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/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
  22 struct rt_sigframe {
  23         unsigned long tramp[2];
  24         struct siginfo info;
  25         struct ucontext uc;
  26 };
  27
  28 static 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
  36 static 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
  65 static 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  */
  96 static 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  */
 137 static 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  */
 182 void 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
 215 no_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
 224 asmlinkage 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
 254 badframe:
 255         force_sig(SIGSEGV);
 256         return 0;
 257 }