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 <linux/uaccess.h>
  30 #include <asm/unistd.h>
  31
  32 struct compat_sigcontext {
  33         /* We always set these two fields to 0 */
  34         compat_ulong_t                  trap_no;
  35         compat_ulong_t                  error_code;
  36
  37         compat_ulong_t                  oldmask;
  38         compat_ulong_t                  arm_r0;
  39         compat_ulong_t                  arm_r1;
  40         compat_ulong_t                  arm_r2;
  41         compat_ulong_t                  arm_r3;
  42         compat_ulong_t                  arm_r4;
  43         compat_ulong_t                  arm_r5;
  44         compat_ulong_t                  arm_r6;
  45         compat_ulong_t                  arm_r7;
  46         compat_ulong_t                  arm_r8;
  47         compat_ulong_t                  arm_r9;
  48         compat_ulong_t                  arm_r10;
  49         compat_ulong_t                  arm_fp;
  50         compat_ulong_t                  arm_ip;
  51         compat_ulong_t                  arm_sp;
  52         compat_ulong_t                  arm_lr;
  53         compat_ulong_t                  arm_pc;
  54         compat_ulong_t                  arm_cpsr;
  55         compat_ulong_t                  fault_address;
  56 };
  57
  58 struct compat_ucontext {
  59         compat_ulong_t                  uc_flags;
  60         compat_uptr_t                   uc_link;
  61         compat_stack_t                  uc_stack;
  62         struct compat_sigcontext        uc_mcontext;
  63         compat_sigset_t                 uc_sigmask;
  64         int             __unused[32 - (sizeof (compat_sigset_t) / sizeof (int))];
  65         compat_ulong_t  uc_regspace[128] __attribute__((__aligned__(8)));
  66 };
  67
  68 struct compat_vfp_sigframe {
  69         compat_ulong_t  magic;
  70         compat_ulong_t  size;
  71         struct compat_user_vfp {
  72                 compat_u64      fpregs[32];
  73                 compat_ulong_t  fpscr;
  74         } ufp;
  75         struct compat_user_vfp_exc {
  76                 compat_ulong_t  fpexc;
  77                 compat_ulong_t  fpinst;
  78                 compat_ulong_t  fpinst2;
  79         } ufp_exc;
  80 } __attribute__((__aligned__(8)));
  81
  82 #define VFP_MAGIC               0x56465001
  83 #define VFP_STORAGE_SIZE        sizeof(struct compat_vfp_sigframe)
  84
  85 #define FSR_WRITE_SHIFT         (11)
  86
  87 struct compat_aux_sigframe {
  88         struct compat_vfp_sigframe      vfp;
  89
  90         /* Something that isn't a valid magic number for any coprocessor.  */
  91         unsigned long                   end_magic;
  92 } __attribute__((__aligned__(8)));
  93
  94 struct compat_sigframe {
  95         struct compat_ucontext  uc;
  96         compat_ulong_t          retcode[2];
  97 };
  98
  99 struct compat_rt_sigframe {
 100         struct compat_siginfo info;
 101         struct compat_sigframe sig;
 102 };
 103
 104 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
 105
 106 static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
 107 {
 108         compat_sigset_t cset;
 109
 110         cset.sig[0] = set->sig[0] & 0xffffffffull;
 111         cset.sig[1] = set->sig[0] >> 32;
 112
 113         return copy_to_user(uset, &cset, sizeof(*uset));
 114 }
 115
 116 static inline int get_sigset_t(sigset_t *set,
 117                                const compat_sigset_t __user *uset)
 118 {
 119         compat_sigset_t s32;
 120
 121         if (copy_from_user(&s32, uset, sizeof(*uset)))
 122                 return -EFAULT;
 123
 124         set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
 125         return 0;
 126 }
 127
 128 /*
 129  * VFP save/restore code.
 130  *
 131  * We have to be careful with endianness, since the fpsimd context-switch
 132  * code operates on 128-bit (Q) register values whereas the compat ABI
 133  * uses an array of 64-bit (D) registers. Consequently, we need to swap
 134  * the two halves of each Q register when running on a big-endian CPU.
 135  */
 136 union __fpsimd_vreg {
 137         __uint128_t     raw;
 138         struct {
 139 #ifdef __AARCH64EB__
 140                 u64     hi;
 141                 u64     lo;
 142 #else
 143                 u64     lo;
 144                 u64     hi;
 145 #endif
 146         };
 147 };
 148
 149 static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
 150 {
 151         struct user_fpsimd_state const *fpsimd =
 152                 &current->thread.fpsimd_state.user_fpsimd;
 153         compat_ulong_t magic = VFP_MAGIC;
 154         compat_ulong_t size = VFP_STORAGE_SIZE;
 155         compat_ulong_t fpscr, fpexc;
 156         int i, err = 0;
 157
 158         /*
 159          * Save the hardware registers to the fpsimd_state structure.
 160          * Note that this also saves V16-31, which aren't visible
 161          * in AArch32.
 162          */
 163         fpsimd_signal_preserve_current_state();
 164
 165         /* Place structure header on the stack */
 166         __put_user_error(magic, &frame->magic, err);
 167         __put_user_error(size, &frame->size, err);
 168
 169         /*
 170          * Now copy the FP registers. Since the registers are packed,
 171          * we can copy the prefix we want (V0-V15) as it is.
 172          */
 173         for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
 174                 union __fpsimd_vreg vreg = {
 175                         .raw = fpsimd->vregs[i >> 1],
 176                 };
 177
 178                 __put_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
 179                 __put_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
 180         }
 181
 182         /* Create an AArch32 fpscr from the fpsr and the fpcr. */
 183         fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) |
 184                 (fpsimd->fpcr & VFP_FPSCR_CTRL_MASK);
 185         __put_user_error(fpscr, &frame->ufp.fpscr, err);
 186
 187         /*
 188          * The exception register aren't available so we fake up a
 189          * basic FPEXC and zero everything else.
 190          */
 191         fpexc = (1 << 30);
 192         __put_user_error(fpexc, &frame->ufp_exc.fpexc, err);
 193         __put_user_error(0, &frame->ufp_exc.fpinst, err);
 194         __put_user_error(0, &frame->ufp_exc.fpinst2, err);
 195
 196         return err ? -EFAULT : 0;
 197 }
 198
 199 static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
 200 {
 201         struct user_fpsimd_state fpsimd;
 202         compat_ulong_t magic = VFP_MAGIC;
 203         compat_ulong_t size = VFP_STORAGE_SIZE;
 204         compat_ulong_t fpscr;
 205         int i, err = 0;
 206
 207         __get_user_error(magic, &frame->magic, err);
 208         __get_user_error(size, &frame->size, err);
 209
 210         if (err)
 211                 return -EFAULT;
 212         if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
 213                 return -EINVAL;
 214
 215         /* Copy the FP registers into the start of the fpsimd_state. */
 216         for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
 217                 union __fpsimd_vreg vreg;
 218
 219                 __get_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
 220                 __get_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
 221                 fpsimd.vregs[i >> 1] = vreg.raw;
 222         }
 223
 224         /* Extract the fpsr and the fpcr from the fpscr */
 225         __get_user_error(fpscr, &frame->ufp.fpscr, err);
 226         fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK;
 227         fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
 228
 229         /*
 230          * We don't need to touch the exception register, so
 231          * reload the hardware state.
 232          */
 233         if (!err)
 234                 fpsimd_update_current_state(&fpsimd);
 235
 236         return err ? -EFAULT : 0;
 237 }
 238
 239 static int compat_restore_sigframe(struct pt_regs *regs,
 240                                    struct compat_sigframe __user *sf)
 241 {
 242         int err;
 243         sigset_t set;
 244         struct compat_aux_sigframe __user *aux;
 245
 246         err = get_sigset_t(&set, &sf->uc.uc_sigmask);
 247         if (err == 0) {
 248                 sigdelsetmask(&set, ~_BLOCKABLE);
 249                 set_current_blocked(&set);
 250         }
 251
 252         __get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
 253         __get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
 254         __get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
 255         __get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
 256         __get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
 257         __get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
 258         __get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
 259         __get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
 260         __get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
 261         __get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
 262         __get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
 263         __get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
 264         __get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
 265         __get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
 266         __get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
 267         __get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
 268         __get_user_error(regs->pstate, &sf->uc.uc_mcontext.arm_cpsr, err);
 269
 270         /*
 271          * Avoid compat_sys_sigreturn() restarting.
 272          */
 273         forget_syscall(regs);
 274
 275         err |= !valid_user_regs(&regs->user_regs, current);
 276
 277         aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
 278         if (err == 0)
 279                 err |= compat_restore_vfp_context(&aux->vfp);
 280
 281         return err;
 282 }
 283
 284 asmlinkage int compat_sys_sigreturn(struct pt_regs *regs)
 285 {
 286         struct compat_sigframe __user *frame;
 287
 288         /* Always make any pending restarted system calls return -EINTR */
 289         current->restart_block.fn = do_no_restart_syscall;
 290
 291         /*
 292          * Since we stacked the signal on a 64-bit boundary,
 293          * then 'sp' should be word aligned here.  If it's
 294          * not, then the user is trying to mess with us.
 295          */
 296         if (regs->compat_sp & 7)
 297                 goto badframe;
 298
 299         frame = (struct compat_sigframe __user *)regs->compat_sp;
 300
 301         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 302                 goto badframe;
 303
 304         if (compat_restore_sigframe(regs, frame))
 305                 goto badframe;
 306
 307         return regs->regs[0];
 308
 309 badframe:
 310         if (show_unhandled_signals)
 311                 pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
 312                                     current->comm, task_pid_nr(current), __func__,
 313                                     regs->pc, regs->compat_sp);
 314         force_sig(SIGSEGV, current);
 315         return 0;
 316 }
 317
 318 asmlinkage int compat_sys_rt_sigreturn(struct pt_regs *regs)
 319 {
 320         struct compat_rt_sigframe __user *frame;
 321
 322         /* Always make any pending restarted system calls return -EINTR */
 323         current->restart_block.fn = do_no_restart_syscall;
 324
 325         /*
 326          * Since we stacked the signal on a 64-bit boundary,
 327          * then 'sp' should be word aligned here.  If it's
 328          * not, then the user is trying to mess with us.
 329          */
 330         if (regs->compat_sp & 7)
 331                 goto badframe;
 332
 333         frame = (struct compat_rt_sigframe __user *)regs->compat_sp;
 334
 335         if (!access_ok(VERIFY_READ, frame, sizeof (*frame)))
 336                 goto badframe;
 337
 338         if (compat_restore_sigframe(regs, &frame->sig))
 339                 goto badframe;
 340
 341         if (compat_restore_altstack(&frame->sig.uc.uc_stack))
 342                 goto badframe;
 343
 344         return regs->regs[0];
 345
 346 badframe:
 347         if (show_unhandled_signals)
 348                 pr_info_ratelimited("%s[%d]: bad frame in %s: pc=%08llx sp=%08llx\n",
 349                                     current->comm, task_pid_nr(current), __func__,
 350                                     regs->pc, regs->compat_sp);
 351         force_sig(SIGSEGV, current);
 352         return 0;
 353 }
 354
 355 static void __user *compat_get_sigframe(struct ksignal *ksig,
 356                                         struct pt_regs *regs,
 357                                         int framesize)
 358 {
 359         compat_ulong_t sp = sigsp(regs->compat_sp, ksig);
 360         void __user *frame;
 361
 362         /*
 363          * ATPCS B01 mandates 8-byte alignment
 364          */
 365         frame = compat_ptr((compat_uptr_t)((sp - framesize) & ~7));
 366
 367         /*
 368          * Check that we can actually write to the signal frame.
 369          */
 370         if (!access_ok(VERIFY_WRITE, frame, framesize))
 371                 frame = NULL;
 372
 373         return frame;
 374 }
 375
 376 static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 377                                 compat_ulong_t __user *rc, void __user *frame,
 378                                 int usig)
 379 {
 380         compat_ulong_t handler = ptr_to_compat(ka->sa.sa_handler);
 381         compat_ulong_t retcode;
 382         compat_ulong_t spsr = regs->pstate & ~(PSR_f | COMPAT_PSR_E_BIT);
 383         int thumb;
 384
 385         /* Check if the handler is written for ARM or Thumb */
 386         thumb = handler & 1;
 387
 388         if (thumb)
 389                 spsr |= COMPAT_PSR_T_BIT;
 390         else
 391                 spsr &= ~COMPAT_PSR_T_BIT;
 392
 393         /* The IT state must be cleared for both ARM and Thumb-2 */
 394         spsr &= ~COMPAT_PSR_IT_MASK;
 395
 396         /* Restore the original endianness */
 397         spsr |= COMPAT_PSR_ENDSTATE;
 398
 399         if (ka->sa.sa_flags & SA_RESTORER) {
 400                 retcode = ptr_to_compat(ka->sa.sa_restorer);
 401         } else {
 402                 /* Set up sigreturn pointer */
 403                 unsigned int idx = thumb << 1;
 404
 405                 if (ka->sa.sa_flags & SA_SIGINFO)
 406                         idx += 3;
 407
 408                 retcode = AARCH32_VECTORS_BASE +
 409                           AARCH32_KERN_SIGRET_CODE_OFFSET +
 410                           (idx << 2) + thumb;
 411         }
 412
 413         regs->regs[0]   = usig;
 414         regs->compat_sp = ptr_to_compat(frame);
 415         regs->compat_lr = retcode;
 416         regs->pc        = handler;
 417         regs->pstate    = spsr;
 418 }
 419
 420 static int compat_setup_sigframe(struct compat_sigframe __user *sf,
 421                                  struct pt_regs *regs, sigset_t *set)
 422 {
 423         struct compat_aux_sigframe __user *aux;
 424         int err = 0;
 425
 426         __put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
 427         __put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
 428         __put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
 429         __put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
 430         __put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
 431         __put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
 432         __put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
 433         __put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
 434         __put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
 435         __put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
 436         __put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
 437         __put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
 438         __put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
 439         __put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
 440         __put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
 441         __put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
 442         __put_user_error(regs->pstate, &sf->uc.uc_mcontext.arm_cpsr, err);
 443
 444         __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
 445         /* set the compat FSR WnR */
 446         __put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) <<
 447                          FSR_WRITE_SHIFT, &sf->uc.uc_mcontext.error_code, err);
 448         __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
 449         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 450
 451         err |= put_sigset_t(&sf->uc.uc_sigmask, set);
 452
 453         aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
 454
 455         if (err == 0)
 456                 err |= compat_preserve_vfp_context(&aux->vfp);
 457         __put_user_error(0, &aux->end_magic, err);
 458
 459         return err;
 460 }
 461
 462 /*
 463  * 32-bit signal handling routines called from signal.c
 464  */
 465 int compat_setup_rt_frame(int usig, struct ksignal *ksig,
 466                           sigset_t *set, struct pt_regs *regs)
 467 {
 468         struct compat_rt_sigframe __user *frame;
 469         int err = 0;
 470
 471         frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
 472
 473         if (!frame)
 474                 return 1;
 475
 476         err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
 477
 478         __put_user_error(0, &frame->sig.uc.uc_flags, err);
 479         __put_user_error(0, &frame->sig.uc.uc_link, err);
 480
 481         err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);
 482
 483         err |= compat_setup_sigframe(&frame->sig, regs, set);
 484
 485         if (err == 0) {
 486                 compat_setup_return(regs, &ksig->ka, frame->sig.retcode, frame, usig);
 487                 regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
 488                 regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
 489         }
 490
 491         return err;
 492 }
 493
 494 int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set,
 495                        struct pt_regs *regs)
 496 {
 497         struct compat_sigframe __user *frame;
 498         int err = 0;
 499
 500         frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
 501
 502         if (!frame)
 503                 return 1;
 504
 505         __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
 506
 507         err |= compat_setup_sigframe(frame, regs, set);
 508         if (err == 0)
 509                 compat_setup_return(regs, &ksig->ka, frame->retcode, frame, usig);
 510
 511         return err;
 512 }
 513
 514 void compat_setup_restart_syscall(struct pt_regs *regs)
 515 {
 516        regs->regs[7] = __NR_compat_restart_syscall;
 517 }