arch/c6x/kernel/signal.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  Port on Texas Instruments TMS320C6x architecture
   4  *
   5  *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
   6  *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
   7  *
   8  *  Updated for 2.6.34: Mark Salter <msalter@redhat.com>
   9  */
  10
  11 #include <linux/kernel.h>
  12 #include <linux/uaccess.h>
  13 #include <linux/syscalls.h>
  14 #include <linux/tracehook.h>
  15
  16 #include <asm/ucontext.h>
  17 #include <asm/cacheflush.h>
  18
  19
  20 /*
  21  * Do a signal return, undo the signal stack.
  22  */
  23
  24 #define RETCODE_SIZE (9 << 2)   /* 9 instructions = 36 bytes */
  25
  26 struct rt_sigframe {
  27         struct siginfo __user *pinfo;
  28         void __user *puc;
  29         struct siginfo info;
  30         struct ucontext uc;
  31         unsigned long retcode[RETCODE_SIZE >> 2];
  32 };
  33
  34 static int restore_sigcontext(struct pt_regs *regs,
  35                               struct sigcontext __user *sc)
  36 {
  37         int err = 0;
  38
  39         /* The access_ok check was done by caller, so use __get_user here */
  40 #define COPY(x)  (err |= __get_user(regs->x, &sc->sc_##x))
  41
  42         COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
  43         COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
  44         COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
  45
  46         COPY(a16); COPY(a17); COPY(a18); COPY(a19);
  47         COPY(a20); COPY(a21); COPY(a22); COPY(a23);
  48         COPY(a24); COPY(a25); COPY(a26); COPY(a27);
  49         COPY(a28); COPY(a29); COPY(a30); COPY(a31);
  50         COPY(b16); COPY(b17); COPY(b18); COPY(b19);
  51         COPY(b20); COPY(b21); COPY(b22); COPY(b23);
  52         COPY(b24); COPY(b25); COPY(b26); COPY(b27);
  53         COPY(b28); COPY(b29); COPY(b30); COPY(b31);
  54
  55         COPY(csr); COPY(pc);
  56
  57 #undef COPY
  58
  59         return err;
  60 }
  61
  62 asmlinkage int do_rt_sigreturn(struct pt_regs *regs)
  63 {
  64         struct rt_sigframe __user *frame;
  65         sigset_t set;
  66
  67         /* Always make any pending restarted system calls return -EINTR */
  68         current->restart_block.fn = do_no_restart_syscall;
  69
  70         /*
  71          * Since we stacked the signal on a dword boundary,
  72          * 'sp' should be dword aligned here.  If it's
  73          * not, then the user is trying to mess with us.
  74          */
  75         if (regs->sp & 7)
  76                 goto badframe;
  77
  78         frame = (struct rt_sigframe __user *) ((unsigned long) regs->sp + 8);
  79
  80         if (!access_ok(frame, sizeof(*frame)))
  81                 goto badframe;
  82         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  83                 goto badframe;
  84
  85         set_current_blocked(&set);
  86
  87         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
  88                 goto badframe;
  89
  90         return regs->a4;
  91
  92 badframe:
  93         force_sig(SIGSEGV);
  94         return 0;
  95 }
  96
  97 static int setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
  98                             unsigned long mask)
  99 {
 100         int err = 0;
 101
 102         err |= __put_user(mask, &sc->sc_mask);
 103
 104         /* The access_ok check was done by caller, so use __put_user here */
 105 #define COPY(x) (err |= __put_user(regs->x, &sc->sc_##x))
 106
 107         COPY(sp); COPY(a4); COPY(b4); COPY(a6); COPY(b6); COPY(a8); COPY(b8);
 108         COPY(a0); COPY(a1); COPY(a2); COPY(a3); COPY(a5); COPY(a7); COPY(a9);
 109         COPY(b0); COPY(b1); COPY(b2); COPY(b3); COPY(b5); COPY(b7); COPY(b9);
 110
 111         COPY(a16); COPY(a17); COPY(a18); COPY(a19);
 112         COPY(a20); COPY(a21); COPY(a22); COPY(a23);
 113         COPY(a24); COPY(a25); COPY(a26); COPY(a27);
 114         COPY(a28); COPY(a29); COPY(a30); COPY(a31);
 115         COPY(b16); COPY(b17); COPY(b18); COPY(b19);
 116         COPY(b20); COPY(b21); COPY(b22); COPY(b23);
 117         COPY(b24); COPY(b25); COPY(b26); COPY(b27);
 118         COPY(b28); COPY(b29); COPY(b30); COPY(b31);
 119
 120         COPY(csr); COPY(pc);
 121
 122 #undef COPY
 123
 124         return err;
 125 }
 126
 127 static inline void __user *get_sigframe(struct ksignal *ksig,
 128                                         struct pt_regs *regs,
 129                                         unsigned long framesize)
 130 {
 131         unsigned long sp = sigsp(regs->sp, ksig);
 132
 133         /*
 134          * No matter what happens, 'sp' must be dword
 135          * aligned. Otherwise, nasty things will happen
 136          */
 137         return (void __user *)((sp - framesize) & ~7);
 138 }
 139
 140 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 141                           struct pt_regs *regs)
 142 {
 143         struct rt_sigframe __user *frame;
 144         unsigned long __user *retcode;
 145         int err = 0;
 146
 147         frame = get_sigframe(ksig, regs, sizeof(*frame));
 148
 149         if (!access_ok(frame, sizeof(*frame)))
 150                 return -EFAULT;
 151
 152         err |= __put_user(&frame->info, &frame->pinfo);
 153         err |= __put_user(&frame->uc, &frame->puc);
 154         err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 155
 156         /* Clear all the bits of the ucontext we don't use.  */
 157         err |= __clear_user(&frame->uc, offsetof(struct ucontext, uc_mcontext));
 158
 159         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs, set->sig[0]);
 160         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 161
 162         /* Set up to return from userspace */
 163         retcode = (unsigned long __user *) &frame->retcode;
 164
 165         /* The access_ok check was done above, so use __put_user here */
 166 #define COPY(x) (err |= __put_user(x, retcode++))
 167
 168         COPY(0x0000002AUL | (__NR_rt_sigreturn << 7));
 169                                 /* MVK __NR_rt_sigreturn,B0 */
 170         COPY(0x10000000UL);     /* SWE */
 171         COPY(0x00006000UL);     /* NOP 4 */
 172         COPY(0x00006000UL);     /* NOP 4 */
 173         COPY(0x00006000UL);     /* NOP 4 */
 174         COPY(0x00006000UL);     /* NOP 4 */
 175         COPY(0x00006000UL);     /* NOP 4 */
 176         COPY(0x00006000UL);     /* NOP 4 */
 177         COPY(0x00006000UL);     /* NOP 4 */
 178
 179 #undef COPY
 180
 181         if (err)
 182                 return -EFAULT;
 183
 184         flush_icache_range((unsigned long) &frame->retcode,
 185                            (unsigned long) &frame->retcode + RETCODE_SIZE);
 186
 187         retcode = (unsigned long __user *) &frame->retcode;
 188
 189         /* Change user context to branch to signal handler */
 190         regs->sp = (unsigned long) frame - 8;
 191         regs->b3 = (unsigned long) retcode;
 192         regs->pc = (unsigned long) ksig->ka.sa.sa_handler;
 193
 194         /* Give the signal number to the handler */
 195         regs->a4 = ksig->sig;
 196
 197         /*
 198          * For realtime signals we must also set the second and third
 199          * arguments for the signal handler.
 200          *   -- Peter Maydell <pmaydell@chiark.greenend.org.uk> 2000-12-06
 201          */
 202         regs->b4 = (unsigned long)&frame->info;
 203         regs->a6 = (unsigned long)&frame->uc;
 204
 205         return 0;
 206 }
 207
 208 static inline void
 209 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 210 {
 211         switch (regs->a4) {
 212         case -ERESTARTNOHAND:
 213                 if (!has_handler)
 214                         goto do_restart;
 215                 regs->a4 = -EINTR;
 216                 break;
 217
 218         case -ERESTARTSYS:
 219                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 220                         regs->a4 = -EINTR;
 221                         break;
 222                 }
 223         /* fallthrough */
 224         case -ERESTARTNOINTR:
 225 do_restart:
 226                 regs->a4 = regs->orig_a4;
 227                 regs->pc -= 4;
 228                 break;
 229         }
 230 }
 231
 232 /*
 233  * handle the actual delivery of a signal to userspace
 234  */
 235 static void handle_signal(struct ksignal *ksig, struct pt_regs *regs,
 236                           int syscall)
 237 {
 238         int ret;
 239
 240         /* Are we from a system call? */
 241         if (syscall) {
 242                 /* If so, check system call restarting.. */
 243                 switch (regs->a4) {
 244                 case -ERESTART_RESTARTBLOCK:
 245                 case -ERESTARTNOHAND:
 246                         regs->a4 = -EINTR;
 247                         break;
 248
 249                 case -ERESTARTSYS:
 250                         if (!(ksig->ka.sa.sa_flags & SA_RESTART)) {
 251                                 regs->a4 = -EINTR;
 252                                 break;
 253                         }
 254
 255                         /* fallthrough */
 256                 case -ERESTARTNOINTR:
 257                         regs->a4 = regs->orig_a4;
 258                         regs->pc -= 4;
 259                 }
 260         }
 261
 262         /* Set up the stack frame */
 263         ret = setup_rt_frame(ksig, sigmask_to_save(), regs);
 264         signal_setup_done(ret, ksig, 0);
 265 }
 266
 267 /*
 268  * handle a potential signal
 269  */
 270 static void do_signal(struct pt_regs *regs, int syscall)
 271 {
 272         struct ksignal ksig;
 273
 274         /* we want the common case to go fast, which is why we may in certain
 275          * cases get here from kernel mode */
 276         if (!user_mode(regs))
 277                 return;
 278
 279         if (get_signal(&ksig)) {
 280                 handle_signal(&ksig, regs, syscall);
 281                 return;
 282         }
 283
 284         /* did we come from a system call? */
 285         if (syscall) {
 286                 /* restart the system call - no handlers present */
 287                 switch (regs->a4) {
 288                 case -ERESTARTNOHAND:
 289                 case -ERESTARTSYS:
 290                 case -ERESTARTNOINTR:
 291                         regs->a4 = regs->orig_a4;
 292                         regs->pc -= 4;
 293                         break;
 294
 295                 case -ERESTART_RESTARTBLOCK:
 296                         regs->a4 = regs->orig_a4;
 297                         regs->b0 = __NR_restart_syscall;
 298                         regs->pc -= 4;
 299                         break;
 300                 }
 301         }
 302
 303         /* if there's no signal to deliver, we just put the saved sigmask
 304          * back */
 305         restore_saved_sigmask();
 306 }
 307
 308 /*
 309  * notification of userspace execution resumption
 310  * - triggered by current->work.notify_resume
 311  */
 312 asmlinkage void do_notify_resume(struct pt_regs *regs, u32 thread_info_flags,
 313                                  int syscall)
 314 {
 315         /* deal with pending signal delivery */
 316         if (thread_info_flags & (1 << TIF_SIGPENDING))
 317                 do_signal(regs, syscall);
 318
 319         if (thread_info_flags & (1 << TIF_NOTIFY_RESUME)) {
 320                 clear_thread_flag(TIF_NOTIFY_RESUME);
 321                 tracehook_notify_resume(regs);
 322         }
 323 }