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 <string.h>
   8 #include <unistd.h>
   9 #include <errno.h>
  10 #include <signal.h>
  11 #include <setjmp.h>
  12 #include <sched.h>
  13 #include <sys/wait.h>
  14 #include <sys/mman.h>
  15 #include <sys/user.h>
  16 #include <asm/unistd.h>
  17 #include "user.h"
  18 #include "ptrace_user.h"
  19 #include "time_user.h"
  20 #include "sysdep/ptrace.h"
  21 #include "user_util.h"
  22 #include "kern_util.h"
  23 #include "skas.h"
  24 #include "sysdep/sigcontext.h"
  25 #include "os.h"
  26 #include "proc_mm.h"
  27 #include "skas_ptrace.h"
  28 #include "chan_user.h"
  29 #include "signal_user.h"
  30 #include "registers.h"
  31 #include "process.h"
  32
  33 int is_skas_winch(int pid, int fd, void *data)
  34 {
  35         if(pid != os_getpgrp())
  36                 return(0);
  37
  38         register_winch_irq(-1, fd, -1, data);
  39         return(1);
  40 }
  41
  42 void get_skas_faultinfo(int pid, struct faultinfo * fi)
  43 {
  44         int err;
  45
  46         err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
  47         if(err)
  48                 panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
  49                       "errno = %d\n", errno);
  50
  51         /* Special handling for i386, which has different structs */
  52         if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
  53                 memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
  54                        sizeof(struct faultinfo) -
  55                        sizeof(struct ptrace_faultinfo));
  56 }
  57
  58 static void handle_segv(int pid, union uml_pt_regs * regs)
  59 {
  60         get_skas_faultinfo(pid, &regs->skas.faultinfo);
  61         segv(regs->skas.faultinfo, 0, 1, NULL);
  62 }
  63
  64 /*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
  65 static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
  66 {
  67         int err, status;
  68
  69         /* Mark this as a syscall */
  70         UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
  71
  72         if (!local_using_sysemu)
  73         {
  74                 err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
  75                 if(err < 0)
  76                         panic("handle_trap - nullifying syscall failed errno = %d\n",
  77                               errno);
  78
  79                 err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
  80                 if(err < 0)
  81                         panic("handle_trap - continuing to end of syscall failed, "
  82                               "errno = %d\n", errno);
  83
  84                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
  85                 if((err < 0) || !WIFSTOPPED(status) ||
  86                    (WSTOPSIG(status) != SIGTRAP + 0x80))
  87                         panic("handle_trap - failed to wait at end of syscall, "
  88                               "errno = %d, status = %d\n", errno, status);
  89         }
  90
  91         handle_syscall(regs);
  92 }
  93
  94 static int userspace_tramp(void *arg)
  95 {
  96         init_new_thread_signals(0);
  97         enable_timer();
  98         ptrace(PTRACE_TRACEME, 0, 0, 0);
  99         os_stop_process(os_getpid());
 100         return(0);
 101 }
 102
 103 /* Each element set once, and only accessed by a single processor anyway */
 104 #undef NR_CPUS
 105 #define NR_CPUS 1
 106 int userspace_pid[NR_CPUS];
 107
 108 void start_userspace(int cpu)
 109 {
 110         void *stack;
 111         unsigned long sp;
 112         int pid, status, n;
 113
 114         stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
 115                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 116         if(stack == MAP_FAILED)
 117                 panic("start_userspace : mmap failed, errno = %d", errno);
 118         sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
 119
 120         pid = clone(userspace_tramp, (void *) sp,
 121                     CLONE_FILES | CLONE_VM | SIGCHLD, NULL);
 122         if(pid < 0)
 123                 panic("start_userspace : clone failed, errno = %d", errno);
 124
 125         do {
 126                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 127                 if(n < 0)
 128                         panic("start_userspace : wait failed, errno = %d",
 129                               errno);
 130         } while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
 131
 132         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
 133                 panic("start_userspace : expected SIGSTOP, got status = %d",
 134                       status);
 135
 136         if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
 137                 panic("start_userspace : PTRACE_SETOPTIONS failed, errno=%d\n",
 138                       errno);
 139
 140         if(munmap(stack, PAGE_SIZE) < 0)
 141                 panic("start_userspace : munmap failed, errno = %d\n", errno);
 142
 143         userspace_pid[cpu] = pid;
 144 }
 145
 146 void userspace(union uml_pt_regs *regs)
 147 {
 148         int err, status, op, pid = userspace_pid[0];
 149         int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
 150
 151         while(1){
 152                 restore_registers(pid, regs);
 153
 154                 /* Now we set local_using_sysemu to be used for one loop */
 155                 local_using_sysemu = get_using_sysemu();
 156
 157                 op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
 158
 159                 err = ptrace(op, pid, 0, 0);
 160                 if(err)
 161                         panic("userspace - could not resume userspace process, "
 162                               "pid=%d, ptrace operation = %d, errno = %d\n",
 163                               op, errno);
 164
 165                 CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
 166                 if(err < 0)
 167                         panic("userspace - waitpid failed, errno = %d\n",
 168                               errno);
 169
 170                 regs->skas.is_user = 1;
 171                 save_registers(pid, regs);
 172                 UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
 173
 174                 if(WIFSTOPPED(status)){
 175                         switch(WSTOPSIG(status)){
 176                         case SIGSEGV:
 177                                 handle_segv(pid, regs);
 178                                 break;
 179                         case SIGTRAP + 0x80:
 180                                 handle_trap(pid, regs, local_using_sysemu);
 181                                 break;
 182                         case SIGTRAP:
 183                                 relay_signal(SIGTRAP, regs);
 184                                 break;
 185                         case SIGIO:
 186                         case SIGVTALRM:
 187                         case SIGILL:
 188                         case SIGBUS:
 189                         case SIGFPE:
 190                         case SIGWINCH:
 191                                 user_signal(WSTOPSIG(status), regs, pid);
 192                                 break;
 193                         default:
 194                                 printk("userspace - child stopped with signal "
 195                                        "%d\n", WSTOPSIG(status));
 196                         }
 197                         interrupt_end();
 198
 199                         /* Avoid -ERESTARTSYS handling in host */
 200                         PT_SYSCALL_NR(regs->skas.regs) = -1;
 201                 }
 202         }
 203 }
 204 #define INIT_JMP_NEW_THREAD 0
 205 #define INIT_JMP_REMOVE_SIGSTACK 1
 206 #define INIT_JMP_CALLBACK 2
 207 #define INIT_JMP_HALT 3
 208 #define INIT_JMP_REBOOT 4
 209
 210 void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
 211                 void (*handler)(int))
 212 {
 213         unsigned long flags;
 214         sigjmp_buf switch_buf, fork_buf;
 215
 216         *switch_buf_ptr = &switch_buf;
 217         *fork_buf_ptr = &fork_buf;
 218
 219         /* Somewhat subtle - siglongjmp restores the signal mask before doing
 220          * the longjmp.  This means that when jumping from one stack to another
 221          * when the target stack has interrupts enabled, an interrupt may occur
 222          * on the source stack.  This is bad when starting up a process because
 223          * it's not supposed to get timer ticks until it has been scheduled.
 224          * So, we disable interrupts around the sigsetjmp to ensure that
 225          * they can't happen until we get back here where they are safe.
 226          */
 227         flags = get_signals();
 228         block_signals();
 229         if(sigsetjmp(fork_buf, 1) == 0)
 230                 new_thread_proc(stack, handler);
 231
 232         remove_sigstack();
 233
 234         set_signals(flags);
 235 }
 236
 237 void thread_wait(void *sw, void *fb)
 238 {
 239         sigjmp_buf buf, **switch_buf = sw, *fork_buf;
 240
 241         *switch_buf = &buf;
 242         fork_buf = fb;
 243         if(sigsetjmp(buf, 1) == 0)
 244                 siglongjmp(*fork_buf, INIT_JMP_REMOVE_SIGSTACK);
 245 }
 246
 247 void switch_threads(void *me, void *next)
 248 {
 249         sigjmp_buf my_buf, **me_ptr = me, *next_buf = next;
 250
 251         *me_ptr = &my_buf;
 252         if(sigsetjmp(my_buf, 1) == 0)
 253                 siglongjmp(*next_buf, 1);
 254 }
 255
 256 static sigjmp_buf initial_jmpbuf;
 257
 258 /* XXX Make these percpu */
 259 static void (*cb_proc)(void *arg);
 260 static void *cb_arg;
 261 static sigjmp_buf *cb_back;
 262
 263 int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
 264 {
 265         sigjmp_buf **switch_buf = switch_buf_ptr;
 266         int n;
 267
 268         set_handler(SIGWINCH, (__sighandler_t) sig_handler,
 269                     SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
 270                     SIGVTALRM, -1);
 271
 272         *fork_buf_ptr = &initial_jmpbuf;
 273         n = sigsetjmp(initial_jmpbuf, 1);
 274         switch(n){
 275         case INIT_JMP_NEW_THREAD:
 276                 new_thread_proc((void *) stack, new_thread_handler);
 277                 break;
 278         case INIT_JMP_REMOVE_SIGSTACK:
 279                 remove_sigstack();
 280                 break;
 281         case INIT_JMP_CALLBACK:
 282                 (*cb_proc)(cb_arg);
 283                 siglongjmp(*cb_back, 1);
 284                 break;
 285         case INIT_JMP_HALT:
 286                 kmalloc_ok = 0;
 287                 return(0);
 288         case INIT_JMP_REBOOT:
 289                 kmalloc_ok = 0;
 290                 return(1);
 291         default:
 292                 panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
 293         }
 294         siglongjmp(**switch_buf, 1);
 295 }
 296
 297 void remove_sigstack(void)
 298 {
 299         stack_t stack = ((stack_t) { .ss_flags  = SS_DISABLE,
 300                                      .ss_sp     = NULL,
 301                                      .ss_size   = 0 });
 302
 303         if(sigaltstack(&stack, NULL) != 0)
 304                 panic("disabling signal stack failed, errno = %d\n", errno);
 305 }
 306
 307 void initial_thread_cb_skas(void (*proc)(void *), void *arg)
 308 {
 309         sigjmp_buf here;
 310
 311         cb_proc = proc;
 312         cb_arg = arg;
 313         cb_back = &here;
 314
 315         block_signals();
 316         if(sigsetjmp(here, 1) == 0)
 317                 siglongjmp(initial_jmpbuf, INIT_JMP_CALLBACK);
 318         unblock_signals();
 319
 320         cb_proc = NULL;
 321         cb_arg = NULL;
 322         cb_back = NULL;
 323 }
 324
 325 void halt_skas(void)
 326 {
 327         block_signals();
 328         siglongjmp(initial_jmpbuf, INIT_JMP_HALT);
 329 }
 330
 331 void reboot_skas(void)
 332 {
 333         block_signals();
 334         siglongjmp(initial_jmpbuf, INIT_JMP_REBOOT);
 335 }
 336
 337 void switch_mm_skas(int mm_fd)
 338 {
 339         int err;
 340
 341 #warning need cpu pid in switch_mm_skas
 342         err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0, mm_fd);
 343         if(err)
 344                 panic("switch_mm_skas - PTRACE_SWITCH_MM failed, errno = %d\n",
 345                       errno);
 346 }
 347
 348 void kill_off_processes_skas(void)
 349 {
 350 #warning need to loop over userspace_pids in kill_off_processes_skas
 351         os_kill_ptraced_process(userspace_pid[0], 1);
 352 }
 353
 354 /*
 355  * Overrides for Emacs so that we follow Linus's tabbing style.
 356  * Emacs will notice this stuff at the end of the file and automatically
 357  * adjust the settings for this buffer only.  This must remain at the end
 358  * of the file.
 359  * ---------------------------------------------------------------------------
 360  * Local variables:
 361  * c-file-style: "linux"
 362  * End:
 363  */