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   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*



  23  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26 
  27 /*      Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. */
  28 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989, 1990 AT&T   */
  29 /*      All Rights Reserved   */
  30 
  31 /*
  32  * Copyright 2023 Oxide Computer Company
  33  */
  34 
  35 #include <sys/types.h>
  36 #include <sys/param.h>
  37 #include <sys/sysmacros.h>
  38 #include <sys/signal.h>
  39 #include <sys/systm.h>
  40 #include <sys/user.h>
  41 #include <sys/mman.h>
  42 #include <sys/class.h>


  74 #include <vm/as.h>
  75 #include <vm/page.h>
  76 #include <vm/seg.h>
  77 #include <vm/seg_kmem.h>
  78 #include <vm/seg_map.h>
  79 #include <vm/seg_vn.h>
  80 #include <sys/exec.h>
  81 #include <sys/acct.h>
  82 #include <sys/core.h>
  83 #include <sys/corectl.h>
  84 #include <sys/modctl.h>
  85 #include <sys/tuneable.h>
  86 #include <c2/audit.h>
  87 #include <sys/bootconf.h>
  88 #include <sys/dumphdr.h>
  89 #include <sys/promif.h>
  90 #include <sys/systeminfo.h>
  91 #include <sys/kdi.h>
  92 #include <sys/contract_impl.h>
  93 #include <sys/x86_archext.h>


  94 
  95 /*
  96  * Construct the execution environment for the user's signal
  97  * handler and arrange for control to be given to it on return
  98  * to userland.  The library code now calls setcontext() to
  99  * clean up after the signal handler, so sigret() is no longer
 100  * needed.
 101  *
 102  * (The various 'volatile' declarations are need to ensure that values
 103  * are correct on the error return from on_fault().)
 104  */
 105 
 106 
 107 /*
 108  * An amd64 signal frame looks like this on the stack:
 109  *
 110  * old %rsp:
 111  *              <128 bytes of untouched stack space>
 112  *              <a siginfo_t [optional]>
 113  *              <a ucontext_t>


 187                 minstacksz += SA(sizeof (siginfo_t));
 188 
 189         if (fpu_xsave_enabled()) {
 190                 xsave_size = SA(fpu_signal_size(lwp));
 191                 minstacksz += xsave_size;
 192         } else {
 193                 xsave_size = 0;
 194         }
 195 
 196         ASSERT((minstacksz & (STACK_ENTRY_ALIGN - 1ul)) == 0);
 197 
 198         /*
 199          * Figure out whether we will be handling this signal on
 200          * an alternate stack specified by the user.  Then allocate
 201          * and validate the stack requirements for the signal handler
 202          * context.  on_fault will catch any faults.
 203          */
 204         newstack = sigismember(&PTOU(curproc)->u_sigonstack, sig) &&
 205             !(lwp->lwp_sigaltstack.ss_flags & (SS_ONSTACK|SS_DISABLE));
 206 
 207         if (newstack) {











 208                 fp = (caddr_t)(SA((uintptr_t)lwp->lwp_sigaltstack.ss_sp) +
 209                     SA(lwp->lwp_sigaltstack.ss_size) - STACK_ALIGN);
 210         } else {
 211                 /*
 212                  * Drop below the 128-byte reserved region of the stack frame
 213                  * we're interrupting.
 214                  */
 215                 fp = (caddr_t)rp->r_sp - STACK_RESERVE;
 216         }
 217 
 218         /*
 219          * Force proper stack pointer alignment, even in the face of a
 220          * misaligned stack pointer from user-level before the signal.
 221          */
 222         fp = (caddr_t)((uintptr_t)fp & ~(STACK_ENTRY_ALIGN - 1ul));
 223 
 224         /*
 225          * Most of the time during normal execution, the stack pointer
 226          * is aligned on a STACK_ALIGN (i.e. 16 byte) boundary.  However,
 227          * (for example) just after a call instruction (which pushes


 307          * ucontext_t and its %xmm registers. The xsave state part of the
 308          * ucontext_t may be inbetween these two. However, we have ensured that
 309          * the size of the stack space is 16-byte aligned as the actual size may
 310          * vary.
 311          */
 312         tuc = kmem_alloc(sizeof (*tuc), KM_SLEEP);
 313         if (xsave_size != 0) {
 314                 tuc->uc_xsave = (unsigned long)(sp + sizeof (struct sigframe));
 315         }
 316         uc = (ucontext_t *)(sp + sizeof (struct sigframe) + xsave_size);
 317         ret = savecontext(tuc, &lwp->lwp_sigoldmask, SAVECTXT_F_EXTD |
 318             SAVECTXT_F_ONFAULT);
 319         if (ret != 0)
 320                 goto postfault;
 321         if (on_fault(&ljb))
 322                 goto badstack;
 323         copyout_noerr(tuc, uc, sizeof (*tuc));
 324         kmem_free(tuc, sizeof (*tuc));
 325         tuc = NULL;
 326 


 327         lwp->lwp_oldcontext = (uintptr_t)uc;
 328 
 329         if (newstack) {
 330                 lwp->lwp_sigaltstack.ss_flags |= SS_ONSTACK;
 331                 if (lwp->lwp_ustack)
 332                         copyout_noerr(&lwp->lwp_sigaltstack,
 333                             (stack_t *)lwp->lwp_ustack, sizeof (stack_t));
 334         }
 335 
 336         /*
 337          * Set up signal handler return and stack linkage
 338          */
 339         {
 340                 struct sigframe frame;
 341 
 342                 /*
 343                  * ensure we never return "normally"
 344                  */
 345                 frame.retaddr = (caddr_t)(uintptr_t)-1L;
 346                 frame.signo = sig;


 356          * Set up user registers for execution of signal handler.
 357          */
 358         rp->r_sp = (greg_t)sp;
 359         rp->r_pc = (greg_t)hdlr;
 360         rp->r_ps = PSL_USER | (rp->r_ps & PS_IOPL);
 361 
 362         rp->r_rdi = sig;
 363         rp->r_rsi = (uintptr_t)sip_addr;
 364         rp->r_rdx = (uintptr_t)uc;
 365 
 366         if ((rp->r_cs & 0xffff) != UCS_SEL ||
 367             (rp->r_ss & 0xffff) != UDS_SEL) {
 368                 /*
 369                  * Try our best to deliver the signal.
 370                  */
 371                 rp->r_cs = UCS_SEL;
 372                 rp->r_ss = UDS_SEL;
 373         }
 374 
 375         /*








 376          * Don't set lwp_eosys here.  sendsig() is called via psig() after
 377          * lwp_eosys is handled, so setting it here would affect the next
 378          * system call.
 379          */
 380         return (1);
 381 
 382 badstack:
 383         no_fault();
 384 postfault:
 385         if (watched)
 386                 watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
 387         if (tuc)
 388                 kmem_free(tuc, sizeof (*tuc));
 389 #ifdef DEBUG
 390         printf("sendsig: bad signal stack cmd=%s, pid=%d, sig=%d\n",
 391             PTOU(p)->u_comm, p->p_pid, sig);
 392         printf("on fault, sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
 393             (void *)sp, (void *)hdlr, (uintptr_t)upc);
 394 #endif
 395         return (0);


 442         if (sip != NULL)
 443                 minstacksz += SA32(sizeof (siginfo32_t));
 444 
 445         if (fpu_xsave_enabled()) {
 446                 xsave_size = SA32(fpu_signal_size(lwp));
 447                 minstacksz += xsave_size;
 448         } else {
 449                 xsave_size = 0;
 450         }
 451         ASSERT((minstacksz & (STACK_ALIGN32 - 1)) == 0);
 452 
 453         /*
 454          * Figure out whether we will be handling this signal on
 455          * an alternate stack specified by the user.  Then allocate
 456          * and validate the stack requirements for the signal handler
 457          * context.  on_fault will catch any faults.
 458          */
 459         newstack = sigismember(&PTOU(curproc)->u_sigonstack, sig) &&
 460             !(lwp->lwp_sigaltstack.ss_flags & (SS_ONSTACK|SS_DISABLE));
 461 
 462         if (newstack) {










 463                 fp = (caddr_t)(SA32((uintptr_t)lwp->lwp_sigaltstack.ss_sp) +
 464                     SA32(lwp->lwp_sigaltstack.ss_size) - STACK_ALIGN32);
 465         } else if ((rp->r_ss & 0xffff) != UDS_SEL) {
 466                 user_desc_t *ldt;
 467                 /*
 468                  * If the stack segment selector is -not- pointing at
 469                  * the UDS_SEL descriptor and we have an LDT entry for
 470                  * it instead, add the base address to find the effective va.
 471                  */
 472                 if ((ldt = p->p_ldt) != NULL)
 473                         fp = (caddr_t)rp->r_sp +
 474                             USEGD_GETBASE(&ldt[SELTOIDX(rp->r_ss)]);
 475                 else
 476                         fp = (caddr_t)rp->r_sp;
 477         } else
 478                 fp = (caddr_t)rp->r_sp;

 479 
 480         /*
 481          * Force proper stack pointer alignment, even in the face of a
 482          * misaligned stack pointer from user-level before the signal.
 483          * Don't use the SA32() macro because that rounds up, not down.
 484          */
 485         fp = (caddr_t)((uintptr_t)fp & ~(STACK_ALIGN32 - 1));
 486         sp = fp - minstacksz;
 487 
 488         /*
 489          * Make sure lwp hasn't trashed its stack
 490          */
 491         if (sp >= (caddr_t)(uintptr_t)USERLIMIT32 ||
 492             fp >= (caddr_t)(uintptr_t)USERLIMIT32) {
 493 #ifdef DEBUG
 494                 printf("sendsig32: bad signal stack cmd=%s, pid=%d, sig=%d\n",
 495                     PTOU(p)->u_comm, p->p_pid, sig);
 496                 printf("sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
 497                     (void *)sp, (void *)hdlr, (uintptr_t)upc);
 498                 printf("sp above USERLIMIT\n");


 546         no_fault();
 547 
 548         /* save the current context on the user stack */
 549         tuc = kmem_alloc(sizeof (*tuc), KM_SLEEP);
 550         fp -= SA32(sizeof (*tuc));
 551         uc = (ucontext32_t *)fp;
 552         if (xsave_size != 0) {
 553                 fp -= xsave_size;
 554                 tuc->uc_xsave = (int32_t)(uintptr_t)fp;
 555         }
 556         ret = savecontext32(tuc, &lwp->lwp_sigoldmask, SAVECTXT_F_EXTD |
 557             SAVECTXT_F_ONFAULT);
 558         if (ret != 0)
 559                 goto postfault;
 560         if (on_fault(&ljb))
 561                 goto badstack;
 562         copyout_noerr(tuc, uc, sizeof (*tuc));
 563         kmem_free(tuc, sizeof (*tuc));
 564         tuc = NULL;
 565 


 566         lwp->lwp_oldcontext = (uintptr_t)uc;
 567 
 568         if (newstack) {
 569                 lwp->lwp_sigaltstack.ss_flags |= SS_ONSTACK;
 570                 if (lwp->lwp_ustack) {
 571                         stack32_t stk32;
 572 
 573                         stk32.ss_sp = (caddr32_t)(uintptr_t)
 574                             lwp->lwp_sigaltstack.ss_sp;
 575                         stk32.ss_size = (size32_t)
 576                             lwp->lwp_sigaltstack.ss_size;
 577                         stk32.ss_flags = (int32_t)
 578                             lwp->lwp_sigaltstack.ss_flags;
 579                         copyout_noerr(&stk32,
 580                             (stack32_t *)lwp->lwp_ustack, sizeof (stk32));
 581                 }
 582         }
 583 
 584         /*
 585          * Set up signal handler arguments


 594                 copyout_noerr(&frame32, sp, sizeof (frame32));
 595         }
 596 
 597         no_fault();
 598         if (watched)
 599                 watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
 600 
 601         rp->r_sp = (greg_t)(uintptr_t)sp;
 602         rp->r_pc = (greg_t)(uintptr_t)hdlr;
 603         rp->r_ps = PSL_USER | (rp->r_ps & PS_IOPL);
 604 
 605         if ((rp->r_cs & 0xffff) != U32CS_SEL ||
 606             (rp->r_ss & 0xffff) != UDS_SEL) {
 607                 /*
 608                  * Try our best to deliver the signal.
 609                  */
 610                 rp->r_cs = U32CS_SEL;
 611                 rp->r_ss = UDS_SEL;
 612         }
 613 








 614         /*
 615          * Don't set lwp_eosys here.  sendsig() is called via psig() after
 616          * lwp_eosys is handled, so setting it here would affect the next
 617          * system call.
 618          */
 619         return (1);
 620 
 621 badstack:
 622         no_fault();
 623 postfault:
 624         if (watched)
 625                 watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
 626         if (tuc)
 627                 kmem_free(tuc, sizeof (*tuc));
 628 #ifdef DEBUG
 629         printf("sendsig32: bad signal stack cmd=%s pid=%d, sig=%d\n",
 630             PTOU(p)->u_comm, p->p_pid, sig);
 631         printf("on fault, sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
 632             (void *)sp, (void *)hdlr, (uintptr_t)upc);
 633 #endif


   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21 
  22 /*
  23  * Copyright 2015 Joyent, Inc.
  24  */
  25 /*
  26  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  27  * Use is subject to license terms.
  28  */
  29 
  30 /*      Copyright (c) 1990, 1991 UNIX System Laboratories, Inc. */
  31 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989, 1990 AT&T   */
  32 /*      All Rights Reserved   */
  33 
  34 /*
  35  * Copyright 2023 Oxide Computer Company
  36  */
  37 
  38 #include <sys/types.h>
  39 #include <sys/param.h>
  40 #include <sys/sysmacros.h>
  41 #include <sys/signal.h>
  42 #include <sys/systm.h>
  43 #include <sys/user.h>
  44 #include <sys/mman.h>
  45 #include <sys/class.h>


  77 #include <vm/as.h>
  78 #include <vm/page.h>
  79 #include <vm/seg.h>
  80 #include <vm/seg_kmem.h>
  81 #include <vm/seg_map.h>
  82 #include <vm/seg_vn.h>
  83 #include <sys/exec.h>
  84 #include <sys/acct.h>
  85 #include <sys/core.h>
  86 #include <sys/corectl.h>
  87 #include <sys/modctl.h>
  88 #include <sys/tuneable.h>
  89 #include <c2/audit.h>
  90 #include <sys/bootconf.h>
  91 #include <sys/dumphdr.h>
  92 #include <sys/promif.h>
  93 #include <sys/systeminfo.h>
  94 #include <sys/kdi.h>
  95 #include <sys/contract_impl.h>
  96 #include <sys/x86_archext.h>
  97 #include <sys/brand.h>
  98 #include <sys/sdt.h>
  99 
 100 /*
 101  * Construct the execution environment for the user's signal
 102  * handler and arrange for control to be given to it on return
 103  * to userland.  The library code now calls setcontext() to
 104  * clean up after the signal handler, so sigret() is no longer
 105  * needed.
 106  *
 107  * (The various 'volatile' declarations are need to ensure that values
 108  * are correct on the error return from on_fault().)
 109  */
 110 
 111 
 112 /*
 113  * An amd64 signal frame looks like this on the stack:
 114  *
 115  * old %rsp:
 116  *              <128 bytes of untouched stack space>
 117  *              <a siginfo_t [optional]>
 118  *              <a ucontext_t>


 192                 minstacksz += SA(sizeof (siginfo_t));
 193 
 194         if (fpu_xsave_enabled()) {
 195                 xsave_size = SA(fpu_signal_size(lwp));
 196                 minstacksz += xsave_size;
 197         } else {
 198                 xsave_size = 0;
 199         }
 200 
 201         ASSERT((minstacksz & (STACK_ENTRY_ALIGN - 1ul)) == 0);
 202 
 203         /*
 204          * Figure out whether we will be handling this signal on
 205          * an alternate stack specified by the user.  Then allocate
 206          * and validate the stack requirements for the signal handler
 207          * context.  on_fault will catch any faults.
 208          */
 209         newstack = sigismember(&PTOU(curproc)->u_sigonstack, sig) &&
 210             !(lwp->lwp_sigaltstack.ss_flags & (SS_ONSTACK|SS_DISABLE));
 211 
 212         /*
 213          * If this is a branded process, the brand may provide an alternate
 214          * stack pointer for signal delivery:
 215          */
 216         if (PROC_IS_BRANDED(p) && BROP(p)->b_sendsig_stack != NULL) {
 217                 /*
 218                  * Use the stack pointer value provided by the brand,
 219                  * accounting for the 128-byte reserved region.
 220                  */
 221                 newstack = 0;
 222                 fp = BROP(p)->b_sendsig_stack(sig) - STACK_RESERVE;
 223         } else if (newstack) {
 224                 fp = (caddr_t)(SA((uintptr_t)lwp->lwp_sigaltstack.ss_sp) +
 225                     SA(lwp->lwp_sigaltstack.ss_size) - STACK_ALIGN);
 226         } else {
 227                 /*
 228                  * Drop below the 128-byte reserved region of the stack frame
 229                  * we're interrupting.
 230                  */
 231                 fp = (caddr_t)rp->r_sp - STACK_RESERVE;
 232         }
 233 
 234         /*
 235          * Force proper stack pointer alignment, even in the face of a
 236          * misaligned stack pointer from user-level before the signal.
 237          */
 238         fp = (caddr_t)((uintptr_t)fp & ~(STACK_ENTRY_ALIGN - 1ul));
 239 
 240         /*
 241          * Most of the time during normal execution, the stack pointer
 242          * is aligned on a STACK_ALIGN (i.e. 16 byte) boundary.  However,
 243          * (for example) just after a call instruction (which pushes


 323          * ucontext_t and its %xmm registers. The xsave state part of the
 324          * ucontext_t may be inbetween these two. However, we have ensured that
 325          * the size of the stack space is 16-byte aligned as the actual size may
 326          * vary.
 327          */
 328         tuc = kmem_alloc(sizeof (*tuc), KM_SLEEP);
 329         if (xsave_size != 0) {
 330                 tuc->uc_xsave = (unsigned long)(sp + sizeof (struct sigframe));
 331         }
 332         uc = (ucontext_t *)(sp + sizeof (struct sigframe) + xsave_size);
 333         ret = savecontext(tuc, &lwp->lwp_sigoldmask, SAVECTXT_F_EXTD |
 334             SAVECTXT_F_ONFAULT);
 335         if (ret != 0)
 336                 goto postfault;
 337         if (on_fault(&ljb))
 338                 goto badstack;
 339         copyout_noerr(tuc, uc, sizeof (*tuc));
 340         kmem_free(tuc, sizeof (*tuc));
 341         tuc = NULL;
 342 
 343         DTRACE_PROBE3(oldcontext__set, klwp_t *, lwp,
 344             uintptr_t, lwp->lwp_oldcontext, uintptr_t, (uintptr_t)uc);
 345         lwp->lwp_oldcontext = (uintptr_t)uc;
 346 
 347         if (newstack) {
 348                 lwp->lwp_sigaltstack.ss_flags |= SS_ONSTACK;
 349                 if (lwp->lwp_ustack)
 350                         copyout_noerr(&lwp->lwp_sigaltstack,
 351                             (stack_t *)lwp->lwp_ustack, sizeof (stack_t));
 352         }
 353 
 354         /*
 355          * Set up signal handler return and stack linkage
 356          */
 357         {
 358                 struct sigframe frame;
 359 
 360                 /*
 361                  * ensure we never return "normally"
 362                  */
 363                 frame.retaddr = (caddr_t)(uintptr_t)-1L;
 364                 frame.signo = sig;


 374          * Set up user registers for execution of signal handler.
 375          */
 376         rp->r_sp = (greg_t)sp;
 377         rp->r_pc = (greg_t)hdlr;
 378         rp->r_ps = PSL_USER | (rp->r_ps & PS_IOPL);
 379 
 380         rp->r_rdi = sig;
 381         rp->r_rsi = (uintptr_t)sip_addr;
 382         rp->r_rdx = (uintptr_t)uc;
 383 
 384         if ((rp->r_cs & 0xffff) != UCS_SEL ||
 385             (rp->r_ss & 0xffff) != UDS_SEL) {
 386                 /*
 387                  * Try our best to deliver the signal.
 388                  */
 389                 rp->r_cs = UCS_SEL;
 390                 rp->r_ss = UDS_SEL;
 391         }
 392 
 393         /*
 394          * Allow the brand to perform additional book-keeping once the signal
 395          * handling frame has been fully assembled:
 396          */
 397         if (PROC_IS_BRANDED(p) && BROP(p)->b_sendsig != NULL) {
 398                 BROP(p)->b_sendsig(sig);
 399         }
 400 
 401         /*
 402          * Don't set lwp_eosys here.  sendsig() is called via psig() after
 403          * lwp_eosys is handled, so setting it here would affect the next
 404          * system call.
 405          */
 406         return (1);
 407 
 408 badstack:
 409         no_fault();
 410 postfault:
 411         if (watched)
 412                 watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
 413         if (tuc)
 414                 kmem_free(tuc, sizeof (*tuc));
 415 #ifdef DEBUG
 416         printf("sendsig: bad signal stack cmd=%s, pid=%d, sig=%d\n",
 417             PTOU(p)->u_comm, p->p_pid, sig);
 418         printf("on fault, sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
 419             (void *)sp, (void *)hdlr, (uintptr_t)upc);
 420 #endif
 421         return (0);


 468         if (sip != NULL)
 469                 minstacksz += SA32(sizeof (siginfo32_t));
 470 
 471         if (fpu_xsave_enabled()) {
 472                 xsave_size = SA32(fpu_signal_size(lwp));
 473                 minstacksz += xsave_size;
 474         } else {
 475                 xsave_size = 0;
 476         }
 477         ASSERT((minstacksz & (STACK_ALIGN32 - 1)) == 0);
 478 
 479         /*
 480          * Figure out whether we will be handling this signal on
 481          * an alternate stack specified by the user.  Then allocate
 482          * and validate the stack requirements for the signal handler
 483          * context.  on_fault will catch any faults.
 484          */
 485         newstack = sigismember(&PTOU(curproc)->u_sigonstack, sig) &&
 486             !(lwp->lwp_sigaltstack.ss_flags & (SS_ONSTACK|SS_DISABLE));
 487 
 488         /*
 489          * If this is a branded process, the brand may provide an alternate
 490          * stack pointer for signal delivery:
 491          */
 492         if (PROC_IS_BRANDED(p) && BROP(p)->b_sendsig_stack != NULL) {
 493                 /*
 494                  * Use the stack pointer value provided by the brand:
 495                  */
 496                 newstack = 0;
 497                 fp = BROP(p)->b_sendsig_stack(sig);
 498         } else if (newstack) {
 499                 fp = (caddr_t)(SA32((uintptr_t)lwp->lwp_sigaltstack.ss_sp) +
 500                     SA32(lwp->lwp_sigaltstack.ss_size) - STACK_ALIGN32);
 501         } else if ((rp->r_ss & 0xffff) != UDS_SEL) {
 502                 user_desc_t *ldt;
 503                 /*
 504                  * If the stack segment selector is -not- pointing at
 505                  * the UDS_SEL descriptor and we have an LDT entry for
 506                  * it instead, add the base address to find the effective va.
 507                  */
 508                 if ((ldt = p->p_ldt) != NULL)
 509                         fp = (caddr_t)rp->r_sp +
 510                             USEGD_GETBASE(&ldt[SELTOIDX(rp->r_ss)]);
 511                 else
 512                         fp = (caddr_t)rp->r_sp;
 513         } else {
 514                 fp = (caddr_t)rp->r_sp;
 515         }
 516 
 517         /*
 518          * Force proper stack pointer alignment, even in the face of a
 519          * misaligned stack pointer from user-level before the signal.
 520          * Don't use the SA32() macro because that rounds up, not down.
 521          */
 522         fp = (caddr_t)((uintptr_t)fp & ~(STACK_ALIGN32 - 1));
 523         sp = fp - minstacksz;
 524 
 525         /*
 526          * Make sure lwp hasn't trashed its stack
 527          */
 528         if (sp >= (caddr_t)(uintptr_t)USERLIMIT32 ||
 529             fp >= (caddr_t)(uintptr_t)USERLIMIT32) {
 530 #ifdef DEBUG
 531                 printf("sendsig32: bad signal stack cmd=%s, pid=%d, sig=%d\n",
 532                     PTOU(p)->u_comm, p->p_pid, sig);
 533                 printf("sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
 534                     (void *)sp, (void *)hdlr, (uintptr_t)upc);
 535                 printf("sp above USERLIMIT\n");


 583         no_fault();
 584 
 585         /* save the current context on the user stack */
 586         tuc = kmem_alloc(sizeof (*tuc), KM_SLEEP);
 587         fp -= SA32(sizeof (*tuc));
 588         uc = (ucontext32_t *)fp;
 589         if (xsave_size != 0) {
 590                 fp -= xsave_size;
 591                 tuc->uc_xsave = (int32_t)(uintptr_t)fp;
 592         }
 593         ret = savecontext32(tuc, &lwp->lwp_sigoldmask, SAVECTXT_F_EXTD |
 594             SAVECTXT_F_ONFAULT);
 595         if (ret != 0)
 596                 goto postfault;
 597         if (on_fault(&ljb))
 598                 goto badstack;
 599         copyout_noerr(tuc, uc, sizeof (*tuc));
 600         kmem_free(tuc, sizeof (*tuc));
 601         tuc = NULL;
 602 
 603         DTRACE_PROBE3(oldcontext__set, klwp_t *, lwp,
 604             uintptr_t, lwp->lwp_oldcontext, uintptr_t, (uintptr_t)uc);
 605         lwp->lwp_oldcontext = (uintptr_t)uc;
 606 
 607         if (newstack) {
 608                 lwp->lwp_sigaltstack.ss_flags |= SS_ONSTACK;
 609                 if (lwp->lwp_ustack) {
 610                         stack32_t stk32;
 611 
 612                         stk32.ss_sp = (caddr32_t)(uintptr_t)
 613                             lwp->lwp_sigaltstack.ss_sp;
 614                         stk32.ss_size = (size32_t)
 615                             lwp->lwp_sigaltstack.ss_size;
 616                         stk32.ss_flags = (int32_t)
 617                             lwp->lwp_sigaltstack.ss_flags;
 618                         copyout_noerr(&stk32,
 619                             (stack32_t *)lwp->lwp_ustack, sizeof (stk32));
 620                 }
 621         }
 622 
 623         /*
 624          * Set up signal handler arguments


 633                 copyout_noerr(&frame32, sp, sizeof (frame32));
 634         }
 635 
 636         no_fault();
 637         if (watched)
 638                 watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
 639 
 640         rp->r_sp = (greg_t)(uintptr_t)sp;
 641         rp->r_pc = (greg_t)(uintptr_t)hdlr;
 642         rp->r_ps = PSL_USER | (rp->r_ps & PS_IOPL);
 643 
 644         if ((rp->r_cs & 0xffff) != U32CS_SEL ||
 645             (rp->r_ss & 0xffff) != UDS_SEL) {
 646                 /*
 647                  * Try our best to deliver the signal.
 648                  */
 649                 rp->r_cs = U32CS_SEL;
 650                 rp->r_ss = UDS_SEL;
 651         }
 652 
 653         /*
 654          * Allow the brand to perform additional book-keeping once the signal
 655          * handling frame has been fully assembled:
 656          */
 657         if (PROC_IS_BRANDED(p) && BROP(p)->b_sendsig != NULL) {
 658                 BROP(p)->b_sendsig(sig);
 659         }
 660 
 661         /*
 662          * Don't set lwp_eosys here.  sendsig() is called via psig() after
 663          * lwp_eosys is handled, so setting it here would affect the next
 664          * system call.
 665          */
 666         return (1);
 667 
 668 badstack:
 669         no_fault();
 670 postfault:
 671         if (watched)
 672                 watch_enable_addr((caddr_t)sp, minstacksz, S_WRITE);
 673         if (tuc)
 674                 kmem_free(tuc, sizeof (*tuc));
 675 #ifdef DEBUG
 676         printf("sendsig32: bad signal stack cmd=%s pid=%d, sig=%d\n",
 677             PTOU(p)->u_comm, p->p_pid, sig);
 678         printf("on fault, sigsp = 0x%p, action = 0x%p, upc = 0x%lx\n",
 679             (void *)sp, (void *)hdlr, (uintptr_t)upc);
 680 #endif