17 files changed, 2089 insertions, 307 deletions

diff --git a/arch/um/os-Linux/Makefile b/arch/um/os-Linux/Makefile
index b83ac8e21c3..08a4e628b24 100644
--- a/arch/um/os-Linux/Makefile
+++ b/arch/um/os-Linux/Makefile
@@ -4,11 +4,13 @@
 #
 
 obj-y = aio.o elf_aux.o file.o helper.o main.o mem.o process.o signal.o \
-	start_up.o time.o tt.o tty.o uaccess.o user_syms.o drivers/ \
-	sys-$(SUBARCH)/
+	start_up.o time.o trap.o tt.o tty.o uaccess.o umid.o user_syms.o \
+	util.o drivers/ sys-$(SUBARCH)/
+
+obj-$(CONFIG_MODE_SKAS) += skas/
 
 USER_OBJS := aio.o elf_aux.o file.o helper.o main.o mem.o process.o signal.o \
-	start_up.o time.o tt.o tty.o uaccess.o
+	start_up.o time.o trap.o tt.o tty.o uaccess.o umid.o util.o
 
 elf_aux.o: $(ARCH_DIR)/kernel-offsets.h
 CFLAGS_elf_aux.o += -I$(objtree)/arch/um
diff --git a/arch/um/os-Linux/aio.c b/arch/um/os-Linux/aio.c
index ffa759addd3..f897140cc4a 100644
--- a/arch/um/os-Linux/aio.c
+++ b/arch/um/os-Linux/aio.c
@@ -16,12 +16,12 @@
 #include "mode.h"
 
 struct aio_thread_req {
-        enum aio_type type;
-        int io_fd;
-        unsigned long long offset;
-        char *buf;
-        int len;
-        struct aio_context *aio;
+	enum aio_type type;
+	int io_fd;
+	unsigned long long offset;
+	char *buf;
+	int len;
+	struct aio_context *aio;
 };
 
 static int aio_req_fd_r = -1;
@@ -38,18 +38,18 @@ static int aio_req_fd_w = -1;
 
 static long io_setup(int n, aio_context_t *ctxp)
 {
-        return syscall(__NR_io_setup, n, ctxp);
+	return syscall(__NR_io_setup, n, ctxp);
 }
 
 static long io_submit(aio_context_t ctx, long nr, struct iocb **iocbpp)
 {
-        return syscall(__NR_io_submit, ctx, nr, iocbpp);
+	return syscall(__NR_io_submit, ctx, nr, iocbpp);
 }
 
 static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
-                         struct io_event *events, struct timespec *timeout)
+			 struct io_event *events, struct timespec *timeout)
 {
-        return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
+	return syscall(__NR_io_getevents, ctx_id, min_nr, nr, events, timeout);
 }
 
 #endif
@@ -66,243 +66,245 @@ static long io_getevents(aio_context_t ctx_id, long min_nr, long nr,
  */
 
 static int do_aio(aio_context_t ctx, enum aio_type type, int fd, char *buf,
-                  int len, unsigned long long offset, struct aio_context *aio)
+		  int len, unsigned long long offset, struct aio_context *aio)
 {
-        struct iocb iocb, *iocbp = &iocb;
-        char c;
-        int err;
-
-        iocb = ((struct iocb) { .aio_data 	= (unsigned long) aio,
-                                .aio_reqprio	= 0,
-                                .aio_fildes	= fd,
-                                .aio_buf	= (unsigned long) buf,
-                                .aio_nbytes	= len,
-                                .aio_offset	= offset,
-                                .aio_reserved1	= 0,
-                                .aio_reserved2	= 0,
-                                .aio_reserved3	= 0 });
-
-        switch(type){
-        case AIO_READ:
-                iocb.aio_lio_opcode = IOCB_CMD_PREAD;
-                err = io_submit(ctx, 1, &iocbp);
-                break;
-        case AIO_WRITE:
-                iocb.aio_lio_opcode = IOCB_CMD_PWRITE;
-                err = io_submit(ctx, 1, &iocbp);
-                break;
-        case AIO_MMAP:
-                iocb.aio_lio_opcode = IOCB_CMD_PREAD;
-                iocb.aio_buf = (unsigned long) &c;
-                iocb.aio_nbytes = sizeof(c);
-                err = io_submit(ctx, 1, &iocbp);
-                break;
-        default:
-                printk("Bogus op in do_aio - %d\n", type);
-                err = -EINVAL;
-                break;
-        }
-
-        if(err > 0)
-                err = 0;
+	struct iocb iocb, *iocbp = &iocb;
+	char c;
+	int err;
+
+	iocb = ((struct iocb) { .aio_data 	= (unsigned long) aio,
+				.aio_reqprio	= 0,
+				.aio_fildes	= fd,
+				.aio_buf	= (unsigned long) buf,
+				.aio_nbytes	= len,
+				.aio_offset	= offset,
+				.aio_reserved1	= 0,
+				.aio_reserved2	= 0,
+				.aio_reserved3	= 0 });
+
+	switch(type){
+	case AIO_READ:
+		iocb.aio_lio_opcode = IOCB_CMD_PREAD;
+		err = io_submit(ctx, 1, &iocbp);
+		break;
+	case AIO_WRITE:
+		iocb.aio_lio_opcode = IOCB_CMD_PWRITE;
+		err = io_submit(ctx, 1, &iocbp);
+		break;
+	case AIO_MMAP:
+		iocb.aio_lio_opcode = IOCB_CMD_PREAD;
+		iocb.aio_buf = (unsigned long) &c;
+		iocb.aio_nbytes = sizeof(c);
+		err = io_submit(ctx, 1, &iocbp);
+		break;
+	default:
+		printk("Bogus op in do_aio - %d\n", type);
+		err = -EINVAL;
+		break;
+	}
+
+	if(err > 0)
+		err = 0;
 	else
 		err = -errno;
 
-        return err;
+	return err;
 }
 
 static aio_context_t ctx = 0;
 
 static int aio_thread(void *arg)
 {
-        struct aio_thread_reply reply;
-        struct io_event event;
-        int err, n, reply_fd;
-
-        signal(SIGWINCH, SIG_IGN);
-
-        while(1){
-                n = io_getevents(ctx, 1, 1, &event, NULL);
-                if(n < 0){
-                        if(errno == EINTR)
-                                continue;
-                        printk("aio_thread - io_getevents failed, "
-                               "errno = %d\n", errno);
-                }
-                else {
-                        reply = ((struct aio_thread_reply)
-				 { .data = (void *) (long) event.data,
-				   .err	= event.res });
+	struct aio_thread_reply reply;
+	struct io_event event;
+	int err, n, reply_fd;
+
+	signal(SIGWINCH, SIG_IGN);
+
+	while(1){
+		n = io_getevents(ctx, 1, 1, &event, NULL);
+		if(n < 0){
+			if(errno == EINTR)
+				continue;
+			printk("aio_thread - io_getevents failed, "
+			       "errno = %d\n", errno);
+		}
+		else {
+			reply = ((struct aio_thread_reply)
+				{ .data = (void *) (long) event.data,
+						.err	= event.res });
 			reply_fd = ((struct aio_context *) reply.data)->reply_fd;
 			err = os_write_file(reply_fd, &reply, sizeof(reply));
-                        if(err != sizeof(reply))
+			if(err != sizeof(reply))
 				printk("aio_thread - write failed, fd = %d, "
-                                       "err = %d\n", aio_req_fd_r, -err);
-                }
-        }
-        return 0;
+				       "err = %d\n", aio_req_fd_r, -err);
+		}
+	}
+	return 0;
 }
 
 #endif
 
 static int do_not_aio(struct aio_thread_req *req)
 {
-        char c;
-        int err;
-
-        switch(req->type){
-        case AIO_READ:
-                err = os_seek_file(req->io_fd, req->offset);
-                if(err)
-                        goto out;
-
-                err = os_read_file(req->io_fd, req->buf, req->len);
-                break;
-        case AIO_WRITE:
-                err = os_seek_file(req->io_fd, req->offset);
-                if(err)
-                        goto out;
-
-                err = os_write_file(req->io_fd, req->buf, req->len);
-                break;
-        case AIO_MMAP:
-                err = os_seek_file(req->io_fd, req->offset);
-                if(err)
-                        goto out;
-
-                err = os_read_file(req->io_fd, &c, sizeof(c));
-                break;
-        default:
-                printk("do_not_aio - bad request type : %d\n", req->type);
-                err = -EINVAL;
-                break;
-        }
-
- out:
-        return err;
+	char c;
+	int err;
+
+	switch(req->type){
+	case AIO_READ:
+		err = os_seek_file(req->io_fd, req->offset);
+		if(err)
+			goto out;
+
+		err = os_read_file(req->io_fd, req->buf, req->len);
+		break;
+	case AIO_WRITE:
+		err = os_seek_file(req->io_fd, req->offset);
+		if(err)
+			goto out;
+
+		err = os_write_file(req->io_fd, req->buf, req->len);
+		break;
+	case AIO_MMAP:
+		err = os_seek_file(req->io_fd, req->offset);
+		if(err)
+			goto out;
+
+		err = os_read_file(req->io_fd, &c, sizeof(c));
+		break;
+	default:
+		printk("do_not_aio - bad request type : %d\n", req->type);
+		err = -EINVAL;
+		break;
+	}
+
+out:
+	return err;
 }
 
 static int not_aio_thread(void *arg)
 {
-        struct aio_thread_req req;
-        struct aio_thread_reply reply;
-        int err;
-
-        signal(SIGWINCH, SIG_IGN);
-        while(1){
-                err = os_read_file(aio_req_fd_r, &req, sizeof(req));
-                if(err != sizeof(req)){
-                        if(err < 0)
-                                printk("not_aio_thread - read failed, "
-                                       "fd = %d, err = %d\n", aio_req_fd_r,
-                                       -err);
-                        else {
-                                printk("not_aio_thread - short read, fd = %d, "
-                                       "length = %d\n", aio_req_fd_r, err);
-                        }
-                        continue;
-                }
-                err = do_not_aio(&req);
-                reply = ((struct aio_thread_reply) { .data 	= req.aio,
-                                                     .err	= err });
-                err = os_write_file(req.aio->reply_fd, &reply, sizeof(reply));
-                if(err != sizeof(reply))
-                        printk("not_aio_thread - write failed, fd = %d, "
-                               "err = %d\n", aio_req_fd_r, -err);
-        }
+	struct aio_thread_req req;
+	struct aio_thread_reply reply;
+	int err;
+
+	signal(SIGWINCH, SIG_IGN);
+	while(1){
+		err = os_read_file(aio_req_fd_r, &req, sizeof(req));
+		if(err != sizeof(req)){
+			if(err < 0)
+				printk("not_aio_thread - read failed, "
+				       "fd = %d, err = %d\n", aio_req_fd_r,
+				       -err);
+			else {
+				printk("not_aio_thread - short read, fd = %d, "
+				       "length = %d\n", aio_req_fd_r, err);
+			}
+			continue;
+		}
+		err = do_not_aio(&req);
+		reply = ((struct aio_thread_reply) { .data 	= req.aio,
+					 .err	= err });
+		err = os_write_file(req.aio->reply_fd, &reply, sizeof(reply));
+		if(err != sizeof(reply))
+			printk("not_aio_thread - write failed, fd = %d, "
+			       "err = %d\n", aio_req_fd_r, -err);
+	}
+
+	return 0;
 }
 
 static int aio_pid = -1;
 
 static int init_aio_24(void)
 {
-        unsigned long stack;
-        int fds[2], err;
-
-        err = os_pipe(fds, 1, 1);
-        if(err)
-                goto out;
-
-        aio_req_fd_w = fds[0];
-        aio_req_fd_r = fds[1];
-        err = run_helper_thread(not_aio_thread, NULL,
-                                CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
-        if(err < 0)
-                goto out_close_pipe;
-
-        aio_pid = err;
-        goto out;
-
- out_close_pipe:
-        os_close_file(fds[0]);
-        os_close_file(fds[1]);
-        aio_req_fd_w = -1;
-        aio_req_fd_r = -1;
- out:
+	unsigned long stack;
+	int fds[2], err;
+
+	err = os_pipe(fds, 1, 1);
+	if(err)
+		goto out;
+
+	aio_req_fd_w = fds[0];
+	aio_req_fd_r = fds[1];
+	err = run_helper_thread(not_aio_thread, NULL,
+				CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+	if(err < 0)
+		goto out_close_pipe;
+
+	aio_pid = err;
+	goto out;
+
+out_close_pipe:
+	os_close_file(fds[0]);
+	os_close_file(fds[1]);
+	aio_req_fd_w = -1;
+	aio_req_fd_r = -1;
+out:
 #ifndef HAVE_AIO_ABI
 	printk("/usr/include/linux/aio_abi.h not present during build\n");
 #endif
 	printk("2.6 host AIO support not used - falling back to I/O "
 	       "thread\n");
-        return 0;
+	return 0;
 }
 
 #ifdef HAVE_AIO_ABI
 #define DEFAULT_24_AIO 0
 static int init_aio_26(void)
 {
-        unsigned long stack;
-        int err;
+	unsigned long stack;
+	int err;
 
-        if(io_setup(256, &ctx)){
+	if(io_setup(256, &ctx)){
 		err = -errno;
-                printk("aio_thread failed to initialize context, err = %d\n",
-                       errno);
-                return err;
-        }
+		printk("aio_thread failed to initialize context, err = %d\n",
+		       errno);
+		return err;
+	}
 
-        err = run_helper_thread(aio_thread, NULL,
-                                CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
-        if(err < 0)
-                return err;
+	err = run_helper_thread(aio_thread, NULL,
+				CLONE_FILES | CLONE_VM | SIGCHLD, &stack, 0);
+	if(err < 0)
+		return err;
 
-        aio_pid = err;
+	aio_pid = err;
 
 	printk("Using 2.6 host AIO\n");
-        return 0;
+	return 0;
 }
 
 static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
-        struct aio_thread_reply reply;
-        int err;
-
-        err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
-        if(err){
-                reply = ((struct aio_thread_reply) { .data = aio,
-                                                     .err  = err });
-                err = os_write_file(aio->reply_fd, &reply, sizeof(reply));
-                if(err != sizeof(reply))
-                        printk("submit_aio_26 - write failed, "
-                               "fd = %d, err = %d\n", aio->reply_fd, -err);
-                else err = 0;
-        }
-
-        return err;
+	struct aio_thread_reply reply;
+	int err;
+
+	err = do_aio(ctx, type, io_fd, buf, len, offset, aio);
+	if(err){
+		reply = ((struct aio_thread_reply) { .data = aio,
+					 .err  = err });
+		err = os_write_file(aio->reply_fd, &reply, sizeof(reply));
+		if(err != sizeof(reply))
+			printk("submit_aio_26 - write failed, "
+			       "fd = %d, err = %d\n", aio->reply_fd, -err);
+		else err = 0;
+	}
+
+	return err;
 }
 
 #else
 #define DEFAULT_24_AIO 1
 static int init_aio_26(void)
 {
-        return -ENOSYS;
+	return -ENOSYS;
 }
 
 static int submit_aio_26(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
-        return -ENOSYS;
+	return -ENOSYS;
 }
 #endif
 
@@ -310,8 +312,8 @@ static int aio_24 = DEFAULT_24_AIO;
 
 static int __init set_aio_24(char *name, int *add)
 {
-        aio_24 = 1;
-        return 0;
+	aio_24 = 1;
+	return 0;
 }
 
 __uml_setup("aio=2.4", set_aio_24,
@@ -328,28 +330,27 @@ __uml_setup("aio=2.4", set_aio_24,
 
 static int init_aio(void)
 {
-        int err;
-
-        CHOOSE_MODE(({
-                if(!aio_24){
-                        printk("Disabling 2.6 AIO in tt mode\n");
-                        aio_24 = 1;
-                } }), (void) 0);
-
-        if(!aio_24){
-                err = init_aio_26();
-                if(err && (errno == ENOSYS)){
-                        printk("2.6 AIO not supported on the host - "
-                               "reverting to 2.4 AIO\n");
-                        aio_24 = 1;
-                }
-                else return err;
-        }
-
-        if(aio_24)
-                return init_aio_24();
-
-        return 0;
+	int err;
+
+	CHOOSE_MODE(({ if(!aio_24){
+			    printk("Disabling 2.6 AIO in tt mode\n");
+			    aio_24 = 1;
+		    } }), (void) 0);
+
+	if(!aio_24){
+		err = init_aio_26();
+		if(err && (errno == ENOSYS)){
+			printk("2.6 AIO not supported on the host - "
+			       "reverting to 2.4 AIO\n");
+			aio_24 = 1;
+		}
+		else return err;
+	}
+
+	if(aio_24)
+		return init_aio_24();
+
+	return 0;
 }
 
 /* The reason for the __initcall/__uml_exitcall asymmetry is that init_aio
@@ -362,8 +363,8 @@ __initcall(init_aio);
 
 static void exit_aio(void)
 {
-        if(aio_pid != -1)
-                os_kill_process(aio_pid, 1);
+	if(aio_pid != -1)
+		os_kill_process(aio_pid, 1);
 }
 
 __uml_exitcall(exit_aio);
@@ -371,30 +372,30 @@ __uml_exitcall(exit_aio);
 static int submit_aio_24(enum aio_type type, int io_fd, char *buf, int len,
 			 unsigned long long offset, struct aio_context *aio)
 {
-        struct aio_thread_req req = { .type 		= type,
-                                      .io_fd		= io_fd,
-                                      .offset		= offset,
-                                      .buf		= buf,
-                                      .len		= len,
-                                      .aio		= aio,
-        };
-        int err;
-
-        err = os_write_file(aio_req_fd_w, &req, sizeof(req));
-        if(err == sizeof(req))
-                err = 0;
-
-        return err;
+	struct aio_thread_req req = { .type 		= type,
+				      .io_fd		= io_fd,
+				      .offset		= offset,
+				      .buf		= buf,
+				      .len		= len,
+				      .aio		= aio,
+	};
+	int err;
+
+	err = os_write_file(aio_req_fd_w, &req, sizeof(req));
+	if(err == sizeof(req))
+		err = 0;
+
+	return err;
 }
 
 int submit_aio(enum aio_type type, int io_fd, char *buf, int len,
-               unsigned long long offset, int reply_fd,
-               struct aio_context *aio)
+	       unsigned long long offset, int reply_fd,
+	       struct aio_context *aio)
 {
-        aio->reply_fd = reply_fd;
-        if(aio_24)
-                return submit_aio_24(type, io_fd, buf, len, offset, aio);
-        else {
-                return submit_aio_26(type, io_fd, buf, len, offset, aio);
-        }
+	aio->reply_fd = reply_fd;
+	if(aio_24)
+		return submit_aio_24(type, io_fd, buf, len, offset, aio);
+	else {
+		return submit_aio_26(type, io_fd, buf, len, offset, aio);
+	}
 }
diff --git a/arch/um/os-Linux/helper.c b/arch/um/os-Linux/helper.c
index 36cc8475bcd..6490a4ff40a 100644
--- a/arch/um/os-Linux/helper.c
+++ b/arch/um/os-Linux/helper.c
@@ -60,7 +60,7 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 
 	if((stack_out != NULL) && (*stack_out != 0))
 		stack = *stack_out;
-	else stack = alloc_stack(0, um_in_interrupt());
+	else stack = alloc_stack(0, __cant_sleep());
 	if(stack == 0)
 		return(-ENOMEM);
 
@@ -124,7 +124,7 @@ int run_helper_thread(int (*proc)(void *), void *arg, unsigned int flags,
 	unsigned long stack, sp;
 	int pid, status, err;
 
-	stack = alloc_stack(stack_order, um_in_interrupt());
+	stack = alloc_stack(stack_order, __cant_sleep());
 	if(stack == 0) return(-ENOMEM);
 
 	sp = stack + (page_size() << stack_order) - sizeof(void *);
diff --git a/arch/um/os-Linux/main.c b/arch/um/os-Linux/main.c
index 23da27d2256..2878e89a674 100644
--- a/arch/um/os-Linux/main.c
+++ b/arch/um/os-Linux/main.c
@@ -16,8 +16,6 @@
 #include "user_util.h"
 #include "kern_util.h"
 #include "mem_user.h"
-#include "signal_user.h"
-#include "time_user.h"
 #include "irq_user.h"
 #include "user.h"
 #include "init.h"
@@ -83,20 +81,8 @@ extern void scan_elf_aux( char **envp);
 int main(int argc, char **argv, char **envp)
 {
 	char **new_argv;
-	sigset_t mask;
 	int ret, i, err;
 
-	/* Enable all signals except SIGIO - in some environments, we can
-	 * enter with some signals blocked
-	 */
-
-	sigemptyset(&mask);
-	sigaddset(&mask, SIGIO);
-	if(sigprocmask(SIG_SETMASK, &mask, NULL) < 0){
-		perror("sigprocmask");
-		exit(1);
-	}
-
 #ifdef UML_CONFIG_CMDLINE_ON_HOST
 	/* Allocate memory for thread command lines */
 	if(argc < 2 || strlen(argv[1]) < THREAD_NAME_LEN - 1){
diff --git a/arch/um/os-Linux/process.c b/arch/um/os-Linux/process.c
index d9c52387c4a..7f5e2dac2a3 100644
--- a/arch/um/os-Linux/process.c
+++ b/arch/um/os-Linux/process.c
@@ -15,10 +15,10 @@
 #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"
+#include "longjmp.h"
 
 #define ARBITRARY_ADDR -1
 #define FAILURE_PID    -1
@@ -206,24 +206,13 @@ void init_new_thread_signals(int 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);
+	sigjmp_buf buf;
+	int n, enable;
+
+	*jmp_ptr = &buf;
+	n = UML_SIGSETJMP(&buf, enable);
+	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
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c
index c7bfd5ee392..f11b3124a0c 100644
--- a/arch/um/os-Linux/signal.c
+++ b/arch/um/os-Linux/signal.c
@@ -4,27 +4,74 @@
  */
 
 #include <signal.h>
-#include "time_user.h"
-#include "mode.h"
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <stdarg.h>
+#include <string.h>
+#include <sys/mman.h>
+#include "user_util.h"
+#include "user.h"
+#include "signal_kern.h"
+#include "sysdep/sigcontext.h"
 #include "sysdep/signal.h"
+#include "sigcontext.h"
+#include "mode.h"
+#include "os.h"
+
+/* These are the asynchronous signals.  SIGVTALRM and SIGARLM are handled
+ * together under SIGVTALRM_BIT.  SIGPROF is excluded because we want to
+ * be able to profile all of UML, not just the non-critical sections.  If
+ * profiling is not thread-safe, then that is not my problem.  We can disable
+ * profiling when SMP is enabled in that case.
+ */
+#define SIGIO_BIT 0
+#define SIGIO_MASK (1 << SIGIO_BIT)
+
+#define SIGVTALRM_BIT 1
+#define SIGVTALRM_MASK (1 << SIGVTALRM_BIT)
+
+#define SIGALRM_BIT 2
+#define SIGALRM_MASK (1 << SIGALRM_BIT)
+
+static int signals_enabled = 1;
+static int pending = 0;
 
 void sig_handler(ARCH_SIGHDLR_PARAM)
 {
 	struct sigcontext *sc;
+	int enabled;
+
+	/* Must be the first thing that this handler does - x86_64 stores
+	 * the sigcontext in %rdx, and we need to save it before it has a
+	 * chance to get trashed.
+	 */
 
 	ARCH_GET_SIGCONTEXT(sc, sig);
+
+	enabled = signals_enabled;
+	if(!enabled && (sig == SIGIO)){
+		pending |= SIGIO_MASK;
+		return;
+	}
+
+	block_signals();
+
 	CHOOSE_MODE_PROC(sig_handler_common_tt, sig_handler_common_skas,
 			 sig, sc);
+
+	set_signals(enabled);
 }
 
 extern int timer_irq_inited;
 
-void alarm_handler(ARCH_SIGHDLR_PARAM)
+static void real_alarm_handler(int sig, struct sigcontext *sc)
 {
-	struct sigcontext *sc;
-
-	ARCH_GET_SIGCONTEXT(sc, sig);
-	if(!timer_irq_inited) return;
+	if(!timer_irq_inited){
+		signals_enabled = 1;
+		return;
+	}
 
 	if(sig == SIGALRM)
 		switch_timers(0);
@@ -34,15 +81,180 @@ void alarm_handler(ARCH_SIGHDLR_PARAM)
 
 	if(sig == SIGALRM)
 		switch_timers(1);
+
 }
 
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */
+void alarm_handler(ARCH_SIGHDLR_PARAM)
+{
+	struct sigcontext *sc;
+	int enabled;
+
+	ARCH_GET_SIGCONTEXT(sc, sig);
+
+	enabled = signals_enabled;
+	if(!signals_enabled){
+		if(sig == SIGVTALRM)
+			pending |= SIGVTALRM_MASK;
+		else pending |= SIGALRM_MASK;
+
+		return;
+	}
+
+	block_signals();
+
+	real_alarm_handler(sig, sc);
+	set_signals(enabled);
+}
+
+extern void do_boot_timer_handler(struct sigcontext * sc);
+
+void boot_timer_handler(ARCH_SIGHDLR_PARAM)
+{
+	struct sigcontext *sc;
+	int enabled;
+
+	ARCH_GET_SIGCONTEXT(sc, sig);
+
+	enabled = signals_enabled;
+	if(!enabled){
+		if(sig == SIGVTALRM)
+			pending |= SIGVTALRM_MASK;
+		else pending |= SIGALRM_MASK;
+		return;
+	}
+
+	block_signals();
+
+	do_boot_timer_handler(sc);
+	set_signals(enabled);
+}
+
+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 *) });
+
+	if(sigaltstack(&stack, NULL) != 0)
+		panic("enabling signal stack failed, errno = %d\n", errno);
+}
+
+void remove_sigstack(void)
+{
+	stack_t stack = ((stack_t) { .ss_flags	= SS_DISABLE,
+				     .ss_sp	= NULL,
+				     .ss_size	= 0 });
+
+	if(sigaltstack(&stack, NULL) != 0)
+		panic("disabling signal stack failed, errno = %d\n", errno);
+}
+
+void set_handler(int sig, void (*handler)(int), int flags, ...)
+{
+	struct sigaction action;
+	va_list ap;
+	sigset_t sig_mask;
+	int mask;
+
+	va_start(ap, flags);
+	action.sa_handler = handler;
+	sigemptyset(&action.sa_mask);
+	while((mask = va_arg(ap, int)) != -1){
+		sigaddset(&action.sa_mask, mask);
+	}
+	va_end(ap);
+	action.sa_flags = flags;
+	action.sa_restorer = NULL;
+	if(sigaction(sig, &action, NULL) < 0)
+		panic("sigaction failed - errno = %d\n", errno);
+
+	sigemptyset(&sig_mask);
+	sigaddset(&sig_mask, sig);
+	if(sigprocmask(SIG_UNBLOCK, &sig_mask, NULL) < 0)
+		panic("sigprocmask failed - errno = %d\n", errno);
+}
+
+int change_sig(int signal, int on)
+{
+	sigset_t sigset, old;
+
+	sigemptyset(&sigset);
+	sigaddset(&sigset, signal);
+	sigprocmask(on ? SIG_UNBLOCK : SIG_BLOCK, &sigset, &old);
+	return(!sigismember(&old, signal));
+}
+
+void block_signals(void)
+{
+	signals_enabled = 0;
+}
+
+void unblock_signals(void)
+{
+	int save_pending;
+
+	if(signals_enabled == 1)
+		return;
+
+	/* We loop because the IRQ handler returns with interrupts off.  So,
+	 * interrupts may have arrived and we need to re-enable them and
+	 * recheck pending.
+	 */
+	while(1){
+		/* Save and reset save_pending after enabling signals.  This
+		 * way, pending won't be changed while we're reading it.
+		 */
+		signals_enabled = 1;
+
+		save_pending = pending;
+		if(save_pending == 0)
+			return;
+
+		pending = 0;
+
+		/* We have pending interrupts, so disable signals, as the
+		 * handlers expect them off when they are called.  They will
+		 * be enabled again above.
+		 */
+
+		signals_enabled = 0;
+
+		/* Deal with SIGIO first because the alarm handler might
+		 * schedule, leaving the pending SIGIO stranded until we come
+		 * back here.
+		 */
+		if(save_pending & SIGIO_MASK)
+			CHOOSE_MODE_PROC(sig_handler_common_tt,
+					 sig_handler_common_skas, SIGIO, NULL);
+
+		if(save_pending & SIGALRM_MASK)
+			real_alarm_handler(SIGALRM, NULL);
+
+		if(save_pending & SIGVTALRM_MASK)
+			real_alarm_handler(SIGVTALRM, NULL);
+	}
+}
+
+int get_signals(void)
+{
+	return signals_enabled;
+}
+
+int set_signals(int enable)
+{
+	int ret;
+	if(signals_enabled == enable)
+		return enable;
+
+	ret = signals_enabled;
+	if(enable)
+		unblock_signals();
+	else block_signals();
+
+	return ret;
+}
+
+void os_usr1_signal(int on)
+{
+	change_sig(SIGUSR1, on);
+}
diff --git a/arch/um/os-Linux/skas/Makefile b/arch/um/os-Linux/skas/Makefile
new file mode 100644
index 00000000000..5fd8d4dad66
--- /dev/null
+++ b/arch/um/os-Linux/skas/Makefile
@@ -0,0 +1,10 @@
+#
+# Copyright (C) 2002 - 2004 Jeff Dike (jdike@addtoit.com)
+# Licensed under the GPL
+#
+
+obj-y := mem.o process.o trap.o
+
+USER_OBJS := mem.o process.o trap.o
+
+include arch/um/scripts/Makefile.rules
diff --git a/arch/um/os-Linux/skas/mem.c b/arch/um/os-Linux/skas/mem.c
new file mode 100644
index 00000000000..9890e9090f5
--- /dev/null
+++ b/arch/um/os-Linux/skas/mem.c
@@ -0,0 +1,283 @@
+/*
+ * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
+ * Licensed under the GPL
+ */
+
+#include <signal.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"
+
+extern unsigned long batch_syscall_stub, __syscall_stub_start;
+
+extern void wait_stub_done(int pid, int sig, char * fname);
+
+static inline unsigned long *check_init_stack(struct mm_id * mm_idp,
+					      unsigned long *stack)
+{
+	if(stack == NULL) {
+		stack = (unsigned long *) mm_idp->stack + 2;
+		*stack = 0;
+	}
+	return stack;
+}
+
+extern int proc_mm;
+
+int single_count = 0;
+int multi_count = 0;
+int multi_op_count = 0;
+
+static inline long do_syscall_stub(struct mm_id * mm_idp, void **addr)
+{
+	unsigned long regs[MAX_REG_NR];
+	int n;
+	long ret, offset;
+	unsigned long * data;
+	unsigned long * syscall;
+	int pid = mm_idp->u.pid;
+
+	if(proc_mm)
+#warning Need to look up userspace_pid by cpu
+		pid = userspace_pid[0];
+
+	multi_count++;
+
+	get_safe_registers(regs);
+	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)
+		panic("do_syscall_stub : PTRACE_SETREGS failed, errno = %d\n",
+		      n);
+
+	wait_stub_done(pid, 0, "do_syscall_stub");
+
+	/* When the stub stops, we find the following values on the
+	 * beginning of the stack: