arm64/kernel/signal32.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Based on arch/arm/kernel/signal.c
0004  *
0005  * Copyright (C) 1995-2009 Russell King
0006  * Copyright (C) 2012 ARM Ltd.
0007  * Modified by Will Deacon <will.deacon@arm.com>
0008  */
0009
0010 #include <linux/compat.h>
0011 #include <linux/signal.h>
0012 #include <linux/syscalls.h>
0013 #include <linux/ratelimit.h>
0014
0015 #include <asm/esr.h>
0016 #include <asm/fpsimd.h>
0017 #include <asm/signal32.h>
0018 #include <asm/traps.h>
0019 #include <linux/uaccess.h>
0020 #include <asm/unistd.h>
0021 #include <asm/vdso.h>
0022
0023 struct compat_vfp_sigframe {
0024     compat_ulong_t  magic;
0025     compat_ulong_t  size;
0026     struct compat_user_vfp {
0027         compat_u64  fpregs[32];
0028         compat_ulong_t  fpscr;
0029     } ufp;
0030     struct compat_user_vfp_exc {
0031         compat_ulong_t  fpexc;
0032         compat_ulong_t  fpinst;
0033         compat_ulong_t  fpinst2;
0034     } ufp_exc;
0035 } __attribute__((__aligned__(8)));
0036
0037 #define VFP_MAGIC       0x56465001
0038 #define VFP_STORAGE_SIZE    sizeof(struct compat_vfp_sigframe)
0039
0040 #define FSR_WRITE_SHIFT     (11)
0041
0042 struct compat_aux_sigframe {
0043     struct compat_vfp_sigframe  vfp;
0044
0045     /* Something that isn't a valid magic number for any coprocessor.  */
0046     unsigned long           end_magic;
0047 } __attribute__((__aligned__(8)));
0048
0049 static inline int put_sigset_t(compat_sigset_t __user *uset, sigset_t *set)
0050 {
0051     compat_sigset_t cset;
0052
0053     cset.sig[0] = set->sig[0] & 0xffffffffull;
0054     cset.sig[1] = set->sig[0] >> 32;
0055
0056     return copy_to_user(uset, &cset, sizeof(*uset));
0057 }
0058
0059 static inline int get_sigset_t(sigset_t *set,
0060                    const compat_sigset_t __user *uset)
0061 {
0062     compat_sigset_t s32;
0063
0064     if (copy_from_user(&s32, uset, sizeof(*uset)))
0065         return -EFAULT;
0066
0067     set->sig[0] = s32.sig[0] | (((long)s32.sig[1]) << 32);
0068     return 0;
0069 }
0070
0071 /*
0072  * VFP save/restore code.
0073  *
0074  * We have to be careful with endianness, since the fpsimd context-switch
0075  * code operates on 128-bit (Q) register values whereas the compat ABI
0076  * uses an array of 64-bit (D) registers. Consequently, we need to swap
0077  * the two halves of each Q register when running on a big-endian CPU.
0078  */
0079 union __fpsimd_vreg {
0080     __uint128_t raw;
0081     struct {
0082 #ifdef __AARCH64EB__
0083         u64 hi;
0084         u64 lo;
0085 #else
0086         u64 lo;
0087         u64 hi;
0088 #endif
0089     };
0090 };
0091
0092 static int compat_preserve_vfp_context(struct compat_vfp_sigframe __user *frame)
0093 {
0094     struct user_fpsimd_state const *fpsimd =
0095         &current->thread.uw.fpsimd_state;
0096     compat_ulong_t magic = VFP_MAGIC;
0097     compat_ulong_t size = VFP_STORAGE_SIZE;
0098     compat_ulong_t fpscr, fpexc;
0099     int i, err = 0;
0100
0101     /*
0102      * Save the hardware registers to the fpsimd_state structure.
0103      * Note that this also saves V16-31, which aren't visible
0104      * in AArch32.
0105      */
0106     fpsimd_signal_preserve_current_state();
0107
0108     /* Place structure header on the stack */
0109     __put_user_error(magic, &frame->magic, err);
0110     __put_user_error(size, &frame->size, err);
0111
0112     /*
0113      * Now copy the FP registers. Since the registers are packed,
0114      * we can copy the prefix we want (V0-V15) as it is.
0115      */
0116     for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
0117         union __fpsimd_vreg vreg = {
0118             .raw = fpsimd->vregs[i >> 1],
0119         };
0120
0121         __put_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
0122         __put_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
0123     }
0124
0125     /* Create an AArch32 fpscr from the fpsr and the fpcr. */
0126     fpscr = (fpsimd->fpsr & VFP_FPSCR_STAT_MASK) |
0127         (fpsimd->fpcr & VFP_FPSCR_CTRL_MASK);
0128     __put_user_error(fpscr, &frame->ufp.fpscr, err);
0129
0130     /*
0131      * The exception register aren't available so we fake up a
0132      * basic FPEXC and zero everything else.
0133      */
0134     fpexc = (1 << 30);
0135     __put_user_error(fpexc, &frame->ufp_exc.fpexc, err);
0136     __put_user_error(0, &frame->ufp_exc.fpinst, err);
0137     __put_user_error(0, &frame->ufp_exc.fpinst2, err);
0138
0139     return err ? -EFAULT : 0;
0140 }
0141
0142 static int compat_restore_vfp_context(struct compat_vfp_sigframe __user *frame)
0143 {
0144     struct user_fpsimd_state fpsimd;
0145     compat_ulong_t magic = VFP_MAGIC;
0146     compat_ulong_t size = VFP_STORAGE_SIZE;
0147     compat_ulong_t fpscr;
0148     int i, err = 0;
0149
0150     __get_user_error(magic, &frame->magic, err);
0151     __get_user_error(size, &frame->size, err);
0152
0153     if (err)
0154         return -EFAULT;
0155     if (magic != VFP_MAGIC || size != VFP_STORAGE_SIZE)
0156         return -EINVAL;
0157
0158     /* Copy the FP registers into the start of the fpsimd_state. */
0159     for (i = 0; i < ARRAY_SIZE(frame->ufp.fpregs); i += 2) {
0160         union __fpsimd_vreg vreg;
0161
0162         __get_user_error(vreg.lo, &frame->ufp.fpregs[i], err);
0163         __get_user_error(vreg.hi, &frame->ufp.fpregs[i + 1], err);
0164         fpsimd.vregs[i >> 1] = vreg.raw;
0165     }
0166
0167     /* Extract the fpsr and the fpcr from the fpscr */
0168     __get_user_error(fpscr, &frame->ufp.fpscr, err);
0169     fpsimd.fpsr = fpscr & VFP_FPSCR_STAT_MASK;
0170     fpsimd.fpcr = fpscr & VFP_FPSCR_CTRL_MASK;
0171
0172     /*
0173      * We don't need to touch the exception register, so
0174      * reload the hardware state.
0175      */
0176     if (!err)
0177         fpsimd_update_current_state(&fpsimd);
0178
0179     return err ? -EFAULT : 0;
0180 }
0181
0182 static int compat_restore_sigframe(struct pt_regs *regs,
0183                    struct compat_sigframe __user *sf)
0184 {
0185     int err;
0186     sigset_t set;
0187     struct compat_aux_sigframe __user *aux;
0188     unsigned long psr;
0189
0190     err = get_sigset_t(&set, &sf->uc.uc_sigmask);
0191     if (err == 0)
0192         set_current_blocked(&set);
0193
0194     __get_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
0195     __get_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
0196     __get_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
0197     __get_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
0198     __get_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
0199     __get_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
0200     __get_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
0201     __get_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
0202     __get_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
0203     __get_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
0204     __get_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
0205     __get_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
0206     __get_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
0207     __get_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
0208     __get_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
0209     __get_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
0210     __get_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
0211
0212     regs->pstate = compat_psr_to_pstate(psr);
0213
0214     /*
0215      * Avoid compat_sys_sigreturn() restarting.
0216      */
0217     forget_syscall(regs);
0218
0219     err |= !valid_user_regs(&regs->user_regs, current);
0220
0221     aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
0222     if (err == 0 && system_supports_fpsimd())
0223         err |= compat_restore_vfp_context(&aux->vfp);
0224
0225     return err;
0226 }
0227
0228 COMPAT_SYSCALL_DEFINE0(sigreturn)
0229 {
0230     struct pt_regs *regs = current_pt_regs();
0231     struct compat_sigframe __user *frame;
0232
0233     /* Always make any pending restarted system calls return -EINTR */
0234     current->restart_block.fn = do_no_restart_syscall;
0235
0236     /*
0237      * Since we stacked the signal on a 64-bit boundary,
0238      * then 'sp' should be word aligned here.  If it's
0239      * not, then the user is trying to mess with us.
0240      */
0241     if (regs->compat_sp & 7)
0242         goto badframe;
0243
0244     frame = (struct compat_sigframe __user *)regs->compat_sp;
0245
0246     if (!access_ok(frame, sizeof (*frame)))
0247         goto badframe;
0248
0249     if (compat_restore_sigframe(regs, frame))
0250         goto badframe;
0251
0252     return regs->regs[0];
0253
0254 badframe:
0255     arm64_notify_segfault(regs->compat_sp);
0256     return 0;
0257 }
0258
0259 COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
0260 {
0261     struct pt_regs *regs = current_pt_regs();
0262     struct compat_rt_sigframe __user *frame;
0263
0264     /* Always make any pending restarted system calls return -EINTR */
0265     current->restart_block.fn = do_no_restart_syscall;
0266
0267     /*
0268      * Since we stacked the signal on a 64-bit boundary,
0269      * then 'sp' should be word aligned here.  If it's
0270      * not, then the user is trying to mess with us.
0271      */
0272     if (regs->compat_sp & 7)
0273         goto badframe;
0274
0275     frame = (struct compat_rt_sigframe __user *)regs->compat_sp;
0276
0277     if (!access_ok(frame, sizeof (*frame)))
0278         goto badframe;
0279
0280     if (compat_restore_sigframe(regs, &frame->sig))
0281         goto badframe;
0282
0283     if (compat_restore_altstack(&frame->sig.uc.uc_stack))
0284         goto badframe;
0285
0286     return regs->regs[0];
0287
0288 badframe:
0289     arm64_notify_segfault(regs->compat_sp);
0290     return 0;
0291 }
0292
0293 static void __user *compat_get_sigframe(struct ksignal *ksig,
0294                     struct pt_regs *regs,
0295                     int framesize)
0296 {
0297     compat_ulong_t sp = sigsp(regs->compat_sp, ksig);
0298     void __user *frame;
0299
0300     /*
0301      * ATPCS B01 mandates 8-byte alignment
0302      */
0303     frame = compat_ptr((compat_uptr_t)((sp - framesize) & ~7));
0304
0305     /*
0306      * Check that we can actually write to the signal frame.
0307      */
0308     if (!access_ok(frame, framesize))
0309         frame = NULL;
0310
0311     return frame;
0312 }
0313
0314 static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
0315                 compat_ulong_t __user *rc, void __user *frame,
0316                 int usig)
0317 {
0318     compat_ulong_t handler = ptr_to_compat(ka->sa.sa_handler);
0319     compat_ulong_t retcode;
0320     compat_ulong_t spsr = regs->pstate & ~(PSR_f | PSR_AA32_E_BIT);
0321     int thumb;
0322
0323     /* Check if the handler is written for ARM or Thumb */
0324     thumb = handler & 1;
0325
0326     if (thumb)
0327         spsr |= PSR_AA32_T_BIT;
0328     else
0329         spsr &= ~PSR_AA32_T_BIT;
0330
0331     /* The IT state must be cleared for both ARM and Thumb-2 */
0332     spsr &= ~PSR_AA32_IT_MASK;
0333
0334     /* Restore the original endianness */
0335     spsr |= PSR_AA32_ENDSTATE;
0336
0337     if (ka->sa.sa_flags & SA_RESTORER) {
0338         retcode = ptr_to_compat(ka->sa.sa_restorer);
0339     } else {
0340         /* Set up sigreturn pointer */
0341         unsigned int idx = thumb << 1;
0342
0343         if (ka->sa.sa_flags & SA_SIGINFO)
0344             idx += 3;
0345
0346         retcode = (unsigned long)current->mm->context.sigpage +
0347               (idx << 2) + thumb;
0348     }
0349
0350     regs->regs[0]   = usig;
0351     regs->compat_sp = ptr_to_compat(frame);
0352     regs->compat_lr = retcode;
0353     regs->pc    = handler;
0354     regs->pstate    = spsr;
0355 }
0356
0357 static int compat_setup_sigframe(struct compat_sigframe __user *sf,
0358                  struct pt_regs *regs, sigset_t *set)
0359 {
0360     struct compat_aux_sigframe __user *aux;
0361     unsigned long psr = pstate_to_compat_psr(regs->pstate);
0362     int err = 0;
0363
0364     __put_user_error(regs->regs[0], &sf->uc.uc_mcontext.arm_r0, err);
0365     __put_user_error(regs->regs[1], &sf->uc.uc_mcontext.arm_r1, err);
0366     __put_user_error(regs->regs[2], &sf->uc.uc_mcontext.arm_r2, err);
0367     __put_user_error(regs->regs[3], &sf->uc.uc_mcontext.arm_r3, err);
0368     __put_user_error(regs->regs[4], &sf->uc.uc_mcontext.arm_r4, err);
0369     __put_user_error(regs->regs[5], &sf->uc.uc_mcontext.arm_r5, err);
0370     __put_user_error(regs->regs[6], &sf->uc.uc_mcontext.arm_r6, err);
0371     __put_user_error(regs->regs[7], &sf->uc.uc_mcontext.arm_r7, err);
0372     __put_user_error(regs->regs[8], &sf->uc.uc_mcontext.arm_r8, err);
0373     __put_user_error(regs->regs[9], &sf->uc.uc_mcontext.arm_r9, err);
0374     __put_user_error(regs->regs[10], &sf->uc.uc_mcontext.arm_r10, err);
0375     __put_user_error(regs->regs[11], &sf->uc.uc_mcontext.arm_fp, err);
0376     __put_user_error(regs->regs[12], &sf->uc.uc_mcontext.arm_ip, err);
0377     __put_user_error(regs->compat_sp, &sf->uc.uc_mcontext.arm_sp, err);
0378     __put_user_error(regs->compat_lr, &sf->uc.uc_mcontext.arm_lr, err);
0379     __put_user_error(regs->pc, &sf->uc.uc_mcontext.arm_pc, err);
0380     __put_user_error(psr, &sf->uc.uc_mcontext.arm_cpsr, err);
0381
0382     __put_user_error((compat_ulong_t)0, &sf->uc.uc_mcontext.trap_no, err);
0383     /* set the compat FSR WnR */
0384     __put_user_error(!!(current->thread.fault_code & ESR_ELx_WNR) <<
0385              FSR_WRITE_SHIFT, &sf->uc.uc_mcontext.error_code, err);
0386     __put_user_error(current->thread.fault_address, &sf->uc.uc_mcontext.fault_address, err);
0387     __put_user_error(set->sig[0], &sf->uc.uc_mcontext.oldmask, err);
0388
0389     err |= put_sigset_t(&sf->uc.uc_sigmask, set);
0390
0391     aux = (struct compat_aux_sigframe __user *) sf->uc.uc_regspace;
0392
0393     if (err == 0 && system_supports_fpsimd())
0394         err |= compat_preserve_vfp_context(&aux->vfp);
0395     __put_user_error(0, &aux->end_magic, err);
0396
0397     return err;
0398 }
0399
0400 /*
0401  * 32-bit signal handling routines called from signal.c
0402  */
0403 int compat_setup_rt_frame(int usig, struct ksignal *ksig,
0404               sigset_t *set, struct pt_regs *regs)
0405 {
0406     struct compat_rt_sigframe __user *frame;
0407     int err = 0;
0408
0409     frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
0410
0411     if (!frame)
0412         return 1;
0413
0414     err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
0415
0416     __put_user_error(0, &frame->sig.uc.uc_flags, err);
0417     __put_user_error(0, &frame->sig.uc.uc_link, err);
0418
0419     err |= __compat_save_altstack(&frame->sig.uc.uc_stack, regs->compat_sp);
0420
0421     err |= compat_setup_sigframe(&frame->sig, regs, set);
0422
0423     if (err == 0) {
0424         compat_setup_return(regs, &ksig->ka, frame->sig.retcode, frame, usig);
0425         regs->regs[1] = (compat_ulong_t)(unsigned long)&frame->info;
0426         regs->regs[2] = (compat_ulong_t)(unsigned long)&frame->sig.uc;
0427     }
0428
0429     return err;
0430 }
0431
0432 int compat_setup_frame(int usig, struct ksignal *ksig, sigset_t *set,
0433                struct pt_regs *regs)
0434 {
0435     struct compat_sigframe __user *frame;
0436     int err = 0;
0437
0438     frame = compat_get_sigframe(ksig, regs, sizeof(*frame));
0439
0440     if (!frame)
0441         return 1;
0442
0443     __put_user_error(0x5ac3c35a, &frame->uc.uc_flags, err);
0444
0445     err |= compat_setup_sigframe(frame, regs, set);
0446     if (err == 0)
0447         compat_setup_return(regs, &ksig->ka, frame->retcode, frame, usig);
0448
0449     return err;
0450 }
0451
0452 void compat_setup_restart_syscall(struct pt_regs *regs)
0453 {
0454        regs->regs[7] = __NR_compat_restart_syscall;
0455 }
0456
0457 /*
0458  * Compile-time assertions for siginfo_t offsets. Check NSIG* as well, as
0459  * changes likely come with new fields that should be added below.
0460  */
0461 static_assert(NSIGILL   == 11);
0462 static_assert(NSIGFPE   == 15);
0463 static_assert(NSIGSEGV  == 9);
0464 static_assert(NSIGBUS   == 5);
0465 static_assert(NSIGTRAP  == 6);
0466 static_assert(NSIGCHLD  == 6);
0467 static_assert(NSIGSYS   == 2);
0468 static_assert(sizeof(compat_siginfo_t) == 128);
0469 static_assert(__alignof__(compat_siginfo_t) == 4);
0470 static_assert(offsetof(compat_siginfo_t, si_signo)  == 0x00);
0471 static_assert(offsetof(compat_siginfo_t, si_errno)  == 0x04);
0472 static_assert(offsetof(compat_siginfo_t, si_code)   == 0x08);
0473 static_assert(offsetof(compat_siginfo_t, si_pid)    == 0x0c);
0474 static_assert(offsetof(compat_siginfo_t, si_uid)    == 0x10);
0475 static_assert(offsetof(compat_siginfo_t, si_tid)    == 0x0c);
0476 static_assert(offsetof(compat_siginfo_t, si_overrun)    == 0x10);
0477 static_assert(offsetof(compat_siginfo_t, si_status) == 0x14);
0478 static_assert(offsetof(compat_siginfo_t, si_utime)  == 0x18);
0479 static_assert(offsetof(compat_siginfo_t, si_stime)  == 0x1c);
0480 static_assert(offsetof(compat_siginfo_t, si_value)  == 0x14);
0481 static_assert(offsetof(compat_siginfo_t, si_int)    == 0x14);
0482 static_assert(offsetof(compat_siginfo_t, si_ptr)    == 0x14);
0483 static_assert(offsetof(compat_siginfo_t, si_addr)   == 0x0c);
0484 static_assert(offsetof(compat_siginfo_t, si_addr_lsb)   == 0x10);
0485 static_assert(offsetof(compat_siginfo_t, si_lower)  == 0x14);
0486 static_assert(offsetof(compat_siginfo_t, si_upper)  == 0x18);
0487 static_assert(offsetof(compat_siginfo_t, si_pkey)   == 0x14);
0488 static_assert(offsetof(compat_siginfo_t, si_perf_data)  == 0x10);
0489 static_assert(offsetof(compat_siginfo_t, si_perf_type)  == 0x14);
0490 static_assert(offsetof(compat_siginfo_t, si_perf_flags) == 0x18);
0491 static_assert(offsetof(compat_siginfo_t, si_band)   == 0x0c);
0492 static_assert(offsetof(compat_siginfo_t, si_fd)     == 0x10);
0493 static_assert(offsetof(compat_siginfo_t, si_call_addr)  == 0x0c);
0494 static_assert(offsetof(compat_siginfo_t, si_syscall)    == 0x10);
0495 static_assert(offsetof(compat_siginfo_t, si_arch)   == 0x14);