.o process.o signal.o start_up.o time.o tt.o \
+	tty.o
 
 CFLAGS_user_syms.o += -DSUBARCH_$(SUBARCH)
 

arch/um/os-Linux/process.c

@@ -3,10 +3,10 @@
  * Licensed under the GPL
  */
 
-#include <unistd.h>
 #include <stdio.h>
 #include <errno.h>
 #include <signal.h>
+#include <setjmp.h>
 #include <linux/unistd.h>
 #include <sys/mman.h>
 #include <sys/wait.h>
@@ -14,6 +14,10 @@
 #include "os.h"
 #include "user.h"
 #include "user_util.h"
+#include "signal_user.h"
+#include "process.h"
+#include "irq_user.h"
+#include "kern_util.h"
 
 #define ARBITRARY_ADDR -1
 #define FAILURE_PID    -1
@@ -114,8 +118,10 @@ void os_usr1_process(int pid)
 	kill(pid, SIGUSR1);
 }
 
-/*Don't use the glibc version, which caches the result in TLS. It misses some
- * syscalls, and also breaks with clone(), which does not unshare the TLS.*/
+/* Don't use the glibc version, which caches the result in TLS. It misses some
+ * syscalls, and also breaks with clone(), which does not unshare the TLS.
+ */
+
 inline _syscall0(pid_t, getpid)
 
 int os_getpid(void)
@@ -164,6 +170,52 @@ int os_unmap_memory(void *addr, int len)
         return(0);
 }
 
+void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
+{
+	int flags = 0, pages;
+
+	if(sig_stack != NULL){
+		pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER);
+		set_sigstack(sig_stack, pages * page_size());
+		flags = SA_ONSTACK;
+	}
+	if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);
+}
+
+void init_new_thread_signals(int altstack)
+{
+	int flags = altstack ? SA_ONSTACK : 0;
+
+	set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,
+		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
+	set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags,
+		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
+	set_handler(SIGFPE, (__sighandler_t) sig_handler, flags,
+		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
+	set_handler(SIGILL, (__sighandler_t) sig_handler, flags,
+		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
+	set_handler(SIGBUS, (__sighandler_t) sig_handler, flags,
+		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
+	set_handler(SIGUSR2, (__sighandler_t) sig_handler,
+		    flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
+	signal(SIGHUP, SIG_IGN);
+
+	init_irq_signals(altstack);
+}
+
+int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr)
+{
+       sigjmp_buf buf;
+       int n;
+
+       *jmp_ptr = &buf;
+       n = sigsetjmp(buf, 1);
+       if(n != 0)
+               return(n);
+       (*fn)(arg);
+       return(0);
+}
+
 /*
  * Overrides for Emacs so that we follow Linus's tabbing style.
  * Emacs will notice this stuff at the end of the file and automatically

arch/um/kernel/process.c → arch/um/os-Linux/start_up.c

-/* 
+/*
  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
  * Licensed under the GPL
  */
@@ -19,7 +19,6 @@
 #include "user_util.h"
 #include "kern_util.h"
 #include "user.h"
-#include "process.h"
 #include "signal_kern.h"
 #include "signal_user.h"
 #include "sysdep/ptrace.h"
@@ -39,98 +38,6 @@
 #include "registers.h"
 #endif
 
-void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
-{
-	int flags = 0, pages;
-
-	if(sig_stack != NULL){
-		pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER);
-		set_sigstack(sig_stack, pages * page_size());
-		flags = SA_ONSTACK;
-	}
-	if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);
-}
-
-void init_new_thread_signals(int altstack)
-{
-	int flags = altstack ? SA_ONSTACK : 0;
-
-	set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,
-		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
-	set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags, 
-		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
-	set_handler(SIGFPE, (__sighandler_t) sig_handler, flags, 
-		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
-	set_handler(SIGILL, (__sighandler_t) sig_handler, flags, 
-		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
-	set_handler(SIGBUS, (__sighandler_t) sig_handler, flags, 
-		    SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
-	set_handler(SIGUSR2, (__sighandler_t) sig_handler, 
-		    flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
-	signal(SIGHUP, SIG_IGN);
-
-	init_irq_signals(altstack);
-}
-
-struct tramp {
-	int (*tramp)(void *);
-	void *tramp_data;
-	unsigned long temp_stack;
-	int flags;
-	int pid;
-};
-
-/* See above for why sigkill is here */
-
-int sigkill = SIGKILL;
-
-int outer_tramp(void *arg)
-{
-	struct tramp *t;
-	int sig = sigkill;
-
-	t = arg;
-	t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2,
-		       t->flags, t->tramp_data);
-	if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL);
-	kill(os_getpid(), sig);
-	_exit(0);
-}
-
-int start_fork_tramp(void *thread_arg, unsigned long temp_stack, 
-		     int clone_flags, int (*tramp)(void *))
-{
-	struct tramp arg;
-	unsigned long sp;
-	int new_pid, status, err;
-
-	/* The trampoline will run on the temporary stack */
-	sp = stack_sp(temp_stack);
-
-	clone_flags |= CLONE_FILES | SIGCHLD;
-
-	arg.tramp = tramp;
-	arg.tramp_data = thread_arg;
-	arg.temp_stack = temp_stack;
-	arg.flags = clone_flags;
-
-	/* Start the process and wait for it to kill itself */
-	new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg);
-	if(new_pid < 0)
-		return(new_pid);
-
-	CATCH_EINTR(err = waitpid(new_pid, &status, 0));
-	if(err < 0)
-		panic("Waiting for outer trampoline failed - errno = %d",
-		      errno);
-
-	if(!WIFSIGNALED(status) || (WTERMSIG(status) != SIGKILL))
-		panic("outer trampoline didn't exit with SIGKILL, "
-		      "status = %d", status);
-
-	return(arg.pid);
-}
-
 static int ptrace_child(void *arg)
 {
 	int ret;
@@ -165,7 +72,7 @@ static int start_ptraced_child(void **stack_out)
 	void *stack;
 	unsigned long sp;
 	int pid, n, status;
-	
+
 	stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
 		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 	if(stack == MAP_FAILED)
@@ -173,10 +80,10 @@ static int start_ptraced_child(void **stack_out)
 	sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
 	pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
 	if(pid < 0)
-		panic("check_ptrace : clone failed, errno = %d", errno);
+		panic("start_ptraced_child : clone failed, errno = %d", errno);
 	CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 	if(n < 0)
-		panic("check_ptrace : wait failed, errno = %d", errno);
+		panic("check_ptrace : clone failed, errno = %d", errno);
 	if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
 		panic("check_ptrace : expected SIGSTOP, got status = %d",
 		      status);
@@ -185,11 +92,14 @@ static int start_ptraced_child(void **stack_out)
 	return(pid);
 }
 
-/* When testing for SYSEMU support, if it is one of the broken versions, we must
- * just avoid using sysemu, not panic, but only if SYSEMU features are broken.
+/* When testing for SYSEMU support, if it is one of the broken versions, we
+ * must just avoid using sysemu, not panic, but only if SYSEMU features are
+ * broken.
  * So only for SYSEMU features we test mustpanic, while normal host features
- * must work anyway!*/
-static int stop_ptraced_child(int pid, void *stack, int exitcode, int mustpanic)
+ * must work anyway!
+ */
+static int stop_ptraced_child(int pid, void *stack, int exitcode,
+			      int mustpanic)
 {
 	int status, n, ret = 0;
 
@@ -217,8 +127,6 @@ static int stop_ptraced_child(int pid, void *stack, int exitcode, int mustpanic)
 	return ret;
 }
 
-static int force_sysemu_disabled = 0;
-
 int ptrace_faultinfo = 1;
 int proc_mm = 1;
 
@@ -228,24 +136,27 @@ static int __init skas0_cmd_param(char *str, int* add)
 	return 0;
 }
 
+__uml_setup("skas0", skas0_cmd_param,
+		"skas0\n"
+		"    Disables SKAS3 usage, so that SKAS0 is used, unless \n"
+	        "    you specify mode=tt.\n\n");
+
+static int force_sysemu_disabled = 0;
+
 static int __init nosysemu_cmd_param(char *str, int* add)
 {
 	force_sysemu_disabled = 1;
 	return 0;
 }
 
-__uml_setup("skas0", skas0_cmd_param,
-		"skas0\n"
-		"    Disables SKAS3 usage, so that SKAS0 is used, unless you \n"
-		"    specify mode=tt.\n\n");
-
 __uml_setup("nosysemu", nosysemu_cmd_param,
-		"nosysemu\n"
-		"    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
-		"    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
-		"    behaviour of ptrace() and helps reducing host context switch rate.\n"
-		"    To make it working, you need a kernel patch for your host, too.\n"
-		"    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n\n");
+"nosysemu\n"
+"    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
+"    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
+"    behaviour of ptrace() and helps reducing host context switch rate.\n"
+"    To make it working, you need a kernel patch for your host, too.\n"
+"    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further \n"
+"    information.\n\n");
 
 static void __init check_sysemu(void)
 {
@@ -321,7 +232,7 @@ static void __init check_sysemu(void)
 	printk("missing\n");
 }
 
-void __init check_ptrace(void)
+static void __init check_ptrace(void)
 {
 	void *stack;
 	int pid, syscall, n, status;
@@ -329,12 +240,12 @@ void __init check_ptrace(void)
 	printk("Checking that ptrace can change system call numbers...");
 	pid = start_ptraced_child(&stack);
 
-	if (ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
-		panic("check_ptrace: PTRACE_SETOPTIONS failed, errno = %d", errno);
+	if(ptrace(PTRACE_OLDSETOPTIONS, pid, 0, (void *)PTRACE_O_TRACESYSGOOD) < 0)
+		panic("check_ptrace: PTRACE_OLDSETOPTIONS failed, errno = %d", errno);
 
 	while(1){
 		if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
-			panic("check_ptrace : ptrace failed, errno = %d", 
+			panic("check_ptrace : ptrace failed, errno = %d",
 			      errno);
 		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 		if(n < 0)
@@ -342,7 +253,7 @@ void __init check_ptrace(void)
 		if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP + 0x80))
 			panic("check_ptrace : expected SIGTRAP + 0x80, "
 			      "got status = %d", status);
-		
+
 		syscall = ptrace(PTRACE_PEEKUSR, pid, PT_SYSCALL_NR_OFFSET,
 				 0);
 		if(syscall == __NR_getpid){
@@ -359,33 +270,12 @@ void __init check_ptrace(void)
 	check_sysemu();
 }
 
-int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr)
-{
-	sigjmp_buf buf;
-	int n;
-
-	*jmp_ptr = &buf;
-	n = sigsetjmp(buf, 1);
-	if(n != 0)
-		return(n);
-	(*fn)(arg);
-	return(0);
-}
-
-void forward_pending_sigio(int target)
+void os_early_checks(void)
 {
-	sigset_t sigs;
-
-	if(sigpending(&sigs)) 
-		panic("forward_pending_sigio : sigpending failed");
-	if(sigismember(&sigs, SIGIO))
-		kill(target, SIGIO);
+	check_ptrace();
 }
 
-extern void *__syscall_stub_start, __syscall_stub_end;
-
 #ifdef UML_CONFIG_MODE_SKAS
-
 static inline void check_skas3_ptrace_support(void)
 {
 	struct ptrace_faultinfo fi;
@@ -400,9 +290,8 @@ static inline void check_skas3_ptrace_support(void)
 		ptrace_faultinfo = 0;
 		if(errno == EIO)
 			printf("not found\n");
-		else {
+		else
 			perror("not found");
-		}
 	}
 	else {
 		if (!ptrace_faultinfo)
@@ -419,9 +308,10 @@ int can_do_skas(void)
 {
 	printf("Checking for /proc/mm...");
 	if (os_access("/proc/mm", OS_ACC_W_OK) < 0) {
-		proc_mm = 0;
+ 		proc_mm = 0;
 		printf("not found\n");
-	} else {
+	}
+	else {
 		if (!proc_mm)
 			printf("found but disabled on command line\n");
 		else

arch/um/os-Linux/tt.c

+/*
+ * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <signal.h>
+#include <sched.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <setjmp.h>
+#include <sys/time.h>
+#include <sys/ptrace.h>
+#include <linux/ptrace.h>
+#include <sys/wait.h>
+#include <sys/mman.h>
+#include <asm/ptrace.h>
+#include <asm/unistd.h>
+#include <asm/page.h>
+#include "user_util.h"
+#include "kern_util.h"
+#include "user.h"
+#include "signal_kern.h"
+#include "signal_user.h"
+#include "sysdep/ptrace.h"
+#include "sysdep/sigcontext.h"
+#include "irq_user.h"
+#include "ptrace_user.h"
+#include "time_user.h"
+#include "init.h"
+#include "os.h"
+#include "uml-config.h"
+#include "choose-mode.h"
+#include "mode.h"
+#include "tempfile.h"
+
+/*
+ *-------------------------
+ * only for tt mode (will be deleted in future...)
+ *-------------------------
+ */
+
+struct tramp {
+	int (*tramp)(void *);
+	void *tramp_data;
+	unsigned long temp_stack;
+	int flags;
+	int pid;
+};
+
+/* See above for why sigkill is here */
+
+int sigkill = SIGKILL;
+
+int outer_tramp(void *arg)
+{
+	struct tramp *t;
+	int sig = sigkill;
+
+	t = arg;
+	t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2,
+		       t->flags, t->tramp_data);
+	if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL);
+	kill(os_getpid(), sig);
+	_exit(0);
+}
+
+int start_fork_tramp(void *thread_arg, unsigned long temp_stack,
+		     int clone_flags, int (*tramp)(void *))
+{
+	struct tramp arg;
+	unsigned long sp;
+	int new_pid, status, err;
+
+	/* The trampoline will run on the temporary stack */
+	sp = stack_sp(temp_stack);
+
+	clone_flags |= CLONE_FILES | SIGCHLD;
+
+	arg.tramp = tramp;
+	arg.tramp_data = thread_arg;
+	arg.temp_stack = temp_stack;
+	arg.flags = clone_flags;
+
+	/* Start the process and wait for it to kill itself */
+	new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg);
+	if(new_pid < 0)
+		return(new_pid);
+
+	CATCH_EINTR(err = waitpid(new_pid, &status, 0));
+	if(err < 0)
+		panic("Waiting for outer trampoline failed - errno = %d",
+		      errno);
+
+	if(!WIFSIGNALED(status) || (WTERMSIG(status) != SIGKILL))
+		panic("outer trampoline didn't exit with SIGKILL, "
+		      "status = %d", status);
+
+	return(arg.pid);
+}
+
+void forward_pending_sigio(int target)
+{
+	sigset_t sigs;
+
+	if(sigpending(&sigs))
+		panic("forward_pending_sigio : sigpending failed");
+	if(sigismember(&sigs, SIGIO))
+		kill(target, SIGIO);
+}
+