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         memset(to, 0, sizeof(*to));
 117
 118         err = __get_user(to->si_signo, &from->si_signo);
 119         err |= __get_user(to->si_errno, &from->si_errno);
 120         err |= __get_user(to->si_code, &from->si_code);
 121
 122         err |= __get_user(to->si_pid, &from->si_pid);
 123         err |= __get_user(to->si_uid, &from->si_uid);
 124         err |= __get_user(to->si_int, &from->si_int);
 125
 126         return err;
 127 }
 128
 129 /* The assembly shim for this function arranges to ignore the return value. */
 130 long compat_sys_rt_sigreturn(void)
 131 {
 132         struct pt_regs *regs = current_pt_regs();
 133         struct compat_rt_sigframe __user *frame =
 134                 (struct compat_rt_sigframe __user *) compat_ptr(regs->sp);
 135         sigset_t set;
 136
 137         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 138                 goto badframe;
 139         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 140                 goto badframe;
 141
 142         set_current_blocked(&set);
 143
 144         if (restore_sigcontext(regs, &frame->uc.uc_mcontext))
 145                 goto badframe;
 146
 147         if (compat_restore_altstack(&frame->uc.uc_stack))
 148                 goto badframe;
 149
 150         return 0;
 151
 152 badframe:
 153         signal_fault("bad sigreturn frame", regs, frame, 0);
 154         return 0;
 155 }
 156
 157 /*
 158  * Determine which stack to use..
 159  */
 160 static inline void __user *compat_get_sigframe(struct k_sigaction *ka,
 161                                                struct pt_regs *regs,
 162                                                size_t frame_size)
 163 {
 164         unsigned long sp;
 165
 166         /* Default to using normal stack */
 167         sp = (unsigned long)compat_ptr(regs->sp);
 168
 169         /*
 170          * If we are on the alternate signal stack and would overflow
 171          * it, don't.  Return an always-bogus address instead so we
 172          * will die with SIGSEGV.
 173          */
 174         if (on_sig_stack(sp) && !likely(on_sig_stack(sp - frame_size)))
 175                 return (void __user __force *)-1UL;
 176
 177         /* This is the X/Open sanctioned signal stack switching.  */
 178         if (ka->sa.sa_flags & SA_ONSTACK) {
 179                 if (sas_ss_flags(sp) == 0)
 180                         sp = current->sas_ss_sp + current->sas_ss_size;
 181         }
 182
 183         sp -= frame_size;
 184         /*
 185          * Align the stack pointer according to the TILE ABI,
 186          * i.e. so that on function entry (sp & 15) == 0.
 187          */
 188         sp &= -16UL;
 189         return (void __user *) sp;
 190 }
 191
 192 int compat_setup_rt_frame(struct ksignal *ksig, sigset_t *set,
 193                           struct pt_regs *regs)
 194 {
 195         unsigned long restorer;
 196         struct compat_rt_sigframe __user *frame;
 197         int err = 0, sig = ksig->sig;
 198
 199         frame = compat_get_sigframe(&ksig->ka, regs, sizeof(*frame));
 200
 201         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 202                 goto err;
 203
 204         /* Always write at least the signal number for the stack backtracer. */
 205         if (ksig->ka.sa.sa_flags & SA_SIGINFO) {
 206                 /* At sigreturn time, restore the callee-save registers too. */
 207                 err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
 208                 regs->flags |= PT_FLAGS_RESTORE_REGS;
 209         } else {
 210                 err |= __put_user(ksig->info.si_signo, &frame->info.si_signo);
 211         }
 212
 213         /* Create the ucontext.  */
 214         err |= __clear_user(&frame->save_area, sizeof(frame->save_area));
 215         err |= __put_user(0, &frame->uc.uc_flags);
 216         err |= __put_user(0, &frame->uc.uc_link);
 217         err |= __compat_save_altstack(&frame->uc.uc_stack, regs->sp);
 218         err |= setup_sigcontext(&frame->uc.uc_mcontext, regs);
 219         err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 220         if (err)
 221                 goto err;
 222
 223         restorer = VDSO_SYM(&__vdso_rt_sigreturn);
 224         if (ksig->ka.sa.sa_flags & SA_RESTORER)
 225                 restorer = ptr_to_compat_reg(ksig->ka.sa.sa_restorer);
 226
 227         /*
 228          * Set up registers for signal handler.
 229          * Registers that we don't modify keep the value they had from
 230          * user-space at the time we took the signal.
 231          * We always pass siginfo and mcontext, regardless of SA_SIGINFO,
 232          * since some things rely on this (e.g. glibc's debug/segfault.c).
 233          */
 234         regs->pc = ptr_to_compat_reg(ksig->ka.sa.sa_handler);
 235         regs->ex1 = PL_ICS_EX1(USER_PL, 1); /* set crit sec in handler */
 236         regs->sp = ptr_to_compat_reg(frame);
 237         regs->lr = restorer;
 238         regs->regs[0] = (unsigned long) sig;
 239         regs->regs[1] = ptr_to_compat_reg(&frame->info);
 240         regs->regs[2] = ptr_to_compat_reg(&frame->uc);
 241         regs->flags |= PT_FLAGS_CALLER_SAVES;
 242         return 0;
 243
 244 err:
 245         trace_unhandled_signal("bad sigreturn frame", regs,
 246                               (unsigned long)frame, SIGSEGV);
 247         return -EFAULT;
 248 }