4 files changed, 554 insertions, 466 deletions

diff --git a/arch/um/os-Linux/skas/Makefile b/arch/um/os-Linux/skas/Makefile
index 5fd8d4dad66..d2ea3409e07 100644
--- a/arch/um/os-Linux/skas/Makefile
+++ b/arch/um/os-Linux/skas/Makefile
@@ -1,10 +1,10 @@
 #
-# Copyright (C) 2002 - 2004 Jeff Dike (jdike@addtoit.com)
+# Copyright (C) 2002 - 2007 Jeff Dike (jdike@{linux.intel,addtoit}.com)
 # Licensed under the GPL
 #
 
-obj-y := mem.o process.o trap.o
+obj-y := mem.o process.o
 
-USER_OBJS := mem.o process.o trap.o
+USER_OBJS := $(obj-y)
 
 include arch/um/scripts/Makefile.rules
diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
index b3c11cfa995..689b18db798 100644
--- a/arch/um/os-Linux/skas/mem.c
+++ b/arch/um/os-Linux/skas/mem.c
@@ -1,78 +1,83 @@
 /*
- * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
 
-#include <signal.h>
+#include <stddef.h>
+#include <unistd.h>
 #include <errno.h>
 #include <string.h>
 #include <sys/mman.h>
-#include <sys/wait.h>
-#include <asm/page.h>
-#include <asm/unistd.h>
-#include "mem_user.h"
-#include "mem.h"
-#include "skas.h"
-#include "user.h"
-#include "os.h"
-#include "proc_mm.h"
-#include "ptrace_user.h"
-#include "user_util.h"
-#include "kern_util.h"
-#include "task.h"
-#include "registers.h"
-#include "uml-config.h"
-#include "sysdep/ptrace.h"
-#include "sysdep/stub.h"
+#include <init.h>
+#include <as-layout.h>
+#include <mm_id.h>
+#include <os.h>
+#include <proc_mm.h>
+#include <ptrace_user.h>
+#include <registers.h>
+#include <skas.h>
+#include <sysdep/ptrace.h>
+#include <sysdep/stub.h>
 
 extern unsigned long batch_syscall_stub, __syscall_stub_start;
 
-extern void wait_stub_done(int pid, int sig, char * fname);
+extern void wait_stub_done(int pid);
 
 static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
 					      unsigned long *stack)
 {
-	if(stack == NULL) {
+	if (stack == NULL) {
 		stack = (unsigned long *) mm_idp->stack + 2;
 		*stack = 0;
 	}
 	return stack;
 }
 
-extern int proc_mm;
+static unsigned long syscall_regs[MAX_REG_NR];
+
+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);
+	return 0;
+}
 
-int single_count = 0;
-int multi_count = 0;
-int multi_op_count = 0;
+__initcall(init_syscall_regs);
+
+extern int proc_mm;
 
 static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
 {
-	unsigned long regs[MAX_REG_NR];
-	int n;
+	int n, i;
 	long ret, offset;
 	unsigned long * data;
 	unsigned long * syscall;
-	int pid = mm_idp->u.pid;
+	int err, pid = mm_idp->u.pid;
 
-	if(proc_mm)
-#warning Need to look up userspace_pid by cpu
+	if (proc_mm)
+		/* FIXME: Need to look up userspace_pid by cpu */
 		pid = userspace_pid[0];
 
-	multi_count++;
-
-	get_safe_registers(regs, NULL);
-	regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
-		((unsigned long) &batch_syscall_stub -
-		 (unsigned long) &__syscall_stub_start);
-
-	n = ptrace_setregs(pid, regs);
-	if(n < 0)
+	n = ptrace_setregs(pid, syscall_regs);
+	if (n < 0) {
+		printk(UM_KERN_ERR "Registers - \n");
+		for (i = 0; i < MAX_REG_NR; i++)
+			printk(UM_KERN_ERR "\t%d\t0x%lx\n", i, syscall_regs[i]);
 		panic("do_syscall_stub : PTRACE_SETREGS failed, errno = %d\n",
-		      n);
+		      -n);
+	}
+
+	err = ptrace(PTRACE_CONT, pid, 0, 0);
+	if (err)
+		panic("Failed to continue stub, pid = %d, errno = %d\n", pid,
+		      errno);
 
-	wait_stub_done(pid, 0, "do_syscall_stub");
+	wait_stub_done(pid);
 
-	/* When the stub stops, we find the following values on the
+	/*
+	 * When the stub stops, we find the following values on the
 	 * beginning of the stack:
 	 * (long )return_value
 	 * (long )offset to failed sycall-data (0, if no error)
@@ -80,26 +85,26 @@ static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
 	ret = *((unsigned long *) mm_idp->stack);
 	offset = *((unsigned long *) mm_idp->stack + 1);
 	if (offset) {
-		data = (unsigned long *)(mm_idp->stack +
-					 offset - UML_CONFIG_STUB_DATA);
-		printk("do_syscall_stub : ret = %ld, offset = %ld, "
+		data = (unsigned long *)(mm_idp->stack + offset - STUB_DATA);
+		printk(UM_KERN_ERR "do_syscall_stub : ret = %ld, offset = %ld, "
 		       "data = %p\n", ret, offset, data);
 		syscall = (unsigned long *)((unsigned long)data + data[0]);
-		printk("do_syscall_stub: syscall %ld failed, return value = "
-		       "0x%lx, expected return value = 0x%lx\n",
+		printk(UM_KERN_ERR "do_syscall_stub: syscall %ld failed, "
+		       "return value = 0x%lx, expected return value = 0x%lx\n",
 		       syscall[0], ret, syscall[7]);
-		printk("    syscall parameters: "
+		printk(UM_KERN_ERR "    syscall parameters: "
 		       "0x%lx 0x%lx 0x%lx 0x%lx 0x%lx 0x%lx\n",
 		       syscall[1], syscall[2], syscall[3],
 		       syscall[4], syscall[5], syscall[6]);
-		for(n = 1; n < data[0]/sizeof(long); n++) {
-			if(n == 1)
-				printk("    additional syscall data:");
-			if(n % 4 == 1)
-				printk("\n      ");
+		for (n = 1; n < data[0]/sizeof(long); n++) {
+			if (n == 1)
+				printk(UM_KERN_ERR "    additional syscall "
+				       "data:");
+			if (n % 4 == 1)
+				printk("\n" UM_KERN_ERR "      ");
 			printk("  0x%lx", data[n]);
 		}
-		if(n > 1)
+		if (n > 1)
 			printk("\n");
 	}
 	else ret = 0;
@@ -115,9 +120,6 @@ long run_syscall_stub(struct mm_id * mm_idp, int syscall,
 {
 	unsigned long *stack = check_init_stack(mm_idp, *addr);
 
-	if(done && *addr == NULL)
-		single_count++;
-
 	*stack += sizeof(long);
 	stack += *stack / sizeof(long);
 
@@ -130,10 +132,9 @@ long run_syscall_stub(struct mm_id * mm_idp, int syscall,
 	*stack++ = args[5];
 	*stack++ = expected;
 	*stack = 0;
-	multi_op_count++;
 
-	if(!done && ((((unsigned long) stack) & ~PAGE_MASK) <
-		     PAGE_SIZE - 10 * sizeof(long))){
+	if (!done && ((((unsigned long) stack) & ~UM_KERN_PAGE_MASK) <
+		     UM_KERN_PAGE_SIZE - 10 * sizeof(long))) {
 		*addr = stack;
 		return 0;
 	}
@@ -148,14 +149,15 @@ long syscall_stub_data(struct mm_id * mm_idp,
 	unsigned long *stack;
 	int ret = 0;
 
-	/* If *addr still is uninitialized, it *must* contain NULL.
+	/*
+	 * If *addr still is uninitialized, it *must* contain NULL.
 	 * Thus in this case do_syscall_stub correctly won't be called.
 	 */
-	if((((unsigned long) *addr) & ~PAGE_MASK) >=
-	   PAGE_SIZE - (10 + data_count) * sizeof(long)) {
+	if ((((unsigned long) *addr) & ~UM_KERN_PAGE_MASK) >=
+	   UM_KERN_PAGE_SIZE - (10 + data_count) * sizeof(long)) {
 		ret = do_syscall_stub(mm_idp, addr);
 		/* in case of error, don't overwrite data on stack */
-		if(ret)
+		if (ret)
 			return ret;
 	}
 
@@ -166,22 +168,18 @@ long syscall_stub_data(struct mm_id * mm_idp,
 
 	memcpy(stack + 1, data, data_count * sizeof(long));
 
-	*stub_addr = (void *)(((unsigned long)(stack + 1) & ~PAGE_MASK) +
-			      UML_CONFIG_STUB_DATA);
+	*stub_addr = (void *)(((unsigned long)(stack + 1) &
+			       ~UM_KERN_PAGE_MASK) + STUB_DATA);
 
 	return 0;
 }
 
-int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len,
-	int r, int w, int x, int phys_fd, unsigned long long offset,
-	int done, void **data)
+int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len, int prot,
+	int phys_fd, unsigned long long offset, int done, void **data)
 {
-	int prot, ret;
-
-	prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
-		(x ? PROT_EXEC : 0);
+	int ret;
 
-	if(proc_mm){
+	if (proc_mm) {
 		struct proc_mm_op map;
 		int fd = mm_idp->u.mm_fd;
 
@@ -196,9 +194,12 @@ int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len,
 					   .fd	= phys_fd,
 					   .offset= offset
 					 } } } );
-		ret = os_write_file(fd, &map, sizeof(map));
-		if(ret != sizeof(map))
-			printk("map : /proc/mm map failed, err = %d\n", -ret);
+		CATCH_EINTR(ret = write(fd, &map, sizeof(map)));
+		if (ret != sizeof(map)) {
+			ret = -errno;
+			printk(UM_KERN_ERR "map : /proc/mm map failed, "
+			       "err = %d\n", -ret);
+		}
 		else ret = 0;
 	}
 	else {
@@ -213,12 +214,12 @@ int map(struct mm_id * mm_idp, unsigned long virt, unsigned long len,
 	return ret;
 }
 
-int unmap(struct mm_id * mm_idp, void *addr, unsigned long len, int done,
-	  void **data)
+int unmap(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
+	  int done, void **data)
 {
 	int ret;
 
-	if(proc_mm){
+	if (proc_mm) {
 		struct proc_mm_op unmap;
 		int fd = mm_idp->u.mm_fd;
 
@@ -228,9 +229,12 @@ int unmap(struct mm_id * mm_idp, void *addr, unsigned long len, int done,
 					   { .addr	=
 					     (unsigned long) addr,
 					     .len		= len } } } );
-		ret = os_write_file(fd, &unmap, sizeof(unmap));
-		if(ret != sizeof(unmap))
-			printk("unmap - proc_mm write returned %d\n", ret);
+		CATCH_EINTR(ret = write(fd, &unmap, sizeof(unmap)));
+		if (ret != sizeof(unmap)) {
+			ret = -errno;
+			printk(UM_KERN_ERR "unmap - proc_mm write returned "
+			       "%d\n", ret);
+		}
 		else ret = 0;
 	}
 	else {
@@ -245,14 +249,12 @@ int unmap(struct mm_id * mm_idp, void *addr, unsigned long len, int done,
 }
 
 int protect(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
-	    int r, int w, int x, int done, void **data)
+	    unsigned int prot, int done, void **data)
 {
 	struct proc_mm_op protect;
-	int prot, ret;
+	int ret;
 
-	prot = (r ? PROT_READ : 0) | (w ? PROT_WRITE : 0) |
-		(x ? PROT_EXEC : 0);
-	if(proc_mm){
+	if (proc_mm) {
 		int fd = mm_idp->u.mm_fd;
 
 		protect = ((struct proc_mm_op) { .op	= MM_MPROTECT,
@@ -263,9 +265,11 @@ int protect(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
 					       .len	= len,
 					       .prot	= prot } } } );
 
-		ret = os_write_file(fd, &protect, sizeof(protect));
-		if(ret != sizeof(protect))
-			printk("protect failed, err = %d", -ret);
+		CATCH_EINTR(ret = write(fd, &protect, sizeof(protect)));
+		if (ret != sizeof(protect)) {
+			ret = -errno;
+			printk(UM_KERN_ERR "protect failed, err = %d", -ret);
+		}
 		else ret = 0;
 	}
 	else {
@@ -277,7 +281,3 @@ int protect(struct mm_id * mm_idp, unsigned long addr, unsigned long len,
 
 	return ret;
 }
-
-void before_mem_skas(unsigned long unused)
-{
-}
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index 42e3d1ed802..908579f2b0a 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -1,101 +1,104 @@
 /*
- * Copyright (C) 2002- 2004 Jeff Dike (jdike@addtoit.com)
+ * Copyright (C) 2002- 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
  * Licensed under the GPL
  */
 
 #include <stdlib.h>
-#include <string.h>
 #include <unistd.h>
-#include <errno.h>
-#include <signal.h>
 #include <sched.h>
-#include "ptrace_user.h"
-#include <sys/wait.h>
+#include <errno.h>
+#include <string.h>
 #include <sys/mman.h>
-#include <sys/user.h>
-#include <sys/time.h>
+#include <sys/wait.h>
 #include <asm/unistd.h>
-#include <asm/types.h>
-#include "user.h"
-#include "sysdep/ptrace.h"
-#include "user_util.h"
-#include "kern_util.h"
-#include "skas.h"
-#include "stub-data.h"
-#include "mm_id.h"
-#include "sysdep/sigcontext.h"
-#include "sysdep/stub.h"
-#include "os.h"
-#include "proc_mm.h"
-#include "skas_ptrace.h"
-#include "chan_user.h"
-#include "registers.h"
-#include "mem.h"
-#include "uml-config.h"
-#include "process.h"
-#include "longjmp.h"
+#include <as-layout.h>
+#include <init.h>
+#include <kern_util.h>
+#include <mem.h>
+#include <os.h>
+#include <proc_mm.h>
+#include <ptrace_user.h>
+#include <registers.h>
+#include <skas.h>
+#include <skas_ptrace.h>
+#include <sysdep/stub.h>
 
 int is_skas_winch(int pid, int fd, void *data)
 {
-	if(pid != os_getpgrp())
-		return(0);
+	return pid == getpgrp();
+}
+
+static int ptrace_dump_regs(int pid)
+{
+	unsigned long regs[MAX_REG_NR];
+	int i;
+
+	if (ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
+		return -errno;
+
+	printk(UM_KERN_ERR "Stub registers -\n");
+	for (i = 0; i < ARRAY_SIZE(regs); i++)
+		printk(UM_KERN_ERR "\t%d - %lx\n", i, regs[i]);
 
-	register_winch_irq(-1, fd, -1, data);
-	return(1);
+	return 0;
 }
 
-void wait_stub_done(int pid, int sig, char * fname)
+/*
+ * Signals that are OK to receive in the stub - we'll just continue it.
+ * SIGWINCH will happen when UML is inside a detached screen.
+ */
+#define STUB_SIG_MASK ((1 << SIGVTALRM) | (1 << SIGWINCH))
+
+/* Signals that the stub will finish with - anything else is an error */
+#define STUB_DONE_MASK (1 << SIGTRAP)
+
+void wait_stub_done(int pid)
 {
 	int n, status, err;
 
-	do {
-		if ( sig != -1 ) {
-			err = ptrace(PTRACE_CONT, pid, 0, sig);
-			if(err)
-				panic("%s : continue failed, errno = %d\n",
-				      fname, errno);
-		}
-		sig = 0;
-
-		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
-	} while((n >= 0) && WIFSTOPPED(status) &&
-	        ((WSTOPSIG(status) == SIGVTALRM) ||
-		 /* running UML inside a detached screen can cause
-		  * SIGWINCHes
-		  */
-		 (WSTOPSIG(status) == SIGWINCH)));
-
-	if((n < 0) || !WIFSTOPPED(status) ||
-	   (WSTOPSIG(status) != SIGUSR1 && WSTOPSIG(status) != SIGTRAP)){
-		unsigned long regs[HOST_FRAME_SIZE];
-
-		if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
-			printk("Failed to get registers from stub, "
-			       "errno = %d\n", errno);
-		else {
-			int i;
+	while (1) {
+		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
+		if ((n < 0) || !WIFSTOPPED(status))
+			goto bad_wait;
 
-			printk("Stub registers -\n");
-			for(i = 0; i < HOST_FRAME_SIZE; i++)
-				printk("\t%d - %lx\n", i, regs[i]);
+		if (((1 << WSTOPSIG(status)) & STUB_SIG_MASK) == 0)
+			break;
+
+		err = ptrace(PTRACE_CONT, pid, 0, 0);
+		if (err) {
+			printk(UM_KERN_ERR "wait_stub_done : continue failed, "
+			       "errno = %d\n", errno);
+			fatal_sigsegv();
 		}
-		panic("%s : failed to wait for SIGUSR1/SIGTRAP, "
-		      "pid = %d, n = %d, errno = %d, status = 0x%x\n",
-		      fname, pid, n, errno, status);
 	}
+
+	if (((1 << WSTOPSIG(status)) & STUB_DONE_MASK) != 0)
+		return;
+
+bad_wait:
+	err = ptrace_dump_regs(pid);
+	if (err)
+		printk(UM_KERN_ERR "Failed to get registers from stub, "
+		       "errno = %d\n", -err);
+	printk(UM_KERN_ERR "wait_stub_done : failed to wait for SIGTRAP, "
+	       "pid = %d, n = %d, errno = %d, status = 0x%x\n", pid, n, errno,
+	       status);
+	fatal_sigsegv();
 }
 
 extern unsigned long current_stub_stack(void);
 
-void get_skas_faultinfo(int pid, struct faultinfo * fi)
+static void get_skas_faultinfo(int pid, struct faultinfo *fi)
 {
 	int err;
 
-	if(ptrace_faultinfo){
+	if (ptrace_faultinfo) {
 		err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
-		if(err)
-			panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
-			      "errno = %d\n", errno);
+		if (err) {
+			printk(UM_KERN_ERR "get_skas_faultinfo - "
+			       "PTRACE_FAULTINFO failed, errno = %d\n", errno);
+			fatal_sigsegv();
+		}
 
 		/* Special handling for i386, which has different structs */
 		if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
@@ -104,47 +107,87 @@ void get_skas_faultinfo(int pid, struct faultinfo * fi)
 			       sizeof(struct ptrace_faultinfo));
 	}
 	else {
-		wait_stub_done(pid, SIGSEGV, "get_skas_faultinfo");
+		unsigned long fpregs[FP_SIZE];
+
+		err = get_fp_registers(pid, fpregs);
+		if (err < 0) {
+			printk(UM_KERN_ERR "save_fp_registers returned %d\n",
+			       err);
+			fatal_sigsegv();
+		}
+		err = ptrace(PTRACE_CONT, pid, 0, SIGSEGV);
+		if (err) {
+			printk(UM_KERN_ERR "Failed to continue stub, pid = %d, "
+			       "errno = %d\n", pid, errno);
+			fatal_sigsegv();
+		}
+		wait_stub_done(pid);
 
-		/* faultinfo is prepared by the stub-segv-handler at start of
+		/*
+		 * faultinfo is prepared by the stub-segv-handler at start of
 		 * the stub stack page. We just have to copy it.
 		 */
 		memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
+
+		err = put_fp_registers(pid, fpregs);
+		if (err < 0) {
+			printk(UM_KERN_ERR "put_fp_registers returned %d\n",
+			       err);
+			fatal_sigsegv();
+		}
 	}
 }
 
-static void handle_segv(int pid, union uml_pt_regs * regs)
+static void handle_segv(int pid, struct uml_pt_regs * regs)
 {
-	get_skas_faultinfo(pid, &regs->skas.faultinfo);
-	segv(regs->skas.faultinfo, 0, 1, NULL);
+	get_skas_faultinfo(pid, &regs->faultinfo);
+	segv(regs->faultinfo, 0, 1, NULL);
 }
 
-/*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
-static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
+/*
+ * To use the same value of using_sysemu as the caller, ask it that value
+ * (in local_using_sysemu
+ */
+static void handle_trap(int pid, struct uml_pt_regs *regs,
+			int local_using_sysemu)
 {
 	int err, status;
 
+	if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
+		fatal_sigsegv();
+
 	/* Mark this as a syscall */
-	UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
+	UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
 
 	if (!local_using_sysemu)
 	{
-		err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
+		err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
 			     __NR_getpid);
-		if(err < 0)
-			panic("handle_trap - nullifying syscall failed errno = %d\n",
-			      errno);
+		if (err < 0) {
+			printk(UM_KERN_ERR "handle_trap - nullifying syscall "
+			       "failed, errno = %d\n", errno);
+			fatal_sigsegv();
+		}
 
 		err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
-		if(err < 0)
-			panic("handle_trap - continuing to end of syscall failed, "
-			      "errno = %d\n", errno);
-
-		CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
-		if((err < 0) || !WIFSTOPPED(status) ||
-		   (WSTOPSIG(status) != SIGTRAP + 0x80))
-			panic("handle_trap - failed to wait at end of syscall, "
-			      "errno = %d, status = %d\n", errno, status);
+		if (err < 0) {
+			printk(UM_KERN_ERR "handle_trap - continuing to end of "
+			       "syscall failed, errno = %d\n", errno);
+			fatal_sigsegv();
+		}
+
+		CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
+		if ((err < 0) || !WIFSTOPPED(status) ||
+		    (WSTOPSIG(status) != SIGTRAP + 0x80)) {
+			err = ptrace_dump_regs(pid);
+			if (err)
+				printk(UM_KERN_ERR "Failed to get registers "
+				       "from process, errno = %d\n", -err);
+			printk(UM_KERN_ERR "handle_trap - failed to wait at "
+			       "end of syscall, errno = %d, status = %d\n",
+			       errno, status);
+			fatal_sigsegv();
+		}
 	}
 
 	handle_syscall(regs);
@@ -159,63 +202,65 @@ static int userspace_tramp(void *stack)
 
 	ptrace(PTRACE_TRACEME, 0, 0, 0);
 
-	init_new_thread_signals();
-	err = set_interval(1);
-	if(err)
-		panic("userspace_tramp - setting timer failed, errno = %d\n",
-		      err);
+	signal(SIGTERM, SIG_DFL);
+	signal(SIGWINCH, SIG_IGN);
+	err = set_interval();
+	if (err) {
+		printk(UM_KERN_ERR "userspace_tramp - setting timer failed, "
+		       "errno = %d\n", err);
+		exit(1);
+	}
 
-	if(!proc_mm){
-		/* This has a pte, but it can't be mapped in with the usual
+	if (!proc_mm) {
+		/*
+		 * This has a pte, but it can't be mapped in with the usual
 		 * tlb_flush mechanism because this is part of that mechanism
 		 */
 		int fd;
-		__u64 offset;
+		unsigned long long offset;
 		fd = phys_mapping(to_phys(&__syscall_stub_start), &offset);
-		addr = mmap64((void *) UML_CONFIG_STUB_CODE, page_size(),
+		addr = mmap64((void *) STUB_CODE, UM_KERN_PAGE_SIZE,
 			      PROT_EXEC, MAP_FIXED | MAP_PRIVATE, fd, offset);
-		if(addr == MAP_FAILED){
-			printk("mapping mmap stub failed, errno = %d\n",
-			       errno);
+		if (addr == MAP_FAILED) {
+			printk(UM_KERN_ERR "mapping mmap stub at 0x%lx failed, "
+			       "errno = %d\n", STUB_CODE, errno);
 			exit(1);
 		}
 
-		if(stack != NULL){
+		if (stack != NULL) {
 			fd = phys_mapping(to_phys(stack), &offset);
-			addr = mmap((void *) UML_CONFIG_STUB_DATA, page_size(),
-				    PROT_READ | PROT_WRITE,
+			addr = mmap((void *) STUB_DATA,
+				    UM_KERN_PAGE_SIZE, PROT_READ | PROT_WRITE,
 				    MAP_FIXED | MAP_SHARED, fd, offset);
-			if(addr == MAP_FAILED){
-				printk("mapping segfault stack failed, "
-				       "errno = %d\n", errno);
+			if (addr == MAP_FAILED) {
+				printk(UM_KERN_ERR "mapping segfault stack "
+				       "at 0x%lx failed, errno = %d\n",
+				       STUB_DATA, errno);
 				exit(1);
 			}
 		}
 	}
-	if(!ptrace_faultinfo && (stack != NULL)){
+	if (!ptrace_faultinfo && (stack != NULL)) {
 		struct sigaction sa;
 
-		unsigned long v = UML_CONFIG_STUB_CODE +
+		unsigned long v = STUB_CODE +
 				  (unsigned long) stub_segv_handler -
 				  (unsigned long) &__syscall_stub_start;
 
-		set_sigstack((void *) UML_CONFIG_STUB_DATA, page_size());
+		set_sigstack((void *) STUB_DATA, UM_KERN_PAGE_SIZE);
 		sigemptyset(&sa.sa_mask);
-		sigaddset(&sa.sa_mask, SIGIO);
-		sigaddset(&sa.sa_mask, SIGWINCH);
-		sigaddset(&sa.sa_mask, SIGALRM);
-		sigaddset(&sa.sa_mask, SIGVTALRM);
-		sigaddset(&sa.sa_mask, SIGUSR1);
-		sa.sa_flags = SA_ONSTACK;
-		sa.sa_handler = (void *) v;
+		sa.sa_flags = SA_ONSTACK | SA_NODEFER | SA_SIGINFO;
+		sa.sa_sigaction = (void *) v;
 		sa.sa_restorer = NULL;
-		if(sigaction(SIGSEGV, &sa, NULL) < 0)
-			panic("userspace_tramp - setting SIGSEGV handler "
-			      "failed - errno = %d\n", errno);
+		if (sigaction(SIGSEGV, &sa, NULL) < 0) {
+			printk(UM_KERN_ERR "userspace_tramp - setting SIGSEGV "
+			       "handler failed - errno = %d\n", errno);
+			exit(1);
+		}
 	}
 
-	os_stop_process(os_getpid());
-	return(0);
+	kill(os_getpid(), SIGSTOP);
+	return 0;
 }
 
 /* Each element set once, and only accessed by a single processor anyway */
@@ -227,184 +272,316 @@ int start_userspace(unsigned long stub_stack)
 {
 	void *stack;
 	unsigned long sp;
-	int pid, status, n, flags;
+	int pid, status, n, flags, err;
 
-	stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
+	stack = mmap(NULL, UM_KERN_PAGE_SIZE,
+		     PROT_READ | PROT_WRITE | PROT_EXEC,
 		     MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
-	if(stack == MAP_FAILED)
-		panic("start_userspace : mmap failed, errno = %d", errno);
-	sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
+	if (stack == MAP_FAILED) {
+		err = -errno;
+		printk(UM_KERN_ERR "start_userspace : mmap failed, "
+		       "errno = %d\n", errno);
+		return err;
+	}
+
+	sp = (unsigned long) stack + UM_KERN_PAGE_SIZE - sizeof(void *);
+
+	flags = CLONE_FILES;
+	if (proc_mm)
+		flags |= CLONE_VM;
+	else
+		flags |= SIGCHLD;
 
-	flags = CLONE_FILES | SIGCHLD;
-	if(proc_mm) flags |= CLONE_VM;
 	pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
-	if(pid < 0)
-		panic("start_userspace : clone failed, errno = %d", errno);
+	if (pid < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "start_userspace : clone failed, "
+		       "errno = %d\n", errno);
+		return err;
+	}
 
 	do {
-		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
-		if(n < 0)
-			panic("start_userspace : wait failed, errno = %d",
-			      errno);
-	} while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
+		CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED | __WALL));
+		if (n < 0) {
+			err = -errno;
+			printk(UM_KERN_ERR "start_userspace : wait failed, "
+			       "errno = %d\n", errno);
+			goto out_kill;
+		}
+	} while (WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 
-	if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
-		panic("start_userspace : expected SIGSTOP, got status = %d",
-		      status);
+	if (!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP)) {
+		err = -EINVAL;
+		printk(UM_KERN_ERR "start_userspace : expected SIGSTOP, got "
+		       "status = %d\n", status);
+		goto out_kill;
+	}
 
-	if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
-		panic("start_userspace : PTRACE_OLDSETOPTIONS failed, errno=%d\n",
-		      errno);
+	if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
+		   (void *) PTRACE_O_TRACESYSGOOD) < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "start_userspace : PTRACE_OLDSETOPTIONS "
+		       "failed, errno = %d\n", errno);
+		goto out_kill;
+	}
 
-	if(munmap(stack, PAGE_SIZE) < 0)
-		panic("start_userspace : munmap failed, errno = %d\n", errno);
+	if (munmap(stack, UM_KERN_PAGE_SIZE) < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "start_userspace : munmap failed, "
+		       "errno = %d\n", errno);
+		goto out_kill;
+	}
 
-	return(pid);
+	return pid;
+
+ out_kill:
+	os_kill_ptraced_process(pid, 1);
+	return err;
 }
 
-void userspace(union uml_pt_regs *regs)
+void userspace(struct uml_pt_regs *regs)
 {
+	struct itimerval timer;
+	unsigned long long nsecs, now;
 	int err, status, op, pid = userspace_pid[0];
-	int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
+	/* To prevent races if using_sysemu changes under us.*/
+	int local_using_sysemu;
+	siginfo_t si;
+
+	/* Handle any immediate reschedules or signals */
+	interrupt_end();
+
+	if (getitimer(ITIMER_VIRTUAL, &timer))
+		printk(UM_KERN_ERR "Failed to get itimer, errno = %d\n", errno);
+	nsecs = timer.it_value.tv_sec * UM_NSEC_PER_SEC +
+		timer.it_value.tv_usec * UM_NSEC_PER_USEC;
+	nsecs += os_nsecs();
+
+	while (1) {
+		/*
+		 * This can legitimately fail if the process loads a
+		 * bogus value into a segment register.  It will
+		 * segfault and PTRACE_GETREGS will read that value
+		 * out of the process.  However, PTRACE_SETREGS will
+		 * fail.  In this case, there is nothing to do but
+		 * just kill the process.
+		 */
+		if (ptrace(PTRACE_SETREGS, pid, 0, regs->gp))
+			fatal_sigsegv();
 
-	while(1){
-		restore_registers(pid, regs);
+		if (put_fp_registers(pid, regs->fp))
+			fatal_sigsegv();
 
 		/* Now we set local_using_sysemu to be used for one loop */
 		local_using_sysemu = get_using_sysemu();
 
-		op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
+		op = SELECT_PTRACE_OPERATION(local_using_sysemu,
+					     singlestepping(NULL));
+
+		if (ptrace(op, pid, 0, 0)) {
+			printk(UM_KERN_ERR "userspace - ptrace continue "
+			       "failed, op = %d, errno = %d\n", op, errno);
+			fatal_sigsegv();
+		}
+
+		CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED | __WALL));
+		if (err < 0) {
+			printk(UM_KERN_ERR "userspace - wait failed, "
+			       "errno = %d\n", errno);
+			fatal_sigsegv();
+		}
 
-		err = ptrace(op, pid, 0, 0);
-		if(err)
-			panic("userspace - could not resume userspace process, "
-			      "pid=%d, ptrace operation = %d, errno = %d\n",
-			      pid, op, errno);
+		regs->is_user = 1;
+		if (ptrace(PTRACE_GETREGS, pid, 0, regs->gp)) {
+			printk(UM_KERN_ERR "userspace - PTRACE_GETREGS failed, "
+			       "errno = %d\n", errno);
+			fatal_sigsegv();
+		}
 
-		CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
-		if(err < 0)
-			panic("userspace - waitpid failed, errno = %d\n",
-			      errno);
+		if (get_fp_registers(pid, regs->fp)) {
+			printk(UM_KERN_ERR "userspace -  get_fp_registers failed, "
+			       "errno = %d\n", errno);
+			fatal_sigsegv();
+		}
 
-		regs->skas.is_user = 1;
-		save_registers(pid, regs);
 		UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 
-		if(WIFSTOPPED(status)){
-		  	switch(WSTOPSIG(status)){
+		if (WIFSTOPPED(status)) {
+			int sig = WSTOPSIG(status);
+
+			ptrace(PTRACE_GETSIGINFO, pid, 0, (struct siginfo *)&si);
+
+			switch (sig) {
 			case SIGSEGV:
-				if(PTRACE_FULL_FAULTINFO || !ptrace_faultinfo)
-					user_signal(SIGSEGV, regs, pid);
+				if (PTRACE_FULL_FAULTINFO ||
+				    !ptrace_faultinfo) {
+					get_skas_faultinfo(pid,
+							   &regs->faultinfo);
+					(*sig_info[SIGSEGV])(SIGSEGV, (struct siginfo *)&si,
+							     regs);
+				}
 				else handle_segv(pid, regs);
 				break;
 			case SIGTRAP + 0x80:
 			        handle_trap(pid, regs, local_using_sysemu);
 				break;
 			case SIGTRAP:
-				relay_signal(SIGTRAP, regs);
+				relay_signal(SIGTRAP, (struct siginfo *)&si, regs);
 				break;
-			case SIGIO:
 			case SIGVTALRM:
+				now = os_nsecs();
+				if (now < nsecs)
+					break;
+				block_signals();
+				(*sig_info[sig])(sig, (struct siginfo *)&si, regs);
+				unblock_signals();
+				nsecs = timer.it_value.tv_sec *
+					UM_NSEC_PER_SEC +
+					timer.it_value.tv_usec *
+					UM_NSEC_PER_USEC;
+				nsecs += os_nsecs();
+				break;
+			case SIGIO:
 			case SIGILL:
 			case SIGBUS:
 			case SIGFPE:
 			case SIGWINCH:
-				user_signal(WSTOPSIG(status), regs, pid);
+				block_signals();
+				(*sig_info[sig])(sig, (struct siginfo *)&si, regs);
+				unblock_signals();
 				break;
 			default:
-			        printk("userspace - child stopped with signal "
-				       "%d\n", WSTOPSIG(status));
+				printk(UM_KERN_ERR "userspace - child stopped "
+				       "with signal %d\n", sig);
+				fatal_sigsegv();
 			}
 			pid = userspace_pid[0];
 			interrupt_end();
 
 			/* Avoid -ERESTARTSYS handling in host */
-			if(PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
-				PT_SYSCALL_NR(regs->skas.regs) = -1;
+			if (PT_SYSCALL_NR_OFFSET != PT_SYSCALL_RET_OFFSET)
+				PT_SYSCALL_NR(regs->gp) = -1;
 		}
 	}
 }
 
+static unsigned long thread_regs[MAX_REG_NR];
+static unsigned long thread_fp_regs[FP_SIZE];
+
+static int __init init_thread_regs(void)
+{
+	get_safe_registers(thread_regs, thread_fp_regs);
+	/* 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;
+	thread_regs[REGS_SP_INDEX] = STUB_DATA + UM_KERN_PAGE_SIZE -
+		sizeof(void *);
+#ifdef __SIGNAL_FRAMESIZE
+	thread_regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
+#endif
+	return 0;
+}
+
+__initcall(init_thread_regs);
+
 int copy_context_skas0(unsigned long new_stack, int pid)
 {
+	struct timeval tv = { .tv_sec = 0, .tv_usec = UM_USEC_PER_SEC / UM_HZ };
 	int err;
-	unsigned long regs[HOST_FRAME_SIZE];
-	unsigned long fp_regs[HOST_FP_SIZE];
 	unsigned long current_stack = current_stub_stack();
 	struct stub_data *data = (struct stub_data *) current_stack;
 	struct stub_data *child_data = (struct stub_data *) new_stack;
-	__u64 new_offset;
+	unsigned long long new_offset;
 	int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
 
-	/* prepare offset and fd of child's stack as argument for parent's
+	/*
+	 * prepare offset and fd of child's stack as argument for parent's
 	 * and child's mmap2 calls
 	 */
 	*data = ((struct stub_data) { .offset	= MMAP_OFFSET(new_offset),
 				      .fd	= new_fd,
 				      .timer    = ((struct itimerval)
-					            { { 0, 1000000 / hz() },
-						      { 0, 1000000 / hz() }})});
-	get_safe_registers(regs, fp_regs);
-
-	/* Set parent's instruction pointer to start of clone-stub */
-	regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
-				(unsigned long) stub_clone_handler -
-				(unsigned long) &__syscall_stub_start;
-	regs[REGS_SP_INDEX] = UML_CONFIG_STUB_DATA + PAGE_SIZE -
-		sizeof(void *);
-#ifdef __SIGNAL_FRAMESIZE
-	regs[REGS_SP_INDEX] -= __SIGNAL_FRAMESIZE;
-#endif
-	err = ptrace_setregs(pid, regs);
-	if(err < 0)
-		panic("copy_context_skas0 : PTRACE_SETREGS failed, "
-		      "pid = %d, errno = %d\n", pid, -err);
+					           { .it_value = tv,
+						     .it_interval = tv }) });
+
+	err = ptrace_setregs(pid, thread_regs);
+	if (err < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_SETREGS "
+		       "failed, pid = %d, errno = %d\n", pid, -err);
+		return err;
+	}
 
-	err = ptrace_setfpregs(pid, fp_regs);
-	if(err < 0)
-		panic("copy_context_skas0 : PTRACE_SETFPREGS failed, "
-		      "pid = %d, errno = %d\n", pid, -err);
+	err = put_fp_registers(pid, thread_fp_regs);
+	if (err < 0) {
+		printk(UM_KERN_ERR "copy_context_skas0 : put_fp_registers "
+		       "failed, pid = %d, err = %d\n", pid, err);
+		return err;
+	}
 
 	/* set a well known return code for detection of child write failure */
 	child_data->err = 12345678;
 
-	/* Wait, until parent has finished its work: read child's pid from
+	/*
+	 * Wait, until parent has finished its work: read child's pid from
 	 * parent's stack, and check, if bad result.
 	 */
-	wait_stub_done(pid, 0, "copy_context_skas0");
+	err = ptrace(PTRACE_CONT, pid, 0, 0);
+	if (err) {
+		err = -errno;
+		printk(UM_KERN_ERR "Failed to continue new process, pid = %d, "
+		       "errno = %d\n", pid, errno);
+		return err;
+	}
+
+	wait_stub_done(pid);
 
 	pid = data->err;
-	if(pid < 0)
-		panic("copy_context_skas0 - stub-parent reports error %d\n",
-		      -pid);
+	if (pid < 0) {
+		printk(UM_KERN_ERR "copy_context_skas0 - stub-parent reports "
+		       "error %d\n", -pid);
+		return pid;
+	}
 
-	/* Wait, until child has finished too: read child's result from
+	/*
+	 * Wait, until child has finished too: read child's result from
 	 * child's stack and check it.
 	 */
-	wait_stub_done(pid, -1, "copy_context_skas0");
-	if (child_data->err != UML_CONFIG_STUB_DATA)
-		panic("copy_context_skas0 - stub-child reports error %ld\n",
-		      child_data->err);
+	wait_stub_done(pid);
+	if (child_data->err != STUB_DATA) {
+		printk(UM_KERN_ERR "copy_context_skas0 - stub-child reports "
+		       "error %ld\n", child_data->err);
+		err = child_data->err;
+		goto out_kill;
+	}
 
 	if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
-		   (void *)PTRACE_O_TRACESYSGOOD) < 0)
-		panic("copy_context_skas0 : PTRACE_OLDSETOPTIONS failed, "
-		      "errno = %d\n", errno);
+		   (void *)PTRACE_O_TRACESYSGOOD) < 0) {
+		err = -errno;
+		printk(UM_KERN_ERR "copy_context_skas0 : PTRACE_OLDSETOPTIONS "
+		       "failed, errno = %d\n", errno);
+		goto out_kill;
+	}
 
 	return pid;
+
+ out_kill:
+	os_kill_ptraced_process(pid, 1);
+	return err;
 }
 
 /*
  * This is used only, if stub pages are needed, while proc_mm is
- * availabl. Opening /proc/mm creates a new mm_context, which lacks
+ * available. Opening /proc/mm creates a new mm_context, which lacks
  * the stub-pages. Thus, we map them using /proc/mm-fd
  */
-void map_stub_pages(int fd, unsigned long code,
-		    unsigned long data, unsigned long stack)
+int map_stub_pages(int fd, unsigned long code, unsigned long data,
+		   unsigned long stack)
 {
 	struct proc_mm_op mmop;
 	int n;
-	__u64 code_offset;
+	unsigned long long code_offset;
 	int code_fd = phys_mapping(to_phys((void *) &__syscall_stub_start),
 				   &code_offset);
 
@@ -412,88 +589,65 @@ void map_stub_pages(int fd, unsigned long code,
 				      .u         =
 				      { .mmap    =
 					{ .addr    = code,
-					  .len     = PAGE_SIZE,
+					  .len     = UM_KERN_PAGE_SIZE,
 					  .prot    = PROT_EXEC,
 					  .flags   = MAP_FIXED | MAP_PRIVATE,
 					  .fd      = code_fd,
 					  .offset  = code_offset
 	} } });
-	n = os_write_file(fd, &mmop, sizeof(mmop));
-	if(n != sizeof(mmop))
-		panic("map_stub_pages : /proc/mm map for code failed, "
-		      "err = %d\n", -n);
+	CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
+	if (n != sizeof(mmop)) {
+		n = errno;
+		printk(UM_KERN_ERR "mmap args - addr = 0x%lx, fd = %d, "
+		       "offset = %llx\n", code, code_fd,
+		       (unsigned long long) code_offset);
+		printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for code "
+		       "failed, err = %d\n", n);
+		return -n;
+	}
 
-	if ( stack ) {
-		__u64 map_offset;
+	if (stack) {
+		unsigned long long map_offset;
 		int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
 		mmop = ((struct proc_mm_op)
 				{ .op        = MM_MMAP,
 				  .u         =
 				  { .mmap    =
 				    { .addr    = data,
-				      .len     = PAGE_SIZE,
+				      .len     = UM_KERN_PAGE_SIZE,
 				      .prot    = PROT_READ | PROT_WRITE,
 				      .flags   = MAP_FIXED | MAP_SHARED,
 				      .fd      = map_fd,
 				      .offset  = map_offset
 		} } });
-		n = os_write_file(fd, &mmop, sizeof(mmop));
-		if(n != sizeof(mmop))
-			panic("map_stub_pages : /proc/mm map for data failed, "
-			      "err = %d\n", -n);
+		CATCH_EINTR(n = write(fd, &mmop, sizeof(mmop)));
+		if (n != sizeof(mmop)) {
+			n = errno;
+			printk(UM_KERN_ERR "map_stub_pages : /proc/mm map for "
+			       "data failed, err = %d\n", n);
+			return -n;
+		}
 	}
+
+	return 0;
 }
 
-void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
-		void (*handler)(int))
+void new_thread(void *stack, jmp_buf *buf, void (*handler)(void))
 {
-	unsigned long flags;
-	jmp_buf switch_buf, fork_buf;
-
-	*switch_buf_ptr = &switch_buf;
-	*fork_buf_ptr = &fork_buf;
-
-	/* Somewhat subtle - siglongjmp restores the signal mask before doing
-	 * the longjmp.  This means that when jumping from one stack to another
-	 * when the target stack has interrupts enabled, an interrupt may occur
-	 * on the source stack.  This is bad when starting up a process because
-	 * it's not supposed to get timer ticks until it has been scheduled.
-	 * So, we disable interrupts around the sigsetjmp to ensure that
-	 * they can't happen until we get back here where they are safe.
-	 */
-	flags = get_signals();
-	block_signals();
-	if(UML_SETJMP(&fork_buf) == 0)
-		new_thread_proc(stack, handler);
-
-	remove_sigstack();
-
-	set_signals(flags);
+	(*buf)[0].JB_IP = (unsigned long) handler;
+	(*buf)[0].JB_SP = (unsigned long) stack + UM_THREAD_SIZE -
+		sizeof(void *);
 }
 
 #define INIT_JMP_NEW_THREAD 0
-#define INIT_JMP_REMOVE_SIGSTACK 1
-#define INIT_JMP_CALLBACK 2
-#define INIT_JMP_HALT 3
-#define INIT_JMP_REBOOT 4
+#define INIT_JMP_CALLBACK 1
+#define INIT_JMP_HALT 2
+#define INIT_JMP_REBOOT 3
 
-void thread_wait(void *sw, void *fb)
+void switch_threads(jmp_buf *me, jmp_buf *you)
 {
-	jmp_buf buf, **switch_buf = sw, *fork_buf;
-
-	*switch_buf = &buf;
-	fork_buf = fb;
-	if(UML_SETJMP(&buf) == 0)
-		UML_LONGJMP(fork_buf, INIT_JMP_REMOVE_SIGSTACK);
-}
-
-void switch_threads(void *me, void *next)
-{
-	jmp_buf my_buf, **me_ptr = me, *next_buf = next;
-
-	*me_ptr = &my_buf;
-	if(UML_SETJMP(&my_buf) == 0)
-		UML_LONGJMP(next_buf, 1);
+	if (UML_SETJMP(me) == 0)
+		UML_LONGJMP(you, 1);
 }
 
 static jmp_buf initial_jmpbuf;
@@ -503,38 +657,43 @@ static void (*cb_proc)(void *arg);
 static void *cb_arg;
 static jmp_buf *cb_back;
 
-int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
+int start_idle_thread(void *stack, jmp_buf *switch_buf)
 {
-	jmp_buf **switch_buf = switch_buf_ptr;
 	int n;
 
-	set_handler(SIGWINCH, (__sighandler_t) sig_handler,
-		    SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
-		    SIGVTALRM, -1);
+	set_handler(SIGWINCH);
 
-	*fork_buf_ptr = &initial_jmpbuf;
-	n = UML_SETJMP(&initial_jmpbuf);
-	switch(n){
+	/*
+	 * Can't use UML_SETJMP or UML_LONGJMP here because they save
+	 * and restore signals, with the possible side-effect of
+	 * trying to handle any signals which came when they were
+	 * blocked, which can't be done on this stack.
+	 * Signals must be blocked when jumping back here and restored
+	 * after returning to the jumper.
+	 */
+	n = setjmp(initial_jmpbuf);
+	switch (n) {
 	case INIT_JMP_NEW_THREAD:
-		new_thread_proc((void *) stack, new_thread_handler);
-		break;
-	case INIT_JMP_REMOVE_SIGSTACK:
-		remove_sigstack();
+		(*switch_buf)[0].JB_IP = (unsigned long) new_thread_handler;
+		(*switch_buf)[0].JB_SP = (unsigned long) stack +
+			UM_THREAD_SIZE - sizeof(void *);
 		break;
 	case INIT_JMP_CALLBACK:
 		(*cb_proc)(cb_arg);
-		UML_LONGJMP(cb_back, 1);
+		longjmp(*cb_back, 1);
 		break;
 	case INIT_JMP_HALT:
 		kmalloc_ok = 0;
-		return(0);
+		return 0;
 	case INIT_JMP_REBOOT:
 		kmalloc_ok = 0;
-		return(1);
+		return 1;
 	default:
-		panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
+		printk(UM_KERN_ERR "Bad sigsetjmp return in "
+		       "start_idle_thread - %d\n", n);
+		fatal_sigsegv();
 	}
-	UML_LONGJMP(*switch_buf, 1);
+	longjmp(*switch_buf, 1);
 }
 
 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
@@ -546,7 +705,7 @@ void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 	cb_back = &here;
 
 	block_signals();
-	if(UML_SETJMP(&here) == 0)
+	if (UML_SETJMP(&here) == 0)
 		UML_LONGJMP(&initial_jmpbuf, INIT_JMP_CALLBACK);
 	unblock_signals();
 
@@ -567,17 +726,19 @@ void reboot_skas(void)
 	UML_LONGJMP(&initial_jmpbuf, INIT_JMP_REBOOT);
 }
 
-void switch_mm_skas(struct mm_id *mm_idp)
+void __switch_mm(struct mm_id *mm_idp)
 {
 	int err;
 
-#warning need cpu pid in switch_mm_skas
-	if(proc_mm){
+	/* FIXME: need cpu pid in __switch_mm */
+	if (proc_mm) {
 		err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
 			     mm_idp->u.mm_fd);
-		if(err)
-			panic("switch_mm_skas - PTRACE_SWITCH_MM failed, "
-			      "errno = %d\n", errno);
+		if (err) {
+			printk(UM_KERN_ERR "__switch_mm - PTRACE_SWITCH_MM "
+			       "failed, errno = %d\n", errno);
+			fatal_sigsegv();
+		}
 	}
 	else userspace_pid[0] = mm_idp->u.pid;
 }
diff --git a/arch/um/os-Linux/skas/trap.c b/arch/um/os-Linux/skas/trap.c
deleted file mode 100644
index 9ad5fbec459..00000000000
--- a/arch/um/os-Linux/skas/trap.c
+++ /dev/null
@@ -1,73 +0,0 @@
-/*
- * Copyright (C) 2002 - 2003 Jeff Dike (jdike@addtoit.com)
- * Licensed under the GPL
- */
-
-#include <signal.h>
-#include <errno.h>
-#include "user_util.h"
-#include "kern_util.h"
-#include "task.h"
-#include "sigcontext.h"
-#include "skas.h"
-#include "ptrace_user.h"
-#include "sysdep/ptrace.h"
-#include "sysdep/ptrace_user.h"
-#include "os.h"
-
-void sig_handler_common_skas(int sig, void *sc_ptr)
-{
-	struct sigcontext *sc = sc_ptr;
-	struct skas_regs *r;
-	void (*handler)(int, union uml_pt_regs *);
-	int save_errno = errno;
-	int save_user;
-
-	/* This is done because to allow SIGSEGV to be delivered inside a SEGV
-	 * handler.  This can happen in copy_user, and if SEGV is disabled,
-	 * the process will die.
-	 * XXX Figure out why this is better than SA_NODEFER
-	 */
-	if(sig == SIGSEGV)
-		change_sig(SIGSEGV, 1);
-
-	r = &TASK_REGS(get_current())->skas;
-	save_user = r->is_user;
-	r->is_user = 0;
-	if ( sig == SIGFPE || sig == SIGSEGV ||
-	     sig == SIGBUS || sig == SIGILL ||
-	     sig == SIGTRAP ) {
-		GET_FAULTINFO_FROM_SC(r->faultinfo, sc);
-	}
-
-	change_sig(SIGUSR1, 1);
-
-	handler = sig_info[sig];
-
-	/* unblock SIGALRM, SIGVTALRM, SIGIO if sig isn't IRQ signal */
-	if (sig != SIGIO && sig != SIGWINCH &&
-	    sig != SIGVTALRM && sig != SIGALRM)
-		unblock_signals();
-
-	handler(sig, (union uml_pt_regs *) r);
-
-	errno = save_errno;
-	r->is_user = save_user;
-}
-
-extern int ptrace_faultinfo;
-
-void user_signal(int sig, union uml_pt_regs *regs, int pid)
-{
-	void (*handler)(int, union uml_pt_regs *);
-	int segv = ((sig == SIGFPE) || (sig == SIGSEGV) || (sig == SIGBUS) ||
-		    (sig == SIGILL) || (sig == SIGTRAP));
-
-	if (segv)
-		get_skas_faultinfo(pid, &regs->skas.faultinfo);
-
-	handler = sig_info[sig];
-	handler(sig, (union uml_pt_regs *) regs);
-
-	unblock_signals();
-}