linux/arch/hexagon/kernel/signal.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Signal support for Hexagon processor
   4 *
   5 * Copyright (c) 2010-2012, The Linux Foundation. All rights reserved.
   6 */
   7
   8#include <linux/linkage.h>
   9#include <linux/syscalls.h>
  10#include <linux/tracehook.h>
  11#include <linux/sched/task_stack.h>
  12
  13#include <asm/registers.h>
  14#include <asm/thread_info.h>
  15#include <asm/unistd.h>
  16#include <linux/uaccess.h>
  17#include <asm/ucontext.h>
  18#include <asm/cacheflush.h>
  19#include <asm/signal.h>
  20#include <asm/vdso.h>
  21
  22struct rt_sigframe {
  23        unsigned long tramp[2];
  24        struct siginfo info;
  25        struct ucontext uc;
  26};
  27
  28static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
  29                          size_t frame_size)
  30{
  31        unsigned long sp = sigsp(regs->r29, ksig);
  32
  33        return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
  34}
  35
  36static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  37{
  38        unsigned long tmp;
  39        int err = 0;
  40
  41        err |= copy_to_user(&sc->sc_regs.r0, &regs->r00,
  42                            32*sizeof(unsigned long));
  43
  44        err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
  45        err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
  46        err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
  47        err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
  48        err |= __put_user(regs->m0, &sc->sc_regs.m0);
  49        err |= __put_user(regs->m1, &sc->sc_regs.m1);
  50        err |= __put_user(regs->usr, &sc->sc_regs.usr);
  51        err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
  52        err |= __put_user(regs->gp, &sc->sc_regs.gp);
  53        err |= __put_user(regs->ugp, &sc->sc_regs.ugp);
  54#if CONFIG_HEXAGON_ARCH_VERSION >= 4
  55        err |= __put_user(regs->cs0, &sc->sc_regs.cs0);
  56        err |= __put_user(regs->cs1, &sc->sc_regs.cs1);
  57#endif
  58        tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
  59        tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
  60        tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);
  61
  62        return err;
  63}
  64
  65static int restore_sigcontext(struct pt_regs *regs,
  66                              struct sigcontext __user *sc)
  67{
  68        unsigned long tmp;
  69        int err = 0;
  70
  71        err |= copy_from_user(&regs->r00, &sc->sc_regs.r0,
  72                              32 * sizeof(unsigned long));
  73
  74        err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
  75        err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
  76        err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
  77        err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
  78        err |= __get_user(regs->m0, &sc->sc_regs.m0);
  79        err |= __get_user(regs->m1, &sc->sc_regs.m1);
  80        err |= __get_user(regs->usr, &sc->sc_regs.usr);
  81        err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
  82        err |= __get_user(regs->gp, &sc->sc_regs.gp);
  83        err |= __get_user(regs->ugp, &sc->sc_regs.ugp);
  84#if CONFIG_HEXAGON_ARCH_VERSION >= 4
  85        err |= __get_user(regs->cs0, &sc->sc_regs.cs0);
  86        err |= __get_user(regs->cs1, &sc->sc_regs.cs1);
  87#endif
  88        err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);
  89
  90        return err;
  91}
  92
  93/*
  94 * Setup signal stack frame with siginfo structure
  95 */
  96static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
  97                          struct pt_regs *regs)
  98{
  99        int err = 0;
 100        struct rt_sigframe __user *frame;
 101        struct hexagon_vdso *vdso = current->mm->context.vdso;
 102
 103        frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
 104
 105        if (!access_ok(frame, sizeof(struct rt_sigframe)))
 106                return -EFAULT;
 107
 108        if (copy_siginfo_to_user(&frame->info, &ksig->info))
 109                return -EFAULT;
 110
 111        /* The on-stack signal trampoline is no longer executed;
 112         * however, the libgcc signal frame unwinding code checks for
 113         * the presence of these two numeric magic values.
 114         */
 115        err |= __put_user(0x7800d166, &frame->tramp[0]);
 116        err |= __put_user(0x5400c004, &frame->tramp[1]);
 117        err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
 118        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 119        err |= __save_altstack(&frame->uc.uc_stack, user_stack_pointer(regs));
 120        if (err)
 121                return -EFAULT;
 122
 123        /* Load r0/r1 pair with signumber/siginfo pointer... */
 124        regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
 125                | (unsigned long long)ksig->sig;
 126        regs->r02 = (unsigned long) &frame->uc;
 127        regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
 128        pt_psp(regs) = (unsigned long) frame;
 129        pt_set_elr(regs, (unsigned long)ksig->ka.sa.sa_handler);
 130
 131        return 0;
 132}
 133
 134/*
 135 * Setup invocation of signal handler
 136 */
 137static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 138{
 139        int ret;
 140
 141        /*
 142         * If we're handling a signal that aborted a system call,
 143         * set up the error return value before adding the signal
 144         * frame to the stack.
 145         */
 146
 147        if (regs->syscall_nr >= 0) {
 148                switch (regs->r00) {
 149                case -ERESTART_RESTARTBLOCK:
 150                case -ERESTARTNOHAND:
 151                        regs->r00 = -EINTR;
 152                        break;
 153                case -ERESTARTSYS:
 154                        if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 155                                regs->r00 = -EINTR;
 156                                break;
 157                        }
 158                        /* Fall through */
 159                case -ERESTARTNOINTR:
 160                        regs->r06 = regs->syscall_nr;
 161                        pt_set_elr(regs, pt_elr(regs) - 4);
 162                        regs->r00 = regs->restart_r0;
 163                        break;
 164                default:
 165                        break;
 166                }
 167        }
 168
 169        /*
 170         * Set up the stack frame; not doing the SA_SIGINFO thing.  We
 171         * only set up the rt_frame flavor.
 172         */
 173        /* If there was an error on setup, no signal was delivered. */
 174        ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 175
 176        signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 177}
 178
 179/*
 180 * Called from return-from-event code.
 181 */
 182void do_signal(struct pt_regs *regs)
 183{
 184        struct ksignal ksig;
 185
 186        if (!user_mode(regs))
 187                return;
 188
 189        if (get_signal(&ksig)) {
 190                handle_signal(&ksig, regs);
 191                return;
 192        }
 193
 194        /*
 195         * No (more) signals; if we came from a system call, handle the restart.
 196         */
 197
 198        if (regs->syscall_nr >= 0) {
 199                switch (regs->r00) {
 200                case -ERESTARTNOHAND:
 201                case -ERESTARTSYS:
 202                case -ERESTARTNOINTR:
 203                        regs->r06 = regs->syscall_nr;
 204                        break;
 205                case -ERESTART_RESTARTBLOCK:
 206                        regs->r06 = __NR_restart_syscall;
 207                        break;
 208                default:
 209                        goto no_restart;
 210                }
 211                pt_set_elr(regs, pt_elr(regs) - 4);
 212                regs->r00 = regs->restart_r0;
 213        }
 214
 215no_restart:
 216        /* If there's no signal to deliver, put the saved sigmask back */
 217        restore_saved_sigmask();
 218}
 219
 220/*
 221 * Architecture-specific wrappers for signal-related system calls
 222 */
 223
 224asmlinkage int sys_rt_sigreturn(void)
 225{
 226        struct pt_regs *regs = current_pt_regs();
 227        struct rt_sigframe __user *frame;
 228        sigset_t blocked;
 229
 230        /* Always make any pending restarted system calls return -EINTR */
 231        current->restart_block.fn = do_no_restart_syscall;
 232
 233        frame = (struct rt_sigframe __user *)pt_psp(regs);
 234        if (!access_ok(frame, sizeof(*frame)))
 235                goto badframe;
 236        if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
 237                goto badframe;
 238
 239        set_current_blocked(&blocked);
 240
 241        if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 242                goto badframe;
 243
 244        /* Restore the user's stack as well */
 245        pt_psp(regs) = regs->r29;
 246
 247        regs->syscall_nr = -1;
 248
 249        if (restore_altstack(&frame->uc.uc_stack))
 250                goto badframe;
 251
 252        return regs->r00;
 253
 254badframe:
 255        force_sig(SIGSEGV);
 256        return 0;
 257}
 258