arch/arm64/kernel/signal32.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Based on arch/arm/kernel/signal.c
   4  *
   5  * Copyright (C) 1995-2009 Russell King
   6  * Copyright (C) 2012 ARM Ltd.
   7  * Modified by Will Deacon <will.deacon@arm.com>
   8  */
   9
  10 #include <linux/compat.h>
  11 #include <linux/signal.h>
  12 #include <linux/syscalls.h>
  13 #include <linux/ratelimit.h>
  14
  15 #include <asm/esr.h>
  16 #include <asm/fpsimd.h>
  17 #include <asm/signal32.h>
  18 #include <asm/traps.h>
  19 #include <linux/uaccess.h>
  20 #include <asm/unistd.h>
  21 #include <asm/vdso.h>
  22
  23 struct compat_vfp_sigframe {
  24         compat_ulong_t  magic;
  25         compat_ulong_t  size;
  26         struct compat_user_vfp {
  27                 compat_u64      fpregs[32];
  28                 compat_ulong_t  fpscr;
  29         } ufp;
  30         struct compat_user_vfp_exc {
  31                 compat_ulong_t  fpexc;
  32                 compat_ulong_t  fpinst;
  33                 compat_ulong_t  fpinst2;
  34         } ufp_exc;
  35 } __attribute__((__aligned__(8)));
  36
  37 #define VFP_MAGIC               0x56465001
  38 #define VFP_STORAGE_SIZE        sizeof(struct compat_vfp_sigframe)
  39
  40 #define FSR_WRITE_SHIFT         (11)
  41
  42 struct compat_aux_sigframe {
  43         struct compat_vfp_sigframe      vfp;
  44
  45         /* Something that isn't a valid magic number for any coprocessor.  */
  46         unsigned long                   end_magic;
  47 } __attribute__((__aligned__(8)));
  48
  49 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  50
  51 static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
  52 {
  53         compat_sigset_t cset;
  54
  55         cset.sig[0] = set->sig[0] & 0xffffffffull;
  56         cset.sig[1] = set->sig[0] >> 32;
  57
  58         return copy_to_user(uset, &cset, sizeof(*uset));
  59 }
  60
  61 static inline int get_sigset_t(sigset_t *set,
  62                                const compat_sigset_t __user *uset)
  63 {
  64         compat_sigset_t s32;
  65
  66         if (copy_from_user(&s32, uset, sizeof(*uset)))
  67                 return -EFAULT;
  68
  69         set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
  70         return 0;
  71 }
  72
  73 /*
  74  * VFP save/restore code.
  75  *
  76  * We have to be careful with endianness, since the fpsimd context-switch
  77  * code operates on 128-bit (Q) register values whereas the compat ABI
  78  * uses an array of 64-bit (D) registers. Consequently, we need to swap
  79  * the two halves of each Q register when running on a big-endian CPU.
  80  */
  81 union __fpsimd_vreg {
  82         __uint128_t     raw;
  83         struct {
  84 #ifdef __AARCH64EB__
  85                 u64     hi;
  86                 u64     lo;
  87 #else
  88                 u64     lo;
  89                 u64     hi;
  90 #endif
  91         };
  92 };
  93
  94 static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
  95 {
  96         struct user_fpsimd_state const *fpsimd =
  97                 &current->thread.uw.fpsimd_state;
  98         compat_ulong_t magic = VFP_MAGIC;
  99         compat_ulong_t size = VFP_STORAGE_SIZE;
 100         compat_ulong_t fpscr, fpexc;
 101         int i, err = 0;
 102
 103         /*
 104          * Save the hardware registers to the fpsimd_state structure.
 105          * Note that this also saves V16-31, which aren't visible
 106          * in AArch32.
 107          */
 108         fpsimd_signal_preserve_current_state();
 109
 110         /* Place structure header on the stack */
 111         __put_user_error(magic, &frame->magic, err);
 112         __put_user_error(size, &frame->size, err);
 113
 114         /*
 115          * Now copy the FP registers. Since the registers are packed,
 116          * we can copy the prefix we want (V0-V15) as it is.
 117          */
 118         for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
 119                 union __fpsimd_vreg vreg = {
 120                         .raw = fpsimd->vregs[i >> 1],
 121                 };
 122
 123                 __put_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
 124                 __put_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
 125         }
 126
 127         /* Create an AArch32 fpscr from the fpsr and the fpcr. */
 128         fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) |
 129                 (fpsimd->fpcr & VFP_FPSCR_CTRL_MASK);
 130         __put_user_error(fpscr, &frame->ufp.fpscr, err);
 131
 132         /*
 133          * The exception register aren't available so we fake up a
 134          * basic FPEXC and zero everything else.
 135          */
 136         fpexc = (1 << 30);
 137         __put_user_error(fpexc, &frame->ufp_exc.fpexc, err);
 138         __put_user_error(0, &frame->ufp_exc.fpinst, err);
 139         __put_user_error(0, &frame->ufp_exc.fpinst2, err);
 140
 141         return err ? -EFAULT : 0;
 142 }
 143
 144 static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
 145 {
 146         struct user_fpsimd_state fpsimd;
 147         compat_ulong_t magic = VFP_MAGIC;
 148         compat_ulong_t size = VFP_STORAGE_SIZE;
 149         compat_ulong_t fpscr;
 150         int i, err = 0;
 151
 152         __get_user_error(magic, &frame->magic, err);
 153         __get_user_error(size, &frame->size, err);
 154
 155         if (err)
 156                 return -EFAULT;
 157         if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
 158                 return -EINVAL;
 159
 160         /* Copy the FP registers into the start of the fpsimd_state. */
 161         for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
 162                 union __fpsimd_vreg vreg;
 163
 164                 __get_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
 165                 __get_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
 166                 fpsimd.vregs[i >> 1] = vreg.raw;
 167         }
 168
 169         /* Extract the fpsr and the fpcr from the fpscr */
 170         __get_user_error(fpscr, &frame->ufp.fpscr, err);
 171         fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK;
 172         fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
 173
 174         /*
 175          * We don't need to touch the exception register, so
 176          * reload the hardware state.
 177          */
 178         if (!err)
 179                 fpsimd_update_current_state(&fpsimd);
 180
 181         return err ? -EFAULT : 0;
 182 }
 183
 184 static int compat_restore_sigframe(struct pt_regs *regs,
 185                                    struct compat_sigframe __user *sf)
 186 {
 187         int err;
 188         sigset_t set;
 189         struct compat_aux_sigframe __user *aux;
 190         unsigned long psr;
 191
 192         err = get_sigset_t(&set, &sf->uc.uc_sigmask);
 193         if (err == 0) {
 194                 sigdelsetmask(&set, ~_BLOCKABLE);
 195                 set_current_blocked(&set);
 196         }
 197
 198         __get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
 199         __get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
 200         __get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
 201         __get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
 202         __get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
 203         __get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
 204         __get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
 205         __get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
 206         __get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
 207         __get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
 208         __get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
 209         __get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
 210         __get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
 211         __get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
 212         __get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
 213         __get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
 214         __get_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
 215
 216         regs->pstate = compat_psr_to_pstate(psr);
 217
 218         /*
 219          * Avoid compat_sys_sigreturn() restarting.
 220          */
 221         forget_syscall(regs);
 222
 223         err |= !valid_user_regs(&regs->user_regs, current);
 224
 225         aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
 226         if (err == 0)
 227                 err |= compat_restore_vfp_context(&aux->vfp);
 228
 229         return err;
 230 }
 231
 232 COMPAT_SYSCALL_DEFINE0(sigreturn)
 233 {
 234         struct pt_regs *regs = current_pt_regs();
 235         struct compat_sigframe __user *frame;
 236
 237         /* Always make any pending restarted system calls return -EINTR */
 238         current->restart_block.fn = do_no_restart_syscall;
 239
 240         /*
 241          * Since we stacked the signal on a 64-bit boundary,
 242          * then 'sp' should be word aligned here.  If it's
 243          * not, then the user is trying to mess with us.
 244          */
 245         if (regs->compat_sp & 7)
 246                 goto badframe;
 247
 248         frame = (struct compat_sigframe __user *)regs->compat_sp;
 249
 250         if (!access_ok(frame, sizeof (*frame)))
 251                 goto badframe;
 252
 253         if (compat_restore_sigframe(regs, frame))
 254                 goto badframe;
 255
 256         return regs->regs[0];
 257
 258 badframe:
 259         arm64_notify_segfault(regs->compat_sp);
 260         return 0;
 261 }
 262
 263 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 264 {
 265         struct pt_regs *regs = current_pt_regs();
 266         struct compat_rt_sigframe __user *frame;
 267
 268         /* Always make any pending restarted system calls return -EINTR */
 269         current->restart_block.fn = do_no_restart_syscall;
 270
 271         /*
 272          * Since we stacked the signal on a 64-bit boundary,
 273          * then 'sp' should be word aligned here.  If it's
 274          * not, then the user is trying to mess with us.
 275          */
 276         if (regs->compat_sp & 7)
 277                 goto badframe;
 278
 279         frame = (struct compat_rt_sigframe __user *)regs->compat_sp;
 280
 281         if (!access_ok(frame, sizeof (*frame)))
 282                 goto badframe;
 283
 284         if (compat_restore_sigframe(regs, &frame->sig))
 285                 goto badframe;
 286
 287         if (compat_restore_altstack(&frame->sig.uc.uc_stack))
 288                 goto badframe;
 289
 290         return regs->regs[0];
 291
 292 badframe:
 293         arm64_notify_segfault(regs->compat_sp);
 294         return 0;
 295 }
 296
 297 static void __user *compat_get_sigframe(struct ksignal *ksig,
 298                                         struct pt_regs *regs,
 299                                         int framesize)
 300 {
 301         compat_ulong_t sp = sigsp(regs->compat_sp, ksig);
 302         void __user *frame;
 303
 304         /*
 305          * ATPCS B01 mandates 8-byte alignment
 306          */
 307         frame = compat_ptr((compat_uptr_t)((sp - framesize) & ~7));
 308
 309         /*
 310          * Check that we can actually write to the signal frame.
 311          */
 312         if (!access_ok(frame, framesize))
 313                 frame = NULL;
 314
 315         return frame;
 316 }
 317
 318 static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
 319                                 compat_ulong_t __user *rc, void __user *frame,
 320                                 int usig)
 321 {
 322         compat_ulong_t handler = ptr_to_compat(ka->sa.sa_handler);
 323         compat_ulong_t retcode;
 324         compat_ulong_t spsr = regs->pstate & ~(PSR_f | PSR_AA32_E_BIT);
 325         int thumb;
 326
 327         /* Check if the handler is written for ARM or Thumb */
 328         thumb = handler & 1;
 329
 330         if (thumb)
 331                 spsr |= PSR_AA32_T_BIT;
 332         else
 333                 spsr &= ~PSR_AA32_T_BIT;
 334
 335         /* The IT state must be cleared for both ARM and Thumb-2 */
 336         spsr &= ~PSR_AA32_IT_MASK;
 337
 338         /* Restore the original endianness */
 339         spsr |= PSR_AA32_ENDSTATE;
 340
 341         if (ka->sa.sa_flags & SA_RESTORER) {
 342                 retcode = ptr_to_compat(ka->sa.sa_restorer);
 343         } else {
 344                 /* Set up sigreturn pointer */
 345 #ifdef CONFIG_COMPAT_VDSO
 346                 void *vdso_base = current->mm->context.vdso;
 347                 void *vdso_trampoline;
 348
 349                 if (ka->sa.sa_flags & SA_SIGINFO) {
 350                         if (thumb) {
 351                                 vdso_trampoline = VDSO_SYMBOL(vdso_base,
 352                                                         compat_rt_sigreturn_thumb);
 353                         } else {
 354                                 vdso_trampoline = VDSO_SYMBOL(vdso_base,
 355                                                         compat_rt_sigreturn_arm);
 356                         }
 357                 } else {
 358                         if (thumb) {
 359                                 vdso_trampoline = VDSO_SYMBOL(vdso_base,
 360                                                         compat_sigreturn_thumb);
 361                         } else {
 362                                 vdso_trampoline = VDSO_SYMBOL(vdso_base,
 363                                                         compat_sigreturn_arm);
 364                         }
 365                 }
 366
 367                 retcode = ptr_to_compat(vdso_trampoline) + thumb;
 368 #else
 369                 unsigned int idx = thumb << 1;
 370
 371                 if (ka->sa.sa_flags & SA_SIGINFO)
 372                         idx += 3;
 373
 374                 retcode = (unsigned long)current->mm->context.vdso +
 375                           (idx << 2) + thumb;
 376 #endif
 377         }
 378
 379         regs->regs[0]   = usig;
 380         regs->compat_sp = ptr_to_compat(frame);
 381         regs->compat_lr = retcode;
 382         regs->pc        = handler;
 383         regs->pstate    = spsr;
 384 }
 385
 386 static int compat_setup_sigframe(struct compat_sigframe __user *sf,
 387                                  struct pt_regs *regs, sigset_t *set)
 388 {
 389         struct compat_aux_sigframe __user *aux;
 390         unsigned long psr = pstate_to_compat_psr(regs->pstate);
 391         int err = 0;
 392
 393         __put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
 394         __put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
 395         __put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
 396         __put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
 397         __put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
 398         __put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
 399         __put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
 400         __put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
 401         __put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
 402         __put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
 403         __put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
 404         __put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
 405         __put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
 406         __put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
 407         __put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
 408         __put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
 409         __put_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
 410
 411         __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
 412         /* set the compat FSR WnR */
 413         __put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) <<
 414                          FSR_WRITE_SHIFT, &sf->uc.uc_mcontext.error_code, err);
 415         __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
 416         __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
 417
 418         err |= put_sigset_t(&sf->uc.uc_sigmask, set);
 419
 420         aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
 421
 422         if (err == 0)
 423                 err |= compat_preserve_vfp_context(&aux->vfp);
 424         __put_user_error(0, &aux->end_magic, err);
 425
 426         return err;
 427 }
 428
 429 /*
 430  * 32-bit signal handling routines called from signal.c
 431  */
 432 int compat_setup_rt_frame(int usig, struct ksignal *ksig,
 433                           sigset_t *set, struct pt_regs *regs)
 434 {
 435         struct compat_rt_sigframe __user *frame;
 436         int err = 0;
 437
 438         frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
 439
 440         if (!frame)
 441                 return 1;
 442
 443         err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
 444
 445         __put_user_error(0, &frame->sig.uc.uc_flags, err);
 446         __put_user_error(0, &frame->sig.uc.uc_link, err);
 447
 448         err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);
 449
 450         err |= compat_setup_sigframe(&frame->sig, regs, set);
 451
 452         if (err == 0) {
 453                 compat_setup_return(regs, &ksig->ka, frame->sig.retcode, frame, usig);
 454                 regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
 455                 regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
 456         }
 457
 458         return err;
 459 }
 460
 461 int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set,
 462                        struct pt_regs *regs)
 463 {
 464         struct compat_sigframe __user *frame;
 465         int err = 0;
 466
 467         frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
 468
 469         if (!frame)
 470                 return 1;
 471
 472         __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
 473
 474         err |= compat_setup_sigframe(frame, regs, set);
 475         if (err == 0)
 476                 compat_setup_return(regs, &ksig->ka, frame->retcode, frame, usig);
 477
 478         return err;
 479 }
 480
 481 void compat_setup_restart_syscall(struct pt_regs *regs)
 482 {
 483        regs->regs[7] = __NR_compat_restart_syscall;
 484 }