arch/um/kernel/process.c

   1 /*
   2  * Copyright (C) 2000, 2001, 2002 Jeff Dike (jdike@karaya.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include <stdio.h>
   7 #include <unistd.h>
   8 #include <signal.h>
   9 #include <sched.h>
  10 #include <errno.h>
  11 #include <stdarg.h>
  12 #include <stdlib.h>
  13 #include <setjmp.h>
  14 #include <sys/time.h>
  15 #include <sys/ptrace.h>
  16 #include <sys/wait.h>
  17 #include <sys/mman.h>
  18 #include <asm/ptrace.h>
  19 #include <asm/sigcontext.h>
  20 #include <asm/unistd.h>
  21 #include <asm/page.h>
  22 #include <asm/user.h>
  23 #include "user_util.h"
  24 #include "kern_util.h"
  25 #include "user.h"
  26 #include "process.h"
  27 #include "signal_kern.h"
  28 #include "signal_user.h"
  29 #include "sysdep/ptrace.h"
  30 #include "sysdep/sigcontext.h"
  31 #include "irq_user.h"
  32 #include "ptrace_user.h"
  33 #include "time_user.h"
  34 #include "init.h"
  35 #include "os.h"
  36 #include "uml-config.h"
  37 #include "choose-mode.h"
  38 #include "mode.h"
  39 #ifdef UML_CONFIG_MODE_SKAS
  40 #include "skas.h"
  41 #include "skas_ptrace.h"
  42 #endif
  43
  44 void init_new_thread_stack(void *sig_stack, void (*usr1_handler)(int))
  45 {
  46         int flags = 0, pages;
  47
  48         if(sig_stack != NULL){
  49                 pages = (1 << UML_CONFIG_KERNEL_STACK_ORDER);
  50                 set_sigstack(sig_stack, pages * page_size());
  51                 flags = SA_ONSTACK;
  52         }
  53         if(usr1_handler) set_handler(SIGUSR1, usr1_handler, flags, -1);
  54 }
  55
  56 void init_new_thread_signals(int altstack)
  57 {
  58         int flags = altstack ? SA_ONSTACK : 0;
  59
  60         set_handler(SIGSEGV, (__sighandler_t) sig_handler, flags,
  61                     SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
  62         set_handler(SIGTRAP, (__sighandler_t) sig_handler, flags,
  63                     SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
  64         set_handler(SIGFPE, (__sighandler_t) sig_handler, flags,
  65                     SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
  66         set_handler(SIGILL, (__sighandler_t) sig_handler, flags,
  67                     SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
  68         set_handler(SIGBUS, (__sighandler_t) sig_handler, flags,
  69                     SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
  70         set_handler(SIGWINCH, (__sighandler_t) sig_handler, flags,
  71                     SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
  72         set_handler(SIGUSR2, (__sighandler_t) sig_handler,
  73                     flags, SIGUSR1, SIGIO, SIGWINCH, SIGALRM, SIGVTALRM, -1);
  74         signal(SIGHUP, SIG_IGN);
  75
  76         init_irq_signals(altstack);
  77 }
  78
  79 struct tramp {
  80         int (*tramp)(void *);
  81         void *tramp_data;
  82         unsigned long temp_stack;
  83         int flags;
  84         int pid;
  85 };
  86
  87 /* See above for why sigkill is here */
  88
  89 int sigkill = SIGKILL;
  90
  91 int outer_tramp(void *arg)
  92 {
  93         struct tramp *t;
  94         int sig = sigkill;
  95
  96         t = arg;
  97         t->pid = clone(t->tramp, (void *) t->temp_stack + page_size()/2,
  98                        t->flags, t->tramp_data);
  99         if(t->pid > 0) wait_for_stop(t->pid, SIGSTOP, PTRACE_CONT, NULL);
 100         kill(os_getpid(), sig);
 101         _exit(0);
 102 }
 103
 104 int start_fork_tramp(void *thread_arg, unsigned long temp_stack,
 105                      int clone_flags, int (*tramp)(void *))
 106 {
 107         struct tramp arg;
 108         unsigned long sp;
 109         int new_pid, status, err;
 110
 111         /* The trampoline will run on the temporary stack */
 112         sp = stack_sp(temp_stack);
 113
 114         clone_flags |= CLONE_FILES | SIGCHLD;
 115
 116         arg.tramp = tramp;
 117         arg.tramp_data = thread_arg;
 118         arg.temp_stack = temp_stack;
 119         arg.flags = clone_flags;
 120
 121         /* Start the process and wait for it to kill itself */
 122         new_pid = clone(outer_tramp, (void *) sp, clone_flags, &arg);
 123         if(new_pid < 0)
 124                 return(new_pid);
 125
 126         CATCH_EINTR(err = waitpid(new_pid, &status, 0));
 127         if(err < 0)
 128                 panic("Waiting for outer trampoline failed - errno = %d",
 129                       errno);
 130
 131         if(!WIFSIGNALED(status) || (WTERMSIG(status) != SIGKILL))
 132                 panic("outer trampoline didn't exit with SIGKILL, "
 133                       "status = %d", status);
 134
 135         return(arg.pid);
 136 }
 137
 138 static int ptrace_child(void *arg)
 139 {
 140         int pid = os_getpid();
 141
 142         if(ptrace(PTRACE_TRACEME, 0, 0, 0) < 0){
 143                 perror("ptrace");
 144                 os_kill_process(pid, 0);
 145         }
 146         os_stop_process(pid);
 147         _exit(os_getpid() == pid);
 148 }
 149
 150 static int start_ptraced_child(void **stack_out)
 151 {
 152         void *stack;
 153         unsigned long sp;
 154         int pid, n, status;
 155
 156         stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
 157                      MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
 158         if(stack == MAP_FAILED)
 159                 panic("check_ptrace : mmap failed, errno = %d", errno);
 160         sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
 161         pid = clone(ptrace_child, (void *) sp, SIGCHLD, NULL);
 162         if(pid < 0)
 163                 panic("check_ptrace : clone failed, errno = %d", errno);
 164         CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 165         if(n < 0)
 166                 panic("check_ptrace : wait failed, errno = %d", errno);
 167         if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
 168                 panic("check_ptrace : expected SIGSTOP, got status = %d",
 169                       status);
 170
 171         *stack_out = stack;
 172         return(pid);
 173 }
 174
 175 static void stop_ptraced_child(int pid, void *stack, int exitcode)
 176 {
 177         int status, n;
 178
 179         if(ptrace(PTRACE_CONT, pid, 0, 0) < 0)
 180                 panic("check_ptrace : ptrace failed, errno = %d", errno);
 181         CATCH_EINTR(n = waitpid(pid, &status, 0));
 182         if(!WIFEXITED(status) || (WEXITSTATUS(status) != exitcode))
 183                 panic("check_ptrace : child exited with status 0x%x", status);
 184
 185         if(munmap(stack, PAGE_SIZE) < 0)
 186                 panic("check_ptrace : munmap failed, errno = %d", errno);
 187 }
 188
 189 static int force_sysemu_disabled = 0;
 190
 191 static int __init nosysemu_cmd_param(char *str, int* add)
 192 {
 193         force_sysemu_disabled = 1;
 194         return 0;
 195 }
 196
 197 __uml_setup("nosysemu", nosysemu_cmd_param,
 198                 "nosysemu\n"
 199                 "    Turns off syscall emulation patch for ptrace (SYSEMU) on.\n"
 200                 "    SYSEMU is a performance-patch introduced by Laurent Vivier. It changes\n"
 201                 "    behaviour of ptrace() and helps reducing host context switch rate.\n"
 202                 "    To make it working, you need a kernel patch for your host, too.\n"
 203                 "    See http://perso.wanadoo.fr/laurent.vivier/UML/ for further information.\n");
 204
 205 static void __init check_sysemu(void)
 206 {
 207         void *stack;
 208         int pid, n, status;
 209
 210         if (mode_tt)
 211                 return;
 212
 213         printk("Checking syscall emulation patch for ptrace...");
 214         sysemu_supported = 0;
 215         pid = start_ptraced_child(&stack);
 216         if(ptrace(PTRACE_SYSEMU, pid, 0, 0) >= 0) {
 217                 struct user_regs_struct regs;
 218
 219                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 220                 if (n < 0)
 221                         panic("check_ptrace : wait failed, errno = %d", errno);
 222                 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
 223                         panic("check_ptrace : expected SIGTRAP, "
 224                               "got status = %d", status);
 225
 226                 if (ptrace(PTRACE_GETREGS, pid, 0, &regs) < 0)
 227                         panic("check_ptrace : failed to read child "
 228                               "registers, errno = %d", errno);
 229                 regs.orig_eax = pid;
 230                 if (ptrace(PTRACE_SETREGS, pid, 0, &regs) < 0)
 231                         panic("check_ptrace : failed to modify child "
 232                               "registers, errno = %d", errno);
 233
 234                 stop_ptraced_child(pid, stack, 0);
 235
 236                 sysemu_supported = 1;
 237                 printk("found\n");
 238         }
 239         else
 240         {
 241                 stop_ptraced_child(pid, stack, 1);
 242                 sysemu_supported = 0;
 243                 printk("missing\n");
 244         }
 245
 246         set_using_sysemu(!force_sysemu_disabled);
 247 }
 248
 249 void __init check_ptrace(void)
 250 {
 251         void *stack;
 252         int pid, syscall, n, status;
 253
 254         printk("Checking that ptrace can change system call numbers...");
 255         pid = start_ptraced_child(&stack);
 256
 257         while(1){
 258                 if(ptrace(PTRACE_SYSCALL, pid, 0, 0) < 0)
 259                         panic("check_ptrace : ptrace failed, errno = %d",
 260                               errno);
 261                 CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
 262                 if(n < 0)
 263                         panic("check_ptrace : wait failed, errno = %d", errno);
 264                 if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGTRAP))
 265                         panic("check_ptrace : expected SIGTRAP, "
 266                               "got status = %d", status);
 267
 268                 syscall = ptrace(PTRACE_PEEKUSER, pid, PT_SYSCALL_NR_OFFSET,
 269                                  0);
 270                 if(syscall == __NR_getpid){
 271                         n = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
 272                                    __NR_getppid);
 273                         if(n < 0)
 274                                 panic("check_ptrace : failed to modify system "
 275                                       "call, errno = %d", errno);
 276                         break;
 277                 }
 278         }
 279         stop_ptraced_child(pid, stack, 0);
 280         printk("OK\n");
 281         check_sysemu();
 282 }
 283
 284 int run_kernel_thread(int (*fn)(void *), void *arg, void **jmp_ptr)
 285 {
 286         sigjmp_buf buf;
 287         int n;
 288
 289         *jmp_ptr = &buf;
 290         n = sigsetjmp(buf, 1);
 291         if(n != 0)
 292                 return(n);
 293         (*fn)(arg);
 294         return(0);
 295 }
 296
 297 void forward_pending_sigio(int target)
 298 {
 299         sigset_t sigs;
 300
 301         if(sigpending(&sigs))
 302                 panic("forward_pending_sigio : sigpending failed");
 303         if(sigismember(&sigs, SIGIO))
 304                 kill(target, SIGIO);
 305 }
 306
 307 int can_do_skas(void)
 308 {
 309 #ifdef UML_CONFIG_MODE_SKAS
 310         struct ptrace_faultinfo fi;
 311         void *stack;
 312         int pid, n, ret = 1;
 313
 314         printf("Checking for the skas3 patch in the host...");
 315         pid = start_ptraced_child(&stack);
 316
 317         n = ptrace(PTRACE_FAULTINFO, pid, 0, &fi);
 318         if(n < 0){
 319                 if(errno == EIO)
 320                         printf("not found\n");
 321                 else printf("No (unexpected errno - %d)\n", errno);
 322                 ret = 0;
 323         }
 324         else printf("found\n");
 325
 326         init_registers(pid);
 327         stop_ptraced_child(pid, stack, 1);
 328
 329         printf("Checking for /proc/mm...");
 330         if(os_access("/proc/mm", OS_ACC_W_OK) < 0){
 331                 printf("not found\n");
 332                 ret = 0;
 333         }
 334         else printf("found\n");
 335
 336         return(ret);
 337 #else
 338         return(0);
 339 #endif
 340 }
 341
 342 /*
 343  * Overrides for Emacs so that we follow Linus's tabbing style.
 344  * Emacs will notice this stuff at the end of the file and automatically
 345  * adjust the settings for this buffer only.  This must remain at the end
 346  * of the file.
 347  * ---------------------------------------------------------------------------
 348  * Local variables:
 349  * c-file-style: "linux"
 350  * End:
 351  */