arch/s390/kernel/compat_signal.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *    Copyright IBM Corp. 2000, 2006
   4  *    Author(s): Denis Joseph Barrow (djbarrow@de.ibm.com,barrow_dj@yahoo.com)
   5  *               Gerhard Tonn (ton@de.ibm.com)
   6  *
   7  *  Copyright (C) 1991, 1992  Linus Torvalds
   8  *
   9  *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
  10  */
  11
  12 #include <linux/compat.h>
  13 #include <linux/sched.h>
  14 #include <linux/sched/task_stack.h>
  15 #include <linux/mm.h>
  16 #include <linux/smp.h>
  17 #include <linux/kernel.h>
  18 #include <linux/signal.h>
  19 #include <linux/errno.h>
  20 #include <linux/wait.h>
  21 #include <linux/ptrace.h>
  22 #include <linux/unistd.h>
  23 #include <linux/stddef.h>
  24 #include <linux/tty.h>
  25 #include <linux/personality.h>
  26 #include <linux/binfmts.h>
  27 #include <asm/ucontext.h>
  28 #include <linux/uaccess.h>
  29 #include <asm/lowcore.h>
  30 #include <asm/switch_to.h>
  31 #include "compat_linux.h"
  32 #include "compat_ptrace.h"
  33 #include "entry.h"
  34
  35 typedef struct
  36 {
  37         __u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
  38         struct sigcontext32 sc;
  39         _sigregs32 sregs;
  40         int signo;
  41         _sigregs_ext32 sregs_ext;
  42         __u16 svc_insn;         /* Offset of svc_insn is NOT fixed! */
  43 } sigframe32;
  44
  45 typedef struct
  46 {
  47         __u8 callee_used_stack[__SIGNAL_FRAMESIZE32];
  48         __u16 svc_insn;
  49         compat_siginfo_t info;
  50         struct ucontext32 uc;
  51 } rt_sigframe32;
  52
  53 /* Store registers needed to create the signal frame */
  54 static void store_sigregs(void)
  55 {
  56         save_access_regs(current->thread.acrs);
  57         save_fpu_regs();
  58 }
  59
  60 /* Load registers after signal return */
  61 static void load_sigregs(void)
  62 {
  63         restore_access_regs(current->thread.acrs);
  64 }
  65
  66 static int save_sigregs32(struct pt_regs *regs, _sigregs32 __user *sregs)
  67 {
  68         _sigregs32 user_sregs;
  69         int i;
  70
  71         user_sregs.regs.psw.mask = (__u32)(regs->psw.mask >> 32);
  72         user_sregs.regs.psw.mask &= PSW32_MASK_USER | PSW32_MASK_RI;
  73         user_sregs.regs.psw.mask |= PSW32_USER_BITS;
  74         user_sregs.regs.psw.addr = (__u32) regs->psw.addr |
  75                 (__u32)(regs->psw.mask & PSW_MASK_BA);
  76         for (i = 0; i < NUM_GPRS; i++)
  77                 user_sregs.regs.gprs[i] = (__u32) regs->gprs[i];
  78         memcpy(&user_sregs.regs.acrs, current->thread.acrs,
  79                sizeof(user_sregs.regs.acrs));
  80         fpregs_store((_s390_fp_regs *) &user_sregs.fpregs, &current->thread.fpu);
  81         if (__copy_to_user(sregs, &user_sregs, sizeof(_sigregs32)))
  82                 return -EFAULT;
  83         return 0;
  84 }
  85
  86 static int restore_sigregs32(struct pt_regs *regs,_sigregs32 __user *sregs)
  87 {
  88         _sigregs32 user_sregs;
  89         int i;
  90
  91         /* Alwys make any pending restarted system call return -EINTR */
  92         current->restart_block.fn = do_no_restart_syscall;
  93
  94         if (__copy_from_user(&user_sregs, &sregs->regs, sizeof(user_sregs)))
  95                 return -EFAULT;
  96
  97         if (!is_ri_task(current) && (user_sregs.regs.psw.mask & PSW32_MASK_RI))
  98                 return -EINVAL;
  99
 100         /* Test the floating-point-control word. */
 101         if (test_fp_ctl(user_sregs.fpregs.fpc))
 102                 return -EINVAL;
 103
 104         /* Use regs->psw.mask instead of PSW_USER_BITS to preserve PER bit. */
 105         regs->psw.mask = (regs->psw.mask & ~(PSW_MASK_USER | PSW_MASK_RI)) |
 106                 (__u64)(user_sregs.regs.psw.mask & PSW32_MASK_USER) << 32 |
 107                 (__u64)(user_sregs.regs.psw.mask & PSW32_MASK_RI) << 32 |
 108                 (__u64)(user_sregs.regs.psw.addr & PSW32_ADDR_AMODE);
 109         /* Check for invalid user address space control. */
 110         if ((regs->psw.mask & PSW_MASK_ASC) == PSW_ASC_HOME)
 111                 regs->psw.mask = PSW_ASC_PRIMARY |
 112                         (regs->psw.mask & ~PSW_MASK_ASC);
 113         regs->psw.addr = (__u64)(user_sregs.regs.psw.addr & PSW32_ADDR_INSN);
 114         for (i = 0; i < NUM_GPRS; i++)
 115                 regs->gprs[i] = (__u64) user_sregs.regs.gprs[i];
 116         memcpy(&current->thread.acrs, &user_sregs.regs.acrs,
 117                sizeof(current->thread.acrs));
 118         fpregs_load((_s390_fp_regs *) &user_sregs.fpregs, &current->thread.fpu);
 119
 120         clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */
 121         return 0;
 122 }
 123
 124 static int save_sigregs_ext32(struct pt_regs *regs,
 125                               _sigregs_ext32 __user *sregs_ext)
 126 {
 127         __u32 gprs_high[NUM_GPRS];
 128         __u64 vxrs[__NUM_VXRS_LOW];
 129         int i;
 130
 131         /* Save high gprs to signal stack */
 132         for (i = 0; i < NUM_GPRS; i++)
 133                 gprs_high[i] = regs->gprs[i] >> 32;
 134         if (__copy_to_user(&sregs_ext->gprs_high, &gprs_high,
 135                            sizeof(sregs_ext->gprs_high)))
 136                 return -EFAULT;
 137
 138         /* Save vector registers to signal stack */
 139         if (MACHINE_HAS_VX) {
 140                 for (i = 0; i < __NUM_VXRS_LOW; i++)
 141                         vxrs[i] = *((__u64 *)(current->thread.fpu.vxrs + i) + 1);
 142                 if (__copy_to_user(&sregs_ext->vxrs_low, vxrs,
 143                                    sizeof(sregs_ext->vxrs_low)) ||
 144                     __copy_to_user(&sregs_ext->vxrs_high,
 145                                    current->thread.fpu.vxrs + __NUM_VXRS_LOW,
 146                                    sizeof(sregs_ext->vxrs_high)))
 147                         return -EFAULT;
 148         }
 149         return 0;
 150 }
 151
 152 static int restore_sigregs_ext32(struct pt_regs *regs,
 153                                  _sigregs_ext32 __user *sregs_ext)
 154 {
 155         __u32 gprs_high[NUM_GPRS];
 156         __u64 vxrs[__NUM_VXRS_LOW];
 157         int i;
 158
 159         /* Restore high gprs from signal stack */
 160         if (__copy_from_user(&gprs_high, &sregs_ext->gprs_high,
 161                              sizeof(sregs_ext->gprs_high)))
 162                 return -EFAULT;
 163         for (i = 0; i < NUM_GPRS; i++)
 164                 *(__u32 *)&regs->gprs[i] = gprs_high[i];
 165
 166         /* Restore vector registers from signal stack */
 167         if (MACHINE_HAS_VX) {
 168                 if (__copy_from_user(vxrs, &sregs_ext->vxrs_low,
 169                                      sizeof(sregs_ext->vxrs_low)) ||
 170                     __copy_from_user(current->thread.fpu.vxrs + __NUM_VXRS_LOW,
 171                                      &sregs_ext->vxrs_high,
 172                                      sizeof(sregs_ext->vxrs_high)))
 173                         return -EFAULT;
 174                 for (i = 0; i < __NUM_VXRS_LOW; i++)
 175                         *((__u64 *)(current->thread.fpu.vxrs + i) + 1) = vxrs[i];
 176         }
 177         return 0;
 178 }
 179
 180 COMPAT_SYSCALL_DEFINE0(sigreturn)
 181 {
 182         struct pt_regs *regs = task_pt_regs(current);
 183         sigframe32 __user *frame = (sigframe32 __user *)regs->gprs[15];
 184         sigset_t set;
 185
 186         if (get_compat_sigset(&set, (compat_sigset_t __user *)frame->sc.oldmask))
 187                 goto badframe;
 188         set_current_blocked(&set);
 189         save_fpu_regs();
 190         if (restore_sigregs32(regs, &frame->sregs))
 191                 goto badframe;
 192         if (restore_sigregs_ext32(regs, &frame->sregs_ext))
 193                 goto badframe;
 194         load_sigregs();
 195         return regs->gprs[2];
 196 badframe:
 197         force_sig(SIGSEGV);
 198         return 0;
 199 }
 200
 201 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 202 {
 203         struct pt_regs *regs = task_pt_regs(current);
 204         rt_sigframe32 __user *frame = (rt_sigframe32 __user *)regs->gprs[15];
 205         sigset_t set;
 206
 207         if (get_compat_sigset(&set, &frame->uc.uc_sigmask))
 208                 goto badframe;
 209         set_current_blocked(&set);
 210         if (compat_restore_altstack(&frame->uc.uc_stack))
 211                 goto badframe;
 212         save_fpu_regs();
 213         if (restore_sigregs32(regs, &frame->uc.uc_mcontext))
 214                 goto badframe;
 215         if (restore_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))
 216                 goto badframe;
 217         load_sigregs();
 218         return regs->gprs[2];
 219 badframe:
 220         force_sig(SIGSEGV);
 221         return 0;
 222 }
 223
 224 /*
 225  * Set up a signal frame.
 226  */
 227
 228
 229 /*
 230  * Determine which stack to use..
 231  */
 232 static inline void __user *
 233 get_sigframe(struct k_sigaction *ka, struct pt_regs * regs, size_t frame_size)
 234 {
 235         unsigned long sp;
 236
 237         /* Default to using normal stack */
 238         sp = (unsigned long) A(regs->gprs[15]);
 239
 240         /* Overflow on alternate signal stack gives SIGSEGV. */
 241         if (on_sig_stack(sp) && !on_sig_stack((sp - frame_size) & -8UL))
 242                 return (void __user *) -1UL;
 243
 244         /* This is the X/Open sanctioned signal stack switching.  */
 245         if (ka->sa.sa_flags & SA_ONSTACK) {
 246                 if (! sas_ss_flags(sp))
 247                         sp = current->sas_ss_sp + current->sas_ss_size;
 248         }
 249
 250         return (void __user *)((sp - frame_size) & -8ul);
 251 }
 252
 253 static int setup_frame32(struct ksignal *ksig, sigset_t *set,
 254                          struct pt_regs *regs)
 255 {
 256         int sig = ksig->sig;
 257         sigframe32 __user *frame;
 258         unsigned long restorer;
 259         size_t frame_size;
 260
 261         /*
 262          * gprs_high are always present for 31-bit compat tasks.
 263          * The space for vector registers is only allocated if
 264          * the machine supports it
 265          */
 266         frame_size = sizeof(*frame) - sizeof(frame->sregs_ext.__reserved);
 267         if (!MACHINE_HAS_VX)
 268                 frame_size -= sizeof(frame->sregs_ext.vxrs_low) +
 269                               sizeof(frame->sregs_ext.vxrs_high);
 270         frame = get_sigframe(&ksig->ka, regs, frame_size);
 271         if (frame == (void __user *) -1UL)
 272                 return -EFAULT;
 273
 274         /* Set up backchain. */
 275         if (__put_user(regs->gprs[15], (unsigned int __user *) frame))
 276                 return -EFAULT;
 277
 278         /* Create struct sigcontext32 on the signal stack */
 279         if (put_compat_sigset((compat_sigset_t __user *)frame->sc.oldmask,
 280                               set, sizeof(compat_sigset_t)))
 281                 return -EFAULT;
 282         if (__put_user(ptr_to_compat(&frame->sregs), &frame->sc.sregs))
 283                 return -EFAULT;
 284
 285         /* Store registers needed to create the signal frame */
 286         store_sigregs();
 287
 288         /* Create _sigregs32 on the signal stack */
 289         if (save_sigregs32(regs, &frame->sregs))
 290                 return -EFAULT;
 291
 292         /* Place signal number on stack to allow backtrace from handler.  */
 293         if (__put_user(regs->gprs[2], (int __force __user *) &frame->signo))
 294                 return -EFAULT;
 295
 296         /* Create _sigregs_ext32 on the signal stack */
 297         if (save_sigregs_ext32(regs, &frame->sregs_ext))
 298                 return -EFAULT;
 299
 300         /* Set up to return from userspace.  If provided, use a stub
 301            already in userspace.  */
 302         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 303                 restorer = (unsigned long __force)
 304                         ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE;
 305         } else {
 306                 /* Signal frames without vectors registers are short ! */
 307                 __u16 __user *svc = (void __user *) frame + frame_size - 2;
 308                 if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc))
 309                         return -EFAULT;
 310                 restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE;
 311         }
 312
 313         /* Set up registers for signal handler */
 314         regs->gprs[14] = restorer;
 315         regs->gprs[15] = (__force __u64) frame;
 316         /* Force 31 bit amode and default user address space control. */
 317         regs->psw.mask = PSW_MASK_BA |
 318                 (PSW_USER_BITS & PSW_MASK_ASC) |
 319                 (regs->psw.mask & ~PSW_MASK_ASC);
 320         regs->psw.addr = (__force __u64) ksig->ka.sa.sa_handler;
 321
 322         regs->gprs[2] = sig;
 323         regs->gprs[3] = (__force __u64) &frame->sc;
 324
 325         /* We forgot to include these in the sigcontext.
 326            To avoid breaking binary compatibility, they are passed as args. */
 327         if (sig == SIGSEGV || sig == SIGBUS || sig == SIGILL ||
 328             sig == SIGTRAP || sig == SIGFPE) {
 329                 /* set extra registers only for synchronous signals */
 330                 regs->gprs[4] = regs->int_code & 127;
 331                 regs->gprs[5] = regs->int_parm_long;
 332                 regs->gprs[6] = current->thread.last_break;
 333         }
 334
 335         return 0;
 336 }
 337
 338 static int setup_rt_frame32(struct ksignal *ksig, sigset_t *set,
 339                             struct pt_regs *regs)
 340 {
 341         rt_sigframe32 __user *frame;
 342         unsigned long restorer;
 343         size_t frame_size;
 344         u32 uc_flags;
 345
 346         frame_size = sizeof(*frame) -
 347                      sizeof(frame->uc.uc_mcontext_ext.__reserved);
 348         /*
 349          * gprs_high are always present for 31-bit compat tasks.
 350          * The space for vector registers is only allocated if
 351          * the machine supports it
 352          */
 353         uc_flags = UC_GPRS_HIGH;
 354         if (MACHINE_HAS_VX) {
 355                 uc_flags |= UC_VXRS;
 356         } else
 357                 frame_size -= sizeof(frame->uc.uc_mcontext_ext.vxrs_low) +
 358                               sizeof(frame->uc.uc_mcontext_ext.vxrs_high);
 359         frame = get_sigframe(&ksig->ka, regs, frame_size);
 360         if (frame == (void __user *) -1UL)
 361                 return -EFAULT;
 362
 363         /* Set up backchain. */
 364         if (__put_user(regs->gprs[15], (unsigned int __force __user *) frame))
 365                 return -EFAULT;
 366
 367         /* Set up to return from userspace.  If provided, use a stub
 368            already in userspace.  */
 369         if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 370                 restorer = (unsigned long __force)
 371                         ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE;
 372         } else {
 373                 __u16 __user *svc = &frame->svc_insn;
 374                 if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc))
 375                         return -EFAULT;
 376                 restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE;
 377         }
 378
 379         /* Create siginfo on the signal stack */
 380         if (copy_siginfo_to_user32(&frame->info, &ksig->info))
 381                 return -EFAULT;
 382
 383         /* Store registers needed to create the signal frame */
 384         store_sigregs();
 385
 386         /* Create ucontext on the signal stack. */
 387         if (__put_user(uc_flags, &frame->uc.uc_flags) ||
 388             __put_user(0, &frame->uc.uc_link) ||
 389             __compat_save_altstack(&frame->uc.uc_stack, regs->gprs[15]) ||
 390             save_sigregs32(regs, &frame->uc.uc_mcontext) ||
 391             put_compat_sigset(&frame->uc.uc_sigmask, set, sizeof(compat_sigset_t)) ||
 392             save_sigregs_ext32(regs, &frame->uc.uc_mcontext_ext))
 393                 return -EFAULT;
 394
 395         /* Set up registers for signal handler */
 396         regs->gprs[14] = restorer;
 397         regs->gprs[15] = (__force __u64) frame;
 398         /* Force 31 bit amode and default user address space control. */
 399         regs->psw.mask = PSW_MASK_BA |
 400                 (PSW_USER_BITS & PSW_MASK_ASC) |
 401                 (regs->psw.mask & ~PSW_MASK_ASC);
 402         regs->psw.addr = (__u64 __force) ksig->ka.sa.sa_handler;
 403
 404         regs->gprs[2] = ksig->sig;
 405         regs->gprs[3] = (__force __u64) &frame->info;
 406         regs->gprs[4] = (__force __u64) &frame->uc;
 407         regs->gprs[5] = current->thread.last_break;
 408         return 0;
 409 }
 410
 411 /*
 412  * OK, we're invoking a handler
 413  */
 414
 415 void handle_signal32(struct ksignal *ksig, sigset_t *oldset,
 416                      struct pt_regs *regs)
 417 {
 418         int ret;
 419
 420         /* Set up the stack frame */
 421         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 422                 ret = setup_rt_frame32(ksig, oldset, regs);
 423         else
 424                 ret = setup_frame32(ksig, oldset, regs);
 425
 426         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLE_STEP));
 427 }
 428