[PATCH] uml: move libc-dependent skas process handling
Gennady Sharapov [Thu, 19 Jan 2006 01:42:46 +0000 (17:42 -0800)]
The serial UML OS-abstraction layer patch (um/kernel/skas dir).

This moves all systemcalls from skas/process.c file under os-Linux dir and
join skas/process.c and skas/process_kern.c files.

Signed-off-by: Gennady Sharapov <gennady.v.sharapov@intel.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/include/os.h
arch/um/include/skas/mode-skas.h
arch/um/include/skas/mode_kern_skas.h
arch/um/include/skas/skas.h
arch/um/kernel/skas/Makefile
arch/um/kernel/skas/process_kern.c
arch/um/os-Linux/signal.c
arch/um/os-Linux/skas/Makefile
arch/um/os-Linux/skas/process.c [new file with mode: 0644]

index 8006e08..eb1710b 100644 (file)
@@ -232,6 +232,7 @@ extern void block_signals(void);
 extern void unblock_signals(void);
 extern int get_signals(void);
 extern int set_signals(int enable);
+extern void os_usr1_signal(int on);
 
 /* trap.c */
 extern void os_fill_handlinfo(struct kern_handlers h);
@@ -272,4 +273,22 @@ extern int protect(struct mm_id * mm_idp, unsigned long addr,
                   unsigned long len, int r, int w, int x, int done,
                   void **data);
 
+/* skas/process.c */
+extern int is_skas_winch(int pid, int fd, void *data);
+extern int start_userspace(unsigned long stub_stack);
+extern int copy_context_skas0(unsigned long stack, int pid);
+extern void userspace(union uml_pt_regs *regs);
+extern void map_stub_pages(int fd, unsigned long code,
+                          unsigned long data, unsigned long stack);
+extern void new_thread(void *stack, void **switch_buf_ptr,
+                        void **fork_buf_ptr, void (*handler)(int));
+extern void thread_wait(void *sw, void *fb);
+extern void switch_threads(void *me, void *next);
+extern int start_idle_thread(void *stack, void *switch_buf_ptr,
+                            void **fork_buf_ptr);
+extern void initial_thread_cb_skas(void (*proc)(void *),
+                                void *arg);
+extern void halt_skas(void);
+extern void reboot_skas(void);
+
 #endif
index 64b9600..260065c 100644 (file)
@@ -14,9 +14,6 @@ extern unsigned long exec_fpx_regs[];
 extern int have_fpx_regs;
 
 extern void sig_handler_common_skas(int sig, void *sc_ptr);
-extern void halt_skas(void);
-extern void reboot_skas(void);
 extern void kill_off_processes_skas(void);
-extern int is_skas_winch(int pid, int fd, void *data);
 
 #endif
index dd9f2d7..63c5873 100644 (file)
@@ -18,7 +18,6 @@ extern int copy_thread_skas(int nr, unsigned long clone_flags,
                            unsigned long sp, unsigned long stack_top,
                            struct task_struct *p, struct pt_regs *regs);
 extern void release_thread_skas(struct task_struct *task);
-extern void initial_thread_cb_skas(void (*proc)(void *), void *arg);
 extern void init_idle_skas(void);
 extern void flush_tlb_kernel_range_skas(unsigned long start,
                                        unsigned long end);
index 7418f2a..8635728 100644 (file)
@@ -13,21 +13,12 @@ extern int userspace_pid[];
 extern int proc_mm, ptrace_faultinfo, ptrace_ldt;
 extern int skas_needs_stub;
 
-extern void switch_threads(void *me, void *next);
-extern void thread_wait(void *sw, void *fb);
-extern void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
-                      void (*handler)(int));
-extern int start_idle_thread(void *stack, void *switch_buf_ptr,
-                            void **fork_buf_ptr);
 extern int user_thread(unsigned long stack, int flags);
-extern void userspace(union uml_pt_regs *regs);
 extern void new_thread_proc(void *stack, void (*handler)(int sig));
 extern void new_thread_handler(int sig);
 extern void handle_syscall(union uml_pt_regs *regs);
 extern void user_signal(int sig, union uml_pt_regs *regs, int pid);
 extern int new_mm(unsigned long stack);
-extern int start_userspace(unsigned long stub_stack);
-extern int copy_context_skas0(unsigned long stack, int pid);
 extern void get_skas_faultinfo(int pid, struct faultinfo * fi);
 extern long execute_syscall_skas(void *r);
 extern unsigned long current_stub_stack(void);
index eb664c6..57181a9 100644 (file)
@@ -3,10 +3,10 @@
 # Licensed under the GPL
 #
 
-obj-y := clone.o exec_kern.o mem.o mmu.o process.o process_kern.o \
+obj-y := clone.o exec_kern.o mem.o mmu.o process_kern.o \
        syscall.o tlb.o uaccess.o
 
-USER_OBJS := process.o clone.o
+USER_OBJS := clone.o
 
 include arch/um/scripts/Makefile.rules
 
index a340006..3f70a2e 100644 (file)
@@ -1,4 +1,4 @@
-/* 
+/*
  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
  * Licensed under the GPL
  */
@@ -32,7 +32,7 @@ void switch_to_skas(void *prev, void *next)
        if(current->pid == 0)
                switch_timers(0);
 
-       switch_threads(&from->thread.mode.skas.switch_buf, 
+       switch_threads(&from->thread.mode.skas.switch_buf,
                       to->thread.mode.skas.switch_buf);
 
        if(current->pid == 0)
@@ -48,8 +48,8 @@ void new_thread_handler(int sig)
 
        fn = current->thread.request.u.thread.proc;
        arg = current->thread.request.u.thread.arg;
-       change_sig(SIGUSR1, 1);
-       thread_wait(&current->thread.mode.skas.switch_buf, 
+       os_usr1_signal(1);
+       thread_wait(&current->thread.mode.skas.switch_buf,
                    current->thread.mode.skas.fork_buf);
 
        if(current->thread.prev_sched != NULL)
@@ -80,8 +80,8 @@ void release_thread_skas(struct task_struct *task)
 
 void fork_handler(int sig)
 {
-        change_sig(SIGUSR1, 1);
-       thread_wait(&current->thread.mode.skas.switch_buf, 
+       os_usr1_signal(1);
+       thread_wait(&current->thread.mode.skas.switch_buf,
                    current->thread.mode.skas.fork_buf);
        
        force_flush_all();
@@ -91,13 +91,13 @@ void fork_handler(int sig)
        schedule_tail(current->thread.prev_sched);
        current->thread.prev_sched = NULL;
 
-       /* Handle any immediate reschedules or signals */
+/* Handle any immediate reschedules or signals */
        interrupt_end();
        userspace(&current->thread.regs.regs);
 }
 
 int copy_thread_skas(int nr, unsigned long clone_flags, unsigned long sp,
-                    unsigned long stack_top, struct task_struct * p, 
+                    unsigned long stack_top, struct task_struct * p,
                     struct pt_regs *regs)
 {
        void (*handler)(int);
@@ -121,8 +121,6 @@ int copy_thread_skas(int nr, unsigned long clone_flags, unsigned long sp,
        return(0);
 }
 
-extern void map_stub_pages(int fd, unsigned long code,
-                          unsigned long data, unsigned long stack);
 int new_mm(unsigned long stack)
 {
        int fd;
index 884e457..56ca959 100644 (file)
@@ -194,3 +194,8 @@ int set_signals(int enable)
 
        return(ret);
 }
+
+void os_usr1_signal(int on)
+{
+       change_sig(SIGUSR1, on);
+}
index 79cc6c7..5fd8d4d 100644 (file)
@@ -3,8 +3,8 @@
 # Licensed under the GPL
 #
 
-obj-y := mem.o trap.o
+obj-y := mem.o process.o trap.o
 
-USER_OBJS := mem.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/process.c b/arch/um/os-Linux/skas/process.c
new file mode 100644 (file)
index 0000000..f787854
--- /dev/null
@@ -0,0 +1,565 @@
+/*
+ * Copyright (C) 2002- 2004 Jeff Dike (jdike@addtoit.com)
+ * Licensed under the GPL
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <errno.h>
+#include <signal.h>
+#include <setjmp.h>
+#include <sched.h>
+#include "ptrace_user.h"
+#include <sys/wait.h>
+#include <sys/mman.h>
+#include <sys/user.h>
+#include <sys/time.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"
+
+int is_skas_winch(int pid, int fd, void *data)
+{
+       if(pid != os_getpgrp())
+               return(0);
+
+       register_winch_irq(-1, fd, -1, data);
+       return(1);
+}
+
+void wait_stub_done(int pid, int sig, char * fname)
+{
+       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;
+
+                       printk("Stub registers -\n");
+                       for(i = 0; i < HOST_FRAME_SIZE; i++)
+                               printk("\t%d - %lx\n", i, regs[i]);
+               }
+               panic("%s : failed to wait for SIGUSR1/SIGTRAP, "
+                     "pid = %d, n = %d, errno = %d, status = 0x%x\n",
+                     fname, pid, n, errno, status);
+       }
+}
+
+extern unsigned long current_stub_stack(void);
+
+void get_skas_faultinfo(int pid, struct faultinfo * fi)
+{
+       int err;
+
+       if(ptrace_faultinfo){
+               err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
+               if(err)
+                       panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
+                             "errno = %d\n", errno);
+
+               /* Special handling for i386, which has different structs */
+               if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
+                       memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
+                              sizeof(struct faultinfo) -
+                              sizeof(struct ptrace_faultinfo));
+       }
+       else {
+               wait_stub_done(pid, SIGSEGV, "get_skas_faultinfo");
+
+               /* 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));
+       }
+}
+
+static void handle_segv(int pid, union uml_pt_regs * regs)
+{
+       get_skas_faultinfo(pid, &regs->skas.faultinfo);
+       segv(regs->skas.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)
+{
+       int err, status;
+
+       /* Mark this as a syscall */
+       UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
+
+       if (!local_using_sysemu)
+       {
+               err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET,
+                            __NR_getpid);
+               if(err < 0)
+                       panic("handle_trap - nullifying syscall failed errno = %d\n",
+                             errno);
+
+               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);
+       }
+
+       handle_syscall(regs);
+}
+
+extern int __syscall_stub_start;
+int stub_code_fd = -1;
+__u64 stub_code_offset;
+
+static int userspace_tramp(void *stack)
+{
+       void *addr;
+
+       ptrace(PTRACE_TRACEME, 0, 0, 0);
+
+       init_new_thread_signals(1);
+       enable_timer();
+
+       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
+                */
+               addr = mmap64((void *) UML_CONFIG_STUB_CODE, page_size(),
+                             PROT_EXEC, MAP_FIXED | MAP_PRIVATE,
+                             stub_code_fd, stub_code_offset);
+               if(addr == MAP_FAILED){
+                       printk("mapping stub code failed, errno = %d\n",
+                              errno);
+                       exit(1);
+               }
+
+               if(stack != NULL){
+                       int fd;
+                       __u64 offset;
+                       fd = phys_mapping(to_phys(stack), &offset);
+                       addr = mmap((void *) UML_CONFIG_STUB_DATA, page_size(),
+                                   PROT_READ | PROT_WRITE,
+                                   MAP_FIXED | MAP_SHARED, fd, offset);
+                       if(addr == MAP_FAILED){
+                               printk("mapping stub stack failed, "
+                                      "errno = %d\n", errno);
+                               exit(1);
+                       }
+               }
+       }
+       if(!ptrace_faultinfo){
+               unsigned long v = UML_CONFIG_STUB_CODE +
+                                 (unsigned long) stub_segv_handler -
+                                 (unsigned long) &__syscall_stub_start;
+
+               set_sigstack((void *) UML_CONFIG_STUB_DATA, page_size());
+               set_handler(SIGSEGV, (void *) v, SA_ONSTACK,
+                           SIGIO, SIGWINCH, SIGALRM, SIGVTALRM,
+                           SIGUSR1, -1);
+       }
+
+       os_stop_process(os_getpid());
+       return(0);
+}
+
+/* Each element set once, and only accessed by a single processor anyway */
+#undef NR_CPUS
+#define NR_CPUS 1
+int userspace_pid[NR_CPUS];
+
+int start_userspace(unsigned long stub_stack)
+{
+       void *stack;
+       unsigned long sp;
+       int pid, status, n, flags;
+
+       if ( stub_code_fd == -1 )
+               stub_code_fd = phys_mapping(to_phys(&__syscall_stub_start),
+                                           &stub_code_offset);
+
+       stack = mmap(NULL, 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 *);
+
+       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);
+
+       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));
+
+       if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
+               panic("start_userspace : expected SIGSTOP, got status = %d",
+                     status);
+
+       if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
+               panic("start_userspace : PTRACE_OLDSETOPTIONS failed, errno=%d\n",
+                     errno);
+
+       if(munmap(stack, PAGE_SIZE) < 0)
+               panic("start_userspace : munmap failed, errno = %d\n", errno);
+
+       return(pid);
+}
+
+void userspace(union uml_pt_regs *regs)
+{
+       int err, status, op, pid = userspace_pid[0];
+       int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
+
+       while(1){
+               restore_registers(pid, regs);
+
+               /* 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));
+
+               err = ptrace(op, pid, 0, 0);
+               if(err)
+                       panic("userspace - could not resume userspace process, "
+                             "pid=%d, ptrace operation = %d, errno = %d\n",
+                             op, errno);
+
+               CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
+               if(err < 0)
+                       panic("userspace - waitpid failed, errno = %d\n",
+                             errno);
+
+               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)){
+                       case SIGSEGV:
+                               if(PTRACE_FULL_FAULTINFO || !ptrace_faultinfo)
+                                       user_signal(SIGSEGV, regs, pid);
+                               else handle_segv(pid, regs);
+                               break;
+                       case SIGTRAP + 0x80:
+                               handle_trap(pid, regs, local_using_sysemu);
+                               break;
+                       case SIGTRAP:
+                               relay_signal(SIGTRAP, regs);
+                               break;
+                       case SIGIO:
+                       case SIGVTALRM:
+                       case SIGILL:
+                       case SIGBUS:
+                       case SIGFPE:
+                       case SIGWINCH:
+                               user_signal(WSTOPSIG(status), regs, pid);
+                               break;
+                       default:
+                               printk("userspace - child stopped with signal "
+                                      "%d\n", WSTOPSIG(status));
+                       }
+                   again:
+                       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;
+               }
+       }
+}
+#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
+
+int copy_context_skas0(unsigned long new_stack, int pid)
+{
+       int err;
+       unsigned long regs[MAX_REG_NR];
+       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;
+       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
+        * 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);
+
+       /* 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, errno);
+
+       /* 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
+        * parent's stack, and check, if bad result.
+        */
+       wait_stub_done(pid, 0, "copy_context_skas0");
+
+       pid = data->err;
+       if(pid < 0)
+               panic("copy_context_skas0 - stub-parent reports error %d\n",
+                     pid);
+
+       /* 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 %d\n",
+                     child_data->err);
+
+       if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
+                  (void *)PTRACE_O_TRACESYSGOOD) < 0)
+               panic("copy_context_skas0 : PTRACE_OLDSETOPTIONS failed, "
+                     "errno = %d\n", errno);
+
+       return pid;
+}
+
+/*
+ * This is used only, if stub pages are needed, while proc_mm is
+ * availabl. 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)
+{
+       struct proc_mm_op mmop;
+       int n;
+
+       mmop = ((struct proc_mm_op) { .op        = MM_MMAP,
+                                     .u         =
+                                     { .mmap    =
+                                       { .addr    = code,
+                                         .len     = PAGE_SIZE,
+                                         .prot    = PROT_EXEC,
+                                         .flags   = MAP_FIXED | MAP_PRIVATE,
+                                         .fd      = stub_code_fd,
+                                         .offset  = stub_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);
+
+       if ( stack ) {
+               __u64 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,
+                                     .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);
+       }
+}
+
+void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
+               void (*handler)(int))
+{
+       unsigned long flags;
+       sigjmp_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(sigsetjmp(fork_buf, 1) == 0)
+               new_thread_proc(stack, handler);
+
+       remove_sigstack();
+
+       set_signals(flags);
+}
+
+void thread_wait(void *sw, void *fb)
+{
+       sigjmp_buf buf, **switch_buf = sw, *fork_buf;
+
+       *switch_buf = &buf;
+       fork_buf = fb;
+       if(sigsetjmp(buf, 1) == 0)
+               siglongjmp(*fork_buf, INIT_JMP_REMOVE_SIGSTACK);
+}
+
+void switch_threads(void *me, void *next)
+{
+       sigjmp_buf my_buf, **me_ptr = me, *next_buf = next;
+
+       *me_ptr = &my_buf;
+       if(sigsetjmp(my_buf, 1) == 0)
+               siglongjmp(*next_buf, 1);
+}
+
+static sigjmp_buf initial_jmpbuf;
+
+/* XXX Make these percpu */
+static void (*cb_proc)(void *arg);
+static void *cb_arg;
+static sigjmp_buf *cb_back;
+
+int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
+{
+       sigjmp_buf **switch_buf = switch_buf_ptr;
+       int n;
+
+       set_handler(SIGWINCH, (__sighandler_t) sig_handler,
+                   SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
+                   SIGVTALRM, -1);
+
+       *fork_buf_ptr = &initial_jmpbuf;
+       n = sigsetjmp(initial_jmpbuf, 1);
+       switch(n){
+       case INIT_JMP_NEW_THREAD:
+               new_thread_proc((void *) stack, new_thread_handler);
+               break;
+       case INIT_JMP_REMOVE_SIGSTACK:
+               remove_sigstack();
+               break;
+       case INIT_JMP_CALLBACK:
+               (*cb_proc)(cb_arg);
+               siglongjmp(*cb_back, 1);
+               break;
+       case INIT_JMP_HALT:
+               kmalloc_ok = 0;
+               return(0);
+       case INIT_JMP_REBOOT:
+               kmalloc_ok = 0;
+               return(1);
+       default:
+               panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
+       }
+       siglongjmp(**switch_buf, 1);
+}
+
+void initial_thread_cb_skas(void (*proc)(void *), void *arg)
+{
+       sigjmp_buf here;
+
+       cb_proc = proc;
+       cb_arg = arg;
+       cb_back = &here;
+
+       block_signals();
+       if(sigsetjmp(here, 1) == 0)
+               siglongjmp(initial_jmpbuf, INIT_JMP_CALLBACK);
+       unblock_signals();
+
+       cb_proc = NULL;
+       cb_arg = NULL;
+       cb_back = NULL;
+}
+
+void halt_skas(void)
+{
+       block_signals();
+       siglongjmp(initial_jmpbuf, INIT_JMP_HALT);
+}
+
+void reboot_skas(void)
+{
+       block_signals();
+       siglongjmp(initial_jmpbuf, INIT_JMP_REBOOT);
+}
+
+void switch_mm_skas(struct mm_id *mm_idp)
+{
+       int err;
+
+#warning need cpu pid in switch_mm_skas
+       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);
+       }
+       else userspace_pid[0] = mm_idp->u.pid;
+}