arch/x86/kernel/fpu/regset.c

   1 /*
   2  * FPU register's regset abstraction, for ptrace, core dumps, etc.
   3  */
   4 #include <asm/fpu/internal.h>
   5 #include <asm/fpu/signal.h>
   6 #include <asm/fpu/regset.h>
   7 #include <asm/fpu/xstate.h>
   8
   9 /*
  10  * The xstateregs_active() routine is the same as the regset_fpregs_active() routine,
  11  * as the "regset->n" for the xstate regset will be updated based on the feature
  12  * capabilities supported by the xsave.
  13  */
  14 int regset_fpregs_active(struct task_struct *target, const struct user_regset *regset)
  15 {
  16         struct fpu *target_fpu = &target->thread.fpu;
  17
  18         return target_fpu->fpstate_active ? regset->n : 0;
  19 }
  20
  21 int regset_xregset_fpregs_active(struct task_struct *target, const struct user_regset *regset)
  22 {
  23         struct fpu *target_fpu = &target->thread.fpu;
  24
  25         if (boot_cpu_has(X86_FEATURE_FXSR) && target_fpu->fpstate_active)
  26                 return regset->n;
  27         else
  28                 return 0;
  29 }
  30
  31 int xfpregs_get(struct task_struct *target, const struct user_regset *regset,
  32                 unsigned int pos, unsigned int count,
  33                 void *kbuf, void __user *ubuf)
  34 {
  35         struct fpu *fpu = &target->thread.fpu;
  36
  37         if (!boot_cpu_has(X86_FEATURE_FXSR))
  38                 return -ENODEV;
  39
  40         fpu__activate_fpstate_read(fpu);
  41         fpstate_sanitize_xstate(fpu);
  42
  43         return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
  44                                    &fpu->state.fxsave, 0, -1);
  45 }
  46
  47 int xfpregs_set(struct task_struct *target, const struct user_regset *regset,
  48                 unsigned int pos, unsigned int count,
  49                 const void *kbuf, const void __user *ubuf)
  50 {
  51         struct fpu *fpu = &target->thread.fpu;
  52         int ret;
  53
  54         if (!boot_cpu_has(X86_FEATURE_FXSR))
  55                 return -ENODEV;
  56
  57         fpu__activate_fpstate_write(fpu);
  58         fpstate_sanitize_xstate(fpu);
  59
  60         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf,
  61                                  &fpu->state.fxsave, 0, -1);
  62
  63         /*
  64          * mxcsr reserved bits must be masked to zero for security reasons.
  65          */
  66         fpu->state.fxsave.mxcsr &= mxcsr_feature_mask;
  67
  68         /*
  69          * update the header bits in the xsave header, indicating the
  70          * presence of FP and SSE state.
  71          */
  72         if (boot_cpu_has(X86_FEATURE_XSAVE))
  73                 fpu->state.xsave.header.xfeatures |= XFEATURE_MASK_FPSSE;
  74
  75         return ret;
  76 }
  77
  78 int xstateregs_get(struct task_struct *target, const struct user_regset *regset,
  79                 unsigned int pos, unsigned int count,
  80                 void *kbuf, void __user *ubuf)
  81 {
  82         struct fpu *fpu = &target->thread.fpu;
  83         struct xregs_state *xsave;
  84         int ret;
  85
  86         if (!boot_cpu_has(X86_FEATURE_XSAVE))
  87                 return -ENODEV;
  88
  89         xsave = &fpu->state.xsave;
  90
  91         fpu__activate_fpstate_read(fpu);
  92
  93         if (using_compacted_format()) {
  94                 ret = copyout_from_xsaves(pos, count, kbuf, ubuf, xsave);
  95         } else {
  96                 fpstate_sanitize_xstate(fpu);
  97                 /*
  98                  * Copy the 48 bytes defined by the software into the xsave
  99                  * area in the thread struct, so that we can copy the whole
 100                  * area to user using one user_regset_copyout().
 101                  */
 102                 memcpy(&xsave->i387.sw_reserved, xstate_fx_sw_bytes, sizeof(xstate_fx_sw_bytes));
 103
 104                 /*
 105                  * Copy the xstate memory layout.
 106                  */
 107                 ret = user_regset_copyout(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
 108         }
 109         return ret;
 110 }
 111
 112 int xstateregs_set(struct task_struct *target, const struct user_regset *regset,
 113                   unsigned int pos, unsigned int count,
 114                   const void *kbuf, const void __user *ubuf)
 115 {
 116         struct fpu *fpu = &target->thread.fpu;
 117         struct xregs_state *xsave;
 118         int ret;
 119
 120         if (!boot_cpu_has(X86_FEATURE_XSAVE))
 121                 return -ENODEV;
 122
 123         /*
 124          * A whole standard-format XSAVE buffer is needed:
 125          */
 126         if ((pos != 0) || (count < fpu_user_xstate_size))
 127                 return -EFAULT;
 128
 129         xsave = &fpu->state.xsave;
 130
 131         fpu__activate_fpstate_write(fpu);
 132
 133         if (boot_cpu_has(X86_FEATURE_XSAVES))
 134                 ret = copyin_to_xsaves(kbuf, ubuf, xsave);
 135         else
 136                 ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, xsave, 0, -1);
 137
 138         /*
 139          * In case of failure, mark all states as init:
 140          */
 141         if (ret)
 142                 fpstate_init(&fpu->state);
 143
 144         /*
 145          * mxcsr reserved bits must be masked to zero for security reasons.
 146          */
 147         xsave->i387.mxcsr &= mxcsr_feature_mask;
 148         xsave->header.xfeatures &= xfeatures_mask;
 149         /*
 150          * These bits must be zero.
 151          */
 152         memset(&xsave->header.reserved, 0, 48);
 153
 154         return ret;
 155 }
 156
 157 #if defined CONFIG_X86_32 || defined CONFIG_IA32_EMULATION
 158
 159 /*
 160  * FPU tag word conversions.
 161  */
 162
 163 static inline unsigned short twd_i387_to_fxsr(unsigned short twd)
 164 {
 165         unsigned int tmp; /* to avoid 16 bit prefixes in the code */
 166
 167         /* Transform each pair of bits into 01 (valid) or 00 (empty) */
 168         tmp = ~twd;
 169         tmp = (tmp | (tmp>>1)) & 0x5555; /* 0V0V0V0V0V0V0V0V */
 170         /* and move the valid bits to the lower byte. */
 171         tmp = (tmp | (tmp >> 1)) & 0x3333; /* 00VV00VV00VV00VV */
 172         tmp = (tmp | (tmp >> 2)) & 0x0f0f; /* 0000VVVV0000VVVV */
 173         tmp = (tmp | (tmp >> 4)) & 0x00ff; /* 00000000VVVVVVVV */
 174
 175         return tmp;
 176 }
 177
 178 #define FPREG_ADDR(f, n)        ((void *)&(f)->st_space + (n) * 16)
 179 #define FP_EXP_TAG_VALID        0
 180 #define FP_EXP_TAG_ZERO         1
 181 #define FP_EXP_TAG_SPECIAL      2
 182 #define FP_EXP_TAG_EMPTY        3
 183
 184 static inline u32 twd_fxsr_to_i387(struct fxregs_state *fxsave)
 185 {
 186         struct _fpxreg *st;
 187         u32 tos = (fxsave->swd >> 11) & 7;
 188         u32 twd = (unsigned long) fxsave->twd;
 189         u32 tag;
 190         u32 ret = 0xffff0000u;
 191         int i;
 192
 193         for (i = 0; i < 8; i++, twd >>= 1) {
 194                 if (twd & 0x1) {
 195                         st = FPREG_ADDR(fxsave, (i - tos) & 7);
 196
 197                         switch (st->exponent & 0x7fff) {
 198                         case 0x7fff:
 199                                 tag = FP_EXP_TAG_SPECIAL;
 200                                 break;
 201                         case 0x0000:
 202                                 if (!st->significand[0] &&
 203                                     !st->significand[1] &&
 204                                     !st->significand[2] &&
 205                                     !st->significand[3])
 206                                         tag = FP_EXP_TAG_ZERO;
 207                                 else
 208                                         tag = FP_EXP_TAG_SPECIAL;
 209                                 break;
 210                         default:
 211                                 if (st->significand[3] & 0x8000)
 212                                         tag = FP_EXP_TAG_VALID;
 213                                 else
 214                                         tag = FP_EXP_TAG_SPECIAL;
 215                                 break;
 216                         }
 217                 } else {
 218                         tag = FP_EXP_TAG_EMPTY;
 219                 }
 220                 ret |= tag << (2 * i);
 221         }
 222         return ret;
 223 }
 224
 225 /*
 226  * FXSR floating point environment conversions.
 227  */
 228
 229 void
 230 convert_from_fxsr(struct user_i387_ia32_struct *env, struct task_struct *tsk)
 231 {
 232         struct fxregs_state *fxsave = &tsk->thread.fpu.state.fxsave;
 233         struct _fpreg *to = (struct _fpreg *) &env->st_space[0];
 234         struct _fpxreg *from = (struct _fpxreg *) &fxsave->st_space[0];
 235         int i;
 236
 237         env->cwd = fxsave->cwd | 0xffff0000u;
 238         env->swd = fxsave->swd | 0xffff0000u;
 239         env->twd = twd_fxsr_to_i387(fxsave);
 240
 241 #ifdef CONFIG_X86_64
 242         env->fip = fxsave->rip;
 243         env->foo = fxsave->rdp;
 244         /*
 245          * should be actually ds/cs at fpu exception time, but
 246          * that information is not available in 64bit mode.
 247          */
 248         env->fcs = task_pt_regs(tsk)->cs;
 249         if (tsk == current) {
 250                 savesegment(ds, env->fos);
 251         } else {
 252                 env->fos = tsk->thread.ds;
 253         }
 254         env->fos |= 0xffff0000;
 255 #else
 256         env->fip = fxsave->fip;
 257         env->fcs = (u16) fxsave->fcs | ((u32) fxsave->fop << 16);
 258         env->foo = fxsave->foo;
 259         env->fos = fxsave->fos;
 260 #endif
 261
 262         for (i = 0; i < 8; ++i)
 263                 memcpy(&to[i], &from[i], sizeof(to[0]));
 264 }
 265
 266 void convert_to_fxsr(struct task_struct *tsk,
 267                      const struct user_i387_ia32_struct *env)
 268
 269 {
 270         struct fxregs_state *fxsave = &tsk->thread.fpu.state.fxsave;
 271         struct _fpreg *from = (struct _fpreg *) &env->st_space[0];
 272         struct _fpxreg *to = (struct _fpxreg *) &fxsave->st_space[0];
 273         int i;
 274
 275         fxsave->cwd = env->cwd;
 276         fxsave->swd = env->swd;
 277         fxsave->twd = twd_i387_to_fxsr(env->twd);
 278         fxsave->fop = (u16) ((u32) env->fcs >> 16);
 279 #ifdef CONFIG_X86_64
 280         fxsave->rip = env->fip;
 281         fxsave->rdp = env->foo;
 282         /* cs and ds ignored */
 283 #else
 284         fxsave->fip = env->fip;
 285         fxsave->fcs = (env->fcs & 0xffff);
 286         fxsave->foo = env->foo;
 287         fxsave->fos = env->fos;
 288 #endif
 289
 290         for (i = 0; i < 8; ++i)
 291                 memcpy(&to[i], &from[i], sizeof(from[0]));
 292 }
 293
 294 int fpregs_get(struct task_struct *target, const struct user_regset *regset,
 295                unsigned int pos, unsigned int count,
 296                void *kbuf, void __user *ubuf)
 297 {
 298         struct fpu *fpu = &target->thread.fpu;
 299         struct user_i387_ia32_struct env;
 300
 301         fpu__activate_fpstate_read(fpu);
 302
 303         if (!boot_cpu_has(X86_FEATURE_FPU))
 304                 return fpregs_soft_get(target, regset, pos, count, kbuf, ubuf);
 305
 306         if (!boot_cpu_has(X86_FEATURE_FXSR))
 307                 return user_regset_copyout(&pos, &count, &kbuf, &ubuf,
 308                                            &fpu->state.fsave, 0,
 309                                            -1);
 310
 311         fpstate_sanitize_xstate(fpu);
 312
 313         if (kbuf && pos == 0 && count == sizeof(env)) {
 314                 convert_from_fxsr(kbuf, target);
 315                 return 0;
 316         }
 317
 318         convert_from_fxsr(&env, target);
 319
 320         return user_regset_copyout(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
 321 }
 322
 323 int fpregs_set(struct task_struct *target, const struct user_regset *regset,
 324                unsigned int pos, unsigned int count,
 325                const void *kbuf, const void __user *ubuf)
 326 {
 327         struct fpu *fpu = &target->thread.fpu;
 328         struct user_i387_ia32_struct env;
 329         int ret;
 330
 331         fpu__activate_fpstate_write(fpu);
 332         fpstate_sanitize_xstate(fpu);
 333
 334         if (!boot_cpu_has(X86_FEATURE_FPU))
 335                 return fpregs_soft_set(target, regset, pos, count, kbuf, ubuf);
 336
 337         if (!boot_cpu_has(X86_FEATURE_FXSR))
 338                 return user_regset_copyin(&pos, &count, &kbuf, &ubuf,
 339                                           &fpu->state.fsave, 0,
 340                                           -1);
 341
 342         if (pos > 0 || count < sizeof(env))
 343                 convert_from_fxsr(&env, target);
 344
 345         ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &env, 0, -1);
 346         if (!ret)
 347                 convert_to_fxsr(target, &env);
 348
 349         /*
 350          * update the header bit in the xsave header, indicating the
 351          * presence of FP.
 352          */
 353         if (boot_cpu_has(X86_FEATURE_XSAVE))
 354                 fpu->state.xsave.header.xfeatures |= XFEATURE_MASK_FP;
 355         return ret;
 356 }
 357
 358 /*
 359  * FPU state for core dumps.
 360  * This is only used for a.out dumps now.
 361  * It is declared generically using elf_fpregset_t (which is
 362  * struct user_i387_struct) but is in fact only used for 32-bit
 363  * dumps, so on 64-bit it is really struct user_i387_ia32_struct.
 364  */
 365 int dump_fpu(struct pt_regs *regs, struct user_i387_struct *ufpu)
 366 {
 367         struct task_struct *tsk = current;
 368         struct fpu *fpu = &tsk->thread.fpu;
 369         int fpvalid;
 370
 371         fpvalid = fpu->fpstate_active;
 372         if (fpvalid)
 373                 fpvalid = !fpregs_get(tsk, NULL,
 374                                       0, sizeof(struct user_i387_ia32_struct),
 375                                       ufpu, NULL);
 376
 377         return fpvalid;
 378 }
 379 EXPORT_SYMBOL(dump_fpu);
 380
 381 #endif  /* CONFIG_X86_32 || CONFIG_IA32_EMULATION */