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0001 /*
0002  * This file is subject to the terms and conditions of the GNU General Public
0003  * License.  See the file "COPYING" in the main directory of this archive
0004  * for more details.
0005  *
0006  * Copyright (C) 1991, 1992  Linus Torvalds
0007  * Copyright (C) 1994 - 2000  Ralf Baechle
0008  * Copyright (C) 1999, 2000 Silicon Graphics, Inc.
0009  * Copyright (C) 2014, Imagination Technologies Ltd.
0010  */
0011 #include <linux/cache.h>
0012 #include <linux/context_tracking.h>
0013 #include <linux/irqflags.h>
0014 #include <linux/sched.h>
0015 #include <linux/mm.h>
0016 #include <linux/personality.h>
0017 #include <linux/smp.h>
0018 #include <linux/kernel.h>
0019 #include <linux/signal.h>
0020 #include <linux/errno.h>
0021 #include <linux/wait.h>
0022 #include <linux/ptrace.h>
0023 #include <linux/unistd.h>
0024 #include <linux/uprobes.h>
0025 #include <linux/compiler.h>
0026 #include <linux/syscalls.h>
0027 #include <linux/uaccess.h>
0028 #include <linux/resume_user_mode.h>
0029 
0030 #include <asm/abi.h>
0031 #include <asm/asm.h>
0032 #include <linux/bitops.h>
0033 #include <asm/cacheflush.h>
0034 #include <asm/fpu.h>
0035 #include <asm/sim.h>
0036 #include <asm/ucontext.h>
0037 #include <asm/cpu-features.h>
0038 #include <asm/dsp.h>
0039 #include <asm/inst.h>
0040 #include <asm/msa.h>
0041 
0042 #include "signal-common.h"
0043 
0044 static int (*save_fp_context)(void __user *sc);
0045 static int (*restore_fp_context)(void __user *sc);
0046 
0047 struct sigframe {
0048     u32 sf_ass[4];      /* argument save space for o32 */
0049     u32 sf_pad[2];      /* Was: signal trampoline */
0050 
0051     /* Matches struct ucontext from its uc_mcontext field onwards */
0052     struct sigcontext sf_sc;
0053     sigset_t sf_mask;
0054     unsigned long long sf_extcontext[];
0055 };
0056 
0057 struct rt_sigframe {
0058     u32 rs_ass[4];      /* argument save space for o32 */
0059     u32 rs_pad[2];      /* Was: signal trampoline */
0060     struct siginfo rs_info;
0061     struct ucontext rs_uc;
0062 };
0063 
0064 #ifdef CONFIG_MIPS_FP_SUPPORT
0065 
0066 /*
0067  * Thread saved context copy to/from a signal context presumed to be on the
0068  * user stack, and therefore accessed with appropriate macros from uaccess.h.
0069  */
0070 static int copy_fp_to_sigcontext(void __user *sc)
0071 {
0072     struct mips_abi *abi = current->thread.abi;
0073     uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
0074     uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
0075     int i;
0076     int err = 0;
0077     int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
0078 
0079     for (i = 0; i < NUM_FPU_REGS; i += inc) {
0080         err |=
0081             __put_user(get_fpr64(&current->thread.fpu.fpr[i], 0),
0082                    &fpregs[i]);
0083     }
0084     err |= __put_user(current->thread.fpu.fcr31, csr);
0085 
0086     return err;
0087 }
0088 
0089 static int copy_fp_from_sigcontext(void __user *sc)
0090 {
0091     struct mips_abi *abi = current->thread.abi;
0092     uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
0093     uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
0094     int i;
0095     int err = 0;
0096     int inc = test_thread_flag(TIF_32BIT_FPREGS) ? 2 : 1;
0097     u64 fpr_val;
0098 
0099     for (i = 0; i < NUM_FPU_REGS; i += inc) {
0100         err |= __get_user(fpr_val, &fpregs[i]);
0101         set_fpr64(&current->thread.fpu.fpr[i], 0, fpr_val);
0102     }
0103     err |= __get_user(current->thread.fpu.fcr31, csr);
0104 
0105     return err;
0106 }
0107 
0108 #else /* !CONFIG_MIPS_FP_SUPPORT */
0109 
0110 static int copy_fp_to_sigcontext(void __user *sc)
0111 {
0112     return 0;
0113 }
0114 
0115 static int copy_fp_from_sigcontext(void __user *sc)
0116 {
0117     return 0;
0118 }
0119 
0120 #endif /* !CONFIG_MIPS_FP_SUPPORT */
0121 
0122 /*
0123  * Wrappers for the assembly _{save,restore}_fp_context functions.
0124  */
0125 static int save_hw_fp_context(void __user *sc)
0126 {
0127     struct mips_abi *abi = current->thread.abi;
0128     uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
0129     uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
0130 
0131     return _save_fp_context(fpregs, csr);
0132 }
0133 
0134 static int restore_hw_fp_context(void __user *sc)
0135 {
0136     struct mips_abi *abi = current->thread.abi;
0137     uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
0138     uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
0139 
0140     return _restore_fp_context(fpregs, csr);
0141 }
0142 
0143 /*
0144  * Extended context handling.
0145  */
0146 
0147 static inline void __user *sc_to_extcontext(void __user *sc)
0148 {
0149     struct ucontext __user *uc;
0150 
0151     /*
0152      * We can just pretend the sigcontext is always embedded in a struct
0153      * ucontext here, because the offset from sigcontext to extended
0154      * context is the same in the struct sigframe case.
0155      */
0156     uc = container_of(sc, struct ucontext, uc_mcontext);
0157     return &uc->uc_extcontext;
0158 }
0159 
0160 #ifdef CONFIG_CPU_HAS_MSA
0161 
0162 static int save_msa_extcontext(void __user *buf)
0163 {
0164     struct msa_extcontext __user *msa = buf;
0165     uint64_t val;
0166     int i, err;
0167 
0168     if (!thread_msa_context_live())
0169         return 0;
0170 
0171     /*
0172      * Ensure that we can't lose the live MSA context between checking
0173      * for it & writing it to memory.
0174      */
0175     preempt_disable();
0176 
0177     if (is_msa_enabled()) {
0178         /*
0179          * There are no EVA versions of the vector register load/store
0180          * instructions, so MSA context has to be saved to kernel memory
0181          * and then copied to user memory. The save to kernel memory
0182          * should already have been done when handling scalar FP
0183          * context.
0184          */
0185         BUG_ON(IS_ENABLED(CONFIG_EVA));
0186 
0187         err = __put_user(read_msa_csr(), &msa->csr);
0188         err |= _save_msa_all_upper(&msa->wr);
0189 
0190         preempt_enable();
0191     } else {
0192         preempt_enable();
0193 
0194         err = __put_user(current->thread.fpu.msacsr, &msa->csr);
0195 
0196         for (i = 0; i < NUM_FPU_REGS; i++) {
0197             val = get_fpr64(&current->thread.fpu.fpr[i], 1);
0198             err |= __put_user(val, &msa->wr[i]);
0199         }
0200     }
0201 
0202     err |= __put_user(MSA_EXTCONTEXT_MAGIC, &msa->ext.magic);
0203     err |= __put_user(sizeof(*msa), &msa->ext.size);
0204 
0205     return err ? -EFAULT : sizeof(*msa);
0206 }
0207 
0208 static int restore_msa_extcontext(void __user *buf, unsigned int size)
0209 {
0210     struct msa_extcontext __user *msa = buf;
0211     unsigned long long val;
0212     unsigned int csr;
0213     int i, err;
0214 
0215     if (size != sizeof(*msa))
0216         return -EINVAL;
0217 
0218     err = get_user(csr, &msa->csr);
0219     if (err)
0220         return err;
0221 
0222     preempt_disable();
0223 
0224     if (is_msa_enabled()) {
0225         /*
0226          * There are no EVA versions of the vector register load/store
0227          * instructions, so MSA context has to be copied to kernel
0228          * memory and later loaded to registers. The same is true of
0229          * scalar FP context, so FPU & MSA should have already been
0230          * disabled whilst handling scalar FP context.
0231          */
0232         BUG_ON(IS_ENABLED(CONFIG_EVA));
0233 
0234         write_msa_csr(csr);
0235         err |= _restore_msa_all_upper(&msa->wr);
0236         preempt_enable();
0237     } else {
0238         preempt_enable();
0239 
0240         current->thread.fpu.msacsr = csr;
0241 
0242         for (i = 0; i < NUM_FPU_REGS; i++) {
0243             err |= __get_user(val, &msa->wr[i]);
0244             set_fpr64(&current->thread.fpu.fpr[i], 1, val);
0245         }
0246     }
0247 
0248     return err;
0249 }
0250 
0251 #else /* !CONFIG_CPU_HAS_MSA */
0252 
0253 static int save_msa_extcontext(void __user *buf)
0254 {
0255     return 0;
0256 }
0257 
0258 static int restore_msa_extcontext(void __user *buf, unsigned int size)
0259 {
0260     return SIGSYS;
0261 }
0262 
0263 #endif /* !CONFIG_CPU_HAS_MSA */
0264 
0265 static int save_extcontext(void __user *buf)
0266 {
0267     int sz;
0268 
0269     sz = save_msa_extcontext(buf);
0270     if (sz < 0)
0271         return sz;
0272     buf += sz;
0273 
0274     /* If no context was saved then trivially return */
0275     if (!sz)
0276         return 0;
0277 
0278     /* Write the end marker */
0279     if (__put_user(END_EXTCONTEXT_MAGIC, (u32 *)buf))
0280         return -EFAULT;
0281 
0282     sz += sizeof(((struct extcontext *)NULL)->magic);
0283     return sz;
0284 }
0285 
0286 static int restore_extcontext(void __user *buf)
0287 {
0288     struct extcontext ext;
0289     int err;
0290 
0291     while (1) {
0292         err = __get_user(ext.magic, (unsigned int *)buf);
0293         if (err)
0294             return err;
0295 
0296         if (ext.magic == END_EXTCONTEXT_MAGIC)
0297             return 0;
0298 
0299         err = __get_user(ext.size, (unsigned int *)(buf
0300             + offsetof(struct extcontext, size)));
0301         if (err)
0302             return err;
0303 
0304         switch (ext.magic) {
0305         case MSA_EXTCONTEXT_MAGIC:
0306             err = restore_msa_extcontext(buf, ext.size);
0307             break;
0308 
0309         default:
0310             err = -EINVAL;
0311             break;
0312         }
0313 
0314         if (err)
0315             return err;
0316 
0317         buf += ext.size;
0318     }
0319 }
0320 
0321 /*
0322  * Helper routines
0323  */
0324 int protected_save_fp_context(void __user *sc)
0325 {
0326     struct mips_abi *abi = current->thread.abi;
0327     uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
0328     uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
0329     uint32_t __user *used_math = sc + abi->off_sc_used_math;
0330     unsigned int used, ext_sz;
0331     int err;
0332 
0333     used = used_math() ? USED_FP : 0;
0334     if (!used)
0335         goto fp_done;
0336 
0337     if (!test_thread_flag(TIF_32BIT_FPREGS))
0338         used |= USED_FR1;
0339     if (test_thread_flag(TIF_HYBRID_FPREGS))
0340         used |= USED_HYBRID_FPRS;
0341 
0342     /*
0343      * EVA does not have userland equivalents of ldc1 or sdc1, so
0344      * save to the kernel FP context & copy that to userland below.
0345      */
0346     if (IS_ENABLED(CONFIG_EVA))
0347         lose_fpu(1);
0348 
0349     while (1) {
0350         lock_fpu_owner();
0351         if (is_fpu_owner()) {
0352             err = save_fp_context(sc);
0353             unlock_fpu_owner();
0354         } else {
0355             unlock_fpu_owner();
0356             err = copy_fp_to_sigcontext(sc);
0357         }
0358         if (likely(!err))
0359             break;
0360         /* touch the sigcontext and try again */
0361         err = __put_user(0, &fpregs[0]) |
0362             __put_user(0, &fpregs[31]) |
0363             __put_user(0, csr);
0364         if (err)
0365             return err; /* really bad sigcontext */
0366     }
0367 
0368 fp_done:
0369     ext_sz = err = save_extcontext(sc_to_extcontext(sc));
0370     if (err < 0)
0371         return err;
0372     used |= ext_sz ? USED_EXTCONTEXT : 0;
0373 
0374     return __put_user(used, used_math);
0375 }
0376 
0377 int protected_restore_fp_context(void __user *sc)
0378 {
0379     struct mips_abi *abi = current->thread.abi;
0380     uint64_t __user *fpregs = sc + abi->off_sc_fpregs;
0381     uint32_t __user *csr = sc + abi->off_sc_fpc_csr;
0382     uint32_t __user *used_math = sc + abi->off_sc_used_math;
0383     unsigned int used;
0384     int err, sig = 0, tmp __maybe_unused;
0385 
0386     err = __get_user(used, used_math);
0387     conditional_used_math(used & USED_FP);
0388 
0389     /*
0390      * The signal handler may have used FPU; give it up if the program
0391      * doesn't want it following sigreturn.
0392      */
0393     if (err || !(used & USED_FP))
0394         lose_fpu(0);
0395     if (err)
0396         return err;
0397     if (!(used & USED_FP))
0398         goto fp_done;
0399 
0400     err = sig = fpcsr_pending(csr);
0401     if (err < 0)
0402         return err;
0403 
0404     /*
0405      * EVA does not have userland equivalents of ldc1 or sdc1, so we
0406      * disable the FPU here such that the code below simply copies to
0407      * the kernel FP context.
0408      */
0409     if (IS_ENABLED(CONFIG_EVA))
0410         lose_fpu(0);
0411 
0412     while (1) {
0413         lock_fpu_owner();
0414         if (is_fpu_owner()) {
0415             err = restore_fp_context(sc);
0416             unlock_fpu_owner();
0417         } else {
0418             unlock_fpu_owner();
0419             err = copy_fp_from_sigcontext(sc);
0420         }
0421         if (likely(!err))
0422             break;
0423         /* touch the sigcontext and try again */
0424         err = __get_user(tmp, &fpregs[0]) |
0425             __get_user(tmp, &fpregs[31]) |
0426             __get_user(tmp, csr);
0427         if (err)
0428             break;  /* really bad sigcontext */
0429     }
0430 
0431 fp_done:
0432     if (!err && (used & USED_EXTCONTEXT))
0433         err = restore_extcontext(sc_to_extcontext(sc));
0434 
0435     return err ?: sig;
0436 }
0437 
0438 int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
0439 {
0440     int err = 0;
0441     int i;
0442 
0443     err |= __put_user(regs->cp0_epc, &sc->sc_pc);
0444 
0445     err |= __put_user(0, &sc->sc_regs[0]);
0446     for (i = 1; i < 32; i++)
0447         err |= __put_user(regs->regs[i], &sc->sc_regs[i]);
0448 
0449 #ifdef CONFIG_CPU_HAS_SMARTMIPS
0450     err |= __put_user(regs->acx, &sc->sc_acx);
0451 #endif
0452     err |= __put_user(regs->hi, &sc->sc_mdhi);
0453     err |= __put_user(regs->lo, &sc->sc_mdlo);
0454     if (cpu_has_dsp) {
0455         err |= __put_user(mfhi1(), &sc->sc_hi1);
0456         err |= __put_user(mflo1(), &sc->sc_lo1);
0457         err |= __put_user(mfhi2(), &sc->sc_hi2);
0458         err |= __put_user(mflo2(), &sc->sc_lo2);
0459         err |= __put_user(mfhi3(), &sc->sc_hi3);
0460         err |= __put_user(mflo3(), &sc->sc_lo3);
0461         err |= __put_user(rddsp(DSP_MASK), &sc->sc_dsp);
0462     }
0463 
0464 
0465     /*
0466      * Save FPU state to signal context. Signal handler
0467      * will "inherit" current FPU state.
0468      */
0469     err |= protected_save_fp_context(sc);
0470 
0471     return err;
0472 }
0473 
0474 static size_t extcontext_max_size(void)
0475 {
0476     size_t sz = 0;
0477 
0478     /*
0479      * The assumption here is that between this point & the point at which
0480      * the extended context is saved the size of the context should only
0481      * ever be able to shrink (if the task is preempted), but never grow.
0482      * That is, what this function returns is an upper bound on the size of
0483      * the extended context for the current task at the current time.
0484      */
0485 
0486     if (thread_msa_context_live())
0487         sz += sizeof(struct msa_extcontext);
0488 
0489     /* If any context is saved then we'll append the end marker */
0490     if (sz)
0491         sz += sizeof(((struct extcontext *)NULL)->magic);
0492 
0493     return sz;
0494 }
0495 
0496 int fpcsr_pending(unsigned int __user *fpcsr)
0497 {
0498     int err, sig = 0;
0499     unsigned int csr, enabled;
0500 
0501     err = __get_user(csr, fpcsr);
0502     enabled = FPU_CSR_UNI_X | ((csr & FPU_CSR_ALL_E) << 5);
0503     /*
0504      * If the signal handler set some FPU exceptions, clear it and
0505      * send SIGFPE.
0506      */
0507     if (csr & enabled) {
0508         csr &= ~enabled;
0509         err |= __put_user(csr, fpcsr);
0510         sig = SIGFPE;
0511     }
0512     return err ?: sig;
0513 }
0514 
0515 int restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
0516 {
0517     unsigned long treg;
0518     int err = 0;
0519     int i;
0520 
0521     /* Always make any pending restarted system calls return -EINTR */
0522     current->restart_block.fn = do_no_restart_syscall;
0523 
0524     err |= __get_user(regs->cp0_epc, &sc->sc_pc);
0525 
0526 #ifdef CONFIG_CPU_HAS_SMARTMIPS
0527     err |= __get_user(regs->acx, &sc->sc_acx);
0528 #endif
0529     err |= __get_user(regs->hi, &sc->sc_mdhi);
0530     err |= __get_user(regs->lo, &sc->sc_mdlo);
0531     if (cpu_has_dsp) {
0532         err |= __get_user(treg, &sc->sc_hi1); mthi1(treg);
0533         err |= __get_user(treg, &sc->sc_lo1); mtlo1(treg);
0534         err |= __get_user(treg, &sc->sc_hi2); mthi2(treg);
0535         err |= __get_user(treg, &sc->sc_lo2); mtlo2(treg);
0536         err |= __get_user(treg, &sc->sc_hi3); mthi3(treg);
0537         err |= __get_user(treg, &sc->sc_lo3); mtlo3(treg);
0538         err |= __get_user(treg, &sc->sc_dsp); wrdsp(treg, DSP_MASK);
0539     }
0540 
0541     for (i = 1; i < 32; i++)
0542         err |= __get_user(regs->regs[i], &sc->sc_regs[i]);
0543 
0544     return err ?: protected_restore_fp_context(sc);
0545 }
0546 
0547 #ifdef CONFIG_WAR_ICACHE_REFILLS
0548 #define SIGMASK     ~(cpu_icache_line_size()-1)
0549 #else
0550 #define SIGMASK     ALMASK
0551 #endif
0552 
0553 void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
0554               size_t frame_size)
0555 {
0556     unsigned long sp;
0557 
0558     /* Leave space for potential extended context */
0559     frame_size += extcontext_max_size();
0560 
0561     /* Default to using normal stack */
0562     sp = regs->regs[29];
0563 
0564     /*
0565      * If we are on the alternate signal stack and would overflow it, don't.
0566      * Return an always-bogus address instead so we will die with SIGSEGV.
0567      */
0568     if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
0569         return (void __user __force *)(-1UL);
0570 
0571     /*
0572      * FPU emulator may have it's own trampoline active just
0573      * above the user stack, 16-bytes before the next lowest
0574      * 16 byte boundary.  Try to avoid trashing it.
0575      */
0576     sp -= 32;
0577 
0578     sp = sigsp(sp, ksig);
0579 
0580     return (void __user *)((sp - frame_size) & SIGMASK);
0581 }
0582 
0583 /*
0584  * Atomically swap in the new signal mask, and wait for a signal.
0585  */
0586 
0587 #ifdef CONFIG_TRAD_SIGNALS
0588 SYSCALL_DEFINE1(sigsuspend, sigset_t __user *, uset)
0589 {
0590     return sys_rt_sigsuspend(uset, sizeof(sigset_t));
0591 }
0592 #endif
0593 
0594 #ifdef CONFIG_TRAD_SIGNALS
0595 SYSCALL_DEFINE3(sigaction, int, sig, const struct sigaction __user *, act,
0596     struct sigaction __user *, oact)
0597 {
0598     struct k_sigaction new_ka, old_ka;
0599     int ret;
0600     int err = 0;
0601 
0602     if (act) {
0603         old_sigset_t mask;
0604 
0605         if (!access_ok(act, sizeof(*act)))
0606             return -EFAULT;
0607         err |= __get_user(new_ka.sa.sa_handler, &act->sa_handler);
0608         err |= __get_user(new_ka.sa.sa_flags, &act->sa_flags);
0609         err |= __get_user(mask, &act->sa_mask.sig[0]);
0610         if (err)
0611             return -EFAULT;
0612 
0613         siginitset(&new_ka.sa.sa_mask, mask);
0614     }
0615 
0616     ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
0617 
0618     if (!ret && oact) {
0619         if (!access_ok(oact, sizeof(*oact)))
0620             return -EFAULT;
0621         err |= __put_user(old_ka.sa.sa_flags, &oact->sa_flags);
0622         err |= __put_user(old_ka.sa.sa_handler, &oact->sa_handler);
0623         err |= __put_user(old_ka.sa.sa_mask.sig[0], oact->sa_mask.sig);
0624         err |= __put_user(0, &oact->sa_mask.sig[1]);
0625         err |= __put_user(0, &oact->sa_mask.sig[2]);
0626         err |= __put_user(0, &oact->sa_mask.sig[3]);
0627         if (err)
0628             return -EFAULT;
0629     }
0630 
0631     return ret;
0632 }
0633 #endif
0634 
0635 #ifdef CONFIG_TRAD_SIGNALS
0636 asmlinkage void sys_sigreturn(void)
0637 {
0638     struct sigframe __user *frame;
0639     struct pt_regs *regs;
0640     sigset_t blocked;
0641     int sig;
0642 
0643     regs = current_pt_regs();
0644     frame = (struct sigframe __user *)regs->regs[29];
0645     if (!access_ok(frame, sizeof(*frame)))
0646         goto badframe;
0647     if (__copy_from_user(&blocked, &frame->sf_mask, sizeof(blocked)))
0648         goto badframe;
0649 
0650     set_current_blocked(&blocked);
0651 
0652     sig = restore_sigcontext(regs, &frame->sf_sc);
0653     if (sig < 0)
0654         goto badframe;
0655     else if (sig)
0656         force_sig(sig);
0657 
0658     /*
0659      * Don't let your children do this ...
0660      */
0661     __asm__ __volatile__(
0662         "move\t$29, %0\n\t"
0663         "j\tsyscall_exit"
0664         : /* no outputs */
0665         : "r" (regs));
0666     /* Unreached */
0667 
0668 badframe:
0669     force_sig(SIGSEGV);
0670 }
0671 #endif /* CONFIG_TRAD_SIGNALS */
0672 
0673 asmlinkage void sys_rt_sigreturn(void)
0674 {
0675     struct rt_sigframe __user *frame;
0676     struct pt_regs *regs;
0677     sigset_t set;
0678     int sig;
0679 
0680     regs = current_pt_regs();
0681     frame = (struct rt_sigframe __user *)regs->regs[29];
0682     if (!access_ok(frame, sizeof(*frame)))
0683         goto badframe;
0684     if (__copy_from_user(&set, &frame->rs_uc.uc_sigmask, sizeof(set)))
0685         goto badframe;
0686 
0687     set_current_blocked(&set);
0688 
0689     sig = restore_sigcontext(regs, &frame->rs_uc.uc_mcontext);
0690     if (sig < 0)
0691         goto badframe;
0692     else if (sig)
0693         force_sig(sig);
0694 
0695     if (restore_altstack(&frame->rs_uc.uc_stack))
0696         goto badframe;
0697 
0698     /*
0699      * Don't let your children do this ...
0700      */
0701     __asm__ __volatile__(
0702         "move\t$29, %0\n\t"
0703         "j\tsyscall_exit"
0704         : /* no outputs */
0705         : "r" (regs));
0706     /* Unreached */
0707 
0708 badframe:
0709     force_sig(SIGSEGV);
0710 }
0711 
0712 #ifdef CONFIG_TRAD_SIGNALS
0713 static int setup_frame(void *sig_return, struct ksignal *ksig,
0714                struct pt_regs *regs, sigset_t *set)
0715 {
0716     struct sigframe __user *frame;
0717     int err = 0;
0718 
0719     frame = get_sigframe(ksig, regs, sizeof(*frame));
0720     if (!access_ok(frame, sizeof (*frame)))
0721         return -EFAULT;
0722 
0723     err |= setup_sigcontext(regs, &frame->sf_sc);
0724     err |= __copy_to_user(&frame->sf_mask, set, sizeof(*set));
0725     if (err)
0726         return -EFAULT;
0727 
0728     /*
0729      * Arguments to signal handler:
0730      *
0731      *   a0 = signal number
0732      *   a1 = 0 (should be cause)
0733      *   a2 = pointer to struct sigcontext
0734      *
0735      * $25 and c0_epc point to the signal handler, $29 points to the
0736      * struct sigframe.
0737      */
0738     regs->regs[ 4] = ksig->sig;
0739     regs->regs[ 5] = 0;
0740     regs->regs[ 6] = (unsigned long) &frame->sf_sc;
0741     regs->regs[29] = (unsigned long) frame;
0742     regs->regs[31] = (unsigned long) sig_return;
0743     regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
0744 
0745     DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
0746            current->comm, current->pid,
0747            frame, regs->cp0_epc, regs->regs[31]);
0748     return 0;
0749 }
0750 #endif
0751 
0752 static int setup_rt_frame(void *sig_return, struct ksignal *ksig,
0753               struct pt_regs *regs, sigset_t *set)
0754 {
0755     struct rt_sigframe __user *frame;
0756 
0757     frame = get_sigframe(ksig, regs, sizeof(*frame));
0758     if (!access_ok(frame, sizeof (*frame)))
0759         return -EFAULT;
0760 
0761     /* Create siginfo.  */
0762     if (copy_siginfo_to_user(&frame->rs_info, &ksig->info))
0763         return -EFAULT;
0764 
0765     /* Create the ucontext.  */
0766     if (__put_user(0, &frame->rs_uc.uc_flags))
0767         return -EFAULT;
0768     if (__put_user(NULL, &frame->rs_uc.uc_link))
0769         return -EFAULT;
0770     if (__save_altstack(&frame->rs_uc.uc_stack, regs->regs[29]))
0771         return -EFAULT;
0772     if (setup_sigcontext(regs, &frame->rs_uc.uc_mcontext))
0773         return -EFAULT;
0774     if (__copy_to_user(&frame->rs_uc.uc_sigmask, set, sizeof(*set)))
0775         return -EFAULT;
0776 
0777     /*
0778      * Arguments to signal handler:
0779      *
0780      *   a0 = signal number
0781      *   a1 = 0 (should be cause)
0782      *   a2 = pointer to ucontext
0783      *
0784      * $25 and c0_epc point to the signal handler, $29 points to
0785      * the struct rt_sigframe.
0786      */
0787     regs->regs[ 4] = ksig->sig;
0788     regs->regs[ 5] = (unsigned long) &frame->rs_info;
0789     regs->regs[ 6] = (unsigned long) &frame->rs_uc;
0790     regs->regs[29] = (unsigned long) frame;
0791     regs->regs[31] = (unsigned long) sig_return;
0792     regs->cp0_epc = regs->regs[25] = (unsigned long) ksig->ka.sa.sa_handler;
0793 
0794     DEBUGP("SIG deliver (%s:%d): sp=0x%p pc=0x%lx ra=0x%lx\n",
0795            current->comm, current->pid,
0796            frame, regs->cp0_epc, regs->regs[31]);
0797 
0798     return 0;
0799 }
0800 
0801 struct mips_abi mips_abi = {
0802 #ifdef CONFIG_TRAD_SIGNALS
0803     .setup_frame    = setup_frame,
0804 #endif
0805     .setup_rt_frame = setup_rt_frame,
0806     .restart    = __NR_restart_syscall,
0807 
0808     .off_sc_fpregs = offsetof(struct sigcontext, sc_fpregs),
0809     .off_sc_fpc_csr = offsetof(struct sigcontext, sc_fpc_csr),
0810     .off_sc_used_math = offsetof(struct sigcontext, sc_used_math),
0811 
0812     .vdso       = &vdso_image,
0813 };
0814 
0815 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
0816 {
0817     sigset_t *oldset = sigmask_to_save();
0818     int ret;
0819     struct mips_abi *abi = current->thread.abi;
0820     void *vdso = current->mm->context.vdso;
0821 
0822     /*
0823      * If we were emulating a delay slot instruction, exit that frame such
0824      * that addresses in the sigframe are as expected for userland and we
0825      * don't have a problem if we reuse the thread's frame for an
0826      * instruction within the signal handler.
0827      */
0828     dsemul_thread_rollback(regs);
0829 
0830     if (regs->regs[0]) {
0831         switch(regs->regs[2]) {
0832         case ERESTART_RESTARTBLOCK:
0833         case ERESTARTNOHAND:
0834             regs->regs[2] = EINTR;
0835             break;
0836         case ERESTARTSYS:
0837             if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
0838                 regs->regs[2] = EINTR;
0839                 break;
0840             }
0841             fallthrough;
0842         case ERESTARTNOINTR:
0843             regs->regs[7] = regs->regs[26];
0844             regs->regs[2] = regs->regs[0];
0845             regs->cp0_epc -= 4;
0846         }
0847 
0848         regs->regs[0] = 0;      /* Don't deal with this again.  */
0849     }
0850 
0851     rseq_signal_deliver(ksig, regs);
0852 
0853     if (sig_uses_siginfo(&ksig->ka, abi))
0854         ret = abi->setup_rt_frame(vdso + abi->vdso->off_rt_sigreturn,
0855                       ksig, regs, oldset);
0856     else
0857         ret = abi->setup_frame(vdso + abi->vdso->off_sigreturn,
0858                        ksig, regs, oldset);
0859 
0860     signal_setup_done(ret, ksig, 0);
0861 }
0862 
0863 static void do_signal(struct pt_regs *regs)
0864 {
0865     struct ksignal ksig;
0866 
0867     if (get_signal(&ksig)) {
0868         /* Whee!  Actually deliver the signal.  */
0869         handle_signal(&ksig, regs);
0870         return;
0871     }
0872 
0873     if (regs->regs[0]) {
0874         switch (regs->regs[2]) {
0875         case ERESTARTNOHAND:
0876         case ERESTARTSYS:
0877         case ERESTARTNOINTR:
0878             regs->regs[2] = regs->regs[0];
0879             regs->regs[7] = regs->regs[26];
0880             regs->cp0_epc -= 4;
0881             break;
0882 
0883         case ERESTART_RESTARTBLOCK:
0884             regs->regs[2] = current->thread.abi->restart;
0885             regs->regs[7] = regs->regs[26];
0886             regs->cp0_epc -= 4;
0887             break;
0888         }
0889         regs->regs[0] = 0;  /* Don't deal with this again.  */
0890     }
0891 
0892     /*
0893      * If there's no signal to deliver, we just put the saved sigmask
0894      * back
0895      */
0896     restore_saved_sigmask();
0897 }
0898 
0899 /*
0900  * notification of userspace execution resumption
0901  * - triggered by the TIF_WORK_MASK flags
0902  */
0903 asmlinkage void do_notify_resume(struct pt_regs *regs, void *unused,
0904     __u32 thread_info_flags)
0905 {
0906     local_irq_enable();
0907 
0908     user_exit();
0909 
0910     if (thread_info_flags & _TIF_UPROBE)
0911         uprobe_notify_resume(regs);
0912 
0913     /* deal with pending signal delivery */
0914     if (thread_info_flags & (_TIF_SIGPENDING | _TIF_NOTIFY_SIGNAL))
0915         do_signal(regs);
0916 
0917     if (thread_info_flags & _TIF_NOTIFY_RESUME)
0918         resume_user_mode_work(regs);
0919 
0920     user_enter();
0921 }
0922 
0923 #if defined(CONFIG_SMP) && defined(CONFIG_MIPS_FP_SUPPORT)
0924 static int smp_save_fp_context(void __user *sc)
0925 {
0926     return raw_cpu_has_fpu
0927            ? save_hw_fp_context(sc)
0928            : copy_fp_to_sigcontext(sc);
0929 }
0930 
0931 static int smp_restore_fp_context(void __user *sc)
0932 {
0933     return raw_cpu_has_fpu
0934            ? restore_hw_fp_context(sc)
0935            : copy_fp_from_sigcontext(sc);
0936 }
0937 #endif
0938 
0939 static int signal_setup(void)
0940 {
0941     /*
0942      * The offset from sigcontext to extended context should be the same
0943      * regardless of the type of signal, such that userland can always know
0944      * where to look if it wishes to find the extended context structures.
0945      */
0946     BUILD_BUG_ON((offsetof(struct sigframe, sf_extcontext) -
0947               offsetof(struct sigframe, sf_sc)) !=
0948              (offsetof(struct rt_sigframe, rs_uc.uc_extcontext) -
0949               offsetof(struct rt_sigframe, rs_uc.uc_mcontext)));
0950 
0951 #if defined(CONFIG_SMP) && defined(CONFIG_MIPS_FP_SUPPORT)
0952     /* For now just do the cpu_has_fpu check when the functions are invoked */
0953     save_fp_context = smp_save_fp_context;
0954     restore_fp_context = smp_restore_fp_context;
0955 #else
0956     if (cpu_has_fpu) {
0957         save_fp_context = save_hw_fp_context;
0958         restore_fp_context = restore_hw_fp_context;
0959     } else {
0960         save_fp_context = copy_fp_to_sigcontext;
0961         restore_fp_context = copy_fp_from_sigcontext;
0962     }
0963 #endif /* CONFIG_SMP */
0964 
0965     return 0;
0966 }
0967 
0968 arch_initcall(signal_setup);
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