arch/microblaze/kernel/signal.c

   1 /*
   2  * Signal handling
   3  *
   4  * Copyright (C) 2008-2009 Michal Simek <monstr@monstr.eu>
   5  * Copyright (C) 2008-2009 PetaLogix
   6  * Copyright (C) 2003,2004 John Williams <jwilliams@itee.uq.edu.au>
   7  * Copyright (C) 2001 NEC Corporation
   8  * Copyright (C) 2001 Miles Bader <miles@gnu.org>
   9  * Copyright (C) 1999,2000 Niibe Yutaka & Kaz Kojima
  10  * Copyright (C) 1991,1992 Linus Torvalds
  11  *
  12  * 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
  13  *
  14  * This file was was derived from the sh version, arch/sh/kernel/signal.c
  15  *
  16  * This file is subject to the terms and conditions of the GNU General
  17  * Public License. See the file COPYING in the main directory of this
  18  * archive for more details.
  19  */
  20
  21 #include <linux/sched.h>
  22 #include <linux/mm.h>
  23 #include <linux/smp.h>
  24 #include <linux/kernel.h>
  25 #include <linux/signal.h>
  26 #include <linux/errno.h>
  27 #include <linux/wait.h>
  28 #include <linux/ptrace.h>
  29 #include <linux/unistd.h>
  30 #include <linux/stddef.h>
  31 #include <linux/personality.h>
  32 #include <linux/percpu.h>
  33 #include <linux/linkage.h>
  34 #include <linux/tracehook.h>
  35 #include <asm/entry.h>
  36 #include <asm/ucontext.h>
  37 #include <linux/uaccess.h>
  38 #include <linux/syscalls.h>
  39 #include <asm/cacheflush.h>
  40 #include <asm/syscalls.h>
  41
  42 /*
  43  * Do a signal return; undo the signal stack.
  44  */
  45 struct sigframe {
  46         struct sigcontext sc;
  47         unsigned long extramask[_NSIG_WORDS-1];
  48         unsigned long tramp[2]; /* signal trampoline */
  49 };
  50
  51 struct rt_sigframe {
  52         struct siginfo info;
  53         struct ucontext uc;
  54         unsigned long tramp[2]; /* signal trampoline */
  55 };
  56
  57 static int restore_sigcontext(struct pt_regs *regs,
  58                                 struct sigcontext __user *sc, int *rval_p)
  59 {
  60         unsigned int err = 0;
  61
  62 #define COPY(x)         {err |= __get_user(regs->x, &sc->regs.x); }
  63         COPY(r0);
  64         COPY(r1);
  65         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
  66         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
  67         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
  68         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
  69         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
  70         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
  71         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
  72         COPY(r30);      COPY(r31);
  73         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
  74 #undef COPY
  75
  76         *rval_p = regs->r3;
  77
  78         return err;
  79 }
  80
  81 asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
  82 {
  83         struct rt_sigframe __user *frame =
  84                 (struct rt_sigframe __user *)(regs->r1);
  85
  86         sigset_t set;
  87         int rval;
  88
  89         /* Always make any pending restarted system calls return -EINTR */
  90         current->restart_block.fn = do_no_restart_syscall;
  91
  92         if (!access_ok(frame, sizeof(*frame)))
  93                 goto badframe;
  94
  95         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
  96                 goto badframe;
  97
  98         set_current_blocked(&set);
  99
 100         if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &rval))
 101                 goto badframe;
 102
 103         if (restore_altstack(&frame->uc.uc_stack))
 104                 goto badframe;
 105
 106         return rval;
 107
 108 badframe:
 109         force_sig(SIGSEGV);
 110         return 0;
 111 }
 112
 113 /*
 114  * Set up a signal frame.
 115  */
 116
 117 static int
 118 setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 119                 unsigned long mask)
 120 {
 121         int err = 0;
 122
 123 #define COPY(x)         {err |= __put_user(regs->x, &sc->regs.x); }
 124         COPY(r0);
 125         COPY(r1);
 126         COPY(r2);       COPY(r3);       COPY(r4);       COPY(r5);
 127         COPY(r6);       COPY(r7);       COPY(r8);       COPY(r9);
 128         COPY(r10);      COPY(r11);      COPY(r12);      COPY(r13);
 129         COPY(r14);      COPY(r15);      COPY(r16);      COPY(r17);
 130         COPY(r18);      COPY(r19);      COPY(r20);      COPY(r21);
 131         COPY(r22);      COPY(r23);      COPY(r24);      COPY(r25);
 132         COPY(r26);      COPY(r27);      COPY(r28);      COPY(r29);
 133         COPY(r30);      COPY(r31);
 134         COPY(pc);       COPY(ear);      COPY(esr);      COPY(fsr);
 135 #undef COPY
 136
 137         err |= __put_user(mask, &sc->oldmask);
 138
 139         return err;
 140 }
 141
 142 /*
 143  * Determine which stack to use..
 144  */
 145 static inline void __user *
 146 get_sigframe(struct ksignal *ksig, struct pt_regs *regs, size_t frame_size)
 147 {
 148         /* Default to using normal stack */
 149         unsigned long sp = sigsp(regs->r1, ksig);
 150
 151         return (void __user *)((sp - frame_size) & -8UL);
 152 }
 153
 154 static int setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 155                           struct pt_regs *regs)
 156 {
 157         struct rt_sigframe __user *frame;
 158         int err = 0, sig = ksig->sig;
 159         unsigned long address = 0;
 160         pmd_t *pmdp;
 161         pte_t *ptep;
 162
 163         frame = get_sigframe(ksig, regs, sizeof(*frame));
 164
 165         if (!access_ok(frame, sizeof(*frame)))
 166                 return -EFAULT;
 167
 168         if (ksig->ka.sa.sa_flags & SA_SIGINFO)
 169                 err |= copy_siginfo_to_user(&frame->info, &ksig->info);
 170
 171         /* Create the ucontext. */
 172         err |= __put_user(0, &frame->uc.uc_flags);
 173         err |= __put_user(NULL, &frame->uc.uc_link);
 174         err |= __save_altstack(&frame->uc.uc_stack, regs->r1);
 175         err |= setup_sigcontext(&frame->uc.uc_mcontext,
 176                         regs, set->sig[0]);
 177         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 178
 179         /* Set up to return from userspace. If provided, use a stub
 180          already in userspace. */
 181         /* minus 8 is offset to cater for "rtsd r15,8" */
 182         /* addi r12, r0, __NR_sigreturn */
 183         err |= __put_user(0x31800000 | __NR_rt_sigreturn ,
 184                         frame->tramp + 0);
 185         /* brki r14, 0x8 */
 186         err |= __put_user(0xb9cc0008, frame->tramp + 1);
 187
 188         /* Return from sighandler will jump to the tramp.
 189          Negative 8 offset because return is rtsd r15, 8 */
 190         regs->r15 = ((unsigned long)frame->tramp)-8;
 191
 192         address = ((unsigned long)frame->tramp);
 193         pmdp = pmd_off(current->mm, address);
 194
 195         preempt_disable();
 196         ptep = pte_offset_map(pmdp, address);
 197         if (pte_present(*ptep)) {
 198                 address = (unsigned long) page_address(pte_page(*ptep));
 199                 /* MS: I need add offset in page */
 200                 address += ((unsigned long)frame->tramp) & ~PAGE_MASK;
 201                 /* MS address is virtual */
 202                 address = __virt_to_phys(address);
 203                 invalidate_icache_range(address, address + 8);
 204                 flush_dcache_range(address, address + 8);
 205         }
 206         pte_unmap(ptep);
 207         preempt_enable();
 208         if (err)
 209                 return -EFAULT;
 210
 211         /* Set up registers for signal handler */
 212         regs->r1 = (unsigned long) frame;
 213
 214         /* Signal handler args: */
 215         regs->r5 = sig; /* arg 0: signum */
 216         regs->r6 = (unsigned long) &frame->info; /* arg 1: siginfo */
 217         regs->r7 = (unsigned long) &frame->uc; /* arg2: ucontext */
 218         /* Offset to handle microblaze rtid r14, 0 */
 219         regs->pc = (unsigned long)ksig->ka.sa.sa_handler;
 220
 221 #ifdef DEBUG_SIG
 222         pr_info("SIG deliver (%s:%d): sp=%p pc=%08lx\n",
 223                 current->comm, current->pid, frame, regs->pc);
 224 #endif
 225
 226         return 0;
 227 }
 228
 229 /* Handle restarting system calls */
 230 static inline void
 231 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 232 {
 233         switch (regs->r3) {
 234         case -ERESTART_RESTARTBLOCK:
 235         case -ERESTARTNOHAND:
 236                 if (!has_handler)
 237                         goto do_restart;
 238                 regs->r3 = -EINTR;
 239                 break;
 240         case -ERESTARTSYS:
 241                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 242                         regs->r3 = -EINTR;
 243                         break;
 244         }
 245                 fallthrough;
 246         case -ERESTARTNOINTR:
 247 do_restart:
 248                 /* offset of 4 bytes to re-execute trap (brki) instruction */
 249                 regs->pc -= 4;
 250                 break;
 251         }
 252 }
 253
 254 /*
 255  * OK, we're invoking a handler
 256  */
 257
 258 static void
 259 handle_signal(struct ksignal *ksig, struct pt_regs *regs)
 260 {
 261         sigset_t *oldset = sigmask_to_save();
 262         int ret;
 263
 264         /* Set up the stack frame */
 265         ret = setup_rt_frame(ksig, oldset, regs);
 266
 267         signal_setup_done(ret, ksig, test_thread_flag(TIF_SINGLESTEP));
 268 }
 269
 270 /*
 271  * Note that 'init' is a special process: it doesn't get signals it doesn't
 272  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 273  * mistake.
 274  *
 275  * Note that we go through the signals twice: once to check the signals that
 276  * the kernel can handle, and then we build all the user-level signal handling
 277  * stack-frames in one go after that.
 278  */
 279 static void do_signal(struct pt_regs *regs, int in_syscall)
 280 {
 281         struct ksignal ksig;
 282
 283 #ifdef DEBUG_SIG
 284         pr_info("do signal: %p %d\n", regs, in_syscall);
 285         pr_info("do signal2: %lx %lx %ld [%lx]\n", regs->pc, regs->r1,
 286                         regs->r12, current_thread_info()->flags);
 287 #endif
 288
 289         if (get_signal(&ksig)) {
 290                 /* Whee! Actually deliver the signal. */
 291                 if (in_syscall)
 292                         handle_restart(regs, &ksig.ka, 1);
 293                 handle_signal(&ksig, regs);
 294                 return;
 295         }
 296
 297         if (in_syscall)
 298                 handle_restart(regs, NULL, 0);
 299
 300         /*
 301          * If there's no signal to deliver, we just put the saved sigmask
 302          * back.
 303          */
 304         restore_saved_sigmask();
 305 }
 306
 307 asmlinkage void do_notify_resume(struct pt_regs *regs, int in_syscall)
 308 {
 309         if (test_thread_flag(TIF_SIGPENDING) ||
 310             test_thread_flag(TIF_NOTIFY_SIGNAL))
 311                 do_signal(regs, in_syscall);
 312
 313         if (test_thread_flag(TIF_NOTIFY_RESUME))
 314                 tracehook_notify_resume(regs);
 315 }