2 * Copyright (C) 1994, David Greenman
3 * Copyright (c) 1990, 1993
4 * The Regents of the University of California. All rights reserved.
6 * This code is derived from software contributed to Berkeley by
7 * the University of Utah, and William Jolitz.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
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.
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
37 * from: @(#)trap.c 7.4 (Berkeley) 5/13/91
38 * $FreeBSD: src/sys/i386/i386/trap.c,v 1.147.2.11 2003/02/27 19:09:59 luoqi Exp $
42 * x86_64 Trap and System call handling
48 #include "opt_ktrace.h"
50 #include <sys/param.h>
51 #include <sys/systm.h>
53 #include <sys/pioctl.h>
54 #include <sys/kernel.h>
55 #include <sys/resourcevar.h>
56 #include <sys/signalvar.h>
57 #include <sys/signal2.h>
58 #include <sys/syscall.h>
59 #include <sys/sysctl.h>
60 #include <sys/sysent.h>
62 #include <sys/vmmeter.h>
63 #include <sys/malloc.h>
65 #include <sys/ktrace.h>
68 #include <sys/vkernel.h>
69 #include <sys/sysproto.h>
70 #include <sys/sysunion.h>
71 #include <sys/vmspace.h>
74 #include <vm/vm_param.h>
77 #include <vm/vm_kern.h>
78 #include <vm/vm_map.h>
79 #include <vm/vm_page.h>
80 #include <vm/vm_extern.h>
82 #include <machine/cpu.h>
83 #include <machine/md_var.h>
84 #include <machine/pcb.h>
85 #include <machine/smp.h>
86 #include <machine/tss.h>
87 #include <machine/globaldata.h>
91 #include <sys/msgport2.h>
92 #include <sys/thread2.h>
93 #include <sys/mplock2.h>
95 #define MAKEMPSAFE(have_mplock) \
96 if (have_mplock == 0) { \
101 int (*pmath_emulate) (struct trapframe *);
103 extern int trapwrite (unsigned addr);
105 static int trap_pfault (struct trapframe *, int, vm_offset_t);
106 static void trap_fatal (struct trapframe *, int, vm_offset_t);
107 void dblfault_handler (void);
110 extern inthand_t IDTVEC(syscall);
113 #define MAX_TRAP_MSG 30
114 static char *trap_msg[] = {
116 "privileged instruction fault", /* 1 T_PRIVINFLT */
118 "breakpoint instruction fault", /* 3 T_BPTFLT */
121 "arithmetic trap", /* 6 T_ARITHTRAP */
122 "system forced exception", /* 7 T_ASTFLT */
124 "general protection fault", /* 9 T_PROTFLT */
125 "trace trap", /* 10 T_TRCTRAP */
127 "page fault", /* 12 T_PAGEFLT */
129 "alignment fault", /* 14 T_ALIGNFLT */
133 "integer divide fault", /* 18 T_DIVIDE */
134 "non-maskable interrupt trap", /* 19 T_NMI */
135 "overflow trap", /* 20 T_OFLOW */
136 "FPU bounds check fault", /* 21 T_BOUND */
137 "FPU device not available", /* 22 T_DNA */
138 "double fault", /* 23 T_DOUBLEFLT */
139 "FPU operand fetch fault", /* 24 T_FPOPFLT */
140 "invalid TSS fault", /* 25 T_TSSFLT */
141 "segment not present fault", /* 26 T_SEGNPFLT */
142 "stack fault", /* 27 T_STKFLT */
143 "machine check trap", /* 28 T_MCHK */
144 "SIMD floating-point exception", /* 29 T_XMMFLT */
145 "reserved (unknown) fault", /* 30 T_RESERVED */
149 static int ddb_on_nmi = 1;
150 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW,
151 &ddb_on_nmi, 0, "Go to DDB on NMI");
153 static int panic_on_nmi = 1;
154 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW,
155 &panic_on_nmi, 0, "Panic on NMI");
156 static int fast_release;
157 SYSCTL_INT(_machdep, OID_AUTO, fast_release, CTLFLAG_RW,
158 &fast_release, 0, "Passive Release was optimal");
159 static int slow_release;
160 SYSCTL_INT(_machdep, OID_AUTO, slow_release, CTLFLAG_RW,
161 &slow_release, 0, "Passive Release was nonoptimal");
163 MALLOC_DEFINE(M_SYSMSG, "sysmsg", "sysmsg structure");
164 extern int max_sysmsg;
167 * Passively intercepts the thread switch function to increase
168 * the thread priority from a user priority to a kernel priority, reducing
169 * syscall and trap overhead for the case where no switch occurs.
171 * Synchronizes td_ucred with p_ucred. This is used by system calls,
172 * signal handling, faults, AST traps, and anything else that enters the
173 * kernel from userland and provides the kernel with a stable read-only
174 * copy of the process ucred.
177 userenter(struct thread *curtd, struct proc *curp)
182 curtd->td_release = lwkt_passive_release;
184 if (curtd->td_ucred != curp->p_ucred) {
185 ncred = crhold(curp->p_ucred);
186 ocred = curtd->td_ucred;
187 curtd->td_ucred = ncred;
194 * Handle signals, profiling, and other AST's and/or tasks that
195 * must be completed before we can return to or try to return to userland.
197 * Note that td_sticks is a 64 bit quantity, but there's no point doing 64
198 * arithmatic on the delta calculation so the absolute tick values are
199 * truncated to an integer.
202 userret(struct lwp *lp, struct trapframe *frame, int sticks)
204 struct proc *p = lp->lwp_proc;
208 * Charge system time if profiling. Note: times are in microseconds.
209 * This may do a copyout and block, so do it first even though it
210 * means some system time will be charged as user time.
212 if (p->p_flags & P_PROFIL) {
213 addupc_task(p, frame->tf_rip,
214 (u_int)((int)lp->lwp_thread->td_sticks - sticks));
219 * Specific on-return-to-usermode checks (LWP_MP_WEXIT,
220 * LWP_MP_VNLRU, etc).
222 if (lp->lwp_mpflags & LWP_MP_URETMASK)
226 * Block here if we are in a stopped state.
228 if (p->p_stat == SSTOP) {
229 lwkt_gettoken(&p->p_token);
231 lwkt_reltoken(&p->p_token);
236 * Post any pending upcalls. If running a virtual kernel be sure
237 * to restore the virtual kernel's vmspace before posting the upcall.
239 if (p->p_flags & (P_SIGVTALRM | P_SIGPROF)) {
240 lwkt_gettoken(&p->p_token);
241 if (p->p_flags & P_SIGVTALRM) {
242 p->p_flags &= ~P_SIGVTALRM;
243 ksignal(p, SIGVTALRM);
245 if (p->p_flags & P_SIGPROF) {
246 p->p_flags &= ~P_SIGPROF;
249 lwkt_reltoken(&p->p_token);
254 * Post any pending signals
256 * WARNING! postsig() can exit and not return.
258 if ((sig = CURSIG_TRACE(lp)) != 0) {
259 lwkt_gettoken(&p->p_token);
261 lwkt_reltoken(&p->p_token);
266 * block here if we are swapped out, but still process signals
267 * (such as SIGKILL). proc0 (the swapin scheduler) is already
268 * aware of our situation, we do not have to wake it up.
270 if (p->p_flags & P_SWAPPEDOUT) {
271 lwkt_gettoken(&p->p_token);
273 p->p_flags |= P_SWAPWAIT;
275 if (p->p_flags & P_SWAPWAIT)
276 tsleep(p, PCATCH, "SWOUT", 0);
277 p->p_flags &= ~P_SWAPWAIT;
279 lwkt_reltoken(&p->p_token);
284 * In a multi-threaded program it is possible for a thread to change
285 * signal state during a system call which temporarily changes the
286 * signal mask. In this case postsig() might not be run and we
287 * have to restore the mask ourselves.
289 if (lp->lwp_flags & LWP_OLDMASK) {
290 lp->lwp_flags &= ~LWP_OLDMASK;
291 lp->lwp_sigmask = lp->lwp_oldsigmask;
297 * Cleanup from userenter and any passive release that might have occured.
298 * We must reclaim the current-process designation before we can return
299 * to usermode. We also handle both LWKT and USER reschedule requests.
302 userexit(struct lwp *lp)
304 struct thread *td = lp->lwp_thread;
305 /* globaldata_t gd = td->td_gd; */
308 * Handle stop requests at kernel priority. Any requests queued
309 * after this loop will generate another AST.
311 while (lp->lwp_proc->p_stat == SSTOP) {
312 lwkt_gettoken(&lp->lwp_proc->p_token);
314 lwkt_reltoken(&lp->lwp_proc->p_token);
318 * Reduce our priority in preparation for a return to userland. If
319 * our passive release function was still in place, our priority was
320 * never raised and does not need to be reduced.
322 lwkt_passive_recover(td);
325 * Become the current user scheduled process if we aren't already,
326 * and deal with reschedule requests and other factors.
328 lp->lwp_proc->p_usched->acquire_curproc(lp);
329 /* WARNING: we may have migrated cpu's */
330 /* gd = td->td_gd; */
333 #if !defined(KTR_KERNENTRY)
334 #define KTR_KERNENTRY KTR_ALL
336 KTR_INFO_MASTER(kernentry);
337 KTR_INFO(KTR_KERNENTRY, kernentry, trap, 0,
338 "TRAP(pid %hd, tid %hd, trapno %ld, eva %lu)",
339 pid_t pid, lwpid_t tid, register_t trapno, vm_offset_t eva);
340 KTR_INFO(KTR_KERNENTRY, kernentry, trap_ret, 0, "TRAP_RET(pid %hd, tid %hd)",
341 pid_t pid, lwpid_t tid);
342 KTR_INFO(KTR_KERNENTRY, kernentry, syscall, 0, "SYSC(pid %hd, tid %hd, nr %ld)",
343 pid_t pid, lwpid_t tid, register_t trapno);
344 KTR_INFO(KTR_KERNENTRY, kernentry, syscall_ret, 0, "SYSRET(pid %hd, tid %hd, err %d)",
345 pid_t pid, lwpid_t tid, int err);
346 KTR_INFO(KTR_KERNENTRY, kernentry, fork_ret, 0, "FORKRET(pid %hd, tid %hd)",
347 pid_t pid, lwpid_t tid);
350 * Exception, fault, and trap interface to the kernel.
351 * This common code is called from assembly language IDT gate entry
352 * routines that prepare a suitable stack frame, and restore this
353 * frame after the exception has been processed.
355 * This function is also called from doreti in an interlock to handle ASTs.
356 * For example: hardwareint->INTROUTINE->(set ast)->doreti->trap
358 * NOTE! We have to retrieve the fault address prior to obtaining the
359 * MP lock because get_mplock() may switch out. YYY cr2 really ought
360 * to be retrieved by the assembly code, not here.
362 * XXX gd_trap_nesting_level currently prevents lwkt_switch() from panicing
363 * if an attempt is made to switch from a fast interrupt or IPI. This is
364 * necessary to properly take fatal kernel traps on SMP machines if
365 * get_mplock() has to block.
369 user_trap(struct trapframe *frame)
371 struct globaldata *gd = mycpu;
372 struct thread *td = gd->gd_curthread;
373 struct lwp *lp = td->td_lwp;
376 int i = 0, ucode = 0, type, code;
379 int crit_count = td->td_critcount;
380 lwkt_tokref_t curstop = td->td_toks_stop;
386 if (frame->tf_trapno == T_PAGEFLT)
387 eva = frame->tf_addr;
391 kprintf("USER_TRAP AT %08lx xflags %ld trapno %ld eva %08lx\n",
392 frame->tf_rip, frame->tf_xflags, frame->tf_trapno, eva);
396 * Everything coming from user mode runs through user_trap,
397 * including system calls.
399 if (frame->tf_trapno == T_FAST_SYSCALL) {
404 KTR_LOG(kernentry_trap, lp->lwp_proc->p_pid, lp->lwp_tid,
405 frame->tf_trapno, eva);
409 eva = (frame->tf_trapno == T_PAGEFLT ? rcr2() : 0);
410 ++gd->gd_trap_nesting_level;
411 MAKEMPSAFE(have_mplock);
412 trap_fatal(frame, TRUE, eva);
413 --gd->gd_trap_nesting_level;
418 type = frame->tf_trapno;
419 code = frame->tf_err;
423 sticks = (int)td->td_sticks;
424 lp->lwp_md.md_regs = frame;
427 case T_PRIVINFLT: /* privileged instruction fault */
432 case T_BPTFLT: /* bpt instruction fault */
433 case T_TRCTRAP: /* trace trap */
434 frame->tf_rflags &= ~PSL_T;
436 ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT);
439 case T_ARITHTRAP: /* arithmetic trap */
444 case T_ASTFLT: /* Allow process switch */
445 mycpu->gd_cnt.v_soft++;
446 if (mycpu->gd_reqflags & RQF_AST_OWEUPC) {
447 atomic_clear_int(&mycpu->gd_reqflags, RQF_AST_OWEUPC);
448 addupc_task(p, p->p_prof.pr_addr, p->p_prof.pr_ticks);
453 * The following two traps can happen in
454 * vm86 mode, and, if so, we want to handle
457 case T_PROTFLT: /* general protection fault */
458 case T_STKFLT: /* stack fault */
460 if (frame->tf_eflags & PSL_VM) {
461 i = vm86_emulate((struct vm86frame *)frame);
469 case T_SEGNPFLT: /* segment not present fault */
470 case T_TSSFLT: /* invalid TSS fault */
471 case T_DOUBLEFLT: /* double fault */
474 ucode = code + BUS_SEGM_FAULT ;
477 case T_PAGEFLT: /* page fault */
478 MAKEMPSAFE(have_mplock);
479 i = trap_pfault(frame, TRUE, eva);
480 if (i == -1 || i == 0)
492 case T_DIVIDE: /* integer divide fault */
499 MAKEMPSAFE(have_mplock);
500 /* machine/parity/power fail/"kitchen sink" faults */
501 if (isa_nmi(code) == 0) {
504 * NMI can be hooked up to a pushbutton
508 kprintf ("NMI ... going to debugger\n");
509 kdb_trap(type, 0, frame);
513 } else if (panic_on_nmi)
514 panic("NMI indicates hardware failure");
516 #endif /* NISA > 0 */
518 case T_OFLOW: /* integer overflow fault */
523 case T_BOUND: /* bounds check fault */
530 * Virtual kernel intercept - pass the DNA exception
531 * to the (emulated) virtual kernel if it asked to handle
532 * it. This occurs when the virtual kernel is holding
533 * onto the FP context for a different emulated
534 * process then the one currently running.
536 * We must still call npxdna() since we may have
537 * saved FP state that the (emulated) virtual kernel
538 * needs to hand over to a different emulated process.
540 if (lp->lwp_vkernel && lp->lwp_vkernel->ve &&
541 (td->td_pcb->pcb_flags & FP_VIRTFP)
548 * The kernel may have switched out the FP unit's
549 * state, causing the user process to take a fault
550 * when it tries to use the FP unit. Restore the
555 if (!pmath_emulate) {
557 ucode = FPE_FPU_NP_TRAP;
560 i = (*pmath_emulate)(frame);
562 if (!(frame->tf_rflags & PSL_T))
564 frame->tf_rflags &= ~PSL_T;
567 /* else ucode = emulator_only_knows() XXX */
570 case T_FPOPFLT: /* FPU operand fetch fault */
575 case T_XMMFLT: /* SIMD floating-point exception */
582 * Virtual kernel intercept - if the fault is directly related to a
583 * VM context managed by a virtual kernel then let the virtual kernel
586 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
587 vkernel_trap(lp, frame);
592 * Translate fault for emulators (e.g. Linux)
594 if (*p->p_sysent->sv_transtrap)
595 i = (*p->p_sysent->sv_transtrap)(i, type);
597 MAKEMPSAFE(have_mplock);
598 trapsignal(lp, i, ucode);
601 if (type <= MAX_TRAP_MSG) {
602 uprintf("fatal process exception: %s",
604 if ((type == T_PAGEFLT) || (type == T_PROTFLT))
605 uprintf(", fault VA = 0x%lx", (u_long)eva);
611 userret(lp, frame, sticks);
616 KTR_LOG(kernentry_trap_ret, lp->lwp_proc->p_pid, lp->lwp_tid);
618 KASSERT(crit_count == td->td_critcount,
619 ("trap: critical section count mismatch! %d/%d",
620 crit_count, td->td_pri));
621 KASSERT(curstop == td->td_toks_stop,
622 ("trap: extra tokens held after trap! %ld/%ld",
623 curstop - &td->td_toks_base,
624 td->td_toks_stop - &td->td_toks_base));
629 kern_trap(struct trapframe *frame)
631 struct globaldata *gd = mycpu;
632 struct thread *td = gd->gd_curthread;
635 int i = 0, ucode = 0, type, code;
638 int crit_count = td->td_critcount;
639 lwkt_tokref_t curstop = td->td_toks_stop;
646 if (frame->tf_trapno == T_PAGEFLT)
647 eva = frame->tf_addr;
653 ++gd->gd_trap_nesting_level;
654 MAKEMPSAFE(have_mplock);
655 trap_fatal(frame, FALSE, eva);
656 --gd->gd_trap_nesting_level;
661 type = frame->tf_trapno;
662 code = frame->tf_err;
670 case T_PAGEFLT: /* page fault */
671 MAKEMPSAFE(have_mplock);
672 trap_pfault(frame, FALSE, eva);
677 * The kernel may be using npx for copying or other
680 panic("kernel NPX should not happen");
685 case T_PROTFLT: /* general protection fault */
686 case T_SEGNPFLT: /* segment not present fault */
688 * Invalid segment selectors and out of bounds
689 * %eip's and %esp's can be set up in user mode.
690 * This causes a fault in kernel mode when the
691 * kernel tries to return to user mode. We want
692 * to get this fault so that we can fix the
693 * problem here and not have to check all the
694 * selectors and pointers when the user changes
697 if (mycpu->gd_intr_nesting_level == 0) {
698 if (td->td_pcb->pcb_onfault) {
700 (register_t)td->td_pcb->pcb_onfault;
708 * PSL_NT can be set in user mode and isn't cleared
709 * automatically when the kernel is entered. This
710 * causes a TSS fault when the kernel attempts to
711 * `iret' because the TSS link is uninitialized. We
712 * want to get this fault so that we can fix the
713 * problem here and not every time the kernel is
716 if (frame->tf_rflags & PSL_NT) {
717 frame->tf_rflags &= ~PSL_NT;
722 case T_TRCTRAP: /* trace trap */
724 if (frame->tf_eip == (int)IDTVEC(syscall)) {
726 * We've just entered system mode via the
727 * syscall lcall. Continue single stepping
728 * silently until the syscall handler has
733 if (frame->tf_eip == (int)IDTVEC(syscall) + 1) {
735 * The syscall handler has now saved the
736 * flags. Stop single stepping it.
738 frame->tf_eflags &= ~PSL_T;
744 * Ignore debug register trace traps due to
745 * accesses in the user's address space, which
746 * can happen under several conditions such as
747 * if a user sets a watchpoint on a buffer and
748 * then passes that buffer to a system call.
749 * We still want to get TRCTRAPS for addresses
750 * in kernel space because that is useful when
751 * debugging the kernel.
753 if (user_dbreg_trap()) {
755 * Reset breakpoint bits because the
758 load_dr6(rdr6() & 0xfffffff0);
763 * Fall through (TRCTRAP kernel mode, kernel address)
767 * If DDB is enabled, let it handle the debugger trap.
768 * Otherwise, debugger traps "can't happen".
771 MAKEMPSAFE(have_mplock);
772 if (kdb_trap (type, 0, frame))
777 MAKEMPSAFE(have_mplock);
778 trap_fatal(frame, FALSE, eva);
781 MAKEMPSAFE(have_mplock);
782 trap_fatal(frame, FALSE, eva);
787 * Ignore this trap generated from a spurious SIGTRAP.
789 * single stepping in / syscalls leads to spurious / SIGTRAP
792 * Haiku (c) 2007 Simon 'corecode' Schubert
798 * Translate fault for emulators (e.g. Linux)
800 if (*p->p_sysent->sv_transtrap)
801 i = (*p->p_sysent->sv_transtrap)(i, type);
803 MAKEMPSAFE(have_mplock);
804 trapsignal(lp, i, ucode);
807 if (type <= MAX_TRAP_MSG) {
808 uprintf("fatal process exception: %s",
810 if ((type == T_PAGEFLT) || (type == T_PROTFLT))
811 uprintf(", fault VA = 0x%lx", (u_long)eva);
821 KASSERT(crit_count == td->td_critcount,
822 ("trap: critical section count mismatch! %d/%d",
823 crit_count, td->td_pri));
824 KASSERT(curstop == td->td_toks_stop,
825 ("trap: extra tokens held after trap! %ld/%ld",
826 curstop - &td->td_toks_base,
827 td->td_toks_stop - &td->td_toks_base));
832 trap_pfault(struct trapframe *frame, int usermode, vm_offset_t eva)
835 struct vmspace *vm = NULL;
839 thread_t td = curthread;
840 struct lwp *lp = td->td_lwp;
843 va = trunc_page(eva);
844 if (usermode == FALSE) {
846 * This is a fault on kernel virtual memory.
851 * This is a fault on non-kernel virtual memory.
852 * vm is initialized above to NULL. If curproc is NULL
853 * or curproc->p_vmspace is NULL the fault is fatal.
856 vm = lp->lwp_vmspace;
864 if (frame->tf_err & PGEX_W)
865 ftype = VM_PROT_READ | VM_PROT_WRITE;
867 ftype = VM_PROT_READ;
869 if (map != &kernel_map) {
871 * Keep swapout from messing with us during this
877 * Grow the stack if necessary
879 /* grow_stack returns false only if va falls into
880 * a growable stack region and the stack growth
881 * fails. It returns true if va was not within
882 * a growable stack region, or if the stack
885 if (!grow_stack (lp->lwp_proc, va)) {
893 fault_flags |= VM_FAULT_BURST;
894 if (ftype & VM_PROT_WRITE)
895 fault_flags |= VM_FAULT_DIRTY;
897 fault_flags |= VM_FAULT_NORMAL;
898 rv = vm_fault(map, va, ftype, fault_flags);
903 * Don't have to worry about process locking or stacks in the kernel.
905 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
908 if (rv == KERN_SUCCESS)
912 if (td->td_gd->gd_intr_nesting_level == 0 &&
913 td->td_pcb->pcb_onfault) {
914 frame->tf_rip = (register_t)td->td_pcb->pcb_onfault;
917 trap_fatal(frame, usermode, eva);
922 * NOTE: on x86_64 we have a tf_addr field in the trapframe, no
923 * kludge is needed to pass the fault address to signal handlers.
925 struct proc *p = td->td_proc;
926 kprintf("seg-fault accessing address %p rip=%p pid=%d p_comm=%s\n",
927 (void *)va, (void *)frame->tf_rip, p->p_pid, p->p_comm);
928 /* Debugger("seg-fault"); */
930 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
934 trap_fatal(struct trapframe *frame, int usermode, vm_offset_t eva)
939 code = frame->tf_xflags;
940 type = frame->tf_trapno;
942 if (type <= MAX_TRAP_MSG) {
943 kprintf("\n\nFatal trap %d: %s while in %s mode\n",
944 type, trap_msg[type],
945 (usermode ? "user" : "kernel"));
947 /* two separate prints in case of a trap on an unmapped page */
948 kprintf("cpuid = %d\n", mycpu->gd_cpuid);
949 if (type == T_PAGEFLT) {
950 kprintf("fault virtual address = %p\n", (void *)eva);
951 kprintf("fault code = %s %s, %s\n",
952 usermode ? "user" : "supervisor",
953 code & PGEX_W ? "write" : "read",
954 code & PGEX_P ? "protection violation" : "page not present");
956 kprintf("instruction pointer = 0x%lx:0x%lx\n",
957 frame->tf_cs & 0xffff, frame->tf_rip);
959 ss = frame->tf_ss & 0xffff;
962 ss = GSEL(GDATA_SEL, SEL_KPL);
963 rsp = (long)&frame->tf_rsp;
965 kprintf("stack pointer = 0x%x:0x%lx\n", ss, rsp);
966 kprintf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp);
967 kprintf("processor eflags = ");
968 if (frame->tf_rflags & PSL_T)
969 kprintf("trace trap, ");
970 if (frame->tf_rflags & PSL_I)
971 kprintf("interrupt enabled, ");
972 if (frame->tf_rflags & PSL_NT)
973 kprintf("nested task, ");
974 if (frame->tf_rflags & PSL_RF)
977 if (frame->tf_eflags & PSL_VM)
980 kprintf("IOPL = %jd\n", (intmax_t)((frame->tf_rflags & PSL_IOPL) >> 12));
981 kprintf("current process = ");
983 kprintf("%lu (%s)\n",
984 (u_long)curproc->p_pid, curproc->p_comm ?
985 curproc->p_comm : "");
989 kprintf("current thread = pri %d ", curthread->td_pri);
990 if (curthread->td_critcount)
995 * we probably SHOULD have stopped the other CPUs before now!
996 * another CPU COULD have been touching cpl at this moment...
998 kprintf(" <- SMP: XXX");
1006 if ((debugger_on_panic || db_active) && kdb_trap(type, code, frame))
1009 kprintf("trap number = %d\n", type);
1010 if (type <= MAX_TRAP_MSG)
1011 panic("%s", trap_msg[type]);
1013 panic("unknown/reserved trap");
1017 * Double fault handler. Called when a fault occurs while writing
1018 * a frame for a trap/exception onto the stack. This usually occurs
1019 * when the stack overflows (such is the case with infinite recursion,
1022 * XXX Note that the current PTD gets replaced by IdlePTD when the
1023 * task switch occurs. This means that the stack that was active at
1024 * the time of the double fault is not available at <kstack> unless
1025 * the machine was idle when the double fault occurred. The downside
1026 * of this is that "trace <ebp>" in ddb won't work.
1029 dblfault_handler(void)
1032 struct mdglobaldata *gd = mdcpu;
1035 kprintf("\nFatal double fault:\n");
1037 kprintf("rip = 0x%lx\n", gd->gd_common_tss.tss_rip);
1038 kprintf("rsp = 0x%lx\n", gd->gd_common_tss.tss_rsp);
1039 kprintf("rbp = 0x%lx\n", gd->gd_common_tss.tss_rbp);
1041 /* two separate prints in case of a trap on an unmapped page */
1042 kprintf("cpuid = %d\n", mycpu->gd_cpuid);
1043 panic("double fault");
1047 * Compensate for 386 brain damage (missing URKR).
1048 * This is a little simpler than the pagefault handler in trap() because
1049 * it the page tables have already been faulted in and high addresses
1050 * are thrown out early for other reasons.
1053 trapwrite(unsigned addr)
1060 va = trunc_page((vm_offset_t)addr);
1062 * XXX - MAX is END. Changed > to >= for temp. fix.
1064 if (va >= VM_MAX_USER_ADDRESS)
1067 lp = curthread->td_lwp;
1068 vm = lp->lwp_vmspace;
1070 PHOLD(lp->lwp_proc);
1072 if (!grow_stack (lp->lwp_proc, va)) {
1073 PRELE(lp->lwp_proc);
1078 * fault the data page
1080 rv = vm_fault(&vm->vm_map, va, VM_PROT_WRITE, VM_FAULT_DIRTY);
1082 PRELE(lp->lwp_proc);
1084 if (rv != KERN_SUCCESS)
1091 * syscall2 - MP aware system call request C handler
1093 * A system call is essentially treated as a trap except that the
1094 * MP lock is not held on entry or return. We are responsible for
1095 * obtaining the MP lock if necessary and for handling ASTs
1096 * (e.g. a task switch) prior to return.
1098 * In general, only simple access and manipulation of curproc and
1099 * the current stack is allowed without having to hold MP lock.
1101 * MPSAFE - note that large sections of this routine are run without
1105 syscall2(struct trapframe *frame)
1107 struct thread *td = curthread;
1108 struct proc *p = td->td_proc;
1109 struct lwp *lp = td->td_lwp;
1111 struct sysent *callp;
1112 register_t orig_tf_rflags;
1117 int crit_count = td->td_critcount;
1118 lwkt_tokref_t curstop = td->td_toks_stop;
1120 int have_mplock = 0;
1124 union sysunion args;
1125 register_t *argsdst;
1127 mycpu->gd_cnt.v_syscall++;
1129 KTR_LOG(kernentry_syscall, lp->lwp_proc->p_pid, lp->lwp_tid,
1132 userenter(td, p); /* lazy raise our priority */
1139 sticks = (int)td->td_sticks;
1140 orig_tf_rflags = frame->tf_rflags;
1143 * Virtual kernel intercept - if a VM context managed by a virtual
1144 * kernel issues a system call the virtual kernel handles it, not us.
1145 * Restore the virtual kernel context and return from its system
1146 * call. The current frame is copied out to the virtual kernel.
1148 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
1149 vkernel_trap(lp, frame);
1150 error = EJUSTRETURN;
1155 * Get the system call parameters and account for time
1157 lp->lwp_md.md_regs = frame;
1158 params = (caddr_t)frame->tf_rsp + sizeof(register_t);
1159 code = frame->tf_rax;
1161 if (p->p_sysent->sv_prepsyscall) {
1162 (*p->p_sysent->sv_prepsyscall)(
1163 frame, (int *)(&args.nosys.sysmsg + 1),
1166 if (code == SYS_syscall || code == SYS___syscall) {
1167 code = frame->tf_rdi;
1173 if (p->p_sysent->sv_mask)
1174 code &= p->p_sysent->sv_mask;
1176 if (code >= p->p_sysent->sv_size)
1177 callp = &p->p_sysent->sv_table[0];
1179 callp = &p->p_sysent->sv_table[code];
1181 narg = callp->sy_narg & SYF_ARGMASK;
1184 * On x86_64 we get up to six arguments in registers. The rest are
1185 * on the stack. The first six members of 'struct trapframe' happen
1186 * to be the registers used to pass arguments, in exactly the right
1189 argp = &frame->tf_rdi;
1191 argsdst = (register_t *)(&args.nosys.sysmsg + 1);
1193 * JG can we overflow the space pointed to by 'argsdst'
1194 * either with 'bcopy' or with 'copyin'?
1196 bcopy(argp, argsdst, sizeof(register_t) * regcnt);
1198 * copyin is MP aware, but the tracing code is not
1200 if (narg > regcnt) {
1201 KASSERT(params != NULL, ("copyin args with no params!"));
1202 error = copyin(params, &argsdst[regcnt],
1203 (narg - regcnt) * sizeof(register_t));
1206 if (KTRPOINT(td, KTR_SYSCALL)) {
1207 MAKEMPSAFE(have_mplock);
1209 ktrsyscall(lp, code, narg,
1210 (void *)(&args.nosys.sysmsg + 1));
1218 if (KTRPOINT(td, KTR_SYSCALL)) {
1219 MAKEMPSAFE(have_mplock);
1220 ktrsyscall(lp, code, narg, (void *)(&args.nosys.sysmsg + 1));
1225 * Default return value is 0 (will be copied to %rax). Double-value
1226 * returns use %rax and %rdx. %rdx is left unchanged for system
1227 * calls which return only one result.
1229 args.sysmsg_fds[0] = 0;
1230 args.sysmsg_fds[1] = frame->tf_rdx;
1233 * The syscall might manipulate the trap frame. If it does it
1234 * will probably return EJUSTRETURN.
1236 args.sysmsg_frame = frame;
1238 STOPEVENT(p, S_SCE, narg); /* MP aware */
1241 * NOTE: All system calls run MPSAFE now. The system call itself
1242 * is responsible for getting the MP lock.
1244 error = (*callp->sy_call)(&args);
1247 kprintf("system call %d returned %d\n", code, error);
1252 * MP SAFE (we may or may not have the MP lock at this point)
1257 * Reinitialize proc pointer `p' as it may be different
1258 * if this is a child returning from fork syscall.
1261 lp = curthread->td_lwp;
1262 frame->tf_rax = args.sysmsg_fds[0];
1263 frame->tf_rdx = args.sysmsg_fds[1];
1264 frame->tf_rflags &= ~PSL_C;
1268 * Reconstruct pc, we know that 'syscall' is 2 bytes.
1269 * We have to do a full context restore so that %r10
1270 * (which was holding the value of %rcx) is restored for
1271 * the next iteration.
1273 frame->tf_rip -= frame->tf_err;
1274 frame->tf_r10 = frame->tf_rcx;
1279 panic("Unexpected EASYNC return value (for now)");
1282 if (p->p_sysent->sv_errsize) {
1283 if (error >= p->p_sysent->sv_errsize)
1284 error = -1; /* XXX */
1286 error = p->p_sysent->sv_errtbl[error];
1288 frame->tf_rax = error;
1289 frame->tf_rflags |= PSL_C;
1294 * Traced syscall. trapsignal() is not MP aware.
1296 if (orig_tf_rflags & PSL_T) {
1297 MAKEMPSAFE(have_mplock);
1298 frame->tf_rflags &= ~PSL_T;
1299 trapsignal(lp, SIGTRAP, 0);
1303 * Handle reschedule and other end-of-syscall issues
1305 userret(lp, frame, sticks);
1308 if (KTRPOINT(td, KTR_SYSRET)) {
1309 MAKEMPSAFE(have_mplock);
1310 ktrsysret(lp, code, error, args.sysmsg_result);
1315 * This works because errno is findable through the
1316 * register set. If we ever support an emulation where this
1317 * is not the case, this code will need to be revisited.
1319 STOPEVENT(p, S_SCX, code);
1323 * Release the MP lock if we had to get it
1327 KTR_LOG(kernentry_syscall_ret, lp->lwp_proc->p_pid, lp->lwp_tid, error);
1329 KASSERT(&td->td_toks_base == td->td_toks_stop,
1330 ("syscall: critical section count mismatch! %d/%d",
1331 crit_count, td->td_pri));
1332 KASSERT(curstop == td->td_toks_stop,
1333 ("syscall: extra tokens held after trap! %ld",
1334 td->td_toks_stop - &td->td_toks_base));
1339 * NOTE: mplock not held at any point
1342 fork_return(struct lwp *lp, struct trapframe *frame)
1344 frame->tf_rax = 0; /* Child returns zero */
1345 frame->tf_rflags &= ~PSL_C; /* success */
1348 generic_lwp_return(lp, frame);
1349 KTR_LOG(kernentry_fork_ret, lp->lwp_proc->p_pid, lp->lwp_tid);
1353 * Simplified back end of syscall(), used when returning from fork()
1354 * directly into user mode.
1356 * This code will return back into the fork trampoline code which then
1359 * NOTE: The mplock is not held at any point.
1362 generic_lwp_return(struct lwp *lp, struct trapframe *frame)
1364 struct proc *p = lp->lwp_proc;
1367 * Newly forked processes are given a kernel priority. We have to
1368 * adjust the priority to a normal user priority and fake entry
1369 * into the kernel (call userenter()) to install a passive release
1370 * function just in case userret() decides to stop the process. This
1371 * can occur when ^Z races a fork. If we do not install the passive
1372 * release function the current process designation will not be
1373 * released when the thread goes to sleep.
1375 lwkt_setpri_self(TDPRI_USER_NORM);
1376 userenter(lp->lwp_thread, p);
1377 userret(lp, frame, 0);
1379 if (KTRPOINT(lp->lwp_thread, KTR_SYSRET))
1380 ktrsysret(lp, SYS_fork, 0, 0);
1382 lp->lwp_flags |= LWP_PASSIVE_ACQ;
1384 lp->lwp_flags &= ~LWP_PASSIVE_ACQ;
1388 * doreti has turned into this. The frame is directly on the stack. We
1389 * pull everything else we need (fpu and tls context) from the current
1392 * Note on fpu interactions: In a virtual kernel, the fpu context for
1393 * an emulated user mode process is not shared with the virtual kernel's
1394 * fpu context, so we only have to 'stack' fpu contexts within the virtual
1395 * kernel itself, and not even then since the signal() contexts that we care
1396 * about save and restore the FPU state (I think anyhow).
1398 * vmspace_ctl() returns an error only if it had problems instaling the
1399 * context we supplied or problems copying data to/from our VM space.
1402 go_user(struct intrframe *frame)
1404 struct trapframe *tf = (void *)&frame->if_rdi;
1408 * Interrupts may be disabled on entry, make sure all signals
1409 * can be received before beginning our loop.
1414 * Switch to the current simulated user process, then call
1415 * user_trap() when we break out of it (usually due to a signal).
1419 * Tell the real kernel whether it is ok to use the FP
1422 if (mdcpu->gd_npxthread == curthread) {
1423 tf->tf_xflags &= ~PGEX_FPFAULT;
1425 tf->tf_xflags |= PGEX_FPFAULT;
1429 * Run emulated user process context. This call interlocks
1430 * with new mailbox signals.
1432 * Set PGEX_U unconditionally, indicating a user frame (the
1433 * bit is normally set only by T_PAGEFLT).
1435 r = vmspace_ctl(&curproc->p_vmspace->vm_pmap, VMSPACE_CTL_RUN,
1436 tf, &curthread->td_savevext);
1437 frame->if_xflags |= PGEX_U;
1439 kprintf("GO USER %d trap %ld EVA %08lx RIP %08lx RSP %08lx XFLAGS %02lx/%02lx\n",
1440 r, tf->tf_trapno, tf->tf_addr, tf->tf_rip, tf->tf_rsp,
1441 tf->tf_xflags, frame->if_xflags);
1445 panic("vmspace_ctl failed error %d", errno);
1447 if (tf->tf_trapno) {
1451 if (mycpu->gd_reqflags & RQF_AST_MASK) {
1452 tf->tf_trapno = T_ASTFLT;
1460 * If PGEX_FPFAULT is set then set FP_VIRTFP in the PCB to force a T_DNA
1461 * fault (which is then passed back to the virtual kernel) if an attempt is
1462 * made to use the FP unit.
1464 * XXX this is a fairly big hack.
1467 set_vkernel_fp(struct trapframe *frame)
1469 struct thread *td = curthread;
1471 if (frame->tf_xflags & PGEX_FPFAULT) {
1472 td->td_pcb->pcb_flags |= FP_VIRTFP;
1473 if (mdcpu->gd_npxthread == td)
1476 td->td_pcb->pcb_flags &= ~FP_VIRTFP;
1481 * Called from vkernel_trap() to fixup the vkernel's syscall
1482 * frame for vmspace_ctl() return.
1485 cpu_vkernel_trap(struct trapframe *frame, int error)
1487 frame->tf_rax = error;
1489 frame->tf_rflags |= PSL_C;
1491 frame->tf_rflags &= ~PSL_C;