arch/parisc/kernel/signal32.c

   1 /*    Signal support for 32-bit kernel builds
   2  *
   3  *    Copyright (C) 2001 Matthew Wilcox <willy at parisc-linux.org>
   4  *    Copyright (C) 2006 Kyle McMartin <kyle at parisc-linux.org>
   5  *
   6  *    Code was mostly borrowed from kernel/signal.c.
   7  *    See kernel/signal.c for additional Copyrights.
   8  *
   9  *
  10  *    This program is free software; you can redistribute it and/or modify
  11  *    it under the terms of the GNU General Public License as published by
  12  *    the Free Software Foundation; either version 2 of the License, or
  13  *    (at your option) any later version.
  14  *
  15  *    This program is distributed in the hope that it will be useful,
  16  *    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  *    GNU General Public License for more details.
  19  *
  20  *    You should have received a copy of the GNU General Public License
  21  *    along with this program; if not, write to the Free Software
  22  *    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  23  */
  24
  25 #include <linux/compat.h>
  26 #include <linux/module.h>
  27 #include <linux/unistd.h>
  28 #include <linux/init.h>
  29 #include <linux/sched.h>
  30 #include <linux/syscalls.h>
  31 #include <linux/types.h>
  32 #include <linux/errno.h>
  33
  34 #include <asm/uaccess.h>
  35
  36 #include "signal32.h"
  37 #include "sys32.h"
  38
  39 #define DEBUG_COMPAT_SIG 0
  40 #define DEBUG_COMPAT_SIG_LEVEL 2
  41
  42 #if DEBUG_COMPAT_SIG
  43 #define DBG(LEVEL, ...) \
  44         ((DEBUG_COMPAT_SIG_LEVEL >= LEVEL) \
  45         ? printk(__VA_ARGS__) : (void) 0)
  46 #else
  47 #define DBG(LEVEL, ...)
  48 #endif
  49
  50 inline void
  51 sigset_32to64(sigset_t *s64, compat_sigset_t *s32)
  52 {
  53         s64->sig[0] = s32->sig[0] | ((unsigned long)s32->sig[1] << 32);
  54 }
  55
  56 inline void
  57 sigset_64to32(compat_sigset_t *s32, sigset_t *s64)
  58 {
  59         s32->sig[0] = s64->sig[0] & 0xffffffffUL;
  60         s32->sig[1] = (s64->sig[0] >> 32) & 0xffffffffUL;
  61 }
  62
  63 static int
  64 put_sigset32(compat_sigset_t __user *up, sigset_t *set, size_t sz)
  65 {
  66         compat_sigset_t s;
  67
  68         if (sz != sizeof *set)
  69                 return -EINVAL;
  70         sigset_64to32(&s, set);
  71
  72         return copy_to_user(up, &s, sizeof s);
  73 }
  74
  75 static int
  76 get_sigset32(compat_sigset_t __user *up, sigset_t *set, size_t sz)
  77 {
  78         compat_sigset_t s;
  79         int r;
  80
  81         if (sz != sizeof *set)
  82                 return -EINVAL;
  83
  84         if ((r = copy_from_user(&s, up, sz)) == 0) {
  85                 sigset_32to64(set, &s);
  86         }
  87
  88         return r;
  89 }
  90
  91 int sys32_rt_sigprocmask(int how, compat_sigset_t __user *set, compat_sigset_t __user *oset,
  92                                     unsigned int sigsetsize)
  93 {
  94         sigset_t old_set, new_set;
  95         int ret;
  96
  97         if (set && get_sigset32(set, &new_set, sigsetsize))
  98                 return -EFAULT;
  99
 100         KERNEL_SYSCALL(ret, sys_rt_sigprocmask, how, set ? (sigset_t __user *)&new_set : NULL,
 101                                  oset ? (sigset_t __user *)&old_set : NULL, sigsetsize);
 102
 103         if (!ret && oset && put_sigset32(oset, &old_set, sigsetsize))
 104                 return -EFAULT;
 105
 106         return ret;
 107 }
 108
 109
 110 int sys32_rt_sigpending(compat_sigset_t __user *uset, unsigned int sigsetsize)
 111 {
 112         int ret;
 113         sigset_t set;
 114
 115         KERNEL_SYSCALL(ret, sys_rt_sigpending, (sigset_t __user *)&set, sigsetsize);
 116
 117         if (!ret && put_sigset32(uset, &set, sigsetsize))
 118                 return -EFAULT;
 119
 120         return ret;
 121 }
 122
 123 long
 124 sys32_rt_sigaction(int sig, const struct sigaction32 __user *act, struct sigaction32 __user *oact,
 125                  size_t sigsetsize)
 126 {
 127         struct k_sigaction32 new_sa32, old_sa32;
 128         struct k_sigaction new_sa, old_sa;
 129         int ret = -EINVAL;
 130
 131         if (act) {
 132                 if (copy_from_user(&new_sa32.sa, act, sizeof new_sa32.sa))
 133                         return -EFAULT;
 134                 new_sa.sa.sa_handler = (__sighandler_t)(unsigned long)new_sa32.sa.sa_handler;
 135                 new_sa.sa.sa_flags = new_sa32.sa.sa_flags;
 136                 sigset_32to64(&new_sa.sa.sa_mask, &new_sa32.sa.sa_mask);
 137         }
 138
 139         ret = do_sigaction(sig, act ? &new_sa : NULL, oact ? &old_sa : NULL);
 140
 141         if (!ret && oact) {
 142                 sigset_64to32(&old_sa32.sa.sa_mask, &old_sa.sa.sa_mask);
 143                 old_sa32.sa.sa_flags = old_sa.sa.sa_flags;
 144                 old_sa32.sa.sa_handler = (__sighandler_t32)(unsigned long)old_sa.sa.sa_handler;
 145                 if (copy_to_user(oact, &old_sa32.sa, sizeof old_sa32.sa))
 146                         return -EFAULT;
 147         }
 148         return ret;
 149 }
 150
 151 int
 152 do_sigaltstack32 (const compat_stack_t __user *uss32, compat_stack_t __user *uoss32, unsigned long sp)
 153 {
 154         compat_stack_t ss32, oss32;
 155         stack_t ss, oss;
 156         stack_t *ssp = NULL, *ossp = NULL;
 157         int ret;
 158
 159         if (uss32) {
 160                 if (copy_from_user(&ss32, uss32, sizeof ss32))
 161                         return -EFAULT;
 162
 163                 ss.ss_sp = (void __user *)(unsigned long)ss32.ss_sp;
 164                 ss.ss_flags = ss32.ss_flags;
 165                 ss.ss_size = ss32.ss_size;
 166
 167                 ssp = &ss;
 168         }
 169
 170         if (uoss32)
 171                 ossp = &oss;
 172
 173         KERNEL_SYSCALL(ret, do_sigaltstack, (const stack_t __user *)ssp, (stack_t __user *)ossp, sp);
 174
 175         if (!ret && uoss32) {
 176                 oss32.ss_sp = (unsigned int)(unsigned long)oss.ss_sp;
 177                 oss32.ss_flags = oss.ss_flags;
 178                 oss32.ss_size = oss.ss_size;
 179                 if (copy_to_user(uoss32, &oss32, sizeof *uoss32))
 180                         return -EFAULT;
 181         }
 182
 183         return ret;
 184 }
 185
 186 long
 187 restore_sigcontext32(struct compat_sigcontext __user *sc, struct compat_regfile __user * rf,
 188                 struct pt_regs *regs)
 189 {
 190         long err = 0;
 191         compat_uint_t compat_reg;
 192         compat_uint_t compat_regt;
 193         int regn;
 194
 195         /* When loading 32-bit values into 64-bit registers make
 196            sure to clear the upper 32-bits */
 197         DBG(2,"restore_sigcontext32: PER_LINUX32 process\n");
 198         DBG(2,"restore_sigcontext32: sc = 0x%p, rf = 0x%p, regs = 0x%p\n", sc, rf, regs);
 199         DBG(2,"restore_sigcontext32: compat_sigcontext is %#lx bytes\n", sizeof(*sc));
 200         for(regn=0; regn < 32; regn++){
 201                 err |= __get_user(compat_reg,&sc->sc_gr[regn]);
 202                 regs->gr[regn] = compat_reg;
 203                 /* Load upper half */
 204                 err |= __get_user(compat_regt,&rf->rf_gr[regn]);
 205                 regs->gr[regn] = ((u64)compat_regt << 32) | (u64)compat_reg;
 206                 DBG(3,"restore_sigcontext32: gr%02d = %#lx (%#x / %#x)\n",
 207                                 regn, regs->gr[regn], compat_regt, compat_reg);
 208         }
 209         DBG(2,"restore_sigcontext32: sc->sc_fr = 0x%p (%#lx)\n",sc->sc_fr, sizeof(sc->sc_fr));
 210         /* XXX: BE WARNED FR's are 64-BIT! */
 211         err |= __copy_from_user(regs->fr, sc->sc_fr, sizeof(regs->fr));
 212
 213         /* Better safe than sorry, pass __get_user two things of
 214            the same size and let gcc do the upward conversion to
 215            64-bits */
 216         err |= __get_user(compat_reg, &sc->sc_iaoq[0]);
 217         /* Load upper half */
 218         err |= __get_user(compat_regt, &rf->rf_iaoq[0]);
 219         regs->iaoq[0] = ((u64)compat_regt << 32) | (u64)compat_reg;
 220         DBG(2,"restore_sigcontext32: upper half of iaoq[0] = %#lx\n", compat_regt);
 221         DBG(2,"restore_sigcontext32: sc->sc_iaoq[0] = %p => %#x\n",
 222                         &sc->sc_iaoq[0], compat_reg);
 223
 224         err |= __get_user(compat_reg, &sc->sc_iaoq[1]);
 225         /* Load upper half */
 226         err |= __get_user(compat_regt, &rf->rf_iaoq[1]);
 227         regs->iaoq[1] = ((u64)compat_regt << 32) | (u64)compat_reg;
 228         DBG(2,"restore_sigcontext32: upper half of iaoq[1] = %#lx\n", compat_regt);
 229         DBG(2,"restore_sigcontext32: sc->sc_iaoq[1] = %p => %#x\n",
 230                         &sc->sc_iaoq[1],compat_reg);
 231         DBG(2,"restore_sigcontext32: iaoq is %#lx / %#lx\n",
 232                         regs->iaoq[0],regs->iaoq[1]);
 233
 234         err |= __get_user(compat_reg, &sc->sc_iasq[0]);
 235         /* Load the upper half for iasq */
 236         err |= __get_user(compat_regt, &rf->rf_iasq[0]);
 237         regs->iasq[0] = ((u64)compat_regt << 32) | (u64)compat_reg;
 238         DBG(2,"restore_sigcontext32: upper half of iasq[0] = %#lx\n", compat_regt);
 239
 240         err |= __get_user(compat_reg, &sc->sc_iasq[1]);
 241         /* Load the upper half for iasq */
 242         err |= __get_user(compat_regt, &rf->rf_iasq[1]);
 243         regs->iasq[1] = ((u64)compat_regt << 32) | (u64)compat_reg;
 244         DBG(2,"restore_sigcontext32: upper half of iasq[1] = %#lx\n", compat_regt);
 245         DBG(2,"restore_sigcontext32: iasq is %#lx / %#lx\n",
 246                 regs->iasq[0],regs->iasq[1]);
 247
 248         err |= __get_user(compat_reg, &sc->sc_sar);
 249         /* Load the upper half for sar */
 250         err |= __get_user(compat_regt, &rf->rf_sar);
 251         regs->sar = ((u64)compat_regt << 32) | (u64)compat_reg;
 252         DBG(2,"restore_sigcontext32: upper_half & sar = %#lx\n", compat_regt);
 253         DBG(2,"restore_sigcontext32: sar is %#lx\n", regs->sar);
 254         DBG(2,"restore_sigcontext32: r28 is %ld\n", regs->gr[28]);
 255
 256         return err;
 257 }
 258
 259 /*
 260  * Set up the sigcontext structure for this process.
 261  * This is not an easy task if the kernel is 64-bit, it will require
 262  * that we examine the process personality to determine if we need to
 263  * truncate for a 32-bit userspace.
 264  */
 265 long
 266 setup_sigcontext32(struct compat_sigcontext __user *sc, struct compat_regfile __user * rf,
 267                 struct pt_regs *regs, int in_syscall)
 268 {
 269         compat_int_t flags = 0;
 270         long err = 0;
 271         compat_uint_t compat_reg;
 272         compat_uint_t compat_regb;
 273         int regn;
 274
 275         if (on_sig_stack((unsigned long) sc))
 276                 flags |= PARISC_SC_FLAG_ONSTACK;
 277
 278         if (in_syscall) {
 279
 280                 DBG(1,"setup_sigcontext32: in_syscall\n");
 281
 282                 flags |= PARISC_SC_FLAG_IN_SYSCALL;
 283                 /* Truncate gr31 */
 284                 compat_reg = (compat_uint_t)(regs->gr[31]);
 285                 /* regs->iaoq is undefined in the syscall return path */
 286                 err |= __put_user(compat_reg, &sc->sc_iaoq[0]);
 287                 DBG(2,"setup_sigcontext32: sc->sc_iaoq[0] = %p <= %#x\n",
 288                                 &sc->sc_iaoq[0], compat_reg);
 289
 290                 /* Store upper half */
 291                 compat_reg = (compat_uint_t)(regs->gr[31] >> 32);
 292                 err |= __put_user(compat_reg, &rf->rf_iaoq[0]);
 293                 DBG(2,"setup_sigcontext32: upper half iaoq[0] = %#x\n", compat_reg);
 294
 295
 296                 compat_reg = (compat_uint_t)(regs->gr[31]+4);
 297                 err |= __put_user(compat_reg, &sc->sc_iaoq[1]);
 298                 DBG(2,"setup_sigcontext32: sc->sc_iaoq[1] = %p <= %#x\n",
 299                                 &sc->sc_iaoq[1], compat_reg);
 300                 /* Store upper half */
 301                 compat_reg = (compat_uint_t)((regs->gr[31]+4) >> 32);
 302                 err |= __put_user(compat_reg, &rf->rf_iaoq[1]);
 303                 DBG(2,"setup_sigcontext32: upper half iaoq[1] = %#x\n", compat_reg);
 304
 305                 /* Truncate sr3 */
 306                 compat_reg = (compat_uint_t)(regs->sr[3]);
 307                 err |= __put_user(compat_reg, &sc->sc_iasq[0]);
 308                 err |= __put_user(compat_reg, &sc->sc_iasq[1]);
 309
 310                 /* Store upper half */
 311                 compat_reg = (compat_uint_t)(regs->sr[3] >> 32);
 312                 err |= __put_user(compat_reg, &rf->rf_iasq[0]);
 313                 err |= __put_user(compat_reg, &rf->rf_iasq[1]);
 314
 315                 DBG(2,"setup_sigcontext32: upper half iasq[0] = %#x\n", compat_reg);
 316                 DBG(2,"setup_sigcontext32: upper half iasq[1] = %#x\n", compat_reg);
 317                 DBG(1,"setup_sigcontext32: iaoq %#lx / %#lx\n",
 318                         regs->gr[31], regs->gr[31]+4);
 319
 320         } else {
 321
 322                 compat_reg = (compat_uint_t)(regs->iaoq[0]);
 323                 err |= __put_user(compat_reg, &sc->sc_iaoq[0]);
 324                 DBG(2,"setup_sigcontext32: sc->sc_iaoq[0] = %p <= %#x\n",
 325                                 &sc->sc_iaoq[0], compat_reg);
 326                 /* Store upper half */
 327                 compat_reg = (compat_uint_t)(regs->iaoq[0] >> 32);
 328                 err |= __put_user(compat_reg, &rf->rf_iaoq[0]);
 329                 DBG(2,"setup_sigcontext32: upper half iaoq[0] = %#x\n", compat_reg);
 330
 331                 compat_reg = (compat_uint_t)(regs->iaoq[1]);
 332                 err |= __put_user(compat_reg, &sc->sc_iaoq[1]);
 333                 DBG(2,"setup_sigcontext32: sc->sc_iaoq[1] = %p <= %#x\n",
 334                                 &sc->sc_iaoq[1], compat_reg);
 335                 /* Store upper half */
 336                 compat_reg = (compat_uint_t)(regs->iaoq[1] >> 32);
 337                 err |= __put_user(compat_reg, &rf->rf_iaoq[1]);
 338                 DBG(2,"setup_sigcontext32: upper half iaoq[1] = %#x\n", compat_reg);
 339
 340
 341                 compat_reg = (compat_uint_t)(regs->iasq[0]);
 342                 err |= __put_user(compat_reg, &sc->sc_iasq[0]);
 343                 DBG(2,"setup_sigcontext32: sc->sc_iasq[0] = %p <= %#x\n",
 344                                 &sc->sc_iasq[0], compat_reg);
 345                 /* Store upper half */
 346                 compat_reg = (compat_uint_t)(regs->iasq[0] >> 32);
 347                 err |= __put_user(compat_reg, &rf->rf_iasq[0]);
 348                 DBG(2,"setup_sigcontext32: upper half iasq[0] = %#x\n", compat_reg);
 349
 350
 351                 compat_reg = (compat_uint_t)(regs->iasq[1]);
 352                 err |= __put_user(compat_reg, &sc->sc_iasq[1]);
 353                 DBG(2,"setup_sigcontext32: sc->sc_iasq[1] = %p <= %#x\n",
 354                                 &sc->sc_iasq[1], compat_reg);
 355                 /* Store upper half */
 356                 compat_reg = (compat_uint_t)(regs->iasq[1] >> 32);
 357                 err |= __put_user(compat_reg, &rf->rf_iasq[1]);
 358                 DBG(2,"setup_sigcontext32: upper half iasq[1] = %#x\n", compat_reg);
 359
 360                 /* Print out the IAOQ for debugging */
 361                 DBG(1,"setup_sigcontext32: ia0q %#lx / %#lx\n",
 362                         regs->iaoq[0], regs->iaoq[1]);
 363         }
 364
 365         err |= __put_user(flags, &sc->sc_flags);
 366
 367         DBG(1,"setup_sigcontext32: Truncating general registers.\n");
 368
 369         for(regn=0; regn < 32; regn++){
 370                 /* Truncate a general register */
 371                 compat_reg = (compat_uint_t)(regs->gr[regn]);
 372                 err |= __put_user(compat_reg, &sc->sc_gr[regn]);
 373                 /* Store upper half */
 374                 compat_regb = (compat_uint_t)(regs->gr[regn] >> 32);
 375                 err |= __put_user(compat_regb, &rf->rf_gr[regn]);
 376
 377                 /* DEBUG: Write out the "upper / lower" register data */
 378                 DBG(2,"setup_sigcontext32: gr%02d = %#x / %#x\n", regn,
 379                                 compat_regb, compat_reg);
 380         }
 381
 382         /* Copy the floating point registers (same size)
 383            XXX: BE WARNED FR's are 64-BIT! */
 384         DBG(1,"setup_sigcontext32: Copying from regs to sc, "
 385               "sc->sc_fr size = %#lx, regs->fr size = %#lx\n",
 386                 sizeof(regs->fr), sizeof(sc->sc_fr));
 387         err |= __copy_to_user(sc->sc_fr, regs->fr, sizeof(regs->fr));
 388
 389         compat_reg = (compat_uint_t)(regs->sar);
 390         err |= __put_user(compat_reg, &sc->sc_sar);
 391         DBG(2,"setup_sigcontext32: sar is %#x\n", compat_reg);
 392         /* Store upper half */
 393         compat_reg = (compat_uint_t)(regs->sar >> 32);
 394         err |= __put_user(compat_reg, &rf->rf_sar);
 395         DBG(2,"setup_sigcontext32: upper half sar = %#x\n", compat_reg);
 396         DBG(1,"setup_sigcontext32: r28 is %ld\n", regs->gr[28]);
 397
 398         return err;
 399 }
 400
 401 int
 402 copy_siginfo_from_user32 (siginfo_t *to, compat_siginfo_t __user *from)
 403 {
 404         compat_uptr_t addr;
 405         int err;
 406
 407         if (!access_ok(VERIFY_READ, from, sizeof(compat_siginfo_t)))
 408                 return -EFAULT;
 409
 410         err = __get_user(to->si_signo, &from->si_signo);
 411         err |= __get_user(to->si_errno, &from->si_errno);
 412         err |= __get_user(to->si_code, &from->si_code);
 413
 414         if (to->si_code < 0)
 415                 err |= __copy_from_user(&to->_sifields._pad, &from->_sifields._pad, SI_PAD_SIZE);
 416         else {
 417                 switch (to->si_code >> 16) {
 418                       case __SI_CHLD >> 16:
 419                         err |= __get_user(to->si_utime, &from->si_utime);
 420                         err |= __get_user(to->si_stime, &from->si_stime);
 421                         err |= __get_user(to->si_status, &from->si_status);
 422                       default:
 423                         err |= __get_user(to->si_pid, &from->si_pid);
 424                         err |= __get_user(to->si_uid, &from->si_uid);
 425                         break;
 426                       case __SI_FAULT >> 16:
 427                         err |= __get_user(addr, &from->si_addr);
 428                         to->si_addr = compat_ptr(addr);
 429                         break;
 430                       case __SI_POLL >> 16:
 431                         err |= __get_user(to->si_band, &from->si_band);
 432                         err |= __get_user(to->si_fd, &from->si_fd);
 433                         break;
 434                       case __SI_RT >> 16: /* This is not generated by the kernel as of now.  */
 435                       case __SI_MESGQ >> 16:
 436                         err |= __get_user(to->si_pid, &from->si_pid);
 437                         err |= __get_user(to->si_uid, &from->si_uid);
 438                         err |= __get_user(to->si_int, &from->si_int);
 439                         break;
 440                 }
 441         }
 442         return err;
 443 }
 444
 445 int
 446 copy_siginfo_to_user32 (compat_siginfo_t __user *to, siginfo_t *from)
 447 {
 448         compat_uptr_t addr;
 449         compat_int_t val;
 450         int err;
 451
 452         if (!access_ok(VERIFY_WRITE, to, sizeof(compat_siginfo_t)))
 453                 return -EFAULT;
 454
 455         /* If you change siginfo_t structure, please be sure
 456            this code is fixed accordingly.
 457            It should never copy any pad contained in the structure
 458            to avoid security leaks, but must copy the generic
 459            3 ints plus the relevant union member.
 460            This routine must convert siginfo from 64bit to 32bit as well
 461            at the same time.  */
 462         err = __put_user(from->si_signo, &to->si_signo);
 463         err |= __put_user(from->si_errno, &to->si_errno);
 464         err |= __put_user((short)from->si_code, &to->si_code);
 465         if (from->si_code < 0)
 466                 err |= __copy_to_user(&to->_sifields._pad, &from->_sifields._pad, SI_PAD_SIZE);
 467         else {
 468                 switch (from->si_code >> 16) {
 469                 case __SI_CHLD >> 16:
 470                         err |= __put_user(from->si_utime, &to->si_utime);
 471                         err |= __put_user(from->si_stime, &to->si_stime);
 472                         err |= __put_user(from->si_status, &to->si_status);
 473                 default:
 474                         err |= __put_user(from->si_pid, &to->si_pid);
 475                         err |= __put_user(from->si_uid, &to->si_uid);
 476                         break;
 477                 case __SI_FAULT >> 16:
 478                         addr = ptr_to_compat(from->si_addr);
 479                         err |= __put_user(addr, &to->si_addr);
 480                         break;
 481                 case __SI_POLL >> 16:
 482                         err |= __put_user(from->si_band, &to->si_band);
 483                         err |= __put_user(from->si_fd, &to->si_fd);
 484                         break;
 485                 case __SI_TIMER >> 16:
 486                         err |= __put_user(from->si_tid, &to->si_tid);
 487                         err |= __put_user(from->si_overrun, &to->si_overrun);
 488                         val = (compat_int_t)from->si_int;
 489                         err |= __put_user(val, &to->si_int);
 490                         break;
 491                 case __SI_RT >> 16:     /* Not generated by the kernel as of now.  */
 492                 case __SI_MESGQ >> 16:
 493                         err |= __put_user(from->si_uid, &to->si_uid);
 494                         err |= __put_user(from->si_pid, &to->si_pid);
 495                         val = (compat_int_t)from->si_int;
 496                         err |= __put_user(val, &to->si_int);
 497                         break;
 498                 }
 499         }
 500         return err;
 501 }
 502
 503 asmlinkage long compat_sys_rt_sigqueueinfo(int pid, int sig,
 504         struct compat_siginfo __user *uinfo)
 505 {
 506         siginfo_t info;
 507
 508         if (copy_siginfo_from_user32(&info, uinfo))
 509                 return -EFAULT;
 510
 511         /* Not even root can pretend to send signals from the kernel.
 512            Nor can they impersonate a kill(), which adds source info.  */
 513         if (info.si_code >= 0)
 514                 return -EPERM;
 515         info.si_signo = sig;
 516
 517         /* POSIX.1b doesn't mention process groups.  */
 518         return kill_proc_info(sig, &info, pid);
 519 }
 520