arch/um/kernel/skas/process.c

   1 /*
   2  * Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <stdlib.h>
   7 #include <unistd.h>
   8 #include <errno.h>
   9 #include <signal.h>
  10 #include <setjmp.h>
  11 #include <sched.h>
  12 #include <sys/wait.h>
  13 #include <sys/mman.h>
  14 #include <sys/user.h>
  15 #include <asm/unistd.h>
  16 #include "user.h"
  17 #include "ptrace_user.h"
  18 #include "time_user.h"
  19 #include "sysdep/ptrace.h"
  20 #include "user_util.h"
  21 #include "kern_util.h"
  22 #include "skas.h"
  23 #include "sysdep/sigcontext.h"
  24 #include "os.h"
  25 #include "proc_mm.h"
  26 #include "skas_ptrace.h"
  27 #include "chan_user.h"
  28 #include "signal_user.h"
  29 #include "registers.h"
  30
  31 int is_skas_winch(int pid, int fd, void *data)
  32 {
  33         if(pid != os_getpid())
  34                 return(0);
  35
  36         register_winch_irq(-1, fd, -1, data);
  37         return(1);
  38 }
  39
  40 static void handle_segv(int pid)
  41 {
  42         struct ptrace_faultinfo fault;
  43         int err;
  44
  45         err = ptrace(PTRACE_FAULTINFO, pid, 0, &fault);
  46         if(err)
  47                 panic("handle_segv - PTRACE_FAULTINFO failed, errno = %d\n",
  48                       errno);
  49
  50         segv(fault.addr, 0, FAULT_WRITE(fault.is_write), 1, NULL);
  51 }
  52
  53 /*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
  54 static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
  55 {
  56         int err, status;
  57
  58         /* Mark this as a syscall */
  59         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
  60
  61         if (!local_using_sysemu)
  62         {
  63                 err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
  64                 if(err < 0)
  65                         panic("handle_trap - nullifying syscall failed errno = %d\n",
  66                               errno);
  67
  68                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
  69                 if(err < 0)
  70                         panic("handle_trap - continuing to end of syscall failed, "
  71                               "errno = %d\n", errno);
  72
  73                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
  74                 if((err < 0) || !WIFSTOPPED(status) ||
  75                    (WSTOPSIG(status) != SIGTRAP + 0x80))
  76                         panic("handle_trap - failed to wait at end of syscall, "
  77                               "errno = %d, status = %d\n", errno, status);
  78         }
  79
  80         handle_syscall(regs);
  81 }
  82
  83 static int userspace_tramp(void *arg)
  84 {
  85         init_new_thread_signals(0);
  86         enable_timer();
  87         ptrace(PTRACE_TRACEME, 0, 0, 0);
  88         os_stop_process(os_getpid());
  89         return(0);
  90 }
  91
  92 /* Each element set once, and only accessed by a single processor anyway */
  93 #undef NR_CPUS
  94 #define NR_CPUS 1
  95 int userspace_pid[NR_CPUS];
  96
  97 void start_userspace(int cpu)
  98 {
  99         void *stack;
 100         unsigned long sp;
 101         int pid, status, n;
 102
 103         stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
 104                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 105         if(stack == MAP_FAILED)
 106                 panic("start_userspace : mmap failed, errno = %d", errno);
 107         sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
 108
 109         pid = clone(userspace_tramp, (void *) sp,
 110                     CLONE_FILES | CLONE_VM | SIGCHLD, NULL);
 111         if(pid < 0)
 112                 panic("start_userspace : clone failed, errno = %d", errno);
 113
 114         do {
 115                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 116                 if(n < 0)
 117                         panic("start_userspace : wait failed, errno = %d",
 118                               errno);
 119         } while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 120
 121         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
 122                 panic("start_userspace : expected SIGSTOP, got status = %d",
 123                       status);
 124
 125         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
 126                 panic("start_userspace : PTRACE_SETOPTIONS failed, errno=%d\n",
 127                       errno);
 128
 129         if(munmap(stack, PAGE_SIZE) < 0)
 130                 panic("start_userspace : munmap failed, errno = %d\n", errno);
 131
 132         userspace_pid[cpu] = pid;
 133 }
 134
 135 void userspace(union uml_pt_regs *regs)
 136 {
 137         int err, status, op, pid = userspace_pid[0];
 138         int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
 139
 140         while(1){
 141                 restore_registers(pid, regs);
 142
 143                 /* Now we set local_using_sysemu to be used for one loop */
 144                 local_using_sysemu = get_using_sysemu();
 145
 146                 op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
 147
 148                 err = ptrace(op, pid, 0, 0);
 149                 if(err)
 150                         panic("userspace - could not resume userspace process, "
 151                               "pid=%d, ptrace operation = %d, errno = %d\n",
 152                               op, errno);
 153
 154                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
 155                 if(err < 0)
 156                         panic("userspace - waitpid failed, errno = %d\n",
 157                               errno);
 158
 159                 regs->skas.is_user = 1;
 160                 save_registers(pid, regs);
 161                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 162
 163                 if(WIFSTOPPED(status)){
 164                         switch(WSTOPSIG(status)){
 165                         case SIGSEGV:
 166                                 handle_segv(pid);
 167                                 break;
 168                         case SIGTRAP + 0x80:
 169                                 handle_trap(pid, regs, local_using_sysemu);
 170                                 break;
 171                         case SIGTRAP:
 172                                 relay_signal(SIGTRAP, regs);
 173                                 break;
 174                         case SIGIO:
 175                         case SIGVTALRM:
 176                         case SIGILL:
 177                         case SIGBUS:
 178                         case SIGFPE:
 179                         case SIGWINCH:
 180                                 user_signal(WSTOPSIG(status), regs);
 181                                 break;
 182                         default:
 183                                 printk("userspace - child stopped with signal "
 184                                        "%d\n", WSTOPSIG(status));
 185                         }
 186                         interrupt_end();
 187
 188                         /* Avoid -ERESTARTSYS handling in host */
 189                         PT_SYSCALL_NR(regs->skas.regs) = -1;
 190                 }
 191         }
 192 }
 193
 194 void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
 195                 void (*handler)(int))
 196 {
 197         unsigned long flags;
 198         sigjmp_buf switch_buf, fork_buf;
 199
 200         *switch_buf_ptr = &switch_buf;
 201         *fork_buf_ptr = &fork_buf;
 202
 203         /* Somewhat subtle - siglongjmp restores the signal mask before doing
 204          * the longjmp.  This means that when jumping from one stack to another
 205          * when the target stack has interrupts enabled, an interrupt may occur
 206          * on the source stack.  This is bad when starting up a process because
 207          * it's not supposed to get timer ticks until it has been scheduled.
 208          * So, we disable interrupts around the sigsetjmp to ensure that
 209          * they can't happen until we get back here where they are safe.
 210          */
 211         flags = get_signals();
 212         block_signals();
 213         if(sigsetjmp(fork_buf, 1) == 0)
 214                 new_thread_proc(stack, handler);
 215
 216         remove_sigstack();
 217
 218         set_signals(flags);
 219 }
 220
 221 void thread_wait(void *sw, void *fb)
 222 {
 223         sigjmp_buf buf, **switch_buf = sw, *fork_buf;
 224
 225         *switch_buf = &buf;
 226         fork_buf = fb;
 227         if(sigsetjmp(buf, 1) == 0)
 228                 siglongjmp(*fork_buf, 1);
 229 }
 230
 231 void switch_threads(void *me, void *next)
 232 {
 233         sigjmp_buf my_buf, **me_ptr = me, *next_buf = next;
 234
 235         *me_ptr = &my_buf;
 236         if(sigsetjmp(my_buf, 1) == 0)
 237                 siglongjmp(*next_buf, 1);
 238 }
 239
 240 static sigjmp_buf initial_jmpbuf;
 241
 242 /* XXX Make these percpu */
 243 static void (*cb_proc)(void *arg);
 244 static void *cb_arg;
 245 static sigjmp_buf *cb_back;
 246
 247 int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
 248 {
 249         sigjmp_buf **switch_buf = switch_buf_ptr;
 250         int n;
 251
 252         *fork_buf_ptr = &initial_jmpbuf;
 253         n = sigsetjmp(initial_jmpbuf, 1);
 254         if(n == 0)
 255                 new_thread_proc((void *) stack, new_thread_handler);
 256         else if(n == 1)
 257                 remove_sigstack();
 258         else if(n == 2){
 259                 (*cb_proc)(cb_arg);
 260                 siglongjmp(*cb_back, 1);
 261         }
 262         else if(n == 3){
 263                 kmalloc_ok = 0;
 264                 return(0);
 265         }
 266         else if(n == 4){
 267                 kmalloc_ok = 0;
 268                 return(1);
 269         }
 270         siglongjmp(**switch_buf, 1);
 271 }
 272
 273 void remove_sigstack(void)
 274 {
 275         stack_t stack = ((stack_t) { .ss_flags  = SS_DISABLE,
 276                                      .ss_sp     = NULL,
 277                                      .ss_size   = 0 });
 278
 279         if(sigaltstack(&stack, NULL) != 0)
 280                 panic("disabling signal stack failed, errno = %d\n", errno);
 281 }
 282
 283 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 284 {
 285         sigjmp_buf here;
 286
 287         cb_proc = proc;
 288         cb_arg = arg;
 289         cb_back = &here;
 290
 291         block_signals();
 292         if(sigsetjmp(here, 1) == 0)
 293                 siglongjmp(initial_jmpbuf, 2);
 294         unblock_signals();
 295
 296         cb_proc = NULL;
 297         cb_arg = NULL;
 298         cb_back = NULL;
 299 }
 300
 301 void halt_skas(void)
 302 {
 303         block_signals();
 304         siglongjmp(initial_jmpbuf, 3);
 305 }
 306
 307 void reboot_skas(void)
 308 {
 309         block_signals();
 310         siglongjmp(initial_jmpbuf, 4);
 311 }
 312
 313 void switch_mm_skas(int mm_fd)
 314 {
 315         int err;
 316
 317 #warning need cpu pid in switch_mm_skas
 318         err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0, mm_fd);
 319         if(err)
 320                 panic("switch_mm_skas - PTRACE_SWITCH_MM failed, errno = %d\n",
 321                       errno);
 322 }
 323
 324 void kill_off_processes_skas(void)
 325 {
 326 #warning need to loop over userspace_pids in kill_off_processes_skas
 327         os_kill_ptraced_process(userspace_pid[0], 1);
 328 }
 329
 330 /*
 331  * Overrides for Emacs so that we follow Linus's tabbing style.
 332  * Emacs will notice this stuff at the end of the file and automatically
 333  * adjust the settings for this buffer only.  This must remain at the end
 334  * of the file.
 335  * ---------------------------------------------------------------------------
 336  * Local variables:
 337  * c-file-style: "linux"
 338  * End:
 339  */