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 #include "target/arm/cpu-features.h"
  25
  26 struct target_sigcontext {
  27     abi_ulong trap_no;
  28     abi_ulong error_code;
  29     abi_ulong oldmask;
  30     abi_ulong arm_r0;
  31     abi_ulong arm_r1;
  32     abi_ulong arm_r2;
  33     abi_ulong arm_r3;
  34     abi_ulong arm_r4;
  35     abi_ulong arm_r5;
  36     abi_ulong arm_r6;
  37     abi_ulong arm_r7;
  38     abi_ulong arm_r8;
  39     abi_ulong arm_r9;
  40     abi_ulong arm_r10;
  41     abi_ulong arm_fp;
  42     abi_ulong arm_ip;
  43     abi_ulong arm_sp;
  44     abi_ulong arm_lr;
  45     abi_ulong arm_pc;
  46     abi_ulong arm_cpsr;
  47     abi_ulong fault_address;
  48 };
  49
  50 struct target_ucontext {
  51     abi_ulong tuc_flags;
  52     abi_ulong tuc_link;
  53     target_stack_t tuc_stack;
  54     struct target_sigcontext tuc_mcontext;
  55     target_sigset_t  tuc_sigmask;       /* mask last for extensibility */
  56     char __unused[128 - sizeof(target_sigset_t)];
  57     abi_ulong tuc_regspace[128] __attribute__((__aligned__(8)));
  58 };
  59
  60 struct target_user_vfp {
  61     uint64_t fpregs[32];
  62     abi_ulong fpscr;
  63 };
  64
  65 struct target_user_vfp_exc {
  66     abi_ulong fpexc;
  67     abi_ulong fpinst;
  68     abi_ulong fpinst2;
  69 };
  70
  71 struct target_vfp_sigframe {
  72     abi_ulong magic;
  73     abi_ulong size;
  74     struct target_user_vfp ufp;
  75     struct target_user_vfp_exc ufp_exc;
  76 } __attribute__((__aligned__(8)));
  77
  78 struct target_iwmmxt_sigframe {
  79     abi_ulong magic;
  80     abi_ulong size;
  81     uint64_t regs[16];
  82     /* Note that not all the coprocessor control registers are stored here */
  83     uint32_t wcssf;
  84     uint32_t wcasf;
  85     uint32_t wcgr0;
  86     uint32_t wcgr1;
  87     uint32_t wcgr2;
  88     uint32_t wcgr3;
  89 } __attribute__((__aligned__(8)));
  90
  91 #define TARGET_VFP_MAGIC 0x56465001
  92 #define TARGET_IWMMXT_MAGIC 0x12ef842a
  93
  94 struct sigframe
  95 {
  96     struct target_ucontext uc;
  97     abi_ulong retcode[4];
  98 };
  99
 100 struct rt_sigframe
 101 {
 102     struct target_siginfo info;
 103     struct sigframe sig;
 104 };
 105
 106 static abi_ptr sigreturn_fdpic_tramp;
 107
 108 /*
 109  * Up to 3 words of 'retcode' in the sigframe are code,
 110  * with retcode[3] being used by fdpic for the function descriptor.
 111  * This code is not actually executed, but is retained for ABI compat.
 112  *
 113  * We will create a table of 8 retcode variants in the sigtramp page.
 114  * Let each table entry use 3 words.
 115  */
 116 #define RETCODE_WORDS  3
 117 #define RETCODE_BYTES  (RETCODE_WORDS * 4)
 118
 119 static inline int valid_user_regs(CPUARMState *regs)
 120 {
 121     return 1;
 122 }
 123
 124 static void
 125 setup_sigcontext(struct target_sigcontext *sc, /*struct _fpstate *fpstate,*/
 126                  CPUARMState *env, abi_ulong mask)
 127 {
 128     __put_user(env->regs[0], &sc->arm_r0);
 129     __put_user(env->regs[1], &sc->arm_r1);
 130     __put_user(env->regs[2], &sc->arm_r2);
 131     __put_user(env->regs[3], &sc->arm_r3);
 132     __put_user(env->regs[4], &sc->arm_r4);
 133     __put_user(env->regs[5], &sc->arm_r5);
 134     __put_user(env->regs[6], &sc->arm_r6);
 135     __put_user(env->regs[7], &sc->arm_r7);
 136     __put_user(env->regs[8], &sc->arm_r8);
 137     __put_user(env->regs[9], &sc->arm_r9);
 138     __put_user(env->regs[10], &sc->arm_r10);
 139     __put_user(env->regs[11], &sc->arm_fp);
 140     __put_user(env->regs[12], &sc->arm_ip);
 141     __put_user(env->regs[13], &sc->arm_sp);
 142     __put_user(env->regs[14], &sc->arm_lr);
 143     __put_user(env->regs[15], &sc->arm_pc);
 144     __put_user(cpsr_read(env), &sc->arm_cpsr);
 145
 146     __put_user(/* current->thread.trap_no */ 0, &sc->trap_no);
 147     __put_user(/* current->thread.error_code */ 0, &sc->error_code);
 148     __put_user(/* current->thread.address */ 0, &sc->fault_address);
 149     __put_user(mask, &sc->oldmask);
 150 }
 151
 152 static inline abi_ulong
 153 get_sigframe(struct target_sigaction *ka, CPUARMState *regs, int framesize)
 154 {
 155     unsigned long sp;
 156
 157     sp = target_sigsp(get_sp_from_cpustate(regs), ka);
 158     /*
 159      * ATPCS B01 mandates 8-byte alignment
 160      */
 161     return (sp - framesize) & ~7;
 162 }
 163
 164 static int
 165 setup_return(CPUARMState *env, struct target_sigaction *ka, int usig,
 166              struct sigframe *frame, abi_ulong sp_addr)
 167 {
 168     abi_ulong handler = 0;
 169     abi_ulong handler_fdpic_GOT = 0;
 170     abi_ulong retcode;
 171     int thumb, retcode_idx;
 172     int is_fdpic = info_is_fdpic(((TaskState *)thread_cpu->opaque)->info);
 173     bool copy_retcode;
 174
 175     if (is_fdpic) {
 176         /* In FDPIC mode, ka->_sa_handler points to a function
 177          * descriptor (FD). The first word contains the address of the
 178          * handler. The second word contains the value of the PIC
 179          * register (r9).  */
 180         abi_ulong funcdesc_ptr = ka->_sa_handler;
 181         if (get_user_ual(handler, funcdesc_ptr)
 182             || get_user_ual(handler_fdpic_GOT, funcdesc_ptr + 4)) {
 183             return 1;
 184         }
 185     } else {
 186         handler = ka->_sa_handler;
 187     }
 188
 189     thumb = handler & 1;
 190     retcode_idx = thumb + (ka->sa_flags & TARGET_SA_SIGINFO ? 2 : 0);
 191
 192     uint32_t cpsr = cpsr_read(env);
 193
 194     cpsr &= ~CPSR_IT;
 195     if (thumb) {
 196         cpsr |= CPSR_T;
 197     } else {
 198         cpsr &= ~CPSR_T;
 199     }
 200     if (env->cp15.sctlr_el[1] & SCTLR_E0E) {
 201         cpsr |= CPSR_E;
 202     } else {
 203         cpsr &= ~CPSR_E;
 204     }
 205
 206     if (ka->sa_flags & TARGET_SA_RESTORER) {
 207         if (is_fdpic) {
 208             __put_user((abi_ulong)ka->sa_restorer, &frame->retcode[3]);
 209             retcode = (sigreturn_fdpic_tramp +
 210                        retcode_idx * RETCODE_BYTES + thumb);
 211             copy_retcode = true;
 212         } else {
 213             retcode = ka->sa_restorer;
 214             copy_retcode = false;
 215         }
 216     } else {
 217         retcode = default_sigreturn + retcode_idx * RETCODE_BYTES + thumb;
 218         copy_retcode = true;
 219     }
 220
 221     /* Copy the code to the stack slot for ABI compatibility. */
 222     if (copy_retcode) {
 223         memcpy(frame->retcode, g2h_untagged(retcode & ~1), RETCODE_BYTES);
 224     }
 225
 226     env->regs[0] = usig;
 227     if (is_fdpic) {
 228         env->regs[9] = handler_fdpic_GOT;
 229     }
 230     env->regs[13] = sp_addr;
 231     env->regs[14] = retcode;
 232     env->regs[15] = handler & (thumb ? ~1 : ~3);
 233     cpsr_write(env, cpsr, CPSR_IT | CPSR_T | CPSR_E, CPSRWriteByInstr);
 234
 235     return 0;
 236 }
 237
 238 static abi_ulong *setup_sigframe_vfp(abi_ulong *regspace, CPUARMState *env)
 239 {
 240     int i;
 241     struct target_vfp_sigframe *vfpframe;
 242     vfpframe = (struct target_vfp_sigframe *)regspace;
 243     __put_user(TARGET_VFP_MAGIC, &vfpframe->magic);
 244     __put_user(sizeof(*vfpframe), &vfpframe->size);
 245     for (i = 0; i < 32; i++) {
 246         __put_user(*aa32_vfp_dreg(env, i), &vfpframe->ufp.fpregs[i]);
 247     }
 248     __put_user(vfp_get_fpscr(env), &vfpframe->ufp.fpscr);
 249     __put_user(env->vfp.xregs[ARM_VFP_FPEXC], &vfpframe->ufp_exc.fpexc);
 250     __put_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
 251     __put_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
 252     return (abi_ulong*)(vfpframe+1);
 253 }
 254
 255 static abi_ulong *setup_sigframe_iwmmxt(abi_ulong *regspace, CPUARMState *env)
 256 {
 257     int i;
 258     struct target_iwmmxt_sigframe *iwmmxtframe;
 259     iwmmxtframe = (struct target_iwmmxt_sigframe *)regspace;
 260     __put_user(TARGET_IWMMXT_MAGIC, &iwmmxtframe->magic);
 261     __put_user(sizeof(*iwmmxtframe), &iwmmxtframe->size);
 262     for (i = 0; i < 16; i++) {
 263         __put_user(env->iwmmxt.regs[i], &iwmmxtframe->regs[i]);
 264     }
 265     __put_user(env->vfp.xregs[ARM_IWMMXT_wCSSF], &iwmmxtframe->wcssf);
 266     __put_user(env->vfp.xregs[ARM_IWMMXT_wCASF], &iwmmxtframe->wcssf);
 267     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR0], &iwmmxtframe->wcgr0);
 268     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR1], &iwmmxtframe->wcgr1);
 269     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR2], &iwmmxtframe->wcgr2);
 270     __put_user(env->vfp.xregs[ARM_IWMMXT_wCGR3], &iwmmxtframe->wcgr3);
 271     return (abi_ulong*)(iwmmxtframe+1);
 272 }
 273
 274 static void setup_sigframe(struct target_ucontext *uc,
 275                            target_sigset_t *set, CPUARMState *env)
 276 {
 277     struct target_sigaltstack stack;
 278     int i;
 279     abi_ulong *regspace;
 280
 281     /* Clear all the bits of the ucontext we don't use.  */
 282     memset(uc, 0, offsetof(struct target_ucontext, tuc_mcontext));
 283
 284     memset(&stack, 0, sizeof(stack));
 285     target_save_altstack(&stack, env);
 286     memcpy(&uc->tuc_stack, &stack, sizeof(stack));
 287
 288     setup_sigcontext(&uc->tuc_mcontext, env, set->sig[0]);
 289     /* Save coprocessor signal frame.  */
 290     regspace = uc->tuc_regspace;
 291     if (cpu_isar_feature(aa32_vfp_simd, env_archcpu(env))) {
 292         regspace = setup_sigframe_vfp(regspace, env);
 293     }
 294     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
 295         regspace = setup_sigframe_iwmmxt(regspace, env);
 296     }
 297
 298     /* Write terminating magic word */
 299     __put_user(0, regspace);
 300
 301     for(i = 0; i < TARGET_NSIG_WORDS; i++) {
 302         __put_user(set->sig[i], &uc->tuc_sigmask.sig[i]);
 303     }
 304 }
 305
 306 void setup_frame(int usig, struct target_sigaction *ka,
 307                  target_sigset_t *set, CPUARMState *regs)
 308 {
 309     struct sigframe *frame;
 310     abi_ulong frame_addr = get_sigframe(ka, regs, sizeof(*frame));
 311
 312     trace_user_setup_frame(regs, frame_addr);
 313     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
 314         goto sigsegv;
 315     }
 316
 317     setup_sigframe(&frame->uc, set, regs);
 318
 319     if (setup_return(regs, ka, usig, frame, frame_addr)) {
 320         goto sigsegv;
 321     }
 322
 323     unlock_user_struct(frame, frame_addr, 1);
 324     return;
 325 sigsegv:
 326     unlock_user_struct(frame, frame_addr, 1);
 327     force_sigsegv(usig);
 328 }
 329
 330 void setup_rt_frame(int usig, struct target_sigaction *ka,
 331                     target_siginfo_t *info,
 332                     target_sigset_t *set, CPUARMState *env)
 333 {
 334     struct rt_sigframe *frame;
 335     abi_ulong frame_addr = get_sigframe(ka, env, sizeof(*frame));
 336     abi_ulong info_addr, uc_addr;
 337
 338     trace_user_setup_rt_frame(env, frame_addr);
 339     if (!lock_user_struct(VERIFY_WRITE, frame, frame_addr, 0)) {
 340         goto sigsegv;
 341     }
 342
 343     info_addr = frame_addr + offsetof(struct rt_sigframe, info);
 344     uc_addr = frame_addr + offsetof(struct rt_sigframe, sig.uc);
 345     tswap_siginfo(&frame->info, info);
 346
 347     setup_sigframe(&frame->sig.uc, set, env);
 348
 349     if (setup_return(env, ka, usig, &frame->sig, frame_addr)) {
 350         goto sigsegv;
 351     }
 352
 353     env->regs[1] = info_addr;
 354     env->regs[2] = uc_addr;
 355
 356     unlock_user_struct(frame, frame_addr, 1);
 357     return;
 358 sigsegv:
 359     unlock_user_struct(frame, frame_addr, 1);
 360     force_sigsegv(usig);
 361 }
 362
 363 static int
 364 restore_sigcontext(CPUARMState *env, struct target_sigcontext *sc)
 365 {
 366     int err = 0;
 367     uint32_t cpsr;
 368
 369     __get_user(env->regs[0], &sc->arm_r0);
 370     __get_user(env->regs[1], &sc->arm_r1);
 371     __get_user(env->regs[2], &sc->arm_r2);
 372     __get_user(env->regs[3], &sc->arm_r3);
 373     __get_user(env->regs[4], &sc->arm_r4);
 374     __get_user(env->regs[5], &sc->arm_r5);
 375     __get_user(env->regs[6], &sc->arm_r6);
 376     __get_user(env->regs[7], &sc->arm_r7);
 377     __get_user(env->regs[8], &sc->arm_r8);
 378     __get_user(env->regs[9], &sc->arm_r9);
 379     __get_user(env->regs[10], &sc->arm_r10);
 380     __get_user(env->regs[11], &sc->arm_fp);
 381     __get_user(env->regs[12], &sc->arm_ip);
 382     __get_user(env->regs[13], &sc->arm_sp);
 383     __get_user(env->regs[14], &sc->arm_lr);
 384     __get_user(env->regs[15], &sc->arm_pc);
 385     __get_user(cpsr, &sc->arm_cpsr);
 386     cpsr_write(env, cpsr, CPSR_USER | CPSR_EXEC, CPSRWriteByInstr);
 387
 388     err |= !valid_user_regs(env);
 389
 390     return err;
 391 }
 392
 393 static abi_ulong *restore_sigframe_vfp(CPUARMState *env, abi_ulong *regspace)
 394 {
 395     int i;
 396     abi_ulong magic, sz;
 397     uint32_t fpscr, fpexc;
 398     struct target_vfp_sigframe *vfpframe;
 399     vfpframe = (struct target_vfp_sigframe *)regspace;
 400
 401     __get_user(magic, &vfpframe->magic);
 402     __get_user(sz, &vfpframe->size);
 403     if (magic != TARGET_VFP_MAGIC || sz != sizeof(*vfpframe)) {
 404         return 0;
 405     }
 406     for (i = 0; i < 32; i++) {
 407         __get_user(*aa32_vfp_dreg(env, i), &vfpframe->ufp.fpregs[i]);
 408     }
 409     __get_user(fpscr, &vfpframe->ufp.fpscr);
 410     vfp_set_fpscr(env, fpscr);
 411     __get_user(fpexc, &vfpframe->ufp_exc.fpexc);
 412     /* Sanitise FPEXC: ensure VFP is enabled, FPINST2 is invalid
 413      * and the exception flag is cleared
 414      */
 415     fpexc |= (1 << 30);
 416     fpexc &= ~((1 << 31) | (1 << 28));
 417     env->vfp.xregs[ARM_VFP_FPEXC] = fpexc;
 418     __get_user(env->vfp.xregs[ARM_VFP_FPINST], &vfpframe->ufp_exc.fpinst);
 419     __get_user(env->vfp.xregs[ARM_VFP_FPINST2], &vfpframe->ufp_exc.fpinst2);
 420     return (abi_ulong*)(vfpframe + 1);
 421 }
 422
 423 static abi_ulong *restore_sigframe_iwmmxt(CPUARMState *env,
 424                                           abi_ulong *regspace)
 425 {
 426     int i;
 427     abi_ulong magic, sz;
 428     struct target_iwmmxt_sigframe *iwmmxtframe;
 429     iwmmxtframe = (struct target_iwmmxt_sigframe *)regspace;
 430
 431     __get_user(magic, &iwmmxtframe->magic);
 432     __get_user(sz, &iwmmxtframe->size);
 433     if (magic != TARGET_IWMMXT_MAGIC || sz != sizeof(*iwmmxtframe)) {
 434         return 0;
 435     }
 436     for (i = 0; i < 16; i++) {
 437         __get_user(env->iwmmxt.regs[i], &iwmmxtframe->regs[i]);
 438     }
 439     __get_user(env->vfp.xregs[ARM_IWMMXT_wCSSF], &iwmmxtframe->wcssf);
 440     __get_user(env->vfp.xregs[ARM_IWMMXT_wCASF], &iwmmxtframe->wcssf);
 441     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR0], &iwmmxtframe->wcgr0);
 442     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR1], &iwmmxtframe->wcgr1);
 443     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR2], &iwmmxtframe->wcgr2);
 444     __get_user(env->vfp.xregs[ARM_IWMMXT_wCGR3], &iwmmxtframe->wcgr3);
 445     return (abi_ulong*)(iwmmxtframe + 1);
 446 }
 447
 448 static int do_sigframe_return(CPUARMState *env,
 449                               target_ulong context_addr,
 450                               struct target_ucontext *uc)
 451 {
 452     sigset_t host_set;
 453     abi_ulong *regspace;
 454
 455     target_to_host_sigset(&host_set, &uc->tuc_sigmask);
 456     set_sigmask(&host_set);
 457
 458     if (restore_sigcontext(env, &uc->tuc_mcontext)) {
 459         return 1;
 460     }
 461
 462     /* Restore coprocessor signal frame */
 463     regspace = uc->tuc_regspace;
 464     if (cpu_isar_feature(aa32_vfp_simd, env_archcpu(env))) {
 465         regspace = restore_sigframe_vfp(env, regspace);
 466         if (!regspace) {
 467             return 1;
 468         }
 469     }
 470     if (arm_feature(env, ARM_FEATURE_IWMMXT)) {
 471         regspace = restore_sigframe_iwmmxt(env, regspace);
 472         if (!regspace) {
 473             return 1;
 474         }
 475     }
 476
 477     target_restore_altstack(&uc->tuc_stack, env);
 478
 479 #if 0
 480     /* Send SIGTRAP if we're single-stepping */
 481     if (ptrace_cancel_bpt(current))
 482         send_sig(SIGTRAP, current, 1);
 483 #endif
 484
 485     return 0;
 486 }
 487
 488 long do_sigreturn(CPUARMState *env)
 489 {
 490     abi_ulong frame_addr;
 491     struct sigframe *frame = NULL;
 492
 493     /*
 494      * Since we stacked the signal on a 64-bit boundary,
 495      * then 'sp' should be word aligned here.  If it's
 496      * not, then the user is trying to mess with us.
 497      */
 498     frame_addr = env->regs[13];
 499     trace_user_do_sigreturn(env, frame_addr);
 500     if (frame_addr & 7) {
 501         goto badframe;
 502     }
 503
 504     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
 505         goto badframe;
 506     }
 507
 508     if (do_sigframe_return(env,
 509                            frame_addr + offsetof(struct sigframe, uc),
 510                            &frame->uc)) {
 511         goto badframe;
 512     }
 513
 514     unlock_user_struct(frame, frame_addr, 0);
 515     return -QEMU_ESIGRETURN;
 516
 517 badframe:
 518     unlock_user_struct(frame, frame_addr, 0);
 519     force_sig(TARGET_SIGSEGV);
 520     return -QEMU_ESIGRETURN;
 521 }
 522
 523 long do_rt_sigreturn(CPUARMState *env)
 524 {
 525     abi_ulong frame_addr;
 526     struct rt_sigframe *frame = NULL;
 527
 528     /*
 529      * Since we stacked the signal on a 64-bit boundary,
 530      * then 'sp' should be word aligned here.  If it's
 531      * not, then the user is trying to mess with us.
 532      */
 533     frame_addr = env->regs[13];
 534     trace_user_do_rt_sigreturn(env, frame_addr);
 535     if (frame_addr & 7) {
 536         goto badframe;
 537     }
 538
 539     if (!lock_user_struct(VERIFY_READ, frame, frame_addr, 1)) {
 540         goto badframe;
 541     }
 542
 543     if (do_sigframe_return(env,
 544                            frame_addr + offsetof(struct rt_sigframe, sig.uc),
 545                            &frame->sig.uc)) {
 546         goto badframe;
 547     }
 548
 549     unlock_user_struct(frame, frame_addr, 0);
 550     return -QEMU_ESIGRETURN;
 551
 552 badframe:
 553     unlock_user_struct(frame, frame_addr, 0);
 554     force_sig(TARGET_SIGSEGV);
 555     return -QEMU_ESIGRETURN;
 556 }
 557
 558 /*
 559  * EABI syscalls pass the number via r7.
 560  * Note that the kernel still adds the OABI syscall number to the trap,
 561  * presumably for backward ABI compatibility with unwinders.
 562  */
 563 #define ARM_MOV_R7_IMM(X)       (0xe3a07000 | (X))
 564 #define ARM_SWI_SYS(X)          (0xef000000 | (X) | ARM_SYSCALL_BASE)
 565
 566 #define THUMB_MOVS_R7_IMM(X)    (0x2700 | (X))
 567 #define THUMB_SWI_SYS           0xdf00
 568
 569 static void write_arm_sigreturn(uint32_t *rc, int syscall)
 570 {
 571     __put_user(ARM_MOV_R7_IMM(syscall), rc);
 572     __put_user(ARM_SWI_SYS(syscall), rc + 1);
 573     /* Wrote 8 of 12 bytes */
 574 }
 575
 576 static void write_thm_sigreturn(uint32_t *rc, int syscall)
 577 {
 578     __put_user(THUMB_SWI_SYS << 16 | THUMB_MOVS_R7_IMM(syscall), rc);
 579     /* Wrote 4 of 12 bytes */
 580 }
 581
 582 /*
 583  * Stub needed to make sure the FD register (r9) contains the right value.
 584  * Use the same instruction sequence as the kernel.
 585  */
 586 static void write_arm_fdpic_sigreturn(uint32_t *rc, int ofs)
 587 {
 588     assert(ofs <= 0xfff);
 589     __put_user(0xe59d3000 | ofs, rc + 0);   /* ldr r3, [sp, #ofs] */
 590     __put_user(0xe8930908, rc + 1);         /* ldm r3, { r3, r9 } */
 591     __put_user(0xe12fff13, rc + 2);         /* bx  r3 */
 592     /* Wrote 12 of 12 bytes */
 593 }
 594
 595 static void write_thm_fdpic_sigreturn(void *vrc, int ofs)
 596 {
 597     uint16_t *rc = vrc;
 598
 599     assert((ofs & ~0x3fc) == 0);
 600     __put_user(0x9b00 | (ofs >> 2), rc + 0);      /* ldr r3, [sp, #ofs] */
 601     __put_user(0xcb0c, rc + 1);                   /* ldm r3, { r2, r3 } */
 602     __put_user(0x4699, rc + 2);                   /* mov r9, r3 */
 603     __put_user(0x4710, rc + 3);                   /* bx  r2 */
 604     /* Wrote 8 of 12 bytes */
 605 }
 606
 607 void setup_sigtramp(abi_ulong sigtramp_page)
 608 {
 609     uint32_t total_size = 8 * RETCODE_BYTES;
 610     uint32_t *tramp = lock_user(VERIFY_WRITE, sigtramp_page, total_size, 0);
 611
 612     assert(tramp != NULL);
 613
 614     default_sigreturn = sigtramp_page;
 615     write_arm_sigreturn(&tramp[0 * RETCODE_WORDS], TARGET_NR_sigreturn);
 616     write_thm_sigreturn(&tramp[1 * RETCODE_WORDS], TARGET_NR_sigreturn);
 617     write_arm_sigreturn(&tramp[2 * RETCODE_WORDS], TARGET_NR_rt_sigreturn);
 618     write_thm_sigreturn(&tramp[3 * RETCODE_WORDS], TARGET_NR_rt_sigreturn);
 619
 620     sigreturn_fdpic_tramp = sigtramp_page + 4 * RETCODE_BYTES;
 621     write_arm_fdpic_sigreturn(tramp + 4 * RETCODE_WORDS,
 622                               offsetof(struct sigframe, retcode[3]));
 623     write_thm_fdpic_sigreturn(tramp + 5 * RETCODE_WORDS,
 624                                 offsetof(struct sigframe, retcode[3]));
 625     write_arm_fdpic_sigreturn(tramp + 6 * RETCODE_WORDS,
 626                               offsetof(struct rt_sigframe, sig.retcode[3]));
 627     write_thm_fdpic_sigreturn(tramp + 7 * RETCODE_WORDS,
 628                               offsetof(struct rt_sigframe, sig.retcode[3]));
 629
 630     unlock_user(tramp, sigtramp_page, total_size);
 631 }