LXR linux/arch/x86/ia32/ia32

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  linux/arch/x86_64/ia32/ia32_signal.c
   4 *
   5 *  Copyright (C) 1991, 1992  Linus Torvalds
   6 *
   7 *  1997-11-28  Modified for POSIX.1b signals by Richard Henderson
   8 *  2000-06-20  Pentium III FXSR, SSE support by Gareth Hughes
   9 *  2000-12-*   x86-64 compatibility mode signal handling by Andi Kleen
  10 */
  11
  12#include <linux/sched.h>
  13#include <linux/sched/task_stack.h>
  14#include <linux/mm.h>
  15#include <linux/smp.h>
  16#include <linux/kernel.h>
  17#include <linux/errno.h>
  18#include <linux/wait.h>
  19#include <linux/unistd.h>
  20#include <linux/stddef.h>
  21#include <linux/personality.h>
  22#include <linux/compat.h>
  23#include <linux/binfmts.h>
  24#include <linux/syscalls.h>
  25#include <asm/ucontext.h>
  26#include <linux/uaccess.h>
  27#include <asm/fpu/internal.h>
  28#include <asm/fpu/signal.h>
  29#include <asm/ptrace.h>
  30#include <asm/ia32_unistd.h>
  31#include <asm/user32.h>
  32#include <uapi/asm/sigcontext.h>
  33#include <asm/proto.h>
  34#include <asm/vdso.h>
  35#include <asm/sigframe.h>
  36#include <asm/sighandling.h>
  37#include <asm/smap.h>
  38
  39static inline void reload_segments(struct sigcontext_32 *sc)
  40{
  41        unsigned int cur;
  42
  43        savesegment(gs, cur);
  44        if ((sc->gs | 0x03) != cur)
  45                load_gs_index(sc->gs | 0x03);
  46        savesegment(fs, cur);
  47        if ((sc->fs | 0x03) != cur)
  48                loadsegment(fs, sc->fs | 0x03);
  49        savesegment(ds, cur);
  50        if ((sc->ds | 0x03) != cur)
  51                loadsegment(ds, sc->ds | 0x03);
  52        savesegment(es, cur);
  53        if ((sc->es | 0x03) != cur)
  54                loadsegment(es, sc->es | 0x03);
  55}
  56
  57/*
  58 * Do a signal return; undo the signal stack.
  59 */
  60static int ia32_restore_sigcontext(struct pt_regs *regs,
  61                                   struct sigcontext_32 __user *usc)
  62{
  63        struct sigcontext_32 sc;
  64
  65        /* Always make any pending restarted system calls return -EINTR */
  66        current->restart_block.fn = do_no_restart_syscall;
  67
  68        if (unlikely(copy_from_user(&sc, usc, sizeof(sc))))
  69                return -EFAULT;
  70
  71        /* Get only the ia32 registers. */
  72        regs->bx = sc.bx;
  73        regs->cx = sc.cx;
  74        regs->dx = sc.dx;
  75        regs->si = sc.si;
  76        regs->di = sc.di;
  77        regs->bp = sc.bp;
  78        regs->ax = sc.ax;
  79        regs->sp = sc.sp;
  80        regs->ip = sc.ip;
  81
  82        /* Get CS/SS and force CPL3 */
  83        regs->cs = sc.cs | 0x03;
  84        regs->ss = sc.ss | 0x03;
  85
  86        regs->flags = (regs->flags & ~FIX_EFLAGS) | (sc.flags & FIX_EFLAGS);
  87        /* disable syscall checks */
  88        regs->orig_ax = -1;
  89
  90        /*
  91         * Reload fs and gs if they have changed in the signal
  92         * handler.  This does not handle long fs/gs base changes in
  93         * the handler, but does not clobber them at least in the
  94         * normal case.
  95         */
  96        reload_segments(&sc);
  97        return fpu__restore_sig(compat_ptr(sc.fpstate), 1);
  98}
  99
 100COMPAT_SYSCALL_DEFINE0(sigreturn)
 101{
 102        struct pt_regs *regs = current_pt_regs();
 103        struct sigframe_ia32 __user *frame = (struct sigframe_ia32 __user *)(regs->sp-8);
 104        sigset_t set;
 105
 106        if (!access_ok(frame, sizeof(*frame)))
 107                goto badframe;
 108        if (__get_user(set.sig[0], &frame->sc.oldmask)
 109            || __get_user(((__u32 *)&set)[1], &frame->extramask[0]))
 110                goto badframe;
 111
 112        set_current_blocked(&set);
 113
 114        if (ia32_restore_sigcontext(regs, &frame->sc))
 115                goto badframe;
 116        return regs->ax;
 117
 118badframe:
 119        signal_fault(regs, frame, "32bit sigreturn");
 120        return 0;
 121}
 122
 123COMPAT_SYSCALL_DEFINE0(rt_sigreturn)
 124{
 125        struct pt_regs *regs = current_pt_regs();
 126        struct rt_sigframe_ia32 __user *frame;
 127        sigset_t set;
 128
 129        frame = (struct rt_sigframe_ia32 __user *)(regs->sp - 4);
 130
 131        if (!access_ok(frame, sizeof(*frame)))
 132                goto badframe;
 133        if (__get_user(set.sig[0], (__u64 __user *)&frame->uc.uc_sigmask))
 134                goto badframe;
 135
 136        set_current_blocked(&set);
 137
 138        if (ia32_restore_sigcontext(regs, &frame->uc.uc_mcontext))
 139                goto badframe;
 140
 141        if (compat_restore_altstack(&frame->uc.uc_stack))
 142                goto badframe;
 143
 144        return regs->ax;
 145
 146badframe:
 147        signal_fault(regs, frame, "32bit rt sigreturn");
 148        return 0;
 149}
 150
 151/*
 152 * Set up a signal frame.
 153 */
 154
 155#define get_user_seg(seg)       ({ unsigned int v; savesegment(seg, v); v; })
 156
 157static __always_inline int
 158__unsafe_setup_sigcontext32(struct sigcontext_32 __user *sc,
 159                            void __user *fpstate,
 160                            struct pt_regs *regs, unsigned int mask)
 161{
 162        unsafe_put_user(get_user_seg(gs), (unsigned int __user *)&sc->gs, Efault);
 163        unsafe_put_user(get_user_seg(fs), (unsigned int __user *)&sc->fs, Efault);
 164        unsafe_put_user(get_user_seg(ds), (unsigned int __user *)&sc->ds, Efault);
 165        unsafe_put_user(get_user_seg(es), (unsigned int __user *)&sc->es, Efault);
 166
 167        unsafe_put_user(regs->di, &sc->di, Efault);
 168        unsafe_put_user(regs->si, &sc->si, Efault);
 169        unsafe_put_user(regs->bp, &sc->bp, Efault);
 170        unsafe_put_user(regs->sp, &sc->sp, Efault);
 171        unsafe_put_user(regs->bx, &sc->bx, Efault);
 172        unsafe_put_user(regs->dx, &sc->dx, Efault);
 173        unsafe_put_user(regs->cx, &sc->cx, Efault);
 174        unsafe_put_user(regs->ax, &sc->ax, Efault);
 175        unsafe_put_user(current->thread.trap_nr, &sc->trapno, Efault);
 176        unsafe_put_user(current->thread.error_code, &sc->err, Efault);
 177        unsafe_put_user(regs->ip, &sc->ip, Efault);
 178        unsafe_put_user(regs->cs, (unsigned int __user *)&sc->cs, Efault);
 179        unsafe_put_user(regs->flags, &sc->flags, Efault);
 180        unsafe_put_user(regs->sp, &sc->sp_at_signal, Efault);
 181        unsafe_put_user(regs->ss, (unsigned int __user *)&sc->ss, Efault);
 182
 183        unsafe_put_user(ptr_to_compat(fpstate), &sc->fpstate, Efault);
 184
 185        /* non-iBCS2 extensions.. */
 186        unsafe_put_user(mask, &sc->oldmask, Efault);
 187        unsafe_put_user(current->thread.cr2, &sc->cr2, Efault);
 188        return 0;
 189
 190Efault:
 191        return -EFAULT;
 192}
 193
 194#define unsafe_put_sigcontext32(sc, fp, regs, set, label)               \
 195do {                                                                    \
 196        if (__unsafe_setup_sigcontext32(sc, fp, regs, set->sig[0]))     \
 197                goto label;                                             \
 198} while(0)
 199
 200/*
 201 * Determine which stack to use..
 202 */
 203static void __user *get_sigframe(struct ksignal *ksig, struct pt_regs *regs,
 204                                 size_t frame_size,
 205                                 void __user **fpstate)
 206{
 207        unsigned long sp, fx_aligned, math_size;
 208
 209        /* Default to using normal stack */
 210        sp = regs->sp;
 211
 212        /* This is the X/Open sanctioned signal stack switching.  */
 213        if (ksig->ka.sa.sa_flags & SA_ONSTACK)
 214                sp = sigsp(sp, ksig);
 215        /* This is the legacy signal stack switching. */
 216        else if (regs->ss != __USER32_DS &&
 217                !(ksig->ka.sa.sa_flags & SA_RESTORER) &&
 218                 ksig->ka.sa.sa_restorer)
 219                sp = (unsigned long) ksig->ka.sa.sa_restorer;
 220
 221        sp = fpu__alloc_mathframe(sp, 1, &fx_aligned, &math_size);
 222        *fpstate = (struct _fpstate_32 __user *) sp;
 223        if (copy_fpstate_to_sigframe(*fpstate, (void __user *)fx_aligned,
 224                                     math_size) < 0)
 225                return (void __user *) -1L;
 226
 227        sp -= frame_size;
 228        /* Align the stack pointer according to the i386 ABI,
 229         * i.e. so that on function entry ((sp + 4) & 15) == 0. */
 230        sp = ((sp + 4) & -16ul) - 4;
 231        return (void __user *) sp;
 232}
 233
 234int ia32_setup_frame(int sig, struct ksignal *ksig,
 235                     compat_sigset_t *set, struct pt_regs *regs)
 236{
 237        struct sigframe_ia32 __user *frame;
 238        void __user *restorer;
 239        void __user *fp = NULL;
 240
 241        /* copy_to_user optimizes that into a single 8 byte store */
 242        static const struct {
 243                u16 poplmovl;
 244                u32 val;
 245                u16 int80;
 246        } __attribute__((packed)) code = {
 247                0xb858,          /* popl %eax ; movl $...,%eax */
 248                __NR_ia32_sigreturn,
 249                0x80cd,         /* int $0x80 */
 250        };
 251
 252        frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
 253
 254        if (ksig->ka.sa.sa_flags & SA_RESTORER) {
 255                restorer = ksig->ka.sa.sa_restorer;
 256        } else {
 257                /* Return stub is in 32bit vsyscall page */
 258                if (current->mm->context.vdso)
 259                        restorer = current->mm->context.vdso +
 260                                vdso_image_32.sym___kernel_sigreturn;
 261                else
 262                        restorer = &frame->retcode;
 263        }
 264
 265        if (!user_access_begin(frame, sizeof(*frame)))
 266                return -EFAULT;
 267
 268        unsafe_put_user(sig, &frame->sig, Efault);
 269        unsafe_put_sigcontext32(&frame->sc, fp, regs, set, Efault);
 270        unsafe_put_user(set->sig[1], &frame->extramask[0], Efault);
 271        unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
 272        /*
 273         * These are actually not used anymore, but left because some
 274         * gdb versions depend on them as a marker.
 275         */
 276        unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
 277        user_access_end();
 278
 279        /* Set up registers for signal handler */
 280        regs->sp = (unsigned long) frame;
 281        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 282
 283        /* Make -mregparm=3 work */
 284        regs->ax = sig;
 285        regs->dx = 0;
 286        regs->cx = 0;
 287
 288        loadsegment(ds, __USER32_DS);
 289        loadsegment(es, __USER32_DS);
 290
 291        regs->cs = __USER32_CS;
 292        regs->ss = __USER32_DS;
 293
 294        return 0;
 295Efault:
 296        user_access_end();
 297        return -EFAULT;
 298}
 299
 300int ia32_setup_rt_frame(int sig, struct ksignal *ksig,
 301                        compat_sigset_t *set, struct pt_regs *regs)
 302{
 303        struct rt_sigframe_ia32 __user *frame;
 304        void __user *restorer;
 305        void __user *fp = NULL;
 306
 307        /* unsafe_put_user optimizes that into a single 8 byte store */
 308        static const struct {
 309                u8 movl;
 310                u32 val;
 311                u16 int80;
 312                u8  pad;
 313        } __attribute__((packed)) code = {
 314                0xb8,
 315                __NR_ia32_rt_sigreturn,
 316                0x80cd,
 317                0,
 318        };
 319
 320        frame = get_sigframe(ksig, regs, sizeof(*frame), &fp);
 321
 322        if (!user_access_begin(frame, sizeof(*frame)))
 323                return -EFAULT;
 324
 325        unsafe_put_user(sig, &frame->sig, Efault);
 326        unsafe_put_user(ptr_to_compat(&frame->info), &frame->pinfo, Efault);
 327        unsafe_put_user(ptr_to_compat(&frame->uc), &frame->puc, Efault);
 328
 329        /* Create the ucontext.  */
 330        if (static_cpu_has(X86_FEATURE_XSAVE))
 331                unsafe_put_user(UC_FP_XSTATE, &frame->uc.uc_flags, Efault);
 332        else
 333                unsafe_put_user(0, &frame->uc.uc_flags, Efault);
 334        unsafe_put_user(0, &frame->uc.uc_link, Efault);
 335        unsafe_compat_save_altstack(&frame->uc.uc_stack, regs->sp, Efault);
 336
 337        if (ksig->ka.sa.sa_flags & SA_RESTORER)
 338                restorer = ksig->ka.sa.sa_restorer;
 339        else
 340                restorer = current->mm->context.vdso +
 341                        vdso_image_32.sym___kernel_rt_sigreturn;
 342        unsafe_put_user(ptr_to_compat(restorer), &frame->pretcode, Efault);
 343
 344        /*
 345         * Not actually used anymore, but left because some gdb
 346         * versions need it.
 347         */
 348        unsafe_put_user(*((u64 *)&code), (u64 __user *)frame->retcode, Efault);
 349        unsafe_put_sigcontext32(&frame->uc.uc_mcontext, fp, regs, set, Efault);
 350        unsafe_put_user(*(__u64 *)set, (__u64 __user *)&frame->uc.uc_sigmask, Efault);
 351        user_access_end();
 352
 353        if (__copy_siginfo_to_user32(&frame->info, &ksig->info))
 354                return -EFAULT;
 355
 356        /* Set up registers for signal handler */
 357        regs->sp = (unsigned long) frame;
 358        regs->ip = (unsigned long) ksig->ka.sa.sa_handler;
 359
 360        /* Make -mregparm=3 work */
 361        regs->ax = sig;
 362        regs->dx = (unsigned long) &frame->info;
 363        regs->cx = (unsigned long) &frame->uc;
 364
 365        loadsegment(ds, __USER32_DS);
 366        loadsegment(es, __USER32_DS);
 367
 368        regs->cs = __USER32_CS;
 369        regs->ss = __USER32_DS;
 370
 371        return 0;
 372Efault:
 373        user_access_end();
 374        return -EFAULT;
 375}
 376