linux/arch/x86/ia32/ia32_signal.c
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   1/*
   2 *  linux/arch/x86_64/ia32/ia32_signal.c
   3 *
   4 *  Copyright (C) 1991, 1992  Linus Torvalds
   5 *
   6 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   7 *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   8 *  2000-12-*   x86-64 compatibility mode signal handling by Andi Kleen
   9 */
  10
  11#include <linux/sched.h>
  12#include <linux/mm.h>
  13#include <linux/smp.h>
  14#include <linux/kernel.h>
  15#include <linux/errno.h>
  16#include <linux/wait.h>
  17#include <linux/unistd.h>
  18#include <linux/stddef.h>
  19#include <linux/personality.h>
  20#include <linux/compat.h>
  21#include <linux/binfmts.h>
  22#include <asm/ucontext.h>
  23#include <asm/uaccess.h>
  24#include <asm/fpu/internal.h>
  25#include <asm/fpu/signal.h>
  26#include <asm/ptrace.h>
  27#include <asm/ia32_unistd.h>
  28#include <asm/user32.h>
  29#include <asm/sigcontext32.h>
  30#include <asm/proto.h>
  31#include <asm/vdso.h>
  32#include <asm/sigframe.h>
  33#include <asm/sighandling.h>
  34#include <asm/sys_ia32.h>
  35#include <asm/smap.h>
  36
  37/*
  38 * Do a signal return; undo the signal stack.
  39 */
  40#define loadsegment_gs(v)       load_gs_index(v)
  41#define loadsegment_fs(v)       loadsegment(fs, v)
  42#define loadsegment_ds(v)       loadsegment(ds, v)
  43#define loadsegment_es(v)       loadsegment(es, v)
  44
  45#define get_user_seg(seg)       ({ unsigned int v; savesegment(seg, v); v; })
  46#define set_user_seg(seg, v)    loadsegment_##seg(v)
  47
  48#define COPY(x)                 {               \
  49        get_user_ex(regs->x, &sc->x);           \
  50}
  51
  52#define GET_SEG(seg)            ({                      \
  53        unsigned short tmp;                             \
  54        get_user_ex(tmp, &sc->seg);                     \
  55        tmp;                                            \
  56})
  57
  58#define COPY_SEG_CPL3(seg)      do {                    \
  59        regs->seg = GET_SEG(seg) | 3;                   \
  60} while (0)
  61
  62#define RELOAD_SEG(seg)         {               \
  63        unsigned int pre = GET_SEG(seg);        \
  64        unsigned int cur = get_user_seg(seg);   \
  65        pre |= 3;                               \
  66        if (pre != cur)                         \
  67                set_user_seg(seg, pre);         \
  68}
  69
  70static int ia32_restore_sigcontext(struct pt_regs *regs,
  71                                   struct sigcontext_ia32 __user *sc)
  72{
  73        unsigned int tmpflags, err = 0;
  74        void __user *buf;
  75        u32 tmp;
  76
  77        /* Always make any pending restarted system calls return -EINTR */
  78        current->restart_block.fn = do_no_restart_syscall;
  79
  80        get_user_try {
  81                /*
  82                 * Reload fs and gs if they have changed in the signal
  83                 * handler.  This does not handle long fs/gs base changes in
  84                 * the handler, but does not clobber them at least in the
  85                 * normal case.
  86                 */
  87                RELOAD_SEG(gs);
  88                RELOAD_SEG(fs);
  89                RELOAD_SEG(ds);
  90                RELOAD_SEG(es);
  91
  92                COPY(di); COPY(si); COPY(bp); COPY(sp); COPY(bx);
  93                COPY(dx); COPY(cx); COPY(ip); COPY(ax);
  94                /* Don't touch extended registers */
  95
  96                COPY_SEG_CPL3(cs);
  97                COPY_SEG_CPL3(ss);
  98
  99                get_user_ex(tmpflags, &sc->flags);
 100                regs->flags = (regs->flags & ~FIX_EFLAGS) | (tmpflags & FIX_EFLAGS);
 101                /* disable syscall checks */
 102                regs->orig_ax = -1;
 103
 104                get_user_ex(tmp, &sc->fpstate);
 105                buf = compat_ptr(tmp);
 106        } get_user_catch(err);
 107
 108        err |= fpu__restore_sig(buf, 1);
 109
 110        force_iret();
 111
 112        return err;
 113}
 114
 115asmlinkage long sys32_sigreturn(void)
 116{
 117        struct pt_regs *regs = current_pt_regs();
 118        struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
 119        sigset_t set;
 120
 121        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 122                goto badframe;
 123        if (__get_user(set.sig[0], &frame->sc.oldmask)
 124            || (_COMPAT_NSIG_WORDS > 1
 125                && __copy_from_user((((char *) &set.sig) + 4),
 126                                    &frame->extramask,
 127                                    sizeof(frame->extramask))))
 128                goto badframe;
 129
 130        set_current_blocked(&set);
 131
 132        if (ia32_restore_sigcontext(regs, &frame->sc))
 133                goto badframe;
 134        return regs->ax;
 135
 136badframe:
 137        signal_fault(regs, frame, "32bit sigreturn");
 138        return 0;
 139}
 140
 141asmlinkage long sys32_rt_sigreturn(void)
 142{
 143        struct pt_regs *regs = current_pt_regs();
 144        struct rt_sigframe_ia32 __user *frame;
 145        sigset_t set;
 146
 147        frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
 148
 149        if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 150                goto badframe;
 151        if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 152                goto badframe;
 153
 154        set_current_blocked(&set);
 155
 156        if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
 157                goto badframe;
 158
 159        if (compat_restore_altstack(&frame->uc.uc_stack))
 160                goto badframe;
 161
 162        return regs->ax;
 163
 164badframe:
 165        signal_fault(regs, frame, "32bit rt sigreturn");
 166        return 0;
 167}
 168
 169/*
 170 * Set up a signal frame.
 171 */
 172
 173static int ia32_setup_sigcontext(struct sigcontext_ia32 __user *sc,
 174                                 void __user *fpstate,
 175                                 struct pt_regs *regs, unsigned int mask)
 176{
 177        int err = 0;
 178
 179        put_user_try {
 180                put_user_ex(get_user_seg(gs), (unsigned int __user *)&sc->gs);
 181                put_user_ex(get_user_seg(fs), (unsigned int __user *)&sc->fs);
 182                put_user_ex(get_user_seg(ds), (unsigned int __user *)&sc->ds);
 183                put_user_ex(get_user_seg(es), (unsigned int __user *)&sc->es);
 184
 185                put_user_ex(regs->di, &sc->di);
 186                put_user_ex(regs->si, &sc->si);
 187                put_user_ex(regs->bp, &sc->bp);
 188                put_user_ex(regs->sp, &sc->sp);
 189                put_user_ex(regs->bx, &sc->bx);
 190                put_user_ex(regs->dx, &sc->dx);
 191                put_user_ex(regs->cx, &sc->cx);
 192                put_user_ex(regs->ax, &sc->ax);
 193                put_user_ex(current->thread.trap_nr, &sc->trapno);
 194                put_user_ex(current->thread.error_code, &sc->err);
 195                put_user_ex(regs->ip, &sc->ip);
 196                put_user_ex(regs->cs, (unsigned int __user *)&sc->cs);
 197                put_user_ex(regs->flags, &sc->flags);
 198                put_user_ex(regs->sp, &sc->sp_at_signal);
 199                put_user_ex(regs->ss, (unsigned int __user *)&sc->ss);
 200
 201                put_user_ex(ptr_to_compat(fpstate), &sc->fpstate);
 202
 203                /* non-iBCS2 extensions.. */
 204                put_user_ex(mask, &sc->oldmask);
 205                put_user_ex(current->thread.cr2, &sc->cr2);
 206        } put_user_catch(err);
 207
 208        return err;
 209}
 210
 211/*
 212 * Determine which stack to use..
 213 */
 214static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 215                                 size_t frame_size,
 216                                 void __user **fpstate)
 217{
 218        struct fpu *fpu = &current->thread.fpu;
 219        unsigned long sp;
 220
 221        /* Default to using normal stack */
 222        sp = regs->sp;
 223
 224        /* This is the X/Open sanctioned signal stack switching.  */
 225        if (ksig->ka.sa.sa_flags & SA_ONSTACK)
 226                sp = sigsp(sp, ksig);
 227        /* This is the legacy signal stack switching. */
 228        else if ((regs->ss & 0xffff) != __USER32_DS &&
 229                !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
 230                 ksig->ka.sa.sa_restorer)
 231                sp = (unsigned long) ksig->ka.sa.sa_restorer;
 232
 233        if (fpu->fpstate_active) {
 234                unsigned long fx_aligned, math_size;
 235
 236                sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
 237                *fpstate = (struct _fpstate_ia32 __user *) sp;
 238                if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
 239                                    math_size) < 0)
 240                        return (void __user *) -1L;
 241        }
 242
 243        sp -= frame_size;
 244        /* Align the stack pointer according to the i386 ABI,
 245         * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 246        sp = ((sp + 4) & -16ul) - 4;
 247        return (void __user *) sp;
 248}
 249
 250int ia32_setup_frame(int sig, struct ksignal *ksig,
 251                     compat_sigset_t *set, struct pt_regs *regs)
 252{
 253        struct sigframe_ia32 __user *frame;
 254        void __user *restorer;
 255        int err = 0;
 256        void __user *fpstate = NULL;
 257
 258        /* copy_to_user optimizes that into a single 8 byte store */
 259        static const struct {
 260                u16 poplmovl;
 261                u32 val;
 262                u16 int80;
 263        } __attribute__((packed)) code = {
 264                0xb858,          /* popl %eax ; movl $...,%eax */
 265                __NR_ia32_sigreturn,
 266                0x80cd,         /* int $0x80 */
 267        };
 268
 269        frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
 270
 271        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 272                return -EFAULT;
 273
 274        if (__put_user(sig, &frame->sig))
 275                return -EFAULT;
 276
 277        if (ia32_setup_sigcontext(&frame->sc, fpstate, regs, set->sig[0]))
 278                return -EFAULT;
 279
 280        if (_COMPAT_NSIG_WORDS > 1) {
 281                if (__copy_to_user(frame->extramask, &set->sig[1],
 282                                   sizeof(frame->extramask)))
 283                        return -EFAULT;
 284        }
 285
 286        if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 287                restorer = ksig->ka.sa.sa_restorer;
 288        } else {
 289                /* Return stub is in 32bit vsyscall page */
 290                if (current->mm->context.vdso)
 291                        restorer = current->mm->context.vdso +
 292                                selected_vdso32->sym___kernel_sigreturn;
 293                else
 294                        restorer = &frame->retcode;
 295        }
 296
 297        put_user_try {
 298                put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 299
 300                /*
 301                 * These are actually not used anymore, but left because some
 302                 * gdb versions depend on them as a marker.
 303                 */
 304                put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
 305        } put_user_catch(err);
 306
 307        if (err)
 308                return -EFAULT;
 309
 310        /* Set up registers for signal handler */
 311        regs->sp = (unsigned long) frame;
 312        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 313
 314        /* Make -mregparm=3 work */
 315        regs->ax = sig;
 316        regs->dx = 0;
 317        regs->cx = 0;
 318
 319        loadsegment(ds, __USER32_DS);
 320        loadsegment(es, __USER32_DS);
 321
 322        regs->cs = __USER32_CS;
 323        regs->ss = __USER32_DS;
 324
 325        return 0;
 326}
 327
 328int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
 329                        compat_sigset_t *set, struct pt_regs *regs)
 330{
 331        struct rt_sigframe_ia32 __user *frame;
 332        void __user *restorer;
 333        int err = 0;
 334        void __user *fpstate = NULL;
 335
 336        /* __copy_to_user optimizes that into a single 8 byte store */
 337        static const struct {
 338                u8 movl;
 339                u32 val;
 340                u16 int80;
 341                u8  pad;
 342        } __attribute__((packed)) code = {
 343                0xb8,
 344                __NR_ia32_rt_sigreturn,
 345                0x80cd,
 346                0,
 347        };
 348
 349        frame = get_sigframe(ksig, regs, sizeof(*frame), &fpstate);
 350
 351        if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
 352                return -EFAULT;
 353
 354        put_user_try {
 355                put_user_ex(sig, &frame->sig);
 356                put_user_ex(ptr_to_compat(&frame->info), &frame->pinfo);
 357                put_user_ex(ptr_to_compat(&frame->uc), &frame->puc);
 358
 359                /* Create the ucontext.  */
 360                if (cpu_has_xsave)
 361                        put_user_ex(UC_FP_XSTATE, &frame->uc.uc_flags);
 362                else
 363                        put_user_ex(0, &frame->uc.uc_flags);
 364                put_user_ex(0, &frame->uc.uc_link);
 365                compat_save_altstack_ex(&frame->uc.uc_stack, regs->sp);
 366
 367                if (ksig->ka.sa.sa_flags & SA_RESTORER)
 368                        restorer = ksig->ka.sa.sa_restorer;
 369                else
 370                        restorer = current->mm->context.vdso +
 371                                selected_vdso32->sym___kernel_rt_sigreturn;
 372                put_user_ex(ptr_to_compat(restorer), &frame->pretcode);
 373
 374                /*
 375                 * Not actually used anymore, but left because some gdb
 376                 * versions need it.
 377                 */
 378                put_user_ex(*((u64 *)&code), (u64 __user *)frame->retcode);
 379        } put_user_catch(err);
 380
 381        err |= copy_siginfo_to_user32(&frame->info, &ksig->info);
 382        err |= ia32_setup_sigcontext(&frame->uc.uc_mcontext, fpstate,
 383                                     regs, set->sig[0]);
 384        err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 385
 386        if (err)
 387                return -EFAULT;
 388
 389        /* Set up registers for signal handler */
 390        regs->sp = (unsigned long) frame;
 391        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 392
 393        /* Make -mregparm=3 work */
 394        regs->ax = sig;
 395        regs->dx = (unsigned long) &frame->info;
 396        regs->cx = (unsigned long) &frame->uc;
 397
 398        loadsegment(ds, __USER32_DS);
 399        loadsegment(es, __USER32_DS);
 400
 401        regs->cs = __USER32_CS;
 402        regs->ss = __USER32_DS;
 403
 404        return 0;
 405}
 406