arch/arm64/kernel/signal32.c

   1 /*
   2  * Based on arch/arm/kernel/signal.c
   3  *
   4  * Copyright (C) 1995-2009 Russell King
   5  * Copyright (C) 2012 ARM Ltd.
   6  * Modified by Will Deacon <will.deacon@arm.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <linux/compat.h>
  22 #include <linux/signal.h>
  23 #include <linux/syscalls.h>
  24 #include <linux/ratelimit.h>
  25
  26 #include <asm/esr.h>
  27 #include <asm/fpsimd.h>
  28 #include <asm/signal32.h>
  29 #include <asm/traps.h>
  30 #include <linux/uaccess.h>
  31 #include <asm/unistd.h>
  32
  33 struct compat_sigcontext {
  34         /* We always set these two fields to 0 */
  35         compat_ulong_t                  trap_no;
  36         compat_ulong_t                  error_code;
  37
  38         compat_ulong_t                  oldmask;
  39         compat_ulong_t                  arm_r0;
  40         compat_ulong_t                  arm_r1;
  41         compat_ulong_t                  arm_r2;
  42         compat_ulong_t                  arm_r3;
  43         compat_ulong_t                  arm_r4;
  44         compat_ulong_t                  arm_r5;
  45         compat_ulong_t                  arm_r6;
  46         compat_ulong_t                  arm_r7;
  47         compat_ulong_t                  arm_r8;
  48         compat_ulong_t                  arm_r9;
  49         compat_ulong_t                  arm_r10;
  50         compat_ulong_t                  arm_fp;
  51         compat_ulong_t                  arm_ip;
  52         compat_ulong_t                  arm_sp;
  53         compat_ulong_t                  arm_lr;
  54         compat_ulong_t                  arm_pc;
  55         compat_ulong_t                  arm_cpsr;
  56         compat_ulong_t                  fault_address;
  57 };
  58
  59 struct compat_ucontext {
  60         compat_ulong_t                  uc_flags;
  61         compat_uptr_t                   uc_link;
  62         compat_stack_t                  uc_stack;
  63         struct compat_sigcontext        uc_mcontext;
  64         compat_sigset_t                 uc_sigmask;
  65         int             __unused[32 - (sizeof (compat_sigset_t) / sizeof (int))];
  66         compat_ulong_t  uc_regspace[128] __attribute__((__aligned__(8)));
  67 };
  68
  69 struct compat_vfp_sigframe {
  70         compat_ulong_t  magic;
  71         compat_ulong_t  size;
  72         struct compat_user_vfp {
  73                 compat_u64      fpregs[32];
  74                 compat_ulong_t  fpscr;
  75         } ufp;
  76         struct compat_user_vfp_exc {
  77                 compat_ulong_t  fpexc;
  78                 compat_ulong_t  fpinst;
  79                 compat_ulong_t  fpinst2;
  80         } ufp_exc;
  81 } __attribute__((__aligned__(8)));
  82
  83 #define VFP_MAGIC               0x56465001
  84 #define VFP_STORAGE_SIZE        sizeof(struct compat_vfp_sigframe)
  85
  86 #define FSR_WRITE_SHIFT         (11)
  87
  88 struct compat_aux_sigframe {
  89         struct compat_vfp_sigframe      vfp;
  90
  91         /* Something that isn't a valid magic number for any coprocessor.  */
  92         unsigned long                   end_magic;
  93 } __attribute__((__aligned__(8)));
  94
  95 struct compat_sigframe {
  96         struct compat_ucontext  uc;
  97         compat_ulong_t          retcode[2];
  98 };
  99
 100 struct compat_rt_sigframe {
 101         struct compat_siginfo info;
 102         struct compat_sigframe sig;
 103 };
 104
 105 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 106
 107 static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
 108 {
 109         compat_sigset_t cset;
 110
 111         cset.sig[0] = set->sig[0] & 0xffffffffull;
 112         cset.sig[1] = set->sig[0] >> 32;
 113
 114         return copy_to_user(uset, &cset, sizeof(*uset));
 115 }
 116
 117 static inline int get_sigset_t(sigset_t *set,
 118                                const compat_sigset_t __user *uset)
 119 {
 120         compat_sigset_t s32;
 121
 122         if (copy_from_user(&s32, uset, sizeof(*uset)))
 123                 return -EFAULT;
 124
 125         set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
 126         return 0;
 127 }
 128
 129 /*
 130  * VFP save/restore code.
 131  *
 132  * We have to be careful with endianness, since the fpsimd context-switch
 133  * code operates on 128-bit (Q) register values whereas the compat ABI
 134  * uses an array of 64-bit (D) registers. Consequently, we need to swap
 135  * the two halves of each Q register when running on a big-endian CPU.
 136  */
 137 union __fpsimd_vreg {
 138         __uint128_t     raw;
 139         struct {
 140 #ifdef __AARCH64EB__
 141                 u64     hi;
 142                 u64     lo;
 143 #else
 144                 u64     lo;
 145                 u64     hi;
 146 #endif
 147         };
 148 };
 149
 150 static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
 151 {
 152         struct user_fpsimd_state const *fpsimd =
 153                 &current->thread.uw.fpsimd_state;
 154         compat_ulong_t magic = VFP_MAGIC;
 155         compat_ulong_t size = VFP_STORAGE_SIZE;
 156         compat_ulong_t fpscr, fpexc;
 157         int i, err = 0;
 158
 159         /*
 160          * Save the hardware registers to the fpsimd_state structure.
 161          * Note that this also saves V16-31, which aren't visible
 162          * in AArch32.
 163          */
 164         fpsimd_signal_preserve_current_state();
 165
 166         /* Place structure header on the stack */
 167         __put_user_error(magic, &frame->magic, err);
 168         __put_user_error(size, &frame->size, err);
 169
 170         /*
 171          * Now copy the FP registers. Since the registers are packed,
 172          * we can copy the prefix we want (V0-V15) as it is.
 173          */
 174         for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
 175                 union __fpsimd_vreg vreg = {
 176                         .raw = fpsimd->vregs[i >> 1],
 177                 };
 178
 179                 __put_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
 180                 __put_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
 181         }
 182
 183         /* Create an AArch32 fpscr from the fpsr and the fpcr. */
 184         fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) |
 185                 (fpsimd->fpcr & VFP_FPSCR_CTRL_MASK);
 186         __put_user_error(fpscr, &frame->ufp.fpscr, err);
 187
 188         /*
 189          * The exception register aren't available so we fake up a
 190          * basic FPEXC and zero everything else.
 191          */
 192         fpexc = (1 << 30);
 193         __put_user_error(fpexc, &frame->ufp_exc.fpexc, err);
 194         __put_user_error(0, &frame->ufp_exc.fpinst, err);
 195         __put_user_error(0, &frame->ufp_exc.fpinst2, err);
 196
 197         return err ? -EFAULT : 0;
 198 }
 199
 200 static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
 201 {
 202         struct user_fpsimd_state fpsimd;
 203         compat_ulong_t magic = VFP_MAGIC;
 204         compat_ulong_t size = VFP_STORAGE_SIZE;
 205         compat_ulong_t fpscr;
 206         int i, err = 0;
 207
 208         __get_user_error(magic, &frame->magic, err);
 209         __get_user_error(size, &frame->size, err);
 210
 211         if (err)
 212                 return -EFAULT;
 213         if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
 214                 return -EINVAL;
 215
 216         /* Copy the FP registers into the start of the fpsimd_state. */
 217         for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
 218                 union __fpsimd_vreg vreg;
 219
 220                 __get_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
 221                 __get_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
 222                 fpsimd.vregs[i >> 1] = vreg.raw;
 223         }
 224
 225         /* Extract the fpsr and the fpcr from the fpscr */
 226         __get_user_error(fpscr, &frame->ufp.fpscr, err);
 227         fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK;
 228         fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
 229
 230         /*
 231          * We don't need to touch the exception register, so
 232          * reload the hardware state.
 233          */
 234         if (!err)
 235                 fpsimd_update_current_state(&fpsimd);
 236
 237         return err ? -EFAULT : 0;
 238 }
 239
 240 static int compat_restore_sigframe(struct pt_regs *regs,
 241                                    struct compat_sigframe __user *sf)
 242 {
 243         int err;
 244         sigset_t set;
 245         struct compat_aux_sigframe __user *aux;
 246         unsigned long psr;
 247
 248         err = get_sigset_t(&set, &sf->uc.uc_sigmask);
 249         if (err == 0) {
 250                 sigdelsetmask(&set, ~_BLOCKABLE);
 251                 set_current_blocked(&set);
 252         }
 253
 254         __get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
 255         __get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
 256         __get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
 257         __get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
 258         __get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
 259         __get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
 260         __get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
 261         __get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
 262         __get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
 263         __get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
 264         __get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
 265         __get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
 266         __get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
 267         __get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
 268         __get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
 269         __get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
 270         __get_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
 271
 272         regs->pstate = compat_psr_to_pstate(psr);
 273
 274         /*
 275          * Avoid compat_sys_sigreturn() restarting.
 276          */
 277         forget_syscall(regs);
 278
 279         err |= !valid_user_regs(&regs->user_regs, current);
 280
 281         aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
 282         if (err == 0)
 283                 err |= compat_restore_vfp_context(&aux->vfp);
 284
 285         return err;
 286 }
 287
 288 COMPAT_SYSCALL_DEFINE0(sigreturn)
 289 {
 290         struct pt_regs *regs = current_pt_regs();
 291         struct compat_sigframe __user *frame;
 292
 293         /* Always make any pending restarted system calls return -EINTR */
 294         current->restart_block.fn = do_no_restart_syscall;
 295
 296         /*
 297          * Since we stacked the signal on a 64-bit boundary,
 298          * then 'sp' should be word aligned here.  If it's
 299          * not, then the user is trying to mess with us.
 300          */
 301         if (regs->compat_sp & 7)
 302                 goto badframe;
 303
 304         frame = (struct compat_sigframe __user *)regs->compat_sp;
 305
 306         if (!access_ok(frame, sizeof (*frame)))
 307                 goto badframe;
 308
 309         if (compat_restore_sigframe(regs, frame))
 310                 goto badframe;
 311
 312         return regs->regs[0];
 313
 314 badframe:
 315         arm64_notify_segfault(regs->compat_sp);
 316         return 0;
 317 }
 318
 319 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 320 {
 321         struct pt_regs *regs = current_pt_regs();
 322         struct compat_rt_sigframe __user *frame;
 323
 324         /* Always make any pending restarted system calls return -EINTR */
 325         current->restart_block.fn = do_no_restart_syscall;
 326
 327         /*
 328          * Since we stacked the signal on a 64-bit boundary,
 329          * then 'sp' should be word aligned here.  If it's
 330          * not, then the user is trying to mess with us.
 331          */
 332         if (regs->compat_sp & 7)
 333                 goto badframe;
 334
 335         frame = (struct compat_rt_sigframe __user *)regs->compat_sp;
 336
 337         if (!access_ok(frame, sizeof (*frame)))
 338                 goto badframe;
 339
 340         if (compat_restore_sigframe(regs, &frame->sig))
 341                 goto badframe;
 342
 343         if (compat_restore_altstack(&frame->sig.uc.uc_stack))
 344                 goto badframe;
 345
 346         return regs->regs[0];
 347
 348 badframe:
 349         arm64_notify_segfault(regs->compat_sp);
 350         return 0;
 351 }
 352
 353 static void __user *compat_get_sigframe(struct ksignal *ksig,
 354                                         struct pt_regs *regs,
 355                                         int framesize)
 356 {
 357         compat_ulong_t sp = sigsp(regs->compat_sp, ksig);
 358         void __user *frame;
 359
 360         /*
 361          * ATPCS B01 mandates 8-byte alignment
 362          */
 363         frame = compat_ptr((compat_uptr_t)((sp - framesize) & ~7));
 364
 365         /*
 366          * Check that we can actually write to the signal frame.
 367          */
 368         if (!access_ok(frame, framesize))
 369                 frame = NULL;
 370
 371         return frame;
 372 }
 373
 374 static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 375                                 compat_ulong_t __user *rc, void __user *frame,
 376                                 int usig)
 377 {
 378         compat_ulong_t handler = ptr_to_compat(ka->sa.sa_handler);
 379         compat_ulong_t retcode;
 380         compat_ulong_t spsr = regs->pstate & ~(PSR_f | PSR_AA32_E_BIT);
 381         int thumb;
 382
 383         /* Check if the handler is written for ARM or Thumb */
 384         thumb = handler & 1;
 385
 386         if (thumb)
 387                 spsr |= PSR_AA32_T_BIT;
 388         else
 389                 spsr &= ~PSR_AA32_T_BIT;
 390
 391         /* The IT state must be cleared for both ARM and Thumb-2 */
 392         spsr &= ~PSR_AA32_IT_MASK;
 393
 394         /* Restore the original endianness */
 395         spsr |= PSR_AA32_ENDSTATE;
 396
 397         if (ka->sa.sa_flags & SA_RESTORER) {
 398                 retcode = ptr_to_compat(ka->sa.sa_restorer);
 399         } else {
 400                 /* Set up sigreturn pointer */
 401                 unsigned int idx = thumb << 1;
 402
 403                 if (ka->sa.sa_flags & SA_SIGINFO)
 404                         idx += 3;
 405
 406                 retcode = (unsigned long)current->mm->context.vdso +
 407                           (idx << 2) + thumb;
 408         }
 409
 410         regs->regs[0]   = usig;
 411         regs->compat_sp = ptr_to_compat(frame);
 412         regs->compat_lr = retcode;
 413         regs->pc        = handler;
 414         regs->pstate    = spsr;
 415 }
 416
 417 static int compat_setup_sigframe(struct compat_sigframe __user *sf,
 418                                  struct pt_regs *regs, sigset_t *set)
 419 {
 420         struct compat_aux_sigframe __user *aux;
 421         unsigned long psr = pstate_to_compat_psr(regs->pstate);
 422         int err = 0;
 423
 424         __put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
 425         __put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
 426         __put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
 427         __put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
 428         __put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
 429         __put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
 430         __put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
 431         __put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
 432         __put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
 433         __put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
 434         __put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
 435         __put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
 436         __put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
 437         __put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
 438         __put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
 439         __put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
 440         __put_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
 441
 442         __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
 443         /* set the compat FSR WnR */
 444         __put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) <<
 445                          FSR_WRITE_SHIFT, &sf->uc.uc_mcontext.error_code, err);
 446         __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
 447         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 448
 449         err |= put_sigset_t(&sf->uc.uc_sigmask, set);
 450
 451         aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
 452
 453         if (err == 0)
 454                 err |= compat_preserve_vfp_context(&aux->vfp);
 455         __put_user_error(0, &aux->end_magic, err);
 456
 457         return err;
 458 }
 459
 460 /*
 461  * 32-bit signal handling routines called from signal.c
 462  */
 463 int compat_setup_rt_frame(int usig, struct ksignal *ksig,
 464                           sigset_t *set, struct pt_regs *regs)
 465 {
 466         struct compat_rt_sigframe __user *frame;
 467         int err = 0;
 468
 469         frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
 470
 471         if (!frame)
 472                 return 1;
 473
 474         err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
 475
 476         __put_user_error(0, &frame->sig.uc.uc_flags, err);
 477         __put_user_error(0, &frame->sig.uc.uc_link, err);
 478
 479         err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);
 480
 481         err |= compat_setup_sigframe(&frame->sig, regs, set);
 482
 483         if (err == 0) {
 484                 compat_setup_return(regs, &ksig->ka, frame->sig.retcode, frame, usig);
 485                 regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
 486                 regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
 487         }
 488
 489         return err;
 490 }
 491
 492 int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set,
 493                        struct pt_regs *regs)
 494 {
 495         struct compat_sigframe __user *frame;
 496         int err = 0;
 497
 498         frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
 499
 500         if (!frame)
 501                 return 1;
 502
 503         __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
 504
 505         err |= compat_setup_sigframe(frame, regs, set);
 506         if (err == 0)
 507                 compat_setup_return(regs, &ksig->ka, frame->retcode, frame, usig);
 508
 509         return err;
 510 }
 511
 512 void compat_setup_restart_syscall(struct pt_regs *regs)
 513 {
 514        regs->regs[7] = __NR_compat_restart_syscall;
 515 }