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   1 /*
   2  * Copyright (C) 2004 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/ptrace.h"
   7 #include "asm/unistd.h"
   8 #include "asm/uaccess.h"
   9 #include "asm/ucontext.h"
  10 #include "frame_kern.h"
  11 #include "skas.h"
  12
  13 void copy_sc(struct uml_pt_regs *regs, void *from)
  14 {
  15         struct sigcontext *sc = from;
  16
  17         REGS_GS(regs->gp) = sc->gs;
  18         REGS_FS(regs->gp) = sc->fs;
  19         REGS_ES(regs->gp) = sc->es;
  20         REGS_DS(regs->gp) = sc->ds;
  21         REGS_EDI(regs->gp) = sc->edi;
  22         REGS_ESI(regs->gp) = sc->esi;
  23         REGS_EBP(regs->gp) = sc->ebp;
  24         REGS_SP(regs->gp) = sc->esp;
  25         REGS_EBX(regs->gp) = sc->ebx;
  26         REGS_EDX(regs->gp) = sc->edx;
  27         REGS_ECX(regs->gp) = sc->ecx;
  28         REGS_EAX(regs->gp) = sc->eax;
  29         REGS_IP(regs->gp) = sc->eip;
  30         REGS_CS(regs->gp) = sc->cs;
  31         REGS_EFLAGS(regs->gp) = sc->eflags;
  32         REGS_SS(regs->gp) = sc->ss;
  33 }
  34
  35 static int copy_sc_from_user(struct pt_regs *regs,
  36                              struct sigcontext __user *from)
  37 {
  38         struct sigcontext sc;
  39         unsigned long fpregs[HOST_FP_SIZE];
  40         int err;
  41
  42         err = copy_from_user(&sc, from, sizeof(sc));
  43         err |= copy_from_user(fpregs, sc.fpstate, sizeof(fpregs));
  44         if (err)
  45                 return err;
  46
  47         copy_sc(&regs->regs, &sc);
  48
  49         err = restore_fp_registers(userspace_pid[0], fpregs);
  50         if (err < 0) {
  51                 printk(KERN_ERR "copy_sc_from_user_skas - PTRACE_SETFPREGS "
  52                        "failed, errno = %d\n", -err);
  53                 return err;
  54         }
  55
  56         return 0;
  57 }
  58
  59 static int copy_sc_to_user(struct sigcontext __user *to,
  60                            struct _fpstate __user *to_fp, struct pt_regs *regs,
  61                            unsigned long sp)
  62 {
  63         struct sigcontext sc;
  64         unsigned long fpregs[HOST_FP_SIZE];
  65         struct faultinfo * fi = &current->thread.arch.faultinfo;
  66         int err;
  67
  68         sc.gs = REGS_GS(regs->regs.gp);
  69         sc.fs = REGS_FS(regs->regs.gp);
  70         sc.es = REGS_ES(regs->regs.gp);
  71         sc.ds = REGS_DS(regs->regs.gp);
  72         sc.edi = REGS_EDI(regs->regs.gp);
  73         sc.esi = REGS_ESI(regs->regs.gp);
  74         sc.ebp = REGS_EBP(regs->regs.gp);
  75         sc.esp = sp;
  76         sc.ebx = REGS_EBX(regs->regs.gp);
  77         sc.edx = REGS_EDX(regs->regs.gp);
  78         sc.ecx = REGS_ECX(regs->regs.gp);
  79         sc.eax = REGS_EAX(regs->regs.gp);
  80         sc.eip = REGS_IP(regs->regs.gp);
  81         sc.cs = REGS_CS(regs->regs.gp);
  82         sc.eflags = REGS_EFLAGS(regs->regs.gp);
  83         sc.esp_at_signal = regs->regs.gp[UESP];
  84         sc.ss = regs->regs.gp[SS];
  85         sc.cr2 = fi->cr2;
  86         sc.err = fi->error_code;
  87         sc.trapno = fi->trap_no;
  88
  89         err = save_fp_registers(userspace_pid[0], fpregs);
  90         if (err < 0) {
  91                 printk(KERN_ERR "copy_sc_to_user_skas - PTRACE_GETFPREGS "
  92                        "failed, errno = %d\n", err);
  93                 return 1;
  94         }
  95         to_fp = (to_fp ? to_fp : (struct _fpstate __user *) (to + 1));
  96         sc.fpstate = to_fp;
  97
  98         if (err)
  99                 return err;
 100
 101         return copy_to_user(to, &sc, sizeof(sc)) ||
 102                copy_to_user(to_fp, fpregs, sizeof(fpregs));
 103 }
 104
 105 static int copy_ucontext_to_user(struct ucontext __user *uc,
 106                                  struct _fpstate __user *fp, sigset_t *set,
 107                                  unsigned long sp)
 108 {
 109         int err = 0;
 110
 111         err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
 112         err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
 113         err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
 114         err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, sp);
 115         err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
 116         return err;
 117 }
 118
 119 struct sigframe
 120 {
 121         char __user *pretcode;
 122         int sig;
 123         struct sigcontext sc;
 124         struct _fpstate fpstate;
 125         unsigned long extramask[_NSIG_WORDS-1];
 126         char retcode[8];
 127 };
 128
 129 struct rt_sigframe
 130 {
 131         char __user *pretcode;
 132         int sig;
 133         struct siginfo __user *pinfo;
 134         void __user *puc;
 135         struct siginfo info;
 136         struct ucontext uc;
 137         struct _fpstate fpstate;
 138         char retcode[8];
 139 };
 140
 141 int setup_signal_stack_sc(unsigned long stack_top, int sig,
 142                           struct k_sigaction *ka, struct pt_regs *regs,
 143                           sigset_t *mask)
 144 {
 145         struct sigframe __user *frame;
 146         void __user *restorer;
 147         unsigned long save_sp = PT_REGS_SP(regs);
 148         int err = 0;
 149
 150         /* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
 151         stack_top = ((stack_top + 4) & -16UL) - 4;
 152         frame = (struct sigframe __user *) stack_top - 1;
 153         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 154                 return 1;
 155
 156         restorer = frame->retcode;
 157         if (ka->sa.sa_flags & SA_RESTORER)
 158                 restorer = ka->sa.sa_restorer;
 159
 160         /* Update SP now because the page fault handler refuses to extend
 161          * the stack if the faulting address is too far below the current
 162          * SP, which frame now certainly is.  If there's an error, the original
 163          * value is restored on the way out.
 164          * When writing the sigcontext to the stack, we have to write the
 165          * original value, so that's passed to copy_sc_to_user, which does
 166          * the right thing with it.
 167          */
 168         PT_REGS_SP(regs) = (unsigned long) frame;
 169
 170         err |= __put_user(restorer, &frame->pretcode);
 171         err |= __put_user(sig, &frame->sig);
 172         err |= copy_sc_to_user(&frame->sc, NULL, regs, save_sp);
 173         err |= __put_user(mask->sig[0], &frame->sc.oldmask);
 174         if (_NSIG_WORDS > 1)
 175                 err |= __copy_to_user(&frame->extramask, &mask->sig[1],
 176                                       sizeof(frame->extramask));
 177
 178         /*
 179          * This is popl %eax ; movl $,%eax ; int $0x80
 180          *
 181          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 182          * reasons and because gdb uses it as a signature to notice
 183          * signal handler stack frames.
 184          */
 185         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 186         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 187         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 188
 189         if (err)
 190                 goto err;
 191
 192         PT_REGS_SP(regs) = (unsigned long) frame;
 193         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 194         PT_REGS_EAX(regs) = (unsigned long) sig;
 195         PT_REGS_EDX(regs) = (unsigned long) 0;
 196         PT_REGS_ECX(regs) = (unsigned long) 0;
 197
 198         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 199                 ptrace_notify(SIGTRAP);
 200         return 0;
 201
 202 err:
 203         PT_REGS_SP(regs) = save_sp;
 204         return err;
 205 }
 206
 207 int setup_signal_stack_si(unsigned long stack_top, int sig,
 208                           struct k_sigaction *ka, struct pt_regs *regs,
 209                           siginfo_t *info, sigset_t *mask)
 210 {
 211         struct rt_sigframe __user *frame;
 212         void __user *restorer;
 213         unsigned long save_sp = PT_REGS_SP(regs);
 214         int err = 0;
 215
 216         stack_top &= -8UL;
 217         frame = (struct rt_sigframe __user *) stack_top - 1;
 218         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 219                 return 1;
 220
 221         restorer = frame->retcode;
 222         if (ka->sa.sa_flags & SA_RESTORER)
 223                 restorer = ka->sa.sa_restorer;
 224
 225         /* See comment above about why this is here */
 226         PT_REGS_SP(regs) = (unsigned long) frame;
 227
 228         err |= __put_user(restorer, &frame->pretcode);
 229         err |= __put_user(sig, &frame->sig);
 230         err |= __put_user(&frame->info, &frame->pinfo);
 231         err |= __put_user(&frame->uc, &frame->puc);
 232         err |= copy_siginfo_to_user(&frame->info, info);
 233         err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
 234                                      save_sp);
 235
 236         /*
 237          * This is movl $,%eax ; int $0x80
 238          *
 239          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 240          * reasons and because gdb uses it as a signature to notice
 241          * signal handler stack frames.
 242          */
 243         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 244         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 245         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 246
 247         if (err)
 248                 goto err;
 249
 250         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 251         PT_REGS_EAX(regs) = (unsigned long) sig;
 252         PT_REGS_EDX(regs) = (unsigned long) &frame->info;
 253         PT_REGS_ECX(regs) = (unsigned long) &frame->uc;
 254
 255         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 256                 ptrace_notify(SIGTRAP);
 257         return 0;
 258
 259 err:
 260         PT_REGS_SP(regs) = save_sp;
 261         return err;
 262 }
 263
 264 long sys_sigreturn(struct pt_regs regs)
 265 {
 266         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 267         struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
 268         sigset_t set;
 269         struct sigcontext __user *sc = &frame->sc;
 270         unsigned long __user *oldmask = &sc->oldmask;
 271         unsigned long __user *extramask = frame->extramask;
 272         int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
 273
 274         if (copy_from_user(&set.sig[0], oldmask, sizeof(set.sig[0])) ||
 275             copy_from_user(&set.sig[1], extramask, sig_size))
 276                 goto segfault;
 277
 278         sigdelsetmask(&set, ~_BLOCKABLE);
 279
 280         spin_lock_irq(&current->sighand->siglock);
 281         current->blocked = set;
 282         recalc_sigpending();
 283         spin_unlock_irq(&current->sighand->siglock);
 284
 285         if (copy_sc_from_user(&current->thread.regs, sc))
 286                 goto segfault;
 287
 288         /* Avoid ERESTART handling */
 289         PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 290         return PT_REGS_SYSCALL_RET(&current->thread.regs);
 291
 292  segfault:
 293         force_sig(SIGSEGV, current);
 294         return 0;
 295 }
 296
 297 long sys_rt_sigreturn(struct pt_regs regs)
 298 {
 299         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 300         struct rt_sigframe __user *frame =
 301                 (struct rt_sigframe __user *) (sp - 4);
 302         sigset_t set;
 303         struct ucontext __user *uc = &frame->uc;
 304         int sig_size = _NSIG_WORDS * sizeof(unsigned long);
 305
 306         if (copy_from_user(&set, &uc->uc_sigmask, sig_size))
 307                 goto segfault;
 308
 309         sigdelsetmask(&set, ~_BLOCKABLE);
 310
 311         spin_lock_irq(&current->sighand->siglock);
 312         current->blocked = set;
 313         recalc_sigpending();
 314         spin_unlock_irq(&current->sighand->siglock);
 315
 316         if (copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
 317                 goto segfault;
 318
 319         /* Avoid ERESTART handling */
 320         PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 321         return PT_REGS_SYSCALL_RET(&current->thread.regs);
 322
 323  segfault:
 324         force_sig(SIGSEGV, current);
 325         return 0;
 326 }