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/upcall.h>
69 #include <sys/vkernel.h>
70 #include <sys/sysproto.h>
71 #include <sys/sysunion.h>
72 #include <sys/vmspace.h>
75 #include <vm/vm_param.h>
78 #include <vm/vm_kern.h>
79 #include <vm/vm_map.h>
80 #include <vm/vm_page.h>
81 #include <vm/vm_extern.h>
83 #include <machine/cpu.h>
84 #include <machine/md_var.h>
85 #include <machine/pcb.h>
86 #include <machine/smp.h>
87 #include <machine/tss.h>
88 #include <machine/globaldata.h>
92 #include <sys/msgport2.h>
93 #include <sys/thread2.h>
94 #include <sys/mplock2.h>
98 #define MAKEMPSAFE(have_mplock) \
99 if (have_mplock == 0) { \
106 #define MAKEMPSAFE(have_mplock)
110 int (*pmath_emulate) (struct trapframe *);
112 extern int trapwrite (unsigned addr);
114 static int trap_pfault (struct trapframe *, int, vm_offset_t);
115 static void trap_fatal (struct trapframe *, int, vm_offset_t);
116 void dblfault_handler (void);
119 extern inthand_t IDTVEC(syscall);
122 #define MAX_TRAP_MSG 30
123 static char *trap_msg[] = {
125 "privileged instruction fault", /* 1 T_PRIVINFLT */
127 "breakpoint instruction fault", /* 3 T_BPTFLT */
130 "arithmetic trap", /* 6 T_ARITHTRAP */
131 "system forced exception", /* 7 T_ASTFLT */
133 "general protection fault", /* 9 T_PROTFLT */
134 "trace trap", /* 10 T_TRCTRAP */
136 "page fault", /* 12 T_PAGEFLT */
138 "alignment fault", /* 14 T_ALIGNFLT */
142 "integer divide fault", /* 18 T_DIVIDE */
143 "non-maskable interrupt trap", /* 19 T_NMI */
144 "overflow trap", /* 20 T_OFLOW */
145 "FPU bounds check fault", /* 21 T_BOUND */
146 "FPU device not available", /* 22 T_DNA */
147 "double fault", /* 23 T_DOUBLEFLT */
148 "FPU operand fetch fault", /* 24 T_FPOPFLT */
149 "invalid TSS fault", /* 25 T_TSSFLT */
150 "segment not present fault", /* 26 T_SEGNPFLT */
151 "stack fault", /* 27 T_STKFLT */
152 "machine check trap", /* 28 T_MCHK */
153 "SIMD floating-point exception", /* 29 T_XMMFLT */
154 "reserved (unknown) fault", /* 30 T_RESERVED */
158 static int ddb_on_nmi = 1;
159 SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW,
160 &ddb_on_nmi, 0, "Go to DDB on NMI");
162 static int panic_on_nmi = 1;
163 SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW,
164 &panic_on_nmi, 0, "Panic on NMI");
165 static int fast_release;
166 SYSCTL_INT(_machdep, OID_AUTO, fast_release, CTLFLAG_RW,
167 &fast_release, 0, "Passive Release was optimal");
168 static int slow_release;
169 SYSCTL_INT(_machdep, OID_AUTO, slow_release, CTLFLAG_RW,
170 &slow_release, 0, "Passive Release was nonoptimal");
172 MALLOC_DEFINE(M_SYSMSG, "sysmsg", "sysmsg structure");
173 extern int max_sysmsg;
176 * Passively intercepts the thread switch function to increase the thread
177 * priority from a user priority to a kernel priority, reducing
178 * syscall and trap overhead for the case where no switch occurs.
180 * Synchronizes td_ucred with p_ucred. This is used by system calls,
181 * signal handling, faults, AST traps, and anything else that enters the
182 * kernel from userland and provides the kernel with a stable read-only
183 * copy of the process ucred.
186 userenter(struct thread *curtd, struct proc *curp)
191 curtd->td_release = lwkt_passive_release;
193 if (curtd->td_ucred != curp->p_ucred) {
194 ncred = crhold(curp->p_ucred);
195 ocred = curtd->td_ucred;
196 curtd->td_ucred = ncred;
203 * Handle signals, upcalls, profiling, and other AST's and/or tasks that
204 * must be completed before we can return to or try to return to userland.
206 * Note that td_sticks is a 64 bit quantity, but there's no point doing 64
207 * arithmatic on the delta calculation so the absolute tick values are
208 * truncated to an integer.
211 userret(struct lwp *lp, struct trapframe *frame, int sticks)
213 struct proc *p = lp->lwp_proc;
217 * Charge system time if profiling. Note: times are in microseconds.
218 * This may do a copyout and block, so do it first even though it
219 * means some system time will be charged as user time.
221 if (p->p_flag & P_PROFIL) {
222 addupc_task(p, frame->tf_rip,
223 (u_int)((int)lp->lwp_thread->td_sticks - sticks));
228 * If the jungle wants us dead, so be it.
230 if (lp->lwp_flag & LWP_WEXIT) {
231 lwkt_gettoken(&p->p_token);
233 lwkt_reltoken(&p->p_token); /* NOT REACHED */
237 * Block here if we are in a stopped state.
239 if (p->p_stat == SSTOP) {
247 * Post any pending upcalls
249 if (p->p_flag & P_UPCALLPEND) {
250 lwkt_gettoken(&p->p_token);
251 p->p_flag &= ~P_UPCALLPEND;
253 lwkt_reltoken(&p->p_token);
258 * Post any pending signals
260 * WARNING! postsig() can exit and not return.
262 if ((sig = CURSIG_TRACE(lp)) != 0) {
263 lwkt_gettoken(&p->p_token);
265 lwkt_reltoken(&p->p_token);
270 * block here if we are swapped out, but still process signals
271 * (such as SIGKILL). proc0 (the swapin scheduler) is already
272 * aware of our situation, we do not have to wake it up.
274 if (p->p_flag & P_SWAPPEDOUT) {
275 lwkt_gettoken(&p->p_token);
277 p->p_flag |= P_SWAPWAIT;
279 if (p->p_flag & P_SWAPWAIT)
280 tsleep(p, PCATCH, "SWOUT", 0);
281 p->p_flag &= ~P_SWAPWAIT;
283 lwkt_reltoken(&p->p_token);
288 * Make sure postsig() handled request to restore old signal mask after
289 * running signal handler.
291 KKASSERT((lp->lwp_flag & LWP_OLDMASK) == 0);
295 * Cleanup from userenter and any passive release that might have occured.
296 * We must reclaim the current-process designation before we can return
297 * to usermode. We also handle both LWKT and USER reschedule requests.
300 userexit(struct lwp *lp)
302 struct thread *td = lp->lwp_thread;
303 /* globaldata_t gd = td->td_gd; */
306 * Handle stop requests at kernel priority. Any requests queued
307 * after this loop will generate another AST.
309 while (lp->lwp_proc->p_stat == SSTOP) {
316 * Reduce our priority in preparation for a return to userland. If
317 * our passive release function was still in place, our priority was
318 * never raised and does not need to be reduced.
320 lwkt_passive_recover(td);
323 * Become the current user scheduled process if we aren't already,
324 * and deal with reschedule requests and other factors.
326 lp->lwp_proc->p_usched->acquire_curproc(lp);
327 /* WARNING: we may have migrated cpu's */
328 /* gd = td->td_gd; */
331 #if !defined(KTR_KERNENTRY)
332 #define KTR_KERNENTRY KTR_ALL
334 KTR_INFO_MASTER(kernentry);
335 KTR_INFO(KTR_KERNENTRY, kernentry, trap, 0, "pid=%d, tid=%d, trapno=%d, eva=%p",
336 sizeof(int) + sizeof(int) + sizeof(int) + sizeof(vm_offset_t));
337 KTR_INFO(KTR_KERNENTRY, kernentry, trap_ret, 0, "pid=%d, tid=%d",
338 sizeof(int) + sizeof(int));
339 KTR_INFO(KTR_KERNENTRY, kernentry, syscall, 0, "pid=%d, tid=%d, call=%d",
340 sizeof(int) + sizeof(int) + sizeof(int));
341 KTR_INFO(KTR_KERNENTRY, kernentry, syscall_ret, 0, "pid=%d, tid=%d, err=%d",
342 sizeof(int) + sizeof(int) + sizeof(int));
343 KTR_INFO(KTR_KERNENTRY, kernentry, fork_ret, 0, "pid=%d, tid=%d",
344 sizeof(int) + sizeof(int));
347 * Exception, fault, and trap interface to the kernel.
348 * This common code is called from assembly language IDT gate entry
349 * routines that prepare a suitable stack frame, and restore this
350 * frame after the exception has been processed.
352 * This function is also called from doreti in an interlock to handle ASTs.
353 * For example: hardwareint->INTROUTINE->(set ast)->doreti->trap
355 * NOTE! We have to retrieve the fault address prior to obtaining the
356 * MP lock because get_mplock() may switch out. YYY cr2 really ought
357 * to be retrieved by the assembly code, not here.
359 * XXX gd_trap_nesting_level currently prevents lwkt_switch() from panicing
360 * if an attempt is made to switch from a fast interrupt or IPI. This is
361 * necessary to properly take fatal kernel traps on SMP machines if
362 * get_mplock() has to block.
366 user_trap(struct trapframe *frame)
368 struct globaldata *gd = mycpu;
369 struct thread *td = gd->gd_curthread;
370 struct lwp *lp = td->td_lwp;
373 int i = 0, ucode = 0, type, code;
378 int crit_count = td->td_critcount;
379 lwkt_tokref_t curstop = td->td_toks_stop;
385 if (frame->tf_trapno == T_PAGEFLT)
386 eva = frame->tf_addr;
390 kprintf("USER_TRAP AT %08lx xflags %ld trapno %ld eva %08lx\n",
391 frame->tf_rip, frame->tf_xflags, frame->tf_trapno, eva);
395 * Everything coming from user mode runs through user_trap,
396 * including system calls.
398 if (frame->tf_trapno == T_FAST_SYSCALL) {
403 KTR_LOG(kernentry_trap, lp->lwp_proc->p_pid, lp->lwp_tid,
404 frame->tf_trapno, eva);
408 eva = (frame->tf_trapno == T_PAGEFLT ? rcr2() : 0);
409 ++gd->gd_trap_nesting_level;
410 MAKEMPSAFE(have_mplock);
411 trap_fatal(frame, TRUE, eva);
412 --gd->gd_trap_nesting_level;
417 type = frame->tf_trapno;
418 code = frame->tf_err;
422 sticks = (int)td->td_sticks;
423 lp->lwp_md.md_regs = frame;
426 case T_PRIVINFLT: /* privileged instruction fault */
431 case T_BPTFLT: /* bpt instruction fault */
432 case T_TRCTRAP: /* trace trap */
433 frame->tf_rflags &= ~PSL_T;
437 case T_ARITHTRAP: /* arithmetic trap */
442 case T_ASTFLT: /* Allow process switch */
443 mycpu->gd_cnt.v_soft++;
444 if (mycpu->gd_reqflags & RQF_AST_OWEUPC) {
445 atomic_clear_int(&mycpu->gd_reqflags, RQF_AST_OWEUPC);
446 addupc_task(p, p->p_prof.pr_addr, p->p_prof.pr_ticks);
451 * The following two traps can happen in
452 * vm86 mode, and, if so, we want to handle
455 case T_PROTFLT: /* general protection fault */
456 case T_STKFLT: /* stack fault */
458 if (frame->tf_eflags & PSL_VM) {
459 i = vm86_emulate((struct vm86frame *)frame);
467 case T_SEGNPFLT: /* segment not present fault */
468 case T_TSSFLT: /* invalid TSS fault */
469 case T_DOUBLEFLT: /* double fault */
471 ucode = code + BUS_SEGM_FAULT ;
475 case T_PAGEFLT: /* page fault */
476 MAKEMPSAFE(have_mplock);
477 i = trap_pfault(frame, TRUE, eva);
478 if (i == -1 || i == 0)
484 case T_DIVIDE: /* integer divide fault */
491 MAKEMPSAFE(have_mplock);
492 /* machine/parity/power fail/"kitchen sink" faults */
493 if (isa_nmi(code) == 0) {
496 * NMI can be hooked up to a pushbutton
500 kprintf ("NMI ... going to debugger\n");
501 kdb_trap (type, 0, frame);
505 } else if (panic_on_nmi)
506 panic("NMI indicates hardware failure");
508 #endif /* NISA > 0 */
510 case T_OFLOW: /* integer overflow fault */
515 case T_BOUND: /* bounds check fault */
522 * Virtual kernel intercept - pass the DNA exception
523 * to the (emulated) virtual kernel if it asked to handle
524 * it. This occurs when the virtual kernel is holding
525 * onto the FP context for a different emulated
526 * process then the one currently running.
528 * We must still call npxdna() since we may have
529 * saved FP state that the (emulated) virtual kernel
530 * needs to hand over to a different emulated process.
532 if (lp->lwp_vkernel && lp->lwp_vkernel->ve &&
533 (td->td_pcb->pcb_flags & FP_VIRTFP)
539 * The kernel may have switched out the FP unit's
540 * state, causing the user process to take a fault
541 * when it tries to use the FP unit. Restore the
546 if (!pmath_emulate) {
548 ucode = FPE_FPU_NP_TRAP;
551 i = (*pmath_emulate)(frame);
553 if (!(frame->tf_rflags & PSL_T))
555 frame->tf_rflags &= ~PSL_T;
558 /* else ucode = emulator_only_knows() XXX */
561 case T_FPOPFLT: /* FPU operand fetch fault */
566 case T_XMMFLT: /* SIMD floating-point exception */
573 * Virtual kernel intercept - if the fault is directly related to a
574 * VM context managed by a virtual kernel then let the virtual kernel
577 if (lp->lwp_vkernel && lp->lwp_vkernel->ve) {
578 vkernel_trap(lp, frame);
583 * Translate fault for emulators (e.g. Linux)
585 if (*p->p_sysent->sv_transtrap)
586 i = (*p->p_sysent->sv_transtrap)(i, type);
588 MAKEMPSAFE(have_mplock);
589 trapsignal(lp, i, ucode);
592 if (type <= MAX_TRAP_MSG) {
593 uprintf("fatal process exception: %s",
595 if ((type == T_PAGEFLT) || (type == T_PROTFLT))
596 uprintf(", fault VA = 0x%lx", (u_long)eva);
602 userret(lp, frame, sticks);
609 KTR_LOG(kernentry_trap_ret, lp->lwp_proc->p_pid, lp->lwp_tid);
611 KASSERT(crit_count == td->td_critcount,
612 ("trap: critical section count mismatch! %d/%d",
613 crit_count, td->td_pri));
614 KASSERT(curstop == td->td_toks_stop,
615 ("trap: extra tokens held after trap! %ld/%ld",
616 curstop - &td->td_toks_base,
617 td->td_toks_stop - &td->td_toks_base));
622 kern_trap(struct trapframe *frame)
624 struct globaldata *gd = mycpu;
625 struct thread *td = gd->gd_curthread;
628 int i = 0, ucode = 0, type, code;
633 int crit_count = td->td_critcount;
634 lwkt_tokref_t curstop = td->td_toks_stop;
641 if (frame->tf_trapno == T_PAGEFLT)
642 eva = frame->tf_addr;
648 ++gd->gd_trap_nesting_level;
649 MAKEMPSAFE(have_mplock);
650 trap_fatal(frame, FALSE, eva);
651 --gd->gd_trap_nesting_level;
656 type = frame->tf_trapno;
657 code = frame->tf_err;
665 case T_PAGEFLT: /* page fault */
666 MAKEMPSAFE(have_mplock);
667 trap_pfault(frame, FALSE, eva);
672 * The kernel may be using npx for copying or other
675 panic("kernel NPX should not happen");
680 case T_PROTFLT: /* general protection fault */
681 case T_SEGNPFLT: /* segment not present fault */
683 * Invalid segment selectors and out of bounds
684 * %eip's and %esp's can be set up in user mode.
685 * This causes a fault in kernel mode when the
686 * kernel tries to return to user mode. We want
687 * to get this fault so that we can fix the
688 * problem here and not have to check all the
689 * selectors and pointers when the user changes
692 if (mycpu->gd_intr_nesting_level == 0) {
693 if (td->td_pcb->pcb_onfault) {
695 (register_t)td->td_pcb->pcb_onfault;
703 * PSL_NT can be set in user mode and isn't cleared
704 * automatically when the kernel is entered. This
705 * causes a TSS fault when the kernel attempts to
706 * `iret' because the TSS link is uninitialized. We
707 * want to get this fault so that we can fix the
708 * problem here and not every time the kernel is
711 if (frame->tf_rflags & PSL_NT) {
712 frame->tf_rflags &= ~PSL_NT;
717 case T_TRCTRAP: /* trace trap */
719 if (frame->tf_eip == (int)IDTVEC(syscall)) {
721 * We've just entered system mode via the
722 * syscall lcall. Continue single stepping
723 * silently until the syscall handler has
728 if (frame->tf_eip == (int)IDTVEC(syscall) + 1) {
730 * The syscall handler has now saved the
731 * flags. Stop single stepping it.
733 frame->tf_eflags &= ~PSL_T;
739 * Ignore debug register trace traps due to
740 * accesses in the user's address space, which
741 * can happen under several conditions such as
742 * if a user sets a watchpoint on a buffer and
743 * then passes that buffer to a system call.
744 * We still want to get TRCTRAPS for addresses
745 * in kernel space because that is useful when
746 * debugging the kernel.
748 if (user_dbreg_trap()) {
750 * Reset breakpoint bits because the
753 load_dr6(rdr6() & 0xfffffff0);
758 * Fall through (TRCTRAP kernel mode, kernel address)
762 * If DDB is enabled, let it handle the debugger trap.
763 * Otherwise, debugger traps "can't happen".
766 MAKEMPSAFE(have_mplock);
767 if (kdb_trap (type, 0, frame))
772 MAKEMPSAFE(have_mplock);
773 trap_fatal(frame, FALSE, eva);
776 MAKEMPSAFE(have_mplock);
777 trap_fatal(frame, FALSE, eva);
782 * Ignore this trap generated from a spurious SIGTRAP.
784 * single stepping in / syscalls leads to spurious / SIGTRAP
787 * Haiku (c) 2007 Simon 'corecode' Schubert
793 * Translate fault for emulators (e.g. Linux)
795 if (*p->p_sysent->sv_transtrap)
796 i = (*p->p_sysent->sv_transtrap)(i, type);
798 MAKEMPSAFE(have_mplock);
799 trapsignal(lp, i, ucode);
802 if (type <= MAX_TRAP_MSG) {
803 uprintf("fatal process exception: %s",
805 if ((type == T_PAGEFLT) || (type == T_PROTFLT))
806 uprintf(", fault VA = 0x%lx", (u_long)eva);
818 KASSERT(crit_count == td->td_critcount,
819 ("trap: critical section count mismatch! %d/%d",
820 crit_count, td->td_pri));
821 KASSERT(curstop == td->td_toks_stop,
822 ("trap: extra tokens held after trap! %ld/%ld",
823 curstop - &td->td_toks_base,
824 td->td_toks_stop - &td->td_toks_base));
829 trap_pfault(struct trapframe *frame, int usermode, vm_offset_t eva)
832 struct vmspace *vm = NULL;
836 thread_t td = curthread;
837 struct lwp *lp = td->td_lwp;
839 va = trunc_page(eva);
840 if (usermode == FALSE) {
842 * This is a fault on kernel virtual memory.
847 * This is a fault on non-kernel virtual memory.
848 * vm is initialized above to NULL. If curproc is NULL
849 * or curproc->p_vmspace is NULL the fault is fatal.
852 vm = lp->lwp_vmspace;
860 if (frame->tf_err & PGEX_W)
861 ftype = VM_PROT_READ | VM_PROT_WRITE;
863 ftype = VM_PROT_READ;
865 if (map != &kernel_map) {
867 * Keep swapout from messing with us during this
873 * Grow the stack if necessary
875 /* grow_stack returns false only if va falls into
876 * a growable stack region and the stack growth
877 * fails. It returns true if va was not within
878 * a growable stack region, or if the stack
881 if (!grow_stack (lp->lwp_proc, va)) {
887 /* Fault in the user page: */
888 rv = vm_fault(map, va, ftype,
889 (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY
895 * Don't have to worry about process locking or stacks in the kernel.
897 rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL);
900 if (rv == KERN_SUCCESS)
904 if (td->td_gd->gd_intr_nesting_level == 0 &&
905 td->td_pcb->pcb_onfault) {
906 frame->tf_rip = (register_t)td->td_pcb->pcb_onfault;
909 trap_fatal(frame, usermode, eva);
914 * NOTE: on x86_64 we have a tf_addr field in the trapframe, no
915 * kludge is needed to pass the fault address to signal handlers.
917 struct proc *p = td->td_proc;
918 kprintf("seg-fault accessing address %p rip=%p pid=%d p_comm=%s\n",
919 (void *)va, (void *)frame->tf_rip, p->p_pid, p->p_comm);
920 /* Debugger("seg-fault"); */
922 return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV);
926 trap_fatal(struct trapframe *frame, int usermode, vm_offset_t eva)
931 code = frame->tf_xflags;
932 type = frame->tf_trapno;
934 if (type <= MAX_TRAP_MSG) {
935 kprintf("\n\nFatal trap %d: %s while in %s mode\n",
936 type, trap_msg[type],
937 (usermode ? "user" : "kernel"));
940 /* two separate prints in case of a trap on an unmapped page */
941 kprintf("cpuid = %d\n", mycpu->gd_cpuid);
943 if (type == T_PAGEFLT) {
944 kprintf("fault virtual address = %p\n", (void *)eva);
945 kprintf("fault code = %s %s, %s\n",
946 usermode ? "user" : "supervisor",
947 code & PGEX_W ? "write" : "read",
948 code & PGEX_P ? "protection violation" : "page not present");
950 kprintf("instruction pointer = 0x%lx:0x%lx\n",
951 frame->tf_cs & 0xffff, frame->tf_rip);
953 ss = frame->tf_ss & 0xffff;
956 ss = GSEL(GDATA_SEL, SEL_KPL);
957 rsp = (long)&frame->tf_rsp;
959 kprintf("stack pointer = 0x%x:0x%lx\n", ss, rsp);
960 kprintf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp);
961 kprintf("processor eflags = ");
962 if (frame->tf_rflags & PSL_T)
963 kprintf("trace trap, ");
964 if (frame->tf_rflags & PSL_I)
965 kprintf("interrupt enabled, ");
966 if (frame->tf_rflags & PSL_NT)
967 kprintf("nested task, ");
968 if (frame->tf_rflags & PSL_RF)
971 if (frame->tf_eflags & PSL_VM)
974 kprintf("IOPL = %jd\n", (intmax_t)((frame->tf_rflags & PSL_IOPL) >> 12));
975 kprintf("current process = ");
977 kprintf("%lu (%s)\n",
978 (u_long)curproc->p_pid, curproc->p_comm ?
979 curproc->p_comm : "");
983 kprintf("current thread = pri %d ", curthread->td_pri);
984 if (curthread->td_critcount)
990 * we probably SHOULD have stopped the other CPUs before now!
991 * another CPU COULD have been touching cpl at this moment...
993 kprintf(" <- SMP: XXX");
1002 if ((debugger_on_panic || db_active) && kdb_trap(type, code, frame))
1005 kprintf("trap number = %d\n", type);
1006 if (type <= MAX_TRAP_MSG)
1007 panic("%s", trap_msg[type]);
1009 panic("unknown/reserved trap");
1013 * Double fault handler. Called when a fault occurs while writing
1014 * a frame for a trap/exception onto the stack. This usually occurs
1015 * when the stack overflows (such is the case with infinite recursion,
1018 * XXX Note that the current PTD gets replaced by IdlePTD when the
1019 * task switch occurs. This means that the stack that was active at
1020 * the time of the double fault is not available at <kstack> unless
1021 * the machine was idle when the double fault occurred. The downside
1022 * of this is that "trace <ebp>" in ddb won't work.
1025 dblfault_handler(void)
1028 struct mdglobaldata *gd = mdcpu;
1031 kprintf("\nFatal double fault:\n");
1033 kprintf("rip = 0x%lx\n", gd->gd_common_tss.tss_rip);
1034 kprintf("rsp = 0x%lx\n", gd->gd_common_tss.tss_rsp);
1035 kprintf("rbp = 0x%lx\n", gd->gd_common_tss.tss_rbp);
1038 /* two separate prints in case of a trap on an unmapped page */
1039 kprintf("cpuid = %d\n", mycpu->gd_cpuid);
1041 panic("double fault");
1045 * Compensate for 386 brain damage (missing URKR).
1046 * This is a little simpler than the pagefault handler in trap() because
1047 * it the page tables have already been faulted in and high addresses
1048 * are thrown out early for other reasons.
1051 trapwrite(unsigned addr)
1058 va = trunc_page((vm_offset_t)addr);
1060 * XXX - MAX is END. Changed > to >= for temp. fix.
1062 if (va >= VM_MAX_USER_ADDRESS)
1065 lp = curthread->td_lwp;
1066 vm = lp->lwp_vmspace;
1068 PHOLD(lp->lwp_proc);
1070 if (!grow_stack (lp->lwp_proc, va)) {
1071 PRELE(lp->lwp_proc);
1076 * fault the data page
1078 rv = vm_fault(&vm->vm_map, va, VM_PROT_WRITE, VM_FAULT_DIRTY);
1080 PRELE(lp->lwp_proc);
1082 if (rv != KERN_SUCCESS)
1089 * syscall2 - MP aware system call request C handler
1091 * A system call is essentially treated as a trap except that the
1092 * MP lock is not held on entry or return. We are responsible for
1093 * obtaining the MP lock if necessary and for handling ASTs
1094 * (e.g. a task switch) prior to return.
1096 * In general, only simple access and manipulation of curproc and
1097 * the current stack is allowed without having to hold MP lock.
1099 * MPSAFE - note that large sections of this routine are run without
1103 syscall2(struct trapframe *frame)
1105 struct thread *td = curthread;
1106 struct proc *p = td->td_proc;
1107 struct lwp *lp = td->td_lwp;
1109 struct sysent *callp;
1110 register_t orig_tf_rflags;
1115 int crit_count = td->td_critcount;
1116 lwkt_tokref_t curstop = td->td_toks_stop;
1119 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);
1324 * Release the MP lock if we had to get it
1329 KTR_LOG(kernentry_syscall_ret, lp->lwp_proc->p_pid, lp->lwp_tid, error);
1331 KASSERT(&td->td_toks_base == td->td_toks_stop,
1332 ("syscall: critical section count mismatch! %d/%d",
1333 crit_count, td->td_pri));
1334 KASSERT(curstop == td->td_toks_stop,
1335 ("syscall: extra tokens held after trap! %ld",
1336 td->td_toks_stop - &td->td_toks_base));
1341 * NOTE: mplock not held at any point
1344 fork_return(struct lwp *lp, struct trapframe *frame)
1346 frame->tf_rax = 0; /* Child returns zero */
1347 frame->tf_rflags &= ~PSL_C; /* success */
1350 generic_lwp_return(lp, frame);
1351 KTR_LOG(kernentry_fork_ret, lp->lwp_proc->p_pid, lp->lwp_tid);
1355 * Simplified back end of syscall(), used when returning from fork()
1356 * directly into user mode.
1358 * This code will return back into the fork trampoline code which then
1361 * NOTE: The mplock is not held at any point.
1364 generic_lwp_return(struct lwp *lp, struct trapframe *frame)
1366 struct proc *p = lp->lwp_proc;
1369 * Newly forked processes are given a kernel priority. We have to
1370 * adjust the priority to a normal user priority and fake entry
1371 * into the kernel (call userenter()) to install a passive release
1372 * function just in case userret() decides to stop the process. This
1373 * can occur when ^Z races a fork. If we do not install the passive
1374 * release function the current process designation will not be
1375 * released when the thread goes to sleep.
1377 lwkt_setpri_self(TDPRI_USER_NORM);
1378 userenter(lp->lwp_thread, p);
1379 userret(lp, frame, 0);
1381 if (KTRPOINT(lp->lwp_thread, KTR_SYSRET))
1382 ktrsysret(lp, SYS_fork, 0, 0);
1384 lp->lwp_flag |= LWP_PASSIVE_ACQ;
1386 lp->lwp_flag &= ~LWP_PASSIVE_ACQ;
1390 * doreti has turned into this. The frame is directly on the stack. We
1391 * pull everything else we need (fpu and tls context) from the current
1394 * Note on fpu interactions: In a virtual kernel, the fpu context for
1395 * an emulated user mode process is not shared with the virtual kernel's
1396 * fpu context, so we only have to 'stack' fpu contexts within the virtual
1397 * kernel itself, and not even then since the signal() contexts that we care
1398 * about save and restore the FPU state (I think anyhow).
1400 * vmspace_ctl() returns an error only if it had problems instaling the
1401 * context we supplied or problems copying data to/from our VM space.
1404 go_user(struct intrframe *frame)
1406 struct trapframe *tf = (void *)&frame->if_rdi;
1410 * Interrupts may be disabled on entry, make sure all signals
1411 * can be received before beginning our loop.
1416 * Switch to the current simulated user process, then call
1417 * user_trap() when we break out of it (usually due to a signal).
1421 * Tell the real kernel whether it is ok to use the FP
1424 if (mdcpu->gd_npxthread == curthread) {
1425 tf->tf_xflags &= ~PGEX_FPFAULT;
1427 tf->tf_xflags |= PGEX_FPFAULT;
1431 * Run emulated user process context. This call interlocks
1432 * with new mailbox signals.
1434 * Set PGEX_U unconditionally, indicating a user frame (the
1435 * bit is normally set only by T_PAGEFLT).
1437 r = vmspace_ctl(&curproc->p_vmspace->vm_pmap, VMSPACE_CTL_RUN,
1438 tf, &curthread->td_savevext);
1439 frame->if_xflags |= PGEX_U;
1441 kprintf("GO USER %d trap %ld EVA %08lx RIP %08lx RSP %08lx XFLAGS %02lx/%02lx\n",
1442 r, tf->tf_trapno, tf->tf_addr, tf->tf_rip, tf->tf_rsp,
1443 tf->tf_xflags, frame->if_xflags);
1447 panic("vmspace_ctl failed error %d", errno);
1449 if (tf->tf_trapno) {
1453 if (mycpu->gd_reqflags & RQF_AST_MASK) {
1454 tf->tf_trapno = T_ASTFLT;
1462 * If PGEX_FPFAULT is set then set FP_VIRTFP in the PCB to force a T_DNA
1463 * fault (which is then passed back to the virtual kernel) if an attempt is
1464 * made to use the FP unit.
1466 * XXX this is a fairly big hack.
1469 set_vkernel_fp(struct trapframe *frame)
1471 struct thread *td = curthread;
1473 if (frame->tf_xflags & PGEX_FPFAULT) {
1474 td->td_pcb->pcb_flags |= FP_VIRTFP;
1475 if (mdcpu->gd_npxthread == td)
1478 td->td_pcb->pcb_flags &= ~FP_VIRTFP;
1483 * Called from vkernel_trap() to fixup the vkernel's syscall
1484 * frame for vmspace_ctl() return.
1487 cpu_vkernel_trap(struct trapframe *frame, int error)
1489 frame->tf_rax = error;
1491 frame->tf_rflags |= PSL_C;
1493 frame->tf_rflags &= ~PSL_C;