arch/um/sys-i386/signal.c

   1 /*
   2  * Copyright (C) 2004 Jeff Dike (jdike@addtoit.com)
   3  * Licensed under the GPL
   4  */
   5
   6 #include "linux/signal.h"
   7 #include "linux/ptrace.h"
   8 #include "asm/current.h"
   9 #include "asm/ucontext.h"
  10 #include "asm/uaccess.h"
  11 #include "asm/unistd.h"
  12 #include "frame_kern.h"
  13 #include "sigcontext.h"
  14 #include "registers.h"
  15 #include "skas.h"
  16
  17 void copy_sc(struct uml_pt_regs *regs, void *from)
  18 {
  19         struct sigcontext *sc = from;
  20
  21         REGS_GS(regs->regs) = sc->gs;
  22         REGS_FS(regs->regs) = sc->fs;
  23         REGS_ES(regs->regs) = sc->es;
  24         REGS_DS(regs->regs) = sc->ds;
  25         REGS_EDI(regs->regs) = sc->edi;
  26         REGS_ESI(regs->regs) = sc->esi;
  27         REGS_EBP(regs->regs) = sc->ebp;
  28         REGS_SP(regs->regs) = sc->esp;
  29         REGS_EBX(regs->regs) = sc->ebx;
  30         REGS_EDX(regs->regs) = sc->edx;
  31         REGS_ECX(regs->regs) = sc->ecx;
  32         REGS_EAX(regs->regs) = sc->eax;
  33         REGS_IP(regs->regs) = sc->eip;
  34         REGS_CS(regs->regs) = sc->cs;
  35         REGS_EFLAGS(regs->regs) = sc->eflags;
  36         REGS_SS(regs->regs) = sc->ss;
  37 }
  38
  39 static int copy_sc_from_user(struct pt_regs *regs,
  40                              struct sigcontext __user *from)
  41 {
  42         struct sigcontext sc;
  43         unsigned long fpregs[HOST_FP_SIZE];
  44         int err;
  45
  46         err = copy_from_user(&sc, from, sizeof(sc));
  47         err |= copy_from_user(fpregs, sc.fpstate, sizeof(fpregs));
  48         if(err)
  49                 return err;
  50
  51         copy_sc(&regs->regs, &sc);
  52
  53         err = restore_fp_registers(userspace_pid[0], fpregs);
  54         if(err < 0) {
  55                 printk("copy_sc_from_user_skas - PTRACE_SETFPREGS failed, "
  56                        "errno = %d\n", -err);
  57                 return err;
  58         }
  59
  60         return 0;
  61 }
  62
  63 static int copy_sc_to_user(struct sigcontext __user *to,
  64                            struct _fpstate __user *to_fp, struct pt_regs *regs,
  65                            unsigned long sp)
  66 {
  67         struct sigcontext sc;
  68         unsigned long fpregs[HOST_FP_SIZE];
  69         struct faultinfo * fi = &current->thread.arch.faultinfo;
  70         int err;
  71
  72         sc.gs = REGS_GS(regs->regs.regs);
  73         sc.fs = REGS_FS(regs->regs.regs);
  74         sc.es = REGS_ES(regs->regs.regs);
  75         sc.ds = REGS_DS(regs->regs.regs);
  76         sc.edi = REGS_EDI(regs->regs.regs);
  77         sc.esi = REGS_ESI(regs->regs.regs);
  78         sc.ebp = REGS_EBP(regs->regs.regs);
  79         sc.esp = sp;
  80         sc.ebx = REGS_EBX(regs->regs.regs);
  81         sc.edx = REGS_EDX(regs->regs.regs);
  82         sc.ecx = REGS_ECX(regs->regs.regs);
  83         sc.eax = REGS_EAX(regs->regs.regs);
  84         sc.eip = REGS_IP(regs->regs.regs);
  85         sc.cs = REGS_CS(regs->regs.regs);
  86         sc.eflags = REGS_EFLAGS(regs->regs.regs);
  87         sc.esp_at_signal = regs->regs.regs[UESP];
  88         sc.ss = regs->regs.regs[SS];
  89         sc.cr2 = fi->cr2;
  90         sc.err = fi->error_code;
  91         sc.trapno = fi->trap_no;
  92
  93         err = save_fp_registers(userspace_pid[0], fpregs);
  94         if(err < 0){
  95                 printk("copy_sc_to_user_skas - PTRACE_GETFPREGS failed, "
  96                        "errno = %d\n", err);
  97                 return 1;
  98         }
  99         to_fp = (to_fp ? to_fp : (struct _fpstate __user *) (to + 1));
 100         sc.fpstate = to_fp;
 101
 102         if(err)
 103                 return err;
 104
 105         return copy_to_user(to, &sc, sizeof(sc)) ||
 106                copy_to_user(to_fp, fpregs, sizeof(fpregs));
 107 }
 108
 109 static int copy_ucontext_to_user(struct ucontext __user *uc, struct _fpstate __user *fp,
 110                                  sigset_t *set, unsigned long sp)
 111 {
 112         int err = 0;
 113
 114         err |= put_user(current->sas_ss_sp, &uc->uc_stack.ss_sp);
 115         err |= put_user(sas_ss_flags(sp), &uc->uc_stack.ss_flags);
 116         err |= put_user(current->sas_ss_size, &uc->uc_stack.ss_size);
 117         err |= copy_sc_to_user(&uc->uc_mcontext, fp, &current->thread.regs, sp);
 118         err |= copy_to_user(&uc->uc_sigmask, set, sizeof(*set));
 119         return err;
 120 }
 121
 122 struct sigframe
 123 {
 124         char __user *pretcode;
 125         int sig;
 126         struct sigcontext sc;
 127         struct _fpstate fpstate;
 128         unsigned long extramask[_NSIG_WORDS-1];
 129         char retcode[8];
 130 };
 131
 132 struct rt_sigframe
 133 {
 134         char __user *pretcode;
 135         int sig;
 136         struct siginfo __user *pinfo;
 137         void __user *puc;
 138         struct siginfo info;
 139         struct ucontext uc;
 140         struct _fpstate fpstate;
 141         char retcode[8];
 142 };
 143
 144 int setup_signal_stack_sc(unsigned long stack_top, int sig,
 145                           struct k_sigaction *ka, struct pt_regs *regs,
 146                           sigset_t *mask)
 147 {
 148         struct sigframe __user *frame;
 149         void __user *restorer;
 150         unsigned long save_sp = PT_REGS_SP(regs);
 151         int err = 0;
 152
 153         /* This is the same calculation as i386 - ((sp + 4) & 15) == 0 */
 154         stack_top = ((stack_top + 4) & -16UL) - 4;
 155         frame = (struct sigframe __user *) stack_top - 1;
 156         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 157                 return 1;
 158
 159         restorer = frame->retcode;
 160         if(ka->sa.sa_flags & SA_RESTORER)
 161                 restorer = ka->sa.sa_restorer;
 162
 163         /* Update SP now because the page fault handler refuses to extend
 164          * the stack if the faulting address is too far below the current
 165          * SP, which frame now certainly is.  If there's an error, the original
 166          * value is restored on the way out.
 167          * When writing the sigcontext to the stack, we have to write the
 168          * original value, so that's passed to copy_sc_to_user, which does
 169          * the right thing with it.
 170          */
 171         PT_REGS_SP(regs) = (unsigned long) frame;
 172
 173         err |= __put_user(restorer, &frame->pretcode);
 174         err |= __put_user(sig, &frame->sig);
 175         err |= copy_sc_to_user(&frame->sc, NULL, regs, save_sp);
 176         err |= __put_user(mask->sig[0], &frame->sc.oldmask);
 177         if (_NSIG_WORDS > 1)
 178                 err |= __copy_to_user(&frame->extramask, &mask->sig[1],
 179                                       sizeof(frame->extramask));
 180
 181         /*
 182          * This is popl %eax ; movl $,%eax ; int $0x80
 183          *
 184          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 185          * reasons and because gdb uses it as a signature to notice
 186          * signal handler stack frames.
 187          */
 188         err |= __put_user(0xb858, (short __user *)(frame->retcode+0));
 189         err |= __put_user(__NR_sigreturn, (int __user *)(frame->retcode+2));
 190         err |= __put_user(0x80cd, (short __user *)(frame->retcode+6));
 191
 192         if(err)
 193                 goto err;
 194
 195         PT_REGS_SP(regs) = (unsigned long) frame;
 196         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 197         PT_REGS_EAX(regs) = (unsigned long) sig;
 198         PT_REGS_EDX(regs) = (unsigned long) 0;
 199         PT_REGS_ECX(regs) = (unsigned long) 0;
 200
 201         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 202                 ptrace_notify(SIGTRAP);
 203         return 0;
 204
 205 err:
 206         PT_REGS_SP(regs) = save_sp;
 207         return err;
 208 }
 209
 210 int setup_signal_stack_si(unsigned long stack_top, int sig,
 211                           struct k_sigaction *ka, struct pt_regs *regs,
 212                           siginfo_t *info, sigset_t *mask)
 213 {
 214         struct rt_sigframe __user *frame;
 215         void __user *restorer;
 216         unsigned long save_sp = PT_REGS_SP(regs);
 217         int err = 0;
 218
 219         stack_top &= -8UL;
 220         frame = (struct rt_sigframe __user *) stack_top - 1;
 221         if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 222                 return 1;
 223
 224         restorer = frame->retcode;
 225         if(ka->sa.sa_flags & SA_RESTORER)
 226                 restorer = ka->sa.sa_restorer;
 227
 228         /* See comment above about why this is here */
 229         PT_REGS_SP(regs) = (unsigned long) frame;
 230
 231         err |= __put_user(restorer, &frame->pretcode);
 232         err |= __put_user(sig, &frame->sig);
 233         err |= __put_user(&frame->info, &frame->pinfo);
 234         err |= __put_user(&frame->uc, &frame->puc);
 235         err |= copy_siginfo_to_user(&frame->info, info);
 236         err |= copy_ucontext_to_user(&frame->uc, &frame->fpstate, mask,
 237                                      save_sp);
 238
 239         /*
 240          * This is movl $,%eax ; int $0x80
 241          *
 242          * WE DO NOT USE IT ANY MORE! It's only left here for historical
 243          * reasons and because gdb uses it as a signature to notice
 244          * signal handler stack frames.
 245          */
 246         err |= __put_user(0xb8, (char __user *)(frame->retcode+0));
 247         err |= __put_user(__NR_rt_sigreturn, (int __user *)(frame->retcode+1));
 248         err |= __put_user(0x80cd, (short __user *)(frame->retcode+5));
 249
 250         if(err)
 251                 goto err;
 252
 253         PT_REGS_IP(regs) = (unsigned long) ka->sa.sa_handler;
 254         PT_REGS_EAX(regs) = (unsigned long) sig;
 255         PT_REGS_EDX(regs) = (unsigned long) &frame->info;
 256         PT_REGS_ECX(regs) = (unsigned long) &frame->uc;
 257
 258         if ((current->ptrace & PT_DTRACE) && (current->ptrace & PT_PTRACED))
 259                 ptrace_notify(SIGTRAP);
 260         return 0;
 261
 262 err:
 263         PT_REGS_SP(regs) = save_sp;
 264         return err;
 265 }
 266
 267 long sys_sigreturn(struct pt_regs regs)
 268 {
 269         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 270         struct sigframe __user *frame = (struct sigframe __user *)(sp - 8);
 271         sigset_t set;
 272         struct sigcontext __user *sc = &frame->sc;
 273         unsigned long __user *oldmask = &sc->oldmask;
 274         unsigned long __user *extramask = frame->extramask;
 275         int sig_size = (_NSIG_WORDS - 1) * sizeof(unsigned long);
 276
 277         if(copy_from_user(&set.sig[0], oldmask, sizeof(set.sig[0])) ||
 278            copy_from_user(&set.sig[1], extramask, sig_size))
 279                 goto segfault;
 280
 281         sigdelsetmask(&set, ~_BLOCKABLE);
 282
 283         spin_lock_irq(&current->sighand->siglock);
 284         current->blocked = set;
 285         recalc_sigpending();
 286         spin_unlock_irq(&current->sighand->siglock);
 287
 288         if(copy_sc_from_user(&current->thread.regs, sc))
 289                 goto segfault;
 290
 291         /* Avoid ERESTART handling */
 292         PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 293         return PT_REGS_SYSCALL_RET(&current->thread.regs);
 294
 295  segfault:
 296         force_sig(SIGSEGV, current);
 297         return 0;
 298 }
 299
 300 long sys_rt_sigreturn(struct pt_regs regs)
 301 {
 302         unsigned long sp = PT_REGS_SP(&current->thread.regs);
 303         struct rt_sigframe __user *frame = (struct rt_sigframe __user *) (sp - 4);
 304         sigset_t set;
 305         struct ucontext __user *uc = &frame->uc;
 306         int sig_size = _NSIG_WORDS * sizeof(unsigned long);
 307
 308         if(copy_from_user(&set, &uc->uc_sigmask, sig_size))
 309                 goto segfault;
 310
 311         sigdelsetmask(&set, ~_BLOCKABLE);
 312
 313         spin_lock_irq(&current->sighand->siglock);
 314         current->blocked = set;
 315         recalc_sigpending();
 316         spin_unlock_irq(&current->sighand->siglock);
 317
 318         if(copy_sc_from_user(&current->thread.regs, &uc->uc_mcontext))
 319                 goto segfault;
 320
 321         /* Avoid ERESTART handling */
 322         PT_REGS_SYSCALL_NR(&current->thread.regs) = -1;
 323         return PT_REGS_SYSCALL_RET(&current->thread.regs);
 324
 325  segfault:
 326         force_sig(SIGSEGV, current);
 327         return 0;
 328 }