arch/hexagon/kernel/signal.c

   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/sched/task_stack.h>
  11
  12 #include <asm/registers.h>
  13 #include <asm/thread_info.h>
  14 #include <asm/unistd.h>
  15 #include <linux/uaccess.h>
  16 #include <asm/ucontext.h>
  17 #include <asm/cacheflush.h>
  18 #include <asm/signal.h>
  19 #include <asm/vdso.h>
  20
  21 struct rt_sigframe {
  22         unsigned long tramp[2];
  23         struct siginfo info;
  24         struct ucontext uc;
  25 };
  26
  27 static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
  28                           size_t frame_size)
  29 {
  30         unsigned long sp = sigsp(regs->r29, ksig);
  31
  32         return (void __user *)((sp - frame_size) & ~(sizeof(long long) - 1));
  33 }
  34
  35 static int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc)
  36 {
  37         unsigned long tmp;
  38         int err = 0;
  39
  40         err |= copy_to_user(&sc->sc_regs.r0, &regs->r00,
  41                             32*sizeof(unsigned long));
  42
  43         err |= __put_user(regs->sa0, &sc->sc_regs.sa0);
  44         err |= __put_user(regs->lc0, &sc->sc_regs.lc0);
  45         err |= __put_user(regs->sa1, &sc->sc_regs.sa1);
  46         err |= __put_user(regs->lc1, &sc->sc_regs.lc1);
  47         err |= __put_user(regs->m0, &sc->sc_regs.m0);
  48         err |= __put_user(regs->m1, &sc->sc_regs.m1);
  49         err |= __put_user(regs->usr, &sc->sc_regs.usr);
  50         err |= __put_user(regs->preds, &sc->sc_regs.p3_0);
  51         err |= __put_user(regs->gp, &sc->sc_regs.gp);
  52         err |= __put_user(regs->ugp, &sc->sc_regs.ugp);
  53 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
  54         err |= __put_user(regs->cs0, &sc->sc_regs.cs0);
  55         err |= __put_user(regs->cs1, &sc->sc_regs.cs1);
  56 #endif
  57         tmp = pt_elr(regs); err |= __put_user(tmp, &sc->sc_regs.pc);
  58         tmp = pt_cause(regs); err |= __put_user(tmp, &sc->sc_regs.cause);
  59         tmp = pt_badva(regs); err |= __put_user(tmp, &sc->sc_regs.badva);
  60
  61         return err;
  62 }
  63
  64 static int restore_sigcontext(struct pt_regs *regs,
  65                               struct sigcontext __user *sc)
  66 {
  67         unsigned long tmp;
  68         int err = 0;
  69
  70         err |= copy_from_user(&regs->r00, &sc->sc_regs.r0,
  71                               32 * sizeof(unsigned long));
  72
  73         err |= __get_user(regs->sa0, &sc->sc_regs.sa0);
  74         err |= __get_user(regs->lc0, &sc->sc_regs.lc0);
  75         err |= __get_user(regs->sa1, &sc->sc_regs.sa1);
  76         err |= __get_user(regs->lc1, &sc->sc_regs.lc1);
  77         err |= __get_user(regs->m0, &sc->sc_regs.m0);
  78         err |= __get_user(regs->m1, &sc->sc_regs.m1);
  79         err |= __get_user(regs->usr, &sc->sc_regs.usr);
  80         err |= __get_user(regs->preds, &sc->sc_regs.p3_0);
  81         err |= __get_user(regs->gp, &sc->sc_regs.gp);
  82         err |= __get_user(regs->ugp, &sc->sc_regs.ugp);
  83 #if CONFIG_HEXAGON_ARCH_VERSION >= 4
  84         err |= __get_user(regs->cs0, &sc->sc_regs.cs0);
  85         err |= __get_user(regs->cs1, &sc->sc_regs.cs1);
  86 #endif
  87         err |= __get_user(tmp, &sc->sc_regs.pc); pt_set_elr(regs, tmp);
  88
  89         return err;
  90 }
  91
  92 /*
  93  * Setup signal stack frame with siginfo structure
  94  */
  95 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
  96                           struct pt_regs *regs)
  97 {
  98         int err = 0;
  99         struct rt_sigframe __user *frame;
 100         struct hexagon_vdso *vdso = current->mm->context.vdso;
 101
 102         frame = get_sigframe(ksig, regs, sizeof(struct rt_sigframe));
 103
 104         if (!access_ok(frame, sizeof(struct rt_sigframe)))
 105                 return -EFAULT;
 106
 107         if (copy_siginfo_to_user(&frame->info, &ksig->info))
 108                 return -EFAULT;
 109
 110         /* The on-stack signal trampoline is no longer executed;
 111          * however, the libgcc signal frame unwinding code checks for
 112          * the presence of these two numeric magic values.
 113          */
 114         err |= __put_user(0x7800d166, &frame->tramp[0]);
 115         err |= __put_user(0x5400c004, &frame->tramp[1]);
 116         err |= setup_sigcontext(regs, &frame->uc.uc_mcontext);
 117         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 118         err |= __save_altstack(&frame->uc.uc_stack, user_stack_pointer(regs));
 119         if (err)
 120                 return -EFAULT;
 121
 122         /* Load r0/r1 pair with signumber/siginfo pointer... */
 123         regs->r0100 = ((unsigned long long)((unsigned long)&frame->info) << 32)
 124                 | (unsigned long long)ksig->sig;
 125         regs->r02 = (unsigned long) &frame->uc;
 126         regs->r31 = (unsigned long) vdso->rt_signal_trampoline;
 127         pt_psp(regs) = (unsigned long) frame;
 128         pt_set_elr(regs, (unsigned long)ksig->ka.sa.sa_handler);
 129
 130         return 0;
 131 }
 132
 133 /*
 134  * Setup invocation of signal handler
 135  */
 136 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 137 {
 138         int ret;
 139
 140         /*
 141          * If we're handling a signal that aborted a system call,
 142          * set up the error return value before adding the signal
 143          * frame to the stack.
 144          */
 145
 146         if (regs->syscall_nr >= 0) {
 147                 switch (regs->r00) {
 148                 case -ERESTART_RESTARTBLOCK:
 149                 case -ERESTARTNOHAND:
 150                         regs->r00 = -EINTR;
 151                         break;
 152                 case -ERESTARTSYS:
 153                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 154                                 regs->r00 = -EINTR;
 155                                 break;
 156                         }
 157                         fallthrough;
 158                 case -ERESTARTNOINTR:
 159                         regs->r06 = regs->syscall_nr;
 160                         pt_set_elr(regs, pt_elr(regs) - 4);
 161                         regs->r00 = regs->restart_r0;
 162                         break;
 163                 default:
 164                         break;
 165                 }
 166         }
 167
 168         /*
 169          * Set up the stack frame; not doing the SA_SIGINFO thing.  We
 170          * only set up the rt_frame flavor.
 171          */
 172         /* If there was an error on setup, no signal was delivered. */
 173         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 174
 175         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 176 }
 177
 178 /*
 179  * Called from return-from-event code.
 180  */
 181 void do_signal(struct pt_regs *regs)
 182 {
 183         struct ksignal ksig;
 184
 185         if (!user_mode(regs))
 186                 return;
 187
 188         if (get_signal(&ksig)) {
 189                 handle_signal(&ksig, regs);
 190                 return;
 191         }
 192
 193         /*
 194          * No (more) signals; if we came from a system call, handle the restart.
 195          */
 196
 197         if (regs->syscall_nr >= 0) {
 198                 switch (regs->r00) {
 199                 case -ERESTARTNOHAND:
 200                 case -ERESTARTSYS:
 201                 case -ERESTARTNOINTR:
 202                         regs->r06 = regs->syscall_nr;
 203                         break;
 204                 case -ERESTART_RESTARTBLOCK:
 205                         regs->r06 = __NR_restart_syscall;
 206                         break;
 207                 default:
 208                         goto no_restart;
 209                 }
 210                 pt_set_elr(regs, pt_elr(regs) - 4);
 211                 regs->r00 = regs->restart_r0;
 212         }
 213
 214 no_restart:
 215         /* If there's no signal to deliver, put the saved sigmask back */
 216         restore_saved_sigmask();
 217 }
 218
 219 /*
 220  * Architecture-specific wrappers for signal-related system calls
 221  */
 222
 223 SYSCALL_DEFINE0(rt_sigreturn)
 224 {
 225         struct pt_regs *regs = current_pt_regs();
 226         struct rt_sigframe __user *frame;
 227         sigset_t blocked;
 228
 229         /* Always make any pending restarted system calls return -EINTR */
 230         current->restart_block.fn = do_no_restart_syscall;
 231
 232         frame = (struct rt_sigframe __user *)pt_psp(regs);
 233         if (!access_ok(frame, sizeof(*frame)))
 234                 goto badframe;
 235         if (__copy_from_user(&blocked, &frame->uc.uc_sigmask, sizeof(blocked)))
 236                 goto badframe;
 237
 238         set_current_blocked(&blocked);
 239
 240         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 241                 goto badframe;
 242
 243         /* Restore the user's stack as well */
 244         pt_psp(regs) = regs->r29;
 245
 246         regs->syscall_nr = -1;
 247
 248         if (restore_altstack(&frame->uc.uc_stack))
 249                 goto badframe;
 250
 251         return regs->r00;
 252
 253 badframe:
 254         force_sig(SIGSEGV);
 255         return 0;
 256 }