arch/tile/kernel/compat_signal.c

   1 /*
   2  * Copyright 2010 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  */
  14
  15 #include <linux/sched.h>
  16 #include <linux/mm.h>
  17 #include <linux/smp.h>
  18 #include <linux/kernel.h>
  19 #include <linux/signal.h>
  20 #include <linux/errno.h>
  21 #include <linux/wait.h>
  22 #include <linux/unistd.h>
  23 #include <linux/stddef.h>
  24 #include <linux/personality.h>
  25 #include <linux/suspend.h>
  26 #include <linux/ptrace.h>
  27 #include <linux/elf.h>
  28 #include <linux/compat.h>
  29 #include <linux/syscalls.h>
  30 #include <linux/uaccess.h>
  31 #include <asm/processor.h>
  32 #include <asm/ucontext.h>
  33 #include <asm/sigframe.h>
  34 #include <asm/syscalls.h>
  35 #include <asm/vdso.h>
  36 #include <arch/interrupts.h>
  37
  38 struct compat_ucontext {
  39         compat_ulong_t    uc_flags;
  40         compat_uptr_t     uc_link;
  41         struct compat_sigaltstack         uc_stack;
  42         struct sigcontext uc_mcontext;
  43         sigset_t          uc_sigmask;   /* mask last for extensibility */
  44 };
  45
  46 struct compat_rt_sigframe {
  47         unsigned char save_area[C_ABI_SAVE_AREA_SIZE]; /* caller save area */
  48         struct compat_siginfo info;
  49         struct compat_ucontext uc;
  50 };
  51
  52 int copy_siginfo_to_user32(struct compat_siginfo __user *to, const siginfo_t *from)
  53 {
  54         int err;
  55
  56         if (!access_ok(VERIFY_WRITE, to, sizeof(struct compat_siginfo)))
  57                 return -EFAULT;
  58
  59         /* If you change siginfo_t structure, please make sure that
  60            this code is fixed accordingly.
  61            It should never copy any pad contained in the structure
  62            to avoid security leaks, but must copy the generic
  63            3 ints plus the relevant union member.  */
  64         err = __put_user(from->si_signo, &to->si_signo);
  65         err |= __put_user(from->si_errno, &to->si_errno);
  66         err |= __put_user((short)from->si_code, &to->si_code);
  67
  68         if (from->si_code < 0) {
  69                 err |= __put_user(from->si_pid, &to->si_pid);
  70                 err |= __put_user(from->si_uid, &to->si_uid);
  71                 err |= __put_user(from->si_int, &to->si_int);
  72         } else {
  73                 /*
  74                  * First 32bits of unions are always present:
  75                  * si_pid === si_band === si_tid === si_addr(LS half)
  76                  */
  77                 err |= __put_user(from->_sifields._pad[0],
  78                                   &to->_sifields._pad[0]);
  79                 switch (from->si_code >> 16) {
  80                 case __SI_FAULT >> 16:
  81                         break;
  82                 case __SI_CHLD >> 16:
  83                         err |= __put_user(from->si_utime, &to->si_utime);
  84                         err |= __put_user(from->si_stime, &to->si_stime);
  85                         err |= __put_user(from->si_status, &to->si_status);
  86                         /* FALL THROUGH */
  87                 default:
  88                 case __SI_KILL >> 16:
  89                         err |= __put_user(from->si_uid, &to->si_uid);
  90                         break;
  91                 case __SI_POLL >> 16:
  92                         err |= __put_user(from->si_fd, &to->si_fd);
  93                         break;
  94                 case __SI_TIMER >> 16:
  95                         err |= __put_user(from->si_overrun, &to->si_overrun);
  96                         err |= __put_user(from->si_int, &to->si_int);
  97                         break;
  98                          /* This is not generated by the kernel as of now.  */
  99                 case __SI_RT >> 16:
 100                 case __SI_MESGQ >> 16:
 101                         err |= __put_user(from->si_uid, &to->si_uid);
 102                         err |= __put_user(from->si_int, &to->si_int);
 103                         break;
 104                 }
 105         }
 106         return err;
 107 }
 108
 109 int copy_siginfo_from_user32(siginfo_t *to, struct compat_siginfo __user *from)
 110 {
 111         int err;
 112
 113         if (!access_ok(VERIFY_READ, from, sizeof(struct compat_siginfo)))
 114                 return -EFAULT;
 115
 116         err = __get_user(to->si_signo, &from->si_signo);
 117         err |= __get_user(to->si_errno, &from->si_errno);
 118         err |= __get_user(to->si_code, &from->si_code);
 119
 120         err |= __get_user(to->si_pid, &from->si_pid);
 121         err |= __get_user(to->si_uid, &from->si_uid);
 122         err |= __get_user(to->si_int, &from->si_int);
 123
 124         return err;
 125 }
 126
 127 /* The assembly shim for this function arranges to ignore the return value. */
 128 long compat_sys_rt_sigreturn(void)
 129 {
 130         struct pt_regs *regs = current_pt_regs();
 131         struct compat_rt_sigframe __user *frame =
 132                 (struct compat_rt_sigframe __user *) compat_ptr(regs->sp);
 133         sigset_t set;
 134
 135         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 136                 goto badframe;
 137         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 138                 goto badframe;
 139
 140         set_current_blocked(&set);
 141
 142         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 143                 goto badframe;
 144
 145         if (compat_restore_altstack(&frame->uc.uc_stack))
 146                 goto badframe;
 147
 148         return 0;
 149
 150 badframe:
 151         signal_fault("bad sigreturn frame", regs, frame, 0);
 152         return 0;
 153 }
 154
 155 /*
 156  * Determine which stack to use..
 157  */
 158 static inline void __user *compat_get_sigframe(struct k_sigaction *ka,
 159                                                struct pt_regs *regs,
 160                                                size_t frame_size)
 161 {
 162         unsigned long sp;
 163
 164         /* Default to using normal stack */
 165         sp = (unsigned long)compat_ptr(regs->sp);
 166
 167         /*
 168          * If we are on the alternate signal stack and would overflow
 169          * it, don't.  Return an always-bogus address instead so we
 170          * will die with SIGSEGV.
 171          */
 172         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 173                 return (void __user __force *)-1UL;
 174
 175         /* This is the X/Open sanctioned signal stack switching.  */
 176         if (ka->sa.sa_flags & SA_ONSTACK) {
 177                 if (sas_ss_flags(sp) == 0)
 178                         sp = current->sas_ss_sp + current->sas_ss_size;
 179         }
 180
 181         sp -= frame_size;
 182         /*
 183          * Align the stack pointer according to the TILE ABI,
 184          * i.e. so that on function entry (sp & 15) == 0.
 185          */
 186         sp &= -16UL;
 187         return (void __user *) sp;
 188 }
 189
 190 int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 191                           struct pt_regs *regs)
 192 {
 193         unsigned long restorer;
 194         struct compat_rt_sigframe __user *frame;
 195         int err = 0, sig = ksig->sig;
 196
 197         frame = compat_get_sigframe(&ksig->ka, regs, sizeof(*frame));
 198
 199         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 200                 goto err;
 201
 202         /* Always write at least the signal number for the stack backtracer. */
 203         if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 204                 /* At sigreturn time, restore the callee-save registers too. */
 205                 err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
 206                 regs->flags |= PT_FLAGS_RESTORE_REGS;
 207         } else {
 208                 err |= __put_user(ksig->info.si_signo, &frame->info.si_signo);
 209         }
 210
 211         /* Create the ucontext.  */
 212         err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 213         err |= __put_user(0, &frame->uc.uc_flags);
 214         err |= __put_user(0, &frame->uc.uc_link);
 215         err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
 216         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 217         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 218         if (err)
 219                 goto err;
 220
 221         restorer = VDSO_SYM(&__vdso_rt_sigreturn);
 222         if (ksig->ka.sa.sa_flags & SA_RESTORER)
 223                 restorer = ptr_to_compat_reg(ksig->ka.sa.sa_restorer);
 224
 225         /*
 226          * Set up registers for signal handler.
 227          * Registers that we don't modify keep the value they had from
 228          * user-space at the time we took the signal.
 229          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 230          * since some things rely on this (e.g. glibc's debug/segfault.c).
 231          */
 232         regs->pc = ptr_to_compat_reg(ksig->ka.sa.sa_handler);
 233         regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 234         regs->sp = ptr_to_compat_reg(frame);
 235         regs->lr = restorer;
 236         regs->regs[0] = (unsigned long) sig;
 237         regs->regs[1] = ptr_to_compat_reg(&frame->info);
 238         regs->regs[2] = ptr_to_compat_reg(&frame->uc);
 239         regs->flags |= PT_FLAGS_CALLER_SAVES;
 240         return 0;
 241
 242 err:
 243         trace_unhandled_signal("bad sigreturn frame", regs,
 244                               (unsigned long)frame, SIGSEGV);
 245         return -EFAULT;
 246 }