linux-user/arm/signal.c

   1 /*
   2  *  Emulation of Linux signals
   3  *
   4  *  Copyright (c) 2003 Fabrice Bellard
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  18  */
  19 #include "qemu/osdep.h"
  20 #include "qemu.h"
  21 #include "user-internals.h"
  22 #include "signal-common.h"
  23 #include "linux-user/trace.h"
  24
  25 struct target_sigcontext {
  26     abi_ulong trap_no;
  27     abi_ulong error_code;
  28     abi_ulong oldmask;
  29     abi_ulong arm_r0;
  30     abi_ulong arm_r1;
  31     abi_ulong arm_r2;
  32     abi_ulong arm_r3;
  33     abi_ulong arm_r4;
  34     abi_ulong arm_r5;
  35     abi_ulong arm_r6;
  36     abi_ulong arm_r7;
  37     abi_ulong arm_r8;
  38     abi_ulong arm_r9;
  39     abi_ulong arm_r10;
  40     abi_ulong arm_fp;
  41     abi_ulong arm_ip;
  42     abi_ulong arm_sp;
  43     abi_ulong arm_lr;
  44     abi_ulong arm_pc;
  45     abi_ulong arm_cpsr;
  46     abi_ulong fault_address;
  47 };
  48
  49 struct target_ucontext {
  50     abi_ulong tuc_flags;
  51     abi_ulong tuc_link;
  52     target_stack_t tuc_stack;
  53     struct target_sigcontext tuc_mcontext;
  54     target_sigset_t  tuc_sigmask;       /* mask last for extensibility */
  55     char __unused[128 - sizeof(target_sigset_t)];
  56     abi_ulong tuc_regspace[128] __attribute__((__aligned__(8)));
  57 };
  58
  59 struct target_user_vfp {
  60     uint64_t fpregs[32];
  61     abi_ulong fpscr;
  62 };
  63
  64 struct target_user_vfp_exc {
  65     abi_ulong fpexc;
  66     abi_ulong fpinst;
  67     abi_ulong fpinst2;
  68 };
  69
  70 struct target_vfp_sigframe {
  71     abi_ulong magic;
  72     abi_ulong size;
  73     struct target_user_vfp ufp;
  74     struct target_user_vfp_exc ufp_exc;
  75 } __attribute__((__aligned__(8)));
  76
  77 struct target_iwmmxt_sigframe {
  78     abi_ulong magic;
  79     abi_ulong size;
  80     uint64_t regs[16];
  81     /* Note that not all the coprocessor control registers are stored here */
  82     uint32_t wcssf;
  83     uint32_t wcasf;
  84     uint32_t wcgr0;
  85     uint32_t wcgr1;
  86     uint32_t wcgr2;
  87     uint32_t wcgr3;
  88 } __attribute__((__aligned__(8)));
  89
  90 #define TARGET_VFP_MAGIC 0x56465001
  91 #define TARGET_IWMMXT_MAGIC 0x12ef842a
  92
  93 struct sigframe
  94 {
  95     struct target_ucontext uc;
  96     abi_ulong retcode[4];
  97 };
  98
  99 struct rt_sigframe
 100 {
 101     struct target_siginfo info;
 102     struct sigframe sig;
 103 };
 104
 105 static abi_ptr sigreturn_fdpic_tramp;
 106
 107 /*
 108  * Up to 3 words of 'retcode' in the sigframe are code,
 109  * with retcode[3] being used by fdpic for the function descriptor.
 110  * This code is not actually executed, but is retained for ABI compat.
 111  *
 112  * We will create a table of 8 retcode variants in the sigtramp page.
 113  * Let each table entry use 3 words.
 114  */
 115 #define RETCODE_WORDS  3
 116 #define RETCODE_BYTES  (RETCODE_WORDS * 4)
 117
 118 static inline int valid_user_regs(CPUARMState *regs)
 119 {
 120     return 1;
 121 }
 122
 123 static void
 124 setup_sigcontext(struct target_sigcontext *sc, /*struct _fpstate *fpstate,*/
 125                  CPUARMState *env, abi_ulong mask)
 126 {
 127     __put_user(env->regs[0], &sc->arm_r0);
 128     __put_user(env->regs[1], &sc->arm_r1);
 129     __put_user(env->regs[2], &sc->arm_r2);
 130     __put_user(env->regs[3], &sc->arm_r3);
 131     __put_user(env->regs[4], &sc->arm_r4);
 132     __put_user(env->regs[5], &sc->arm_r5);
 133     __put_user(env->regs[6], &sc->arm_r6);
 134     __put_user(env->regs[7], &sc->arm_r7);
 135     __put_user(env->regs[8], &sc->arm_r8);
 136     __put_user(env->regs[9], &sc->arm_r9);
 137     __put_user(env->regs[10], &sc->arm_r10);
 138     __put_user(env->regs[11], &sc->arm_fp);
 139     __put_user(env->regs[12], &sc->arm_ip);
 140     __put_user(env->regs[13], &sc->arm_sp);
 141     __put_user(env->regs[14], &sc->arm_lr);
 142     __put_user(env->regs[15], &sc->arm_pc);
 143     __put_user(cpsr_read(env), &sc->arm_cpsr);
 144
 145     __put_user(/* current->thread.trap_no */ 0, &sc->trap_no);
 146     __put_user(/* current->thread.error_code */ 0, &sc->error_code);
 147     __put_user(/* current->thread.address */ 0, &sc->fault_address);
 148     __put_user(mask, &sc->oldmask);
 149 }
 150
 151 static inline abi_ulong
 152 get_sigframe(struct target_sigaction *ka, CPUARMState *regs, int framesize)
 153 {
 154     unsigned long sp;
 155
 156     sp = target_sigsp(get_sp_from_cpustate(regs), ka);
 157     /*
 158      * ATPCS B01 mandates 8-byte alignment
 159      */
 160     return (sp - framesize) & ~7;
 161 }
 162
 163 static int
 164 setup_return(CPUARMState *env, struct target_sigaction *ka, int usig,
 165              struct sigframe *frame, abi_ulong sp_addr)
 166 {
 167     abi_ulong handler = 0;
 168     abi_ulong handler_fdpic_GOT = 0;
 169     abi_ulong retcode;
 170     int thumb, retcode_idx;
 171     int is_fdpic = info_is_fdpic(((TaskState *)thread_cpu->opaque)->info);
 172     bool copy_retcode;
 173
 174     if (is_fdpic) {
 175         /* In FDPIC mode, ka->_sa_handler points to a function
 176          * descriptor (FD). The first word contains the address of the
 177          * handler. The second word contains the value of the PIC
 178          * register (r9).  */
 179         abi_ulong funcdesc_ptr = ka->_sa_handler;
 180         if (get_user_ual(handler, funcdesc_ptr)
 181             || get_user_ual(handler_fdpic_GOT, funcdesc_ptr + 4)) {
 182             return 1;
 183         }
 184     } else {
 185         handler = ka->_sa_handler;
 186     }
 187
 188     thumb = handler & 1;
 189     retcode_idx = thumb + (ka->sa_flags & TARGET_SA_SIGINFO ? 2 : 0);
 190
 191     uint32_t cpsr = cpsr_read(env);
 192
 193     cpsr &= ~CPSR_IT;
 194     if (thumb) {
 195         cpsr |= CPSR_T;
 196     } else {
 197         cpsr &= ~CPSR_T;
 198     }
 199     if (env->cp15.sctlr_el[1] & SCTLR_E0E) {
 200         cpsr |= CPSR_E;
 201     } else {
 202         cpsr &= ~CPSR_E;
 203     }
 204
 205     if (ka->sa_flags & TARGET_SA_RESTORER) {
 206         if (is_fdpic) {
 207             __put_user((abi_ulong)ka->sa_restorer, &frame->retcode[3]);
 208             retcode = (sigreturn_fdpic_tramp +
 209                        retcode_idx * RETCODE_BYTES + thumb);
 210             copy_retcode = true;
 211         } else {
 212             retcode = ka->sa_restorer;
 213             copy_retcode = false;
 214         }
 215     } else {
 216         retcode = default_sigreturn + retcode_idx * RETCODE_BYTES + thumb;
 217         copy_retcode = true;
 218     }
 219
 220     /* Copy the code to the stack slot for ABI compatibility. */
 221     if (copy_retcode) {
 222         memcpy(frame->retcode, g2h_untagged(retcode & ~1), RETCODE_BYTES);
 223     }
 224
 225     env->regs[0] = usig;
 226     if (is_fdpic) {
 227         env->regs[9] = handler_fdpic_GOT;
 228     }
 229     env->regs[13] = sp_addr;
 230     env->regs[14] = retcode;
 231     env->regs[15] = handler & (thumb ? ~1 : ~3);
 232     cpsr_write(env, cpsr, CPSR_IT | CPSR_T | CPSR_E, CPSRWriteByInstr);
 233
 234     return 0;
 235 }
 236
 237 static abi_ulong *setup_sigframe_vfp(abi_ulong *regspace, CPUARMState *env)
 238 {
 239     int i;
 240     struct target_vfp_sigframe *vfpframe;
 241     vfpframe = (struct target_vfp_sigframe *)regspace;
 242     __put_user(TARGET_VFP_MAGIC, &vfpframe->magic);
 243     __put_user(sizeof(*vfpframe), &vfpframe->size);
 244     for (i = 0; i < 32; i++) {
 245         __put_user(*aa32_vfp_dreg(env, i), &vfpframe->ufp.fpregs[i]);
 246     }
 247     __put_user(vfp_get_fpscr(env), &vfpframe->ufp.fpscr);
 248     __put_user(env->vfp.xregs[ARM_VFP_FPEXC], &vfpframe->ufp_exc.fpexc);
 249     __put_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
 250     __put_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
 251     return (abi_ulong*)(vfpframe+1);
 252 }
 253
 254 static abi_ulong *setup_sigframe_iwmmxt(abi_ulong *regspace, CPUARMState *env)
 255 {
 256     int i;
 257     struct target_iwmmxt_sigframe *iwmmxtframe;
 258     iwmmxtframe = (struct target_iwmmxt_sigframe *)regspace;
 259     __put_user(TARGET_IWMMXT_MAGIC, &iwmmxtframe->magic);
 260     __put_user(sizeof(*iwmmxtframe), &iwmmxtframe->size);
 261     for (i = 0; i < 16; i++) {
 262         __put_user(env->iwmmxt.regs[i], &iwmmxtframe->regs[i]);
 263     }
 264     __put_user(env->vfp.xregs[ARM_IWMMXT_wCSSF], &iwmmxtframe->wcssf);
 265     __put_user(env->vfp.xregs[ARM_IWMMXT_wCASF], &iwmmxtframe->wcssf);
 266     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR0], &iwmmxtframe->wcgr0);
 267     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR1], &iwmmxtframe->wcgr1);
 268     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR2], &iwmmxtframe->wcgr2);
 269     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR3], &iwmmxtframe->wcgr3);
 270     return (abi_ulong*)(iwmmxtframe+1);
 271 }
 272
 273 static void setup_sigframe(struct target_ucontext *uc,
 274                            target_sigset_t *set, CPUARMState *env)
 275 {
 276     struct target_sigaltstack stack;
 277     int i;
 278     abi_ulong *regspace;
 279
 280     /* Clear all the bits of the ucontext we don't use.  */
 281     memset(uc, 0, offsetof(struct target_ucontext, tuc_mcontext));
 282
 283     memset(&stack, 0, sizeof(stack));
 284     target_save_altstack(&stack, env);
 285     memcpy(&uc->tuc_stack, &stack, sizeof(stack));
 286
 287     setup_sigcontext(&uc->tuc_mcontext, env, set->sig[0]);
 288     /* Save coprocessor signal frame.  */
 289     regspace = uc->tuc_regspace;
 290     if (cpu_isar_feature(aa32_vfp_simd, env_archcpu(env))) {
 291         regspace = setup_sigframe_vfp(regspace, env);
 292     }
 293     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
 294         regspace = setup_sigframe_iwmmxt(regspace, env);
 295     }
 296
 297     /* Write terminating magic word */
 298     __put_user(0, regspace);
 299
 300     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
 301         __put_user(set->sig[i], &uc->tuc_sigmask.sig[i]);
 302     }
 303 }
 304
 305 void setup_frame(int usig, struct target_sigaction *ka,
 306                  target_sigset_t *set, CPUARMState *regs)
 307 {
 308     struct sigframe *frame;
 309     abi_ulong frame_addr = get_sigframe(ka, regs, sizeof(*frame));
 310
 311     trace_user_setup_frame(regs, frame_addr);
 312     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
 313         goto sigsegv;
 314     }
 315
 316     setup_sigframe(&frame->uc, set, regs);
 317
 318     if (setup_return(regs, ka, usig, frame, frame_addr)) {
 319         goto sigsegv;
 320     }
 321
 322     unlock_user_struct(frame, frame_addr, 1);
 323     return;
 324 sigsegv:
 325     unlock_user_struct(frame, frame_addr, 1);
 326     force_sigsegv(usig);
 327 }
 328
 329 void setup_rt_frame(int usig, struct target_sigaction *ka,
 330                     target_siginfo_t *info,
 331                     target_sigset_t *set, CPUARMState *env)
 332 {
 333     struct rt_sigframe *frame;
 334     abi_ulong frame_addr = get_sigframe(ka, env, sizeof(*frame));
 335     abi_ulong info_addr, uc_addr;
 336
 337     trace_user_setup_rt_frame(env, frame_addr);
 338     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
 339         goto sigsegv;
 340     }
 341
 342     info_addr = frame_addr + offsetof(struct rt_sigframe, info);
 343     uc_addr = frame_addr + offsetof(struct rt_sigframe, sig.uc);
 344     tswap_siginfo(&frame->info, info);
 345
 346     setup_sigframe(&frame->sig.uc, set, env);
 347
 348     if (setup_return(env, ka, usig, &frame->sig, frame_addr)) {
 349         goto sigsegv;
 350     }
 351
 352     env->regs[1] = info_addr;
 353     env->regs[2] = uc_addr;
 354
 355     unlock_user_struct(frame, frame_addr, 1);
 356     return;
 357 sigsegv:
 358     unlock_user_struct(frame, frame_addr, 1);
 359     force_sigsegv(usig);
 360 }
 361
 362 static int
 363 restore_sigcontext(CPUARMState *env, struct target_sigcontext *sc)
 364 {
 365     int err = 0;
 366     uint32_t cpsr;
 367
 368     __get_user(env->regs[0], &sc->arm_r0);
 369     __get_user(env->regs[1], &sc->arm_r1);
 370     __get_user(env->regs[2], &sc->arm_r2);
 371     __get_user(env->regs[3], &sc->arm_r3);
 372     __get_user(env->regs[4], &sc->arm_r4);
 373     __get_user(env->regs[5], &sc->arm_r5);
 374     __get_user(env->regs[6], &sc->arm_r6);
 375     __get_user(env->regs[7], &sc->arm_r7);
 376     __get_user(env->regs[8], &sc->arm_r8);
 377     __get_user(env->regs[9], &sc->arm_r9);
 378     __get_user(env->regs[10], &sc->arm_r10);
 379     __get_user(env->regs[11], &sc->arm_fp);
 380     __get_user(env->regs[12], &sc->arm_ip);
 381     __get_user(env->regs[13], &sc->arm_sp);
 382     __get_user(env->regs[14], &sc->arm_lr);
 383     __get_user(env->regs[15], &sc->arm_pc);
 384     __get_user(cpsr, &sc->arm_cpsr);
 385     cpsr_write(env, cpsr, CPSR_USER | CPSR_EXEC, CPSRWriteByInstr);
 386
 387     err |= !valid_user_regs(env);
 388
 389     return err;
 390 }
 391
 392 static abi_ulong *restore_sigframe_vfp(CPUARMState *env, abi_ulong *regspace)
 393 {
 394     int i;
 395     abi_ulong magic, sz;
 396     uint32_t fpscr, fpexc;
 397     struct target_vfp_sigframe *vfpframe;
 398     vfpframe = (struct target_vfp_sigframe *)regspace;
 399
 400     __get_user(magic, &vfpframe->magic);
 401     __get_user(sz, &vfpframe->size);
 402     if (magic != TARGET_VFP_MAGIC || sz != sizeof(*vfpframe)) {
 403         return 0;
 404     }
 405     for (i = 0; i < 32; i++) {
 406         __get_user(*aa32_vfp_dreg(env, i), &vfpframe->ufp.fpregs[i]);
 407     }
 408     __get_user(fpscr, &vfpframe->ufp.fpscr);
 409     vfp_set_fpscr(env, fpscr);
 410     __get_user(fpexc, &vfpframe->ufp_exc.fpexc);
 411     /* Sanitise FPEXC: ensure VFP is enabled, FPINST2 is invalid
 412      * and the exception flag is cleared
 413      */
 414     fpexc |= (1 << 30);
 415     fpexc &= ~((1 << 31) | (1 << 28));
 416     env->vfp.xregs[ARM_VFP_FPEXC] = fpexc;
 417     __get_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
 418     __get_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
 419     return (abi_ulong*)(vfpframe + 1);
 420 }
 421
 422 static abi_ulong *restore_sigframe_iwmmxt(CPUARMState *env,
 423                                           abi_ulong *regspace)
 424 {
 425     int i;
 426     abi_ulong magic, sz;
 427     struct target_iwmmxt_sigframe *iwmmxtframe;
 428     iwmmxtframe = (struct target_iwmmxt_sigframe *)regspace;
 429
 430     __get_user(magic, &iwmmxtframe->magic);
 431     __get_user(sz, &iwmmxtframe->size);
 432     if (magic != TARGET_IWMMXT_MAGIC || sz != sizeof(*iwmmxtframe)) {
 433         return 0;
 434     }
 435     for (i = 0; i < 16; i++) {
 436         __get_user(env->iwmmxt.regs[i], &iwmmxtframe->regs[i]);
 437     }
 438     __get_user(env->vfp.xregs[ARM_IWMMXT_wCSSF], &iwmmxtframe->wcssf);
 439     __get_user(env->vfp.xregs[ARM_IWMMXT_wCASF], &iwmmxtframe->wcssf);
 440     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR0], &iwmmxtframe->wcgr0);
 441     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR1], &iwmmxtframe->wcgr1);
 442     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR2], &iwmmxtframe->wcgr2);
 443     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR3], &iwmmxtframe->wcgr3);
 444     return (abi_ulong*)(iwmmxtframe + 1);
 445 }
 446
 447 static int do_sigframe_return(CPUARMState *env,
 448                               target_ulong context_addr,
 449                               struct target_ucontext *uc)
 450 {
 451     sigset_t host_set;
 452     abi_ulong *regspace;
 453
 454     target_to_host_sigset(&host_set, &uc->tuc_sigmask);
 455     set_sigmask(&host_set);
 456
 457     if (restore_sigcontext(env, &uc->tuc_mcontext)) {
 458         return 1;
 459     }
 460
 461     /* Restore coprocessor signal frame */
 462     regspace = uc->tuc_regspace;
 463     if (cpu_isar_feature(aa32_vfp_simd, env_archcpu(env))) {
 464         regspace = restore_sigframe_vfp(env, regspace);
 465         if (!regspace) {
 466             return 1;
 467         }
 468     }
 469     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
 470         regspace = restore_sigframe_iwmmxt(env, regspace);
 471         if (!regspace) {
 472             return 1;
 473         }
 474     }
 475
 476     target_restore_altstack(&uc->tuc_stack, env);
 477
 478 #if 0
 479     /* Send SIGTRAP if we're single-stepping */
 480     if (ptrace_cancel_bpt(current))
 481         send_sig(SIGTRAP, current, 1);
 482 #endif
 483
 484     return 0;
 485 }
 486
 487 long do_sigreturn(CPUARMState *env)
 488 {
 489     abi_ulong frame_addr;
 490     struct sigframe *frame = NULL;
 491
 492     /*
 493      * Since we stacked the signal on a 64-bit boundary,
 494      * then 'sp' should be word aligned here.  If it's
 495      * not, then the user is trying to mess with us.
 496      */
 497     frame_addr = env->regs[13];
 498     trace_user_do_sigreturn(env, frame_addr);
 499     if (frame_addr & 7) {
 500         goto badframe;
 501     }
 502
 503     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
 504         goto badframe;
 505     }
 506
 507     if (do_sigframe_return(env,
 508                            frame_addr + offsetof(struct sigframe, uc),
 509                            &frame->uc)) {
 510         goto badframe;
 511     }
 512
 513     unlock_user_struct(frame, frame_addr, 0);
 514     return -QEMU_ESIGRETURN;
 515
 516 badframe:
 517     unlock_user_struct(frame, frame_addr, 0);
 518     force_sig(TARGET_SIGSEGV);
 519     return -QEMU_ESIGRETURN;
 520 }
 521
 522 long do_rt_sigreturn(CPUARMState *env)
 523 {
 524     abi_ulong frame_addr;
 525     struct rt_sigframe *frame = NULL;
 526
 527     /*
 528      * Since we stacked the signal on a 64-bit boundary,
 529      * then 'sp' should be word aligned here.  If it's
 530      * not, then the user is trying to mess with us.
 531      */
 532     frame_addr = env->regs[13];
 533     trace_user_do_rt_sigreturn(env, frame_addr);
 534     if (frame_addr & 7) {
 535         goto badframe;
 536     }
 537
 538     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
 539         goto badframe;
 540     }
 541
 542     if (do_sigframe_return(env,
 543                            frame_addr + offsetof(struct rt_sigframe, sig.uc),
 544                            &frame->sig.uc)) {
 545         goto badframe;
 546     }
 547
 548     unlock_user_struct(frame, frame_addr, 0);
 549     return -QEMU_ESIGRETURN;
 550
 551 badframe:
 552     unlock_user_struct(frame, frame_addr, 0);
 553     force_sig(TARGET_SIGSEGV);
 554     return -QEMU_ESIGRETURN;
 555 }
 556
 557 /*
 558  * EABI syscalls pass the number via r7.
 559  * Note that the kernel still adds the OABI syscall number to the trap,
 560  * presumably for backward ABI compatibility with unwinders.
 561  */
 562 #define ARM_MOV_R7_IMM(X)       (0xe3a07000 | (X))
 563 #define ARM_SWI_SYS(X)          (0xef000000 | (X) | ARM_SYSCALL_BASE)
 564
 565 #define THUMB_MOVS_R7_IMM(X)    (0x2700 | (X))
 566 #define THUMB_SWI_SYS           0xdf00
 567
 568 static void write_arm_sigreturn(uint32_t *rc, int syscall)
 569 {
 570     __put_user(ARM_MOV_R7_IMM(syscall), rc);
 571     __put_user(ARM_SWI_SYS(syscall), rc + 1);
 572     /* Wrote 8 of 12 bytes */
 573 }
 574
 575 static void write_thm_sigreturn(uint32_t *rc, int syscall)
 576 {
 577     __put_user(THUMB_SWI_SYS << 16 | THUMB_MOVS_R7_IMM(syscall), rc);
 578     /* Wrote 4 of 12 bytes */
 579 }
 580
 581 /*
 582  * Stub needed to make sure the FD register (r9) contains the right value.
 583  * Use the same instruction sequence as the kernel.
 584  */
 585 static void write_arm_fdpic_sigreturn(uint32_t *rc, int ofs)
 586 {
 587     assert(ofs <= 0xfff);
 588     __put_user(0xe59d3000 | ofs, rc + 0);   /* ldr r3, [sp, #ofs] */
 589     __put_user(0xe8930908, rc + 1);         /* ldm r3, { r3, r9 } */
 590     __put_user(0xe12fff13, rc + 2);         /* bx  r3 */
 591     /* Wrote 12 of 12 bytes */
 592 }
 593
 594 static void write_thm_fdpic_sigreturn(void *vrc, int ofs)
 595 {
 596     uint16_t *rc = vrc;
 597
 598     assert((ofs & ~0x3fc) == 0);
 599     __put_user(0x9b00 | (ofs >> 2), rc + 0);      /* ldr r3, [sp, #ofs] */
 600     __put_user(0xcb0c, rc + 1);                   /* ldm r3, { r2, r3 } */
 601     __put_user(0x4699, rc + 2);                   /* mov r9, r3 */
 602     __put_user(0x4710, rc + 3);                   /* bx  r2 */
 603     /* Wrote 8 of 12 bytes */
 604 }
 605
 606 void setup_sigtramp(abi_ulong sigtramp_page)
 607 {
 608     uint32_t total_size = 8 * RETCODE_BYTES;
 609     uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, total_size, 0);
 610
 611     assert(tramp != NULL);
 612
 613     default_sigreturn = sigtramp_page;
 614     write_arm_sigreturn(&tramp[0 * RETCODE_WORDS], TARGET_NR_sigreturn);
 615     write_thm_sigreturn(&tramp[1 * RETCODE_WORDS], TARGET_NR_sigreturn);
 616     write_arm_sigreturn(&tramp[2 * RETCODE_WORDS], TARGET_NR_rt_sigreturn);
 617     write_thm_sigreturn(&tramp[3 * RETCODE_WORDS], TARGET_NR_rt_sigreturn);
 618
 619     sigreturn_fdpic_tramp = sigtramp_page + 4 * RETCODE_BYTES;
 620     write_arm_fdpic_sigreturn(tramp + 4 * RETCODE_WORDS,
 621                               offsetof(struct sigframe, retcode[3]));
 622     write_thm_fdpic_sigreturn(tramp + 5 * RETCODE_WORDS,
 623                                 offsetof(struct sigframe, retcode[3]));
 624     write_arm_fdpic_sigreturn(tramp + 6 * RETCODE_WORDS,
 625                               offsetof(struct rt_sigframe, sig.retcode[3]));
 626     write_thm_fdpic_sigreturn(tramp + 7 * RETCODE_WORDS,
 627                               offsetof(struct rt_sigframe, sig.retcode[3]));
 628
 629     unlock_user(tramp, sigtramp_page, total_size);
 630 }