The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/trap.c

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    1 /*-
    2  * Copyright (C) 1994, David Greenman
    3  * Copyright (c) 1990, 1993
    4  *      The Regents of the University of California.  All rights reserved.
    5  *
    6  * This code is derived from software contributed to Berkeley by
    7  * the University of Utah, and William Jolitz.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. All advertising materials mentioning features or use of this software
   18  *    must display the following acknowledgement:
   19  *      This product includes software developed by the University of
   20  *      California, Berkeley and its contributors.
   21  * 4. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      from: @(#)trap.c        7.4 (Berkeley) 5/13/91
   38  */
   39 
   40 #include <sys/cdefs.h>
   41 __FBSDID("$FreeBSD: releng/11.2/sys/amd64/amd64/trap.c 333369 2018-05-08 17:03:33Z emaste $");
   42 
   43 /*
   44  * AMD64 Trap and System call handling
   45  */
   46 
   47 #include "opt_clock.h"
   48 #include "opt_compat.h"
   49 #include "opt_cpu.h"
   50 #include "opt_hwpmc_hooks.h"
   51 #include "opt_isa.h"
   52 #include "opt_kdb.h"
   53 #include "opt_stack.h"
   54 
   55 #include <sys/param.h>
   56 #include <sys/bus.h>
   57 #include <sys/systm.h>
   58 #include <sys/proc.h>
   59 #include <sys/pioctl.h>
   60 #include <sys/ptrace.h>
   61 #include <sys/kdb.h>
   62 #include <sys/kernel.h>
   63 #include <sys/ktr.h>
   64 #include <sys/lock.h>
   65 #include <sys/mutex.h>
   66 #include <sys/resourcevar.h>
   67 #include <sys/signalvar.h>
   68 #include <sys/syscall.h>
   69 #include <sys/sysctl.h>
   70 #include <sys/sysent.h>
   71 #include <sys/uio.h>
   72 #include <sys/vmmeter.h>
   73 #ifdef HWPMC_HOOKS
   74 #include <sys/pmckern.h>
   75 PMC_SOFT_DEFINE( , , page_fault, all);
   76 PMC_SOFT_DEFINE( , , page_fault, read);
   77 PMC_SOFT_DEFINE( , , page_fault, write);
   78 #endif
   79 
   80 #include <vm/vm.h>
   81 #include <vm/vm_param.h>
   82 #include <vm/pmap.h>
   83 #include <vm/vm_kern.h>
   84 #include <vm/vm_map.h>
   85 #include <vm/vm_page.h>
   86 #include <vm/vm_extern.h>
   87 
   88 #include <machine/cpu.h>
   89 #include <machine/intr_machdep.h>
   90 #include <x86/mca.h>
   91 #include <machine/md_var.h>
   92 #include <machine/pcb.h>
   93 #ifdef SMP
   94 #include <machine/smp.h>
   95 #endif
   96 #include <machine/stack.h>
   97 #include <machine/tss.h>
   98 
   99 #ifdef KDTRACE_HOOKS
  100 #include <sys/dtrace_bsd.h>
  101 #endif
  102 
  103 extern inthand_t IDTVEC(bpt), IDTVEC(bpt_pti), IDTVEC(dbg),
  104     IDTVEC(fast_syscall), IDTVEC(fast_syscall_pti), IDTVEC(fast_syscall32),
  105     IDTVEC(int0x80_syscall_pti), IDTVEC(int0x80_syscall);
  106 
  107 void __noinline trap(struct trapframe *frame);
  108 void trap_check(struct trapframe *frame);
  109 void dblfault_handler(struct trapframe *frame);
  110 
  111 static int trap_pfault(struct trapframe *, int);
  112 static void trap_fatal(struct trapframe *, vm_offset_t);
  113 
  114 #define MAX_TRAP_MSG            32
  115 static char *trap_msg[] = {
  116         "",                                     /*  0 unused */
  117         "privileged instruction fault",         /*  1 T_PRIVINFLT */
  118         "",                                     /*  2 unused */
  119         "breakpoint instruction fault",         /*  3 T_BPTFLT */
  120         "",                                     /*  4 unused */
  121         "",                                     /*  5 unused */
  122         "arithmetic trap",                      /*  6 T_ARITHTRAP */
  123         "",                                     /*  7 unused */
  124         "",                                     /*  8 unused */
  125         "general protection fault",             /*  9 T_PROTFLT */
  126         "trace trap",                           /* 10 T_TRCTRAP */
  127         "",                                     /* 11 unused */
  128         "page fault",                           /* 12 T_PAGEFLT */
  129         "",                                     /* 13 unused */
  130         "alignment fault",                      /* 14 T_ALIGNFLT */
  131         "",                                     /* 15 unused */
  132         "",                                     /* 16 unused */
  133         "",                                     /* 17 unused */
  134         "integer divide fault",                 /* 18 T_DIVIDE */
  135         "non-maskable interrupt trap",          /* 19 T_NMI */
  136         "overflow trap",                        /* 20 T_OFLOW */
  137         "FPU bounds check fault",               /* 21 T_BOUND */
  138         "FPU device not available",             /* 22 T_DNA */
  139         "double fault",                         /* 23 T_DOUBLEFLT */
  140         "FPU operand fetch fault",              /* 24 T_FPOPFLT */
  141         "invalid TSS fault",                    /* 25 T_TSSFLT */
  142         "segment not present fault",            /* 26 T_SEGNPFLT */
  143         "stack fault",                          /* 27 T_STKFLT */
  144         "machine check trap",                   /* 28 T_MCHK */
  145         "SIMD floating-point exception",        /* 29 T_XMMFLT */
  146         "reserved (unknown) fault",             /* 30 T_RESERVED */
  147         "",                                     /* 31 unused (reserved) */
  148         "DTrace pid return trap",               /* 32 T_DTRACE_RET */
  149 };
  150 
  151 static int prot_fault_translation;
  152 SYSCTL_INT(_machdep, OID_AUTO, prot_fault_translation, CTLFLAG_RWTUN,
  153     &prot_fault_translation, 0,
  154     "Select signal to deliver on protection fault");
  155 static int uprintf_signal;
  156 SYSCTL_INT(_machdep, OID_AUTO, uprintf_signal, CTLFLAG_RWTUN,
  157     &uprintf_signal, 0,
  158     "Print debugging information on trap signal to ctty");
  159 
  160 /*
  161  * Exception, fault, and trap interface to the FreeBSD kernel.
  162  * This common code is called from assembly language IDT gate entry
  163  * routines that prepare a suitable stack frame, and restore this
  164  * frame after the exception has been processed.
  165  */
  166 
  167 void
  168 trap(struct trapframe *frame)
  169 {
  170         ksiginfo_t ksi;
  171         struct thread *td;
  172         struct proc *p;
  173         register_t addr;
  174 #ifdef KDB
  175         register_t dr6;
  176 #endif
  177         int signo, ucode;
  178         u_int type;
  179 
  180         td = curthread;
  181         p = td->td_proc;
  182         signo = 0;
  183         ucode = 0;
  184         addr = 0;
  185 
  186         PCPU_INC(cnt.v_trap);
  187         type = frame->tf_trapno;
  188 
  189 #ifdef SMP
  190         /* Handler for NMI IPIs used for stopping CPUs. */
  191         if (type == T_NMI && ipi_nmi_handler() == 0)
  192                 return;
  193 #endif
  194 
  195 #ifdef KDB
  196         if (kdb_active) {
  197                 kdb_reenter();
  198                 return;
  199         }
  200 #endif
  201 
  202         if (type == T_RESERVED) {
  203                 trap_fatal(frame, 0);
  204                 return;
  205         }
  206 
  207         if (type == T_NMI) {
  208 #ifdef HWPMC_HOOKS
  209                 /*
  210                  * CPU PMCs interrupt using an NMI.  If the PMC module is
  211                  * active, pass the 'rip' value to the PMC module's interrupt
  212                  * handler.  A non-zero return value from the handler means that
  213                  * the NMI was consumed by it and we can return immediately.
  214                  */
  215                 if (pmc_intr != NULL &&
  216                     (*pmc_intr)(PCPU_GET(cpuid), frame) != 0)
  217                         return;
  218 #endif
  219 
  220 #ifdef STACK
  221                 if (stack_nmi_handler(frame) != 0)
  222                         return;
  223 #endif
  224         }
  225 
  226         if ((frame->tf_rflags & PSL_I) == 0) {
  227                 /*
  228                  * Buggy application or kernel code has disabled
  229                  * interrupts and then trapped.  Enabling interrupts
  230                  * now is wrong, but it is better than running with
  231                  * interrupts disabled until they are accidentally
  232                  * enabled later.
  233                  */
  234                 if (TRAPF_USERMODE(frame))
  235                         uprintf(
  236                             "pid %ld (%s): trap %d with interrupts disabled\n",
  237                             (long)curproc->p_pid, curthread->td_name, type);
  238                 else if (type != T_NMI && type != T_BPTFLT &&
  239                     type != T_TRCTRAP) {
  240                         /*
  241                          * XXX not quite right, since this may be for a
  242                          * multiple fault in user mode.
  243                          */
  244                         printf("kernel trap %d with interrupts disabled\n",
  245                             type);
  246 
  247                         /*
  248                          * We shouldn't enable interrupts while holding a
  249                          * spin lock.
  250                          */
  251                         if (td->td_md.md_spinlock_count == 0)
  252                                 enable_intr();
  253                 }
  254         }
  255 
  256         if (TRAPF_USERMODE(frame)) {
  257                 /* user trap */
  258 
  259                 td->td_pticks = 0;
  260                 td->td_frame = frame;
  261                 addr = frame->tf_rip;
  262                 if (td->td_cowgen != p->p_cowgen)
  263                         thread_cow_update(td);
  264 
  265                 switch (type) {
  266                 case T_PRIVINFLT:       /* privileged instruction fault */
  267                         signo = SIGILL;
  268                         ucode = ILL_PRVOPC;
  269                         break;
  270 
  271                 case T_BPTFLT:          /* bpt instruction fault */
  272                 case T_TRCTRAP:         /* trace trap */
  273                         enable_intr();
  274 #ifdef KDTRACE_HOOKS
  275                         if (type == T_BPTFLT) {
  276                                 if (dtrace_pid_probe_ptr != NULL &&
  277                                     dtrace_pid_probe_ptr(frame) == 0)
  278                                         return;
  279                         }
  280 #endif
  281                         frame->tf_rflags &= ~PSL_T;
  282                         signo = SIGTRAP;
  283                         ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT);
  284                         break;
  285 
  286                 case T_ARITHTRAP:       /* arithmetic trap */
  287                         ucode = fputrap_x87();
  288                         if (ucode == -1)
  289                                 return;
  290                         signo = SIGFPE;
  291                         break;
  292 
  293                 case T_PROTFLT:         /* general protection fault */
  294                         signo = SIGBUS;
  295                         ucode = BUS_OBJERR;
  296                         break;
  297                 case T_STKFLT:          /* stack fault */
  298                 case T_SEGNPFLT:        /* segment not present fault */
  299                         signo = SIGBUS;
  300                         ucode = BUS_ADRERR;
  301                         break;
  302                 case T_TSSFLT:          /* invalid TSS fault */
  303                         signo = SIGBUS;
  304                         ucode = BUS_OBJERR;
  305                         break;
  306                 case T_ALIGNFLT:
  307                         signo = SIGBUS;
  308                         ucode = BUS_ADRALN;
  309                         break;
  310                 case T_DOUBLEFLT:       /* double fault */
  311                 default:
  312                         signo = SIGBUS;
  313                         ucode = BUS_OBJERR;
  314                         break;
  315 
  316                 case T_PAGEFLT:         /* page fault */
  317                         /*
  318                          * Emulator can take care about this trap?
  319                          */
  320                         if (*p->p_sysent->sv_trap != NULL &&
  321                             (*p->p_sysent->sv_trap)(td) == 0)
  322                                 return;
  323 
  324                         addr = frame->tf_addr;
  325                         signo = trap_pfault(frame, TRUE);
  326                         if (signo == -1)
  327                                 return;
  328                         if (signo == 0)
  329                                 goto userret;
  330                         if (signo == SIGSEGV) {
  331                                 ucode = SEGV_MAPERR;
  332                         } else if (prot_fault_translation == 0) {
  333                                 /*
  334                                  * Autodetect.  This check also covers
  335                                  * the images without the ABI-tag ELF
  336                                  * note.
  337                                  */
  338                                 if (SV_CURPROC_ABI() == SV_ABI_FREEBSD &&
  339                                     p->p_osrel >= P_OSREL_SIGSEGV) {
  340                                         signo = SIGSEGV;
  341                                         ucode = SEGV_ACCERR;
  342                                 } else {
  343                                         signo = SIGBUS;
  344                                         ucode = BUS_PAGE_FAULT;
  345                                 }
  346                         } else if (prot_fault_translation == 1) {
  347                                 /*
  348                                  * Always compat mode.
  349                                  */
  350                                 signo = SIGBUS;
  351                                 ucode = BUS_PAGE_FAULT;
  352                         } else {
  353                                 /*
  354                                  * Always SIGSEGV mode.
  355                                  */
  356                                 signo = SIGSEGV;
  357                                 ucode = SEGV_ACCERR;
  358                         }
  359                         break;
  360 
  361                 case T_DIVIDE:          /* integer divide fault */
  362                         ucode = FPE_INTDIV;
  363                         signo = SIGFPE;
  364                         break;
  365 
  366 #ifdef DEV_ISA
  367                 case T_NMI:
  368                         nmi_handle_intr(type, frame);
  369                         return;
  370 #endif
  371 
  372                 case T_OFLOW:           /* integer overflow fault */
  373                         ucode = FPE_INTOVF;
  374                         signo = SIGFPE;
  375                         break;
  376 
  377                 case T_BOUND:           /* bounds check fault */
  378                         ucode = FPE_FLTSUB;
  379                         signo = SIGFPE;
  380                         break;
  381 
  382                 case T_DNA:
  383                         /* transparent fault (due to context switch "late") */
  384                         KASSERT(PCB_USER_FPU(td->td_pcb),
  385                             ("kernel FPU ctx has leaked"));
  386                         fpudna();
  387                         return;
  388 
  389                 case T_FPOPFLT:         /* FPU operand fetch fault */
  390                         ucode = ILL_COPROC;
  391                         signo = SIGILL;
  392                         break;
  393 
  394                 case T_XMMFLT:          /* SIMD floating-point exception */
  395                         ucode = fputrap_sse();
  396                         if (ucode == -1)
  397                                 return;
  398                         signo = SIGFPE;
  399                         break;
  400 #ifdef KDTRACE_HOOKS
  401                 case T_DTRACE_RET:
  402                         enable_intr();
  403                         if (dtrace_return_probe_ptr != NULL)
  404                                 dtrace_return_probe_ptr(frame);
  405                         return;
  406 #endif
  407                 }
  408         } else {
  409                 /* kernel trap */
  410 
  411                 KASSERT(cold || td->td_ucred != NULL,
  412                     ("kernel trap doesn't have ucred"));
  413                 switch (type) {
  414                 case T_PAGEFLT:                 /* page fault */
  415                         (void) trap_pfault(frame, FALSE);
  416                         return;
  417 
  418                 case T_DNA:
  419                         if (PCB_USER_FPU(td->td_pcb))
  420                                 panic("Unregistered use of FPU in kernel");
  421                         fpudna();
  422                         return;
  423 
  424                 case T_ARITHTRAP:       /* arithmetic trap */
  425                 case T_XMMFLT:          /* SIMD floating-point exception */
  426                 case T_FPOPFLT:         /* FPU operand fetch fault */
  427                         /*
  428                          * For now, supporting kernel handler
  429                          * registration for FPU traps is overkill.
  430                          */
  431                         trap_fatal(frame, 0);
  432                         return;
  433 
  434                 case T_STKFLT:          /* stack fault */
  435                 case T_PROTFLT:         /* general protection fault */
  436                 case T_SEGNPFLT:        /* segment not present fault */
  437                         if (td->td_intr_nesting_level != 0)
  438                                 break;
  439 
  440                         /*
  441                          * Invalid segment selectors and out of bounds
  442                          * %rip's and %rsp's can be set up in user mode.
  443                          * This causes a fault in kernel mode when the
  444                          * kernel tries to return to user mode.  We want
  445                          * to get this fault so that we can fix the
  446                          * problem here and not have to check all the
  447                          * selectors and pointers when the user changes
  448                          * them.
  449                          *
  450                          * In case of PTI, the IRETQ faulted while the
  451                          * kernel used the pti stack, and exception
  452                          * frame records %rsp value pointing to that
  453                          * stack.  If we return normally to
  454                          * doreti_iret_fault, the trapframe is
  455                          * reconstructed on pti stack, and calltrap()
  456                          * called on it as well.  Due to the very
  457                          * limited pti stack size, kernel does not
  458                          * survive for too long.  Switch to the normal
  459                          * thread stack for the trap handling.
  460                          *
  461                          * Magic '5' is the number of qwords occupied by
  462                          * the hardware trap frame.
  463                          */
  464                         if (frame->tf_rip == (long)doreti_iret) {
  465                                 frame->tf_rip = (long)doreti_iret_fault;
  466                                 if (pti && frame->tf_rsp == (uintptr_t)PCPU_PTR(
  467                                     pti_stack) + (PC_PTI_STACK_SZ - 5) *
  468                                     sizeof(register_t))
  469                                         frame->tf_rsp = PCPU_GET(rsp0) - 5 *
  470                                             sizeof(register_t);
  471                                 return;
  472                         }
  473                         if (frame->tf_rip == (long)ld_ds) {
  474                                 frame->tf_rip = (long)ds_load_fault;
  475                                 return;
  476                         }
  477                         if (frame->tf_rip == (long)ld_es) {
  478                                 frame->tf_rip = (long)es_load_fault;
  479                                 return;
  480                         }
  481                         if (frame->tf_rip == (long)ld_fs) {
  482                                 frame->tf_rip = (long)fs_load_fault;
  483                                 return;
  484                         }
  485                         if (frame->tf_rip == (long)ld_gs) {
  486                                 frame->tf_rip = (long)gs_load_fault;
  487                                 return;
  488                         }
  489                         if (frame->tf_rip == (long)ld_gsbase) {
  490                                 frame->tf_rip = (long)gsbase_load_fault;
  491                                 return;
  492                         }
  493                         if (frame->tf_rip == (long)ld_fsbase) {
  494                                 frame->tf_rip = (long)fsbase_load_fault;
  495                                 return;
  496                         }
  497                         if (curpcb->pcb_onfault != NULL) {
  498                                 frame->tf_rip = (long)curpcb->pcb_onfault;
  499                                 return;
  500                         }
  501                         break;
  502 
  503                 case T_TSSFLT:
  504                         /*
  505                          * PSL_NT can be set in user mode and isn't cleared
  506                          * automatically when the kernel is entered.  This
  507                          * causes a TSS fault when the kernel attempts to
  508                          * `iret' because the TSS link is uninitialized.  We
  509                          * want to get this fault so that we can fix the
  510                          * problem here and not every time the kernel is
  511                          * entered.
  512                          */
  513                         if (frame->tf_rflags & PSL_NT) {
  514                                 frame->tf_rflags &= ~PSL_NT;
  515                                 return;
  516                         }
  517                         break;
  518 
  519                 case T_TRCTRAP:  /* trace trap */
  520                         /*
  521                          * Ignore debug register trace traps due to
  522                          * accesses in the user's address space, which
  523                          * can happen under several conditions such as
  524                          * if a user sets a watchpoint on a buffer and
  525                          * then passes that buffer to a system call.
  526                          * We still want to get TRCTRAPS for addresses
  527                          * in kernel space because that is useful when
  528                          * debugging the kernel.
  529                          */
  530                         if (user_dbreg_trap()) {
  531                                 /*
  532                                  * Reset breakpoint bits because the
  533                                  * processor doesn't
  534                                  */
  535                                 load_dr6(rdr6() & ~0xf);
  536                                 return;
  537                         }
  538 
  539                         /*
  540                          * Malicious user code can configure a debug
  541                          * register watchpoint to trap on data access
  542                          * to the top of stack and then execute 'pop
  543                          * %ss; int 3'.  Due to exception deferral for
  544                          * 'pop %ss', the CPU will not interrupt 'int
  545                          * 3' to raise the DB# exception for the debug
  546                          * register but will postpone the DB# until
  547                          * execution of the first instruction of the
  548                          * BP# handler (in kernel mode).  Normally the
  549                          * previous check would ignore DB# exceptions
  550                          * for watchpoints on user addresses raised in
  551                          * kernel mode.  However, some CPU errata
  552                          * include cases where DB# exceptions do not
  553                          * properly set bits in %dr6, e.g. Haswell
  554                          * HSD23 and Skylake-X SKZ24.
  555                          *
  556                          * A deferred DB# can also be raised on the
  557                          * first instructions of system call entry
  558                          * points or single-step traps via similar use
  559                          * of 'pop %ss' or 'mov xxx, %ss'.
  560                          */
  561                         if (pti) {
  562                                 if (frame->tf_rip ==
  563                                     (uintptr_t)IDTVEC(fast_syscall_pti) ||
  564 #ifdef COMPAT_FREEBSD32
  565                                     frame->tf_rip ==
  566                                     (uintptr_t)IDTVEC(int0x80_syscall_pti) ||
  567 #endif
  568                                     frame->tf_rip == (uintptr_t)IDTVEC(bpt_pti))
  569                                         return;
  570                         } else {
  571                                 if (frame->tf_rip ==
  572                                     (uintptr_t)IDTVEC(fast_syscall) ||
  573 #ifdef COMPAT_FREEBSD32
  574                                     frame->tf_rip ==
  575                                     (uintptr_t)IDTVEC(int0x80_syscall) ||
  576 #endif
  577                                     frame->tf_rip == (uintptr_t)IDTVEC(bpt))
  578                                         return;
  579                         }
  580                         if (frame->tf_rip == (uintptr_t)IDTVEC(dbg) ||
  581                             /* Needed for AMD. */
  582                             frame->tf_rip == (uintptr_t)IDTVEC(fast_syscall32))
  583                                 return;
  584                         /*
  585                          * FALLTHROUGH (TRCTRAP kernel mode, kernel address)
  586                          */
  587                 case T_BPTFLT:
  588                         /*
  589                          * If KDB is enabled, let it handle the debugger trap.
  590                          * Otherwise, debugger traps "can't happen".
  591                          */
  592 #ifdef KDB
  593                         /* XXX %dr6 is not quite reentrant. */
  594                         dr6 = rdr6();
  595                         load_dr6(dr6 & ~0x4000);
  596                         if (kdb_trap(type, dr6, frame))
  597                                 return;
  598 #endif
  599                         break;
  600 
  601 #ifdef DEV_ISA
  602                 case T_NMI:
  603                         nmi_handle_intr(type, frame);
  604                         return;
  605 #endif
  606                 }
  607 
  608                 trap_fatal(frame, 0);
  609                 return;
  610         }
  611 
  612         /* Translate fault for emulators (e.g. Linux) */
  613         if (*p->p_sysent->sv_transtrap != NULL)
  614                 signo = (*p->p_sysent->sv_transtrap)(signo, type);
  615 
  616         ksiginfo_init_trap(&ksi);
  617         ksi.ksi_signo = signo;
  618         ksi.ksi_code = ucode;
  619         ksi.ksi_trapno = type;
  620         ksi.ksi_addr = (void *)addr;
  621         if (uprintf_signal) {
  622                 uprintf("pid %d comm %s: signal %d err %lx code %d type %d "
  623                     "addr 0x%lx rsp 0x%lx rip 0x%lx "
  624                     "<%02x %02x %02x %02x %02x %02x %02x %02x>\n",
  625                     p->p_pid, p->p_comm, signo, frame->tf_err, ucode, type,
  626                     addr, frame->tf_rsp, frame->tf_rip,
  627                     fubyte((void *)(frame->tf_rip + 0)),
  628                     fubyte((void *)(frame->tf_rip + 1)),
  629                     fubyte((void *)(frame->tf_rip + 2)),
  630                     fubyte((void *)(frame->tf_rip + 3)),
  631                     fubyte((void *)(frame->tf_rip + 4)),
  632                     fubyte((void *)(frame->tf_rip + 5)),
  633                     fubyte((void *)(frame->tf_rip + 6)),
  634                     fubyte((void *)(frame->tf_rip + 7)));
  635         }
  636         KASSERT((read_rflags() & PSL_I) != 0, ("interrupts disabled"));
  637         trapsignal(td, &ksi);
  638 userret:
  639         userret(td, frame);
  640         KASSERT(PCB_USER_FPU(td->td_pcb),
  641             ("Return from trap with kernel FPU ctx leaked"));
  642 }
  643 
  644 /*
  645  * Ensure that we ignore any DTrace-induced faults. This function cannot
  646  * be instrumented, so it cannot generate such faults itself.
  647  */
  648 void
  649 trap_check(struct trapframe *frame)
  650 {
  651 
  652 #ifdef KDTRACE_HOOKS
  653         if (dtrace_trap_func != NULL &&
  654             (*dtrace_trap_func)(frame, frame->tf_trapno) != 0)
  655                 return;
  656 #endif
  657         trap(frame);
  658 }
  659 
  660 static int
  661 trap_pfault(struct trapframe *frame, int usermode)
  662 {
  663         struct thread *td;
  664         struct proc *p;
  665         vm_map_t map;
  666         vm_offset_t va;
  667         int rv;
  668         vm_prot_t ftype;
  669         vm_offset_t eva;
  670 
  671         td = curthread;
  672         p = td->td_proc;
  673         eva = frame->tf_addr;
  674 
  675         if (__predict_false((td->td_pflags & TDP_NOFAULTING) != 0)) {
  676                 /*
  677                  * Due to both processor errata and lazy TLB invalidation when
  678                  * access restrictions are removed from virtual pages, memory
  679                  * accesses that are allowed by the physical mapping layer may
  680                  * nonetheless cause one spurious page fault per virtual page. 
  681                  * When the thread is executing a "no faulting" section that
  682                  * is bracketed by vm_fault_{disable,enable}_pagefaults(),
  683                  * every page fault is treated as a spurious page fault,
  684                  * unless it accesses the same virtual address as the most
  685                  * recent page fault within the same "no faulting" section.
  686                  */
  687                 if (td->td_md.md_spurflt_addr != eva ||
  688                     (td->td_pflags & TDP_RESETSPUR) != 0) {
  689                         /*
  690                          * Do nothing to the TLB.  A stale TLB entry is
  691                          * flushed automatically by a page fault.
  692                          */
  693                         td->td_md.md_spurflt_addr = eva;
  694                         td->td_pflags &= ~TDP_RESETSPUR;
  695                         return (0);
  696                 }
  697         } else {
  698                 /*
  699                  * If we get a page fault while in a critical section, then
  700                  * it is most likely a fatal kernel page fault.  The kernel
  701                  * is already going to panic trying to get a sleep lock to
  702                  * do the VM lookup, so just consider it a fatal trap so the
  703                  * kernel can print out a useful trap message and even get
  704                  * to the debugger.
  705                  *
  706                  * If we get a page fault while holding a non-sleepable
  707                  * lock, then it is most likely a fatal kernel page fault.
  708                  * If WITNESS is enabled, then it's going to whine about
  709                  * bogus LORs with various VM locks, so just skip to the
  710                  * fatal trap handling directly.
  711                  */
  712                 if (td->td_critnest != 0 ||
  713                     WITNESS_CHECK(WARN_SLEEPOK | WARN_GIANTOK, NULL,
  714                     "Kernel page fault") != 0) {
  715                         trap_fatal(frame, eva);
  716                         return (-1);
  717                 }
  718         }
  719         va = trunc_page(eva);
  720         if (va >= VM_MIN_KERNEL_ADDRESS) {
  721                 /*
  722                  * Don't allow user-mode faults in kernel address space.
  723                  */
  724                 if (usermode)
  725                         return (SIGSEGV);
  726 
  727                 map = kernel_map;
  728         } else {
  729                 map = &p->p_vmspace->vm_map;
  730 
  731                 /*
  732                  * When accessing a usermode address, kernel must be
  733                  * ready to accept the page fault, and provide a
  734                  * handling routine.  Since accessing the address
  735                  * without the handler is a bug, do not try to handle
  736                  * it normally, and panic immediately.
  737                  */
  738                 if (!usermode && (td->td_intr_nesting_level != 0 ||
  739                     curpcb->pcb_onfault == NULL)) {
  740                         trap_fatal(frame, eva);
  741                         return (-1);
  742                 }
  743         }
  744 
  745         /*
  746          * If the trap was caused by errant bits in the PTE then panic.
  747          */
  748         if (frame->tf_err & PGEX_RSV) {
  749                 trap_fatal(frame, eva);
  750                 return (-1);
  751         }
  752 
  753         /*
  754          * If nx protection of the usermode portion of kernel page
  755          * tables caused trap, panic.
  756          */
  757         if (pti && usermode && pg_nx != 0 && (frame->tf_err & (PGEX_P | PGEX_W |
  758             PGEX_U | PGEX_I)) == (PGEX_P | PGEX_U | PGEX_I) &&
  759             (curpcb->pcb_saved_ucr3 & ~CR3_PCID_MASK)==
  760             (PCPU_GET(curpmap)->pm_cr3 & ~CR3_PCID_MASK))
  761                 panic("PTI: pid %d comm %s tf_err %#lx\n", p->p_pid,
  762                     p->p_comm, frame->tf_err);
  763 
  764         /*
  765          * PGEX_I is defined only if the execute disable bit capability is
  766          * supported and enabled.
  767          */
  768         if (frame->tf_err & PGEX_W)
  769                 ftype = VM_PROT_WRITE;
  770         else if ((frame->tf_err & PGEX_I) && pg_nx != 0)
  771                 ftype = VM_PROT_EXECUTE;
  772         else
  773                 ftype = VM_PROT_READ;
  774 
  775         /* Fault in the page. */
  776         rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
  777         if (rv == KERN_SUCCESS) {
  778 #ifdef HWPMC_HOOKS
  779                 if (ftype == VM_PROT_READ || ftype == VM_PROT_WRITE) {
  780                         PMC_SOFT_CALL_TF( , , page_fault, all, frame);
  781                         if (ftype == VM_PROT_READ)
  782                                 PMC_SOFT_CALL_TF( , , page_fault, read,
  783                                     frame);
  784                         else
  785                                 PMC_SOFT_CALL_TF( , , page_fault, write,
  786                                     frame);
  787                 }
  788 #endif
  789                 return (0);
  790         }
  791         if (!usermode) {
  792                 if (td->td_intr_nesting_level == 0 &&
  793                     curpcb->pcb_onfault != NULL) {
  794                         frame->tf_rip = (long)curpcb->pcb_onfault;
  795                         return (0);
  796                 }
  797                 trap_fatal(frame, eva);
  798                 return (-1);
  799         }
  800         return ((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
  801 }
  802 
  803 static void
  804 trap_fatal(frame, eva)
  805         struct trapframe *frame;
  806         vm_offset_t eva;
  807 {
  808         int code, ss;
  809         u_int type;
  810         struct soft_segment_descriptor softseg;
  811         char *msg;
  812 #ifdef KDB
  813         bool handled;
  814 #endif
  815 
  816         code = frame->tf_err;
  817         type = frame->tf_trapno;
  818         sdtossd(&gdt[NGDT * PCPU_GET(cpuid) + IDXSEL(frame->tf_cs & 0xffff)],
  819             &softseg);
  820 
  821         if (type <= MAX_TRAP_MSG)
  822                 msg = trap_msg[type];
  823         else
  824                 msg = "UNKNOWN";
  825         printf("\n\nFatal trap %d: %s while in %s mode\n", type, msg,
  826             TRAPF_USERMODE(frame) ? "user" : "kernel");
  827 #ifdef SMP
  828         /* two separate prints in case of a trap on an unmapped page */
  829         printf("cpuid = %d; ", PCPU_GET(cpuid));
  830         printf("apic id = %02x\n", PCPU_GET(apic_id));
  831 #endif
  832         if (type == T_PAGEFLT) {
  833                 printf("fault virtual address   = 0x%lx\n", eva);
  834                 printf("fault code              = %s %s %s, %s\n",
  835                         code & PGEX_U ? "user" : "supervisor",
  836                         code & PGEX_W ? "write" : "read",
  837                         code & PGEX_I ? "instruction" : "data",
  838                         code & PGEX_RSV ? "reserved bits in PTE" :
  839                         code & PGEX_P ? "protection violation" : "page not present");
  840         }
  841         printf("instruction pointer     = 0x%lx:0x%lx\n",
  842                frame->tf_cs & 0xffff, frame->tf_rip);
  843         ss = frame->tf_ss & 0xffff;
  844         printf("stack pointer           = 0x%x:0x%lx\n", ss, frame->tf_rsp);
  845         printf("frame pointer           = 0x%x:0x%lx\n", ss, frame->tf_rbp);
  846         printf("code segment            = base 0x%lx, limit 0x%lx, type 0x%x\n",
  847                softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type);
  848         printf("                        = DPL %d, pres %d, long %d, def32 %d, gran %d\n",
  849                softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32,
  850                softseg.ssd_gran);
  851         printf("processor eflags        = ");
  852         if (frame->tf_rflags & PSL_T)
  853                 printf("trace trap, ");
  854         if (frame->tf_rflags & PSL_I)
  855                 printf("interrupt enabled, ");
  856         if (frame->tf_rflags & PSL_NT)
  857                 printf("nested task, ");
  858         if (frame->tf_rflags & PSL_RF)
  859                 printf("resume, ");
  860         printf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12);
  861         printf("current process         = %d (%s)\n",
  862             curproc->p_pid, curthread->td_name);
  863 
  864 #ifdef KDB
  865         if (debugger_on_panic) {
  866                 kdb_why = KDB_WHY_TRAP;
  867                 handled = kdb_trap(type, 0, frame);
  868                 kdb_why = KDB_WHY_UNSET;
  869                 if (handled)
  870                         return;
  871         }
  872 #endif
  873         printf("trap number             = %d\n", type);
  874         if (type <= MAX_TRAP_MSG)
  875                 panic("%s", trap_msg[type]);
  876         else
  877                 panic("unknown/reserved trap");
  878 }
  879 
  880 /*
  881  * Double fault handler. Called when a fault occurs while writing
  882  * a frame for a trap/exception onto the stack. This usually occurs
  883  * when the stack overflows (such is the case with infinite recursion,
  884  * for example).
  885  */
  886 void
  887 dblfault_handler(struct trapframe *frame)
  888 {
  889 #ifdef KDTRACE_HOOKS
  890         if (dtrace_doubletrap_func != NULL)
  891                 (*dtrace_doubletrap_func)();
  892 #endif
  893         printf("\nFatal double fault\n"
  894             "rip %#lx rsp %#lx rbp %#lx\n"
  895             "rax %#lx rdx %#lx rbx %#lx\n"
  896             "rcx %#lx rsi %#lx rdi %#lx\n"
  897             "r8 %#lx r9 %#lx r10 %#lx\n"
  898             "r11 %#lx r12 %#lx r13 %#lx\n"
  899             "r14 %#lx r15 %#lx rflags %#lx\n"
  900             "cs %#lx ss %#lx ds %#hx es %#hx fs %#hx gs %#hx\n"
  901             "fsbase %#lx gsbase %#lx kgsbase %#lx\n",
  902             frame->tf_rip, frame->tf_rsp, frame->tf_rbp,
  903             frame->tf_rax, frame->tf_rdx, frame->tf_rbx,
  904             frame->tf_rcx, frame->tf_rdi, frame->tf_rsi,
  905             frame->tf_r8, frame->tf_r9, frame->tf_r10,
  906             frame->tf_r11, frame->tf_r12, frame->tf_r13,
  907             frame->tf_r14, frame->tf_r15, frame->tf_rflags,
  908             frame->tf_cs, frame->tf_ss, frame->tf_ds, frame->tf_es,
  909             frame->tf_fs, frame->tf_gs,
  910             rdmsr(MSR_FSBASE), rdmsr(MSR_GSBASE), rdmsr(MSR_KGSBASE));
  911 #ifdef SMP
  912         /* two separate prints in case of a trap on an unmapped page */
  913         printf("cpuid = %d; ", PCPU_GET(cpuid));
  914         printf("apic id = %02x\n", PCPU_GET(apic_id));
  915 #endif
  916         panic("double fault");
  917 }
  918 
  919 int
  920 cpu_fetch_syscall_args(struct thread *td)
  921 {
  922         struct proc *p;
  923         struct trapframe *frame;
  924         register_t *argp;
  925         struct syscall_args *sa;
  926         caddr_t params;
  927         int reg, regcnt, error;
  928 
  929         p = td->td_proc;
  930         frame = td->td_frame;
  931         sa = &td->td_sa;
  932         reg = 0;
  933         regcnt = 6;
  934 
  935         params = (caddr_t)frame->tf_rsp + sizeof(register_t);
  936         sa->code = frame->tf_rax;
  937 
  938         if (sa->code == SYS_syscall || sa->code == SYS___syscall) {
  939                 sa->code = frame->tf_rdi;
  940                 reg++;
  941                 regcnt--;
  942         }
  943         if (p->p_sysent->sv_mask)
  944                 sa->code &= p->p_sysent->sv_mask;
  945 
  946         if (sa->code >= p->p_sysent->sv_size)
  947                 sa->callp = &p->p_sysent->sv_table[0];
  948         else
  949                 sa->callp = &p->p_sysent->sv_table[sa->code];
  950 
  951         sa->narg = sa->callp->sy_narg;
  952         KASSERT(sa->narg <= sizeof(sa->args) / sizeof(sa->args[0]),
  953             ("Too many syscall arguments!"));
  954         error = 0;
  955         argp = &frame->tf_rdi;
  956         argp += reg;
  957         bcopy(argp, sa->args, sizeof(sa->args[0]) * regcnt);
  958         if (sa->narg > regcnt) {
  959                 KASSERT(params != NULL, ("copyin args with no params!"));
  960                 error = copyin(params, &sa->args[regcnt],
  961                     (sa->narg - regcnt) * sizeof(sa->args[0]));
  962         }
  963 
  964         if (error == 0) {
  965                 td->td_retval[0] = 0;
  966                 td->td_retval[1] = frame->tf_rdx;
  967         }
  968 
  969         return (error);
  970 }
  971 
  972 #include "../../kern/subr_syscall.c"
  973 
  974 /*
  975  * System call handler for native binaries.  The trap frame is already
  976  * set up by the assembler trampoline and a pointer to it is saved in
  977  * td_frame.
  978  */
  979 void
  980 amd64_syscall(struct thread *td, int traced)
  981 {
  982         int error;
  983         ksiginfo_t ksi;
  984 
  985 #ifdef DIAGNOSTIC
  986         if (!TRAPF_USERMODE(td->td_frame)) {
  987                 panic("syscall");
  988                 /* NOT REACHED */
  989         }
  990 #endif
  991         error = syscallenter(td);
  992 
  993         /*
  994          * Traced syscall.
  995          */
  996         if (__predict_false(traced)) {
  997                 td->td_frame->tf_rflags &= ~PSL_T;
  998                 ksiginfo_init_trap(&ksi);
  999                 ksi.ksi_signo = SIGTRAP;
 1000                 ksi.ksi_code = TRAP_TRACE;
 1001                 ksi.ksi_addr = (void *)td->td_frame->tf_rip;
 1002                 trapsignal(td, &ksi);
 1003         }
 1004 
 1005         KASSERT(PCB_USER_FPU(td->td_pcb),
 1006             ("System call %s returning with kernel FPU ctx leaked",
 1007              syscallname(td->td_proc, td->td_sa.code)));
 1008         KASSERT(td->td_pcb->pcb_save == get_pcb_user_save_td(td),
 1009             ("System call %s returning with mangled pcb_save",
 1010              syscallname(td->td_proc, td->td_sa.code)));
 1011         KASSERT(td->td_md.md_invl_gen.gen == 0,
 1012             ("System call %s returning with leaked invl_gen %lu",
 1013             syscallname(td->td_proc, td->td_sa.code),
 1014             td->td_md.md_invl_gen.gen));
 1015 
 1016         syscallret(td, error);
 1017 
 1018         /*
 1019          * If the user-supplied value of %rip is not a canonical
 1020          * address, then some CPUs will trigger a ring 0 #GP during
 1021          * the sysret instruction.  However, the fault handler would
 1022          * execute in ring 0 with the user's %gs and %rsp which would
 1023          * not be safe.  Instead, use the full return path which
 1024          * catches the problem safely.
 1025          */
 1026         if (__predict_false(td->td_frame->tf_rip >= VM_MAXUSER_ADDRESS))
 1027                 set_pcb_flags(td->td_pcb, PCB_FULL_IRET);
 1028 }

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