/*- * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * Copyright (C) 1994, David Greenman * Copyright (c) 2008-2018 The DragonFly Project. * Copyright (c) 2008 Jordan Gordeev. * * This code is derived from software contributed to Berkeley by * the University of Utah, and William Jolitz. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from: @(#)trap.c 7.4 (Berkeley) 5/13/91 * $FreeBSD: src/sys/i386/i386/trap.c,v 1.147.2.11 2003/02/27 19:09:59 luoqi Exp $ */ /* * x86_64 Trap and System call handling */ #include "use_isa.h" #include "opt_ddb.h" #include "opt_ktrace.h" #include #include #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #endif #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * These %rip's are used to detect a historical CPU artifact on syscall or * int $3 entry, if not shortcutted in exception.S via * DIRECT_DISALLOW_SS_CPUBUG. */ extern void Xbpt(void); extern void Xfast_syscall(void); #define IDTVEC(vec) X##vec extern void trap(struct trapframe *frame); static int trap_pfault(struct trapframe *, int); static void trap_fatal(struct trapframe *, vm_offset_t); void dblfault_handler(struct trapframe *frame); #define MAX_TRAP_MSG 30 static char *trap_msg[] = { "", /* 0 unused */ "privileged instruction fault", /* 1 T_PRIVINFLT */ "", /* 2 unused */ "breakpoint instruction fault", /* 3 T_BPTFLT */ "", /* 4 unused */ "", /* 5 unused */ "arithmetic trap", /* 6 T_ARITHTRAP */ "system forced exception", /* 7 T_ASTFLT */ "", /* 8 unused */ "general protection fault", /* 9 T_PROTFLT */ "trace trap", /* 10 T_TRCTRAP */ "", /* 11 unused */ "page fault", /* 12 T_PAGEFLT */ "", /* 13 unused */ "alignment fault", /* 14 T_ALIGNFLT */ "", /* 15 unused */ "", /* 16 unused */ "", /* 17 unused */ "integer divide fault", /* 18 T_DIVIDE */ "non-maskable interrupt trap", /* 19 T_NMI */ "overflow trap", /* 20 T_OFLOW */ "FPU bounds check fault", /* 21 T_BOUND */ "FPU device not available", /* 22 T_DNA */ "double fault", /* 23 T_DOUBLEFLT */ "FPU operand fetch fault", /* 24 T_FPOPFLT */ "invalid TSS fault", /* 25 T_TSSFLT */ "segment not present fault", /* 26 T_SEGNPFLT */ "stack fault", /* 27 T_STKFLT */ "machine check trap", /* 28 T_MCHK */ "SIMD floating-point exception", /* 29 T_XMMFLT */ "reserved (unknown) fault", /* 30 T_RESERVED */ }; #ifdef DDB static int ddb_on_nmi = 1; SYSCTL_INT(_machdep, OID_AUTO, ddb_on_nmi, CTLFLAG_RW, &ddb_on_nmi, 0, "Go to DDB on NMI"); static int ddb_on_seg_fault = 0; SYSCTL_INT(_machdep, OID_AUTO, ddb_on_seg_fault, CTLFLAG_RW, &ddb_on_seg_fault, 0, "Go to DDB on user seg-fault"); __read_mostly static int freeze_on_seg_fault = 0; SYSCTL_INT(_machdep, OID_AUTO, freeze_on_seg_fault, CTLFLAG_RW, &freeze_on_seg_fault, 0, "Go to DDB on user seg-fault"); #endif static int panic_on_nmi = 1; SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, &panic_on_nmi, 0, "Panic on NMI"); /* * System call debugging records the worst-case system call * overhead (inclusive of blocking), but may be inaccurate. */ /*#define SYSCALL_DEBUG*/ #ifdef SYSCALL_DEBUG #define SCWC_MAXT 30 struct syscallwc { uint32_t idx; uint32_t dummy; uint64_t tot[SYS_MAXSYSCALL]; uint64_t timings[SYS_MAXSYSCALL][SCWC_MAXT]; } __cachealign; struct syscallwc SysCallsWorstCase[MAXCPU]; #endif /* * Passively intercepts the thread switch function to increase * the thread priority from a user priority to a kernel priority, reducing * syscall and trap overhead for the case where no switch occurs. * * Synchronizes td_ucred with p_ucred. This is used by system calls, * signal handling, faults, AST traps, and anything else that enters the * kernel from userland and provides the kernel with a stable read-only * copy of the process ucred. * * To avoid races with another thread updating p_ucred we obtain p_spin. * The other thread doing the update will obtain both p_token and p_spin. * In the case where the cached cred pointer matches, we will already have * the ref and we don't have to do one blessed thing. */ static __inline void userenter(struct thread *curtd, struct proc *curp) { struct ucred *ocred; struct ucred *ncred; curtd->td_release = lwkt_passive_release; if (__predict_false(curtd->td_ucred != curp->p_ucred)) { spin_lock(&curp->p_spin); ncred = crhold(curp->p_ucred); spin_unlock(&curp->p_spin); ocred = curtd->td_ucred; curtd->td_ucred = ncred; if (ocred) crfree(ocred); } } /* * Handle signals, upcalls, profiling, and other AST's and/or tasks that * must be completed before we can return to or try to return to userland. * * Note that td_sticks is a 64 bit quantity, but there's no point doing 64 * arithmatic on the delta calculation so the absolute tick values are * truncated to an integer. */ static void userret(struct lwp *lp, struct trapframe *frame, int sticks) { struct proc *p = lp->lwp_proc; int sig; int ptok; /* * Charge system time if profiling. Note: times are in microseconds. * This may do a copyout and block, so do it first even though it * means some system time will be charged as user time. */ if (__predict_false(p->p_flags & P_PROFIL)) { addupc_task(p, frame->tf_rip, (u_int)((int)lp->lwp_thread->td_sticks - sticks)); } recheck: /* * Specific on-return-to-usermode checks (LWP_MP_WEXIT, * LWP_MP_VNLRU, etc). */ if (lp->lwp_mpflags & LWP_MP_URETMASK) lwpuserret(lp); /* * Block here if we are in a stopped state. */ if (__predict_false(STOPLWP(p, lp))) { lwkt_gettoken(&p->p_token); tstop(); lwkt_reltoken(&p->p_token); goto recheck; } while (__predict_false(dump_stop_usertds)) { tsleep(&dump_stop_usertds, 0, "dumpstp", 0); } /* * Post any pending upcalls. If running a virtual kernel be sure * to restore the virtual kernel's vmspace before posting the upcall. */ if (__predict_false(p->p_flags & (P_SIGVTALRM | P_SIGPROF))) { lwkt_gettoken(&p->p_token); if (p->p_flags & P_SIGVTALRM) { p->p_flags &= ~P_SIGVTALRM; ksignal(p, SIGVTALRM); } if (p->p_flags & P_SIGPROF) { p->p_flags &= ~P_SIGPROF; ksignal(p, SIGPROF); } lwkt_reltoken(&p->p_token); goto recheck; } /* * Post any pending signals. If running a virtual kernel be sure * to restore the virtual kernel's vmspace before posting the signal. * * WARNING! postsig() can exit and not return. */ if (__predict_false((sig = CURSIG_LCK_TRACE(lp, &ptok)) != 0)) { postsig(sig, ptok); goto recheck; } /* * In a multi-threaded program it is possible for a thread to change * signal state during a system call which temporarily changes the * signal mask. In this case postsig() might not be run and we * have to restore the mask ourselves. */ if (__predict_false(lp->lwp_flags & LWP_OLDMASK)) { lp->lwp_flags &= ~LWP_OLDMASK; lp->lwp_sigmask = lp->lwp_oldsigmask; goto recheck; } } /* * Cleanup from userenter and any passive release that might have occured. * We must reclaim the current-process designation before we can return * to usermode. We also handle both LWKT and USER reschedule requests. */ static __inline void userexit(struct lwp *lp) { struct thread *td = lp->lwp_thread; /* globaldata_t gd = td->td_gd; */ /* * Handle stop requests at kernel priority. Any requests queued * after this loop will generate another AST. */ while (__predict_false(STOPLWP(lp->lwp_proc, lp))) { lwkt_gettoken(&lp->lwp_proc->p_token); tstop(); lwkt_reltoken(&lp->lwp_proc->p_token); } /* * Reduce our priority in preparation for a return to userland. If * our passive release function was still in place, our priority was * never raised and does not need to be reduced. */ lwkt_passive_recover(td); /* WARNING: we may have migrated cpu's */ /* gd = td->td_gd; */ /* * Become the current user scheduled process if we aren't already, * and deal with reschedule requests and other factors. * * Do a silly hack to avoid RETPOLINE nonsense. */ if (lp->lwp_proc->p_usched == &usched_dfly) dfly_acquire_curproc(lp); else lp->lwp_proc->p_usched->acquire_curproc(lp); } /* * A page fault on a userspace address is classified as SMAP-induced * if: * - SMAP is supported * - kernel mode accessed present data page * - rflags.AC was cleared */ static int trap_is_smap(struct trapframe *frame) { if ((cpu_stdext_feature & CPUID_STDEXT_SMAP) != 0 && (frame->tf_err & (PGEX_P | PGEX_U | PGEX_I | PGEX_RSV)) == PGEX_P && (frame->tf_rflags & PSL_AC) == 0) { return 1; } else { return 0; } } #if !defined(KTR_KERNENTRY) #define KTR_KERNENTRY KTR_ALL #endif KTR_INFO_MASTER(kernentry); KTR_INFO(KTR_KERNENTRY, kernentry, trap, 0, "TRAP(pid %d, tid %d, trapno %ld, eva %lu)", pid_t pid, lwpid_t tid, register_t trapno, vm_offset_t eva); KTR_INFO(KTR_KERNENTRY, kernentry, trap_ret, 0, "TRAP_RET(pid %d, tid %d)", pid_t pid, lwpid_t tid); KTR_INFO(KTR_KERNENTRY, kernentry, syscall, 0, "SYSC(pid %d, tid %d, nr %ld)", pid_t pid, lwpid_t tid, register_t trapno); KTR_INFO(KTR_KERNENTRY, kernentry, syscall_ret, 0, "SYSRET(pid %d, tid %d, err %d)", pid_t pid, lwpid_t tid, int err); KTR_INFO(KTR_KERNENTRY, kernentry, fork_ret, 0, "FORKRET(pid %d, tid %d)", pid_t pid, lwpid_t tid); /* * Exception, fault, and trap interface to the kernel. * This common code is called from assembly language IDT gate entry * routines that prepare a suitable stack frame, and restore this * frame after the exception has been processed. * * This function is also called from doreti in an interlock to handle ASTs. * For example: hardwareint->INTROUTINE->(set ast)->doreti->trap * * NOTE! We have to retrieve the fault address prior to potentially * blocking, including blocking on any token. * * NOTE! NMI and kernel DBG traps remain on their respective pcpu IST * stacks if taken from a kernel RPL. trap() cannot block in this * situation. DDB entry or a direct report-and-return is ok. * * XXX gd_trap_nesting_level currently prevents lwkt_switch() from panicing * if an attempt is made to switch from a fast interrupt or IPI. */ void trap(struct trapframe *frame) { static struct krate sscpubugrate = { 1 }; struct globaldata *gd = mycpu; struct thread *td = gd->gd_curthread; struct lwp *lp = td->td_lwp; struct proc *p; int sticks = 0; int i = 0, ucode = 0, type, code; #ifdef INVARIANTS int crit_count = td->td_critcount; lwkt_tokref_t curstop = td->td_toks_stop; #endif vm_offset_t eva; p = td->td_proc; clear_quickret(); #ifdef DDB /* * We need to allow T_DNA faults when the debugger is active since * some dumping paths do large bcopy() which use the floating * point registers for faster copying. */ if (db_active && frame->tf_trapno != T_DNA) { eva = (frame->tf_trapno == T_PAGEFLT ? frame->tf_addr : 0); ++gd->gd_trap_nesting_level; trap_fatal(frame, eva); --gd->gd_trap_nesting_level; goto out2; } #endif eva = 0; if ((frame->tf_rflags & PSL_I) == 0) { /* * Buggy application or kernel code has disabled interrupts * and then trapped. Enabling interrupts now is wrong, but * it is better than running with interrupts disabled until * they are accidentally enabled later. */ type = frame->tf_trapno; if (ISPL(frame->tf_cs) == SEL_UPL) { /* JG curproc can be NULL */ kprintf( "pid %ld (%s): trap %d with interrupts disabled\n", (long)curproc->p_pid, curproc->p_comm, type); } else if ((type == T_STKFLT || type == T_PROTFLT || type == T_SEGNPFLT) && frame->tf_rip == (long)doreti_iret) { /* * iretq fault from kernel mode during return to * userland. * * This situation is expected, don't complain. */ } else if (type != T_NMI && type != T_BPTFLT && type != T_TRCTRAP) { /* * XXX not quite right, since this may be for a * multiple fault in user mode. */ kprintf("kernel trap %d (%s @ 0x%016jx) with " "interrupts disabled\n", type, td->td_comm, frame->tf_rip); } cpu_enable_intr(); } type = frame->tf_trapno; code = frame->tf_err; if (ISPL(frame->tf_cs) == SEL_UPL) { /* user trap */ KTR_LOG(kernentry_trap, p->p_pid, lp->lwp_tid, frame->tf_trapno, eva); userenter(td, p); sticks = (int)td->td_sticks; KASSERT(lp->lwp_md.md_regs == frame, ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); switch (type) { case T_PRIVINFLT: /* privileged instruction fault */ i = SIGILL; ucode = ILL_PRVOPC; break; case T_BPTFLT: /* bpt instruction fault */ case T_TRCTRAP: /* trace trap */ frame->tf_rflags &= ~PSL_T; i = SIGTRAP; ucode = (type == T_TRCTRAP ? TRAP_TRACE : TRAP_BRKPT); break; case T_ARITHTRAP: /* arithmetic trap */ ucode = code; i = SIGFPE; break; case T_ASTFLT: /* Allow process switch */ mycpu->gd_cnt.v_soft++; if (mycpu->gd_reqflags & RQF_AST_OWEUPC) { atomic_clear_int(&mycpu->gd_reqflags, RQF_AST_OWEUPC); addupc_task(p, p->p_prof.pr_addr, p->p_prof.pr_ticks); } goto out; case T_PROTFLT: /* general protection fault */ i = SIGBUS; ucode = BUS_OBJERR; break; case T_STKFLT: /* stack fault */ case T_SEGNPFLT: /* segment not present fault */ i = SIGBUS; ucode = BUS_ADRERR; break; case T_TSSFLT: /* invalid TSS fault */ case T_DOUBLEFLT: /* double fault */ default: i = SIGBUS; ucode = BUS_OBJERR; break; case T_PAGEFLT: /* page fault */ i = trap_pfault(frame, TRUE); #ifdef DDB if (frame->tf_rip == 0) { /* used for kernel debugging only */ while (freeze_on_seg_fault) tsleep(p, 0, "freeze", hz * 20); } #endif if (i == -1 || i == 0) goto out; if (i == SIGSEGV) { ucode = SEGV_MAPERR; } else { i = SIGSEGV; ucode = SEGV_ACCERR; } break; case T_DIVIDE: /* integer divide fault */ ucode = FPE_INTDIV; i = SIGFPE; break; #if NISA > 0 case T_NMI: /* machine/parity/power fail/"kitchen sink" faults */ if (isa_nmi(code) == 0) { #ifdef DDB /* * NMI can be hooked up to a pushbutton * for debugging. */ if (ddb_on_nmi) { kprintf ("NMI ... going to debugger\n"); kdb_trap(type, 0, frame); } #endif /* DDB */ goto out2; } else if (panic_on_nmi) panic("NMI indicates hardware failure"); break; #endif /* NISA > 0 */ case T_OFLOW: /* integer overflow fault */ ucode = FPE_INTOVF; i = SIGFPE; break; case T_BOUND: /* bounds check fault */ ucode = FPE_FLTSUB; i = SIGFPE; break; case T_DNA: /* * Virtual kernel intercept - pass the DNA exception * to the virtual kernel if it asked to handle it. * This occurs when the virtual kernel is holding * onto the FP context for a different emulated * process then the one currently running. * * We must still call npxdna() since we may have * saved FP state that the virtual kernel needs * to hand over to a different emulated process. */ if (lp->lwp_vkernel && lp->lwp_vkernel->ve && (td->td_pcb->pcb_flags & FP_VIRTFP) ) { npxdna(); break; } /* * The kernel may have switched out the FP unit's * state, causing the user process to take a fault * when it tries to use the FP unit. Restore the * state here */ if (npxdna()) { gd->gd_cnt.v_trap++; goto out; } i = SIGFPE; ucode = FPE_FPU_NP_TRAP; break; case T_FPOPFLT: /* FPU operand fetch fault */ ucode = ILL_COPROC; i = SIGILL; break; case T_XMMFLT: /* SIMD floating-point exception */ ucode = 0; /* XXX */ i = SIGFPE; break; } } else { /* kernel trap */ switch (type) { case T_PAGEFLT: /* page fault */ trap_pfault(frame, FALSE); goto out2; case T_DNA: /* * The kernel is apparently using fpu for copying. * XXX this should be fatal unless the kernel has * registered such use. */ if (npxdna()) { gd->gd_cnt.v_trap++; goto out2; } break; case T_STKFLT: /* stack fault */ case T_PROTFLT: /* general protection fault */ case T_SEGNPFLT: /* segment not present fault */ /* * Invalid segment selectors and out of bounds * %rip's and %rsp's can be set up in user mode. * This causes a fault in kernel mode when the * kernel tries to return to user mode. We want * to get this fault so that we can fix the * problem here and not have to check all the * selectors and pointers when the user changes * them. */ if (mycpu->gd_intr_nesting_level == 0) { /* * NOTE: in 64-bit mode traps push rsp/ss * even if no ring change occurs. */ if (td->td_pcb->pcb_onfault && td->td_pcb->pcb_onfault_sp == frame->tf_rsp) { frame->tf_rip = (register_t) td->td_pcb->pcb_onfault; goto out2; } /* * If the iretq in doreti faults during * return to user, it will be special-cased * in IDTVEC(prot) to get here. We want * to 'return' to doreti_iret_fault in * ipl.s in approximately the same state we * were in at the iretq. */ if (frame->tf_rip == (long)doreti_iret) { frame->tf_rip = (long)doreti_iret_fault; goto out2; } } break; case T_TSSFLT: /* * PSL_NT can be set in user mode and isn't cleared * automatically when the kernel is entered. This * causes a TSS fault when the kernel attempts to * `iret' because the TSS link is uninitialized. We * want to get this fault so that we can fix the * problem here and not every time the kernel is * entered. */ if (frame->tf_rflags & PSL_NT) { frame->tf_rflags &= ~PSL_NT; #if 0 /* do we need this? */ if (frame->tf_rip == (long)doreti_iret) frame->tf_rip = (long)doreti_iret_fault; #endif goto out2; } break; case T_TRCTRAP: /* trace trap */ /* * Detect historical CPU artifact on syscall or int $3 * entry (if not shortcutted in exception.s via * DIRECT_DISALLOW_SS_CPUBUG). */ gd->gd_cnt.v_trap++; if (frame->tf_rip == (register_t)IDTVEC(fast_syscall)) { krateprintf(&sscpubugrate, "Caught #DB at syscall cpu artifact\n"); goto out2; } if (frame->tf_rip == (register_t)IDTVEC(bpt)) { krateprintf(&sscpubugrate, "Caught #DB at int $N cpu artifact\n"); goto out2; } /* * Ignore debug register trace traps due to * accesses in the user's address space, which * can happen under several conditions such as * if a user sets a watchpoint on a buffer and * then passes that buffer to a system call. * We still want to get TRCTRAPS for addresses * in kernel space because that is useful when * debugging the kernel. */ if (user_dbreg_trap()) { /* * Reset breakpoint bits because the * processor doesn't */ load_dr6(rdr6() & ~0xf); goto out2; } /* * FALLTHROUGH (TRCTRAP kernel mode, kernel address) */ case T_BPTFLT: /* * If DDB is enabled, let it handle the debugger trap. * Otherwise, debugger traps "can't happen". */ ucode = TRAP_BRKPT; #ifdef DDB if (kdb_trap(type, 0, frame)) goto out2; #endif break; #if NISA > 0 case T_NMI: /* machine/parity/power fail/"kitchen sink" faults */ if (isa_nmi(code) == 0) { #ifdef DDB /* * NMI can be hooked up to a pushbutton * for debugging. */ if (ddb_on_nmi) { kprintf ("NMI ... going to debugger\n"); kdb_trap(type, 0, frame); } #endif /* DDB */ goto out2; } else if (panic_on_nmi == 0) goto out2; #endif /* NISA > 0 */ break; default: if (type >= T_RESERVED && type < T_RESERVED + 256) { kprintf("Ignoring spurious unknown " "cpu trap T_RESERVED+%d\n", type - T_RESERVED); gd->gd_cnt.v_trap++; goto out2; } break; } trap_fatal(frame, 0); goto out2; } /* * Fault from user mode, virtual kernel interecept. * * If the fault is directly related to a VM context managed by a * virtual kernel then let the virtual kernel handle it. */ if (lp->lwp_vkernel && lp->lwp_vkernel->ve) { vkernel_trap(lp, frame); goto out; } /* Translate fault for emulators (e.g. Linux) */ if (*p->p_sysent->sv_transtrap) i = (*p->p_sysent->sv_transtrap)(i, type); gd->gd_cnt.v_trap++; trapsignal(lp, i, ucode); #ifdef DEBUG if (type <= MAX_TRAP_MSG) { uprintf("fatal process exception: %s", trap_msg[type]); if ((type == T_PAGEFLT) || (type == T_PROTFLT)) uprintf(", fault VA = 0x%lx", frame->tf_addr); uprintf("\n"); } #endif out: userret(lp, frame, sticks); userexit(lp); out2: ; if (p != NULL && lp != NULL) KTR_LOG(kernentry_trap_ret, p->p_pid, lp->lwp_tid); #ifdef INVARIANTS KASSERT(crit_count == td->td_critcount, ("trap: critical section count mismatch! %d/%d", crit_count, td->td_critcount)); KASSERT(curstop == td->td_toks_stop, ("trap: extra tokens held after trap! %ld/%ld (%s)", curstop - &td->td_toks_base, td->td_toks_stop - &td->td_toks_base, td->td_toks_stop[-1].tr_tok->t_desc)); #endif } void trap_handle_userenter(struct thread *td) { userenter(td, td->td_proc); } void trap_handle_userexit(struct trapframe *frame, int sticks) { struct lwp *lp = curthread->td_lwp; if (lp) { userret(lp, frame, sticks); userexit(lp); } } static int trap_pfault(struct trapframe *frame, int usermode) { vm_offset_t va; struct vmspace *vm = NULL; vm_map_t map; int rv = 0; int fault_flags; vm_prot_t ftype; thread_t td = curthread; struct lwp *lp = td->td_lwp; struct proc *p; va = trunc_page(frame->tf_addr); if (va >= VM_MIN_KERNEL_ADDRESS) { /* * Don't allow user-mode faults in kernel address space. */ if (usermode) { fault_flags = -1; ftype = -1; goto nogo; } map = kernel_map; } else { /* * This is a fault on non-kernel virtual memory. * vm is initialized above to NULL. If curproc is NULL * or curproc->p_vmspace is NULL the fault is fatal. */ if (lp != NULL) vm = lp->lwp_vmspace; if (vm == NULL) { fault_flags = -1; ftype = -1; goto nogo; } if (usermode == 0) { #ifdef DDB /* * Debugging, catch kernel faults on the user address * space when not inside on onfault (e.g. copyin/ * copyout) routine. */ if (td->td_pcb == NULL || td->td_pcb->pcb_onfault == NULL) { if (freeze_on_seg_fault) { kprintf("trap_pfault: user address " "fault from kernel mode " "%016lx\n", (long)frame->tf_addr); while (freeze_on_seg_fault) { tsleep(&freeze_on_seg_fault, 0, "frzseg", hz * 20); } } } #endif if (td->td_gd->gd_intr_nesting_level || trap_is_smap(frame) || td->td_pcb == NULL || td->td_pcb->pcb_onfault == NULL) { kprintf("Fatal user address access " "from kernel mode from %s at %016jx\n", td->td_comm, frame->tf_rip); trap_fatal(frame, frame->tf_addr); return (-1); } } map = &vm->vm_map; } /* * PGEX_I is defined only if the execute disable bit capability is * supported and enabled. */ if (frame->tf_err & PGEX_W) ftype = VM_PROT_WRITE; else if (frame->tf_err & PGEX_I) ftype = VM_PROT_EXECUTE; else ftype = VM_PROT_READ; lwkt_tokref_t stop = td->td_toks_stop; if (map != kernel_map) { /* * Keep swapout from messing with us during this * critical time. */ PHOLD(lp->lwp_proc); /* * Issue fault */ fault_flags = 0; if (usermode) fault_flags |= VM_FAULT_BURST | VM_FAULT_USERMODE; if (ftype & VM_PROT_WRITE) fault_flags |= VM_FAULT_DIRTY; else fault_flags |= VM_FAULT_NORMAL; rv = vm_fault(map, va, ftype, fault_flags); if (td->td_toks_stop != stop) { stop = td->td_toks_stop - 1; kprintf("A-HELD TOKENS DURING PFAULT td=%p(%s) map=%p va=%p ftype=%d fault_flags=%d\n", td, td->td_comm, map, (void *)va, ftype, fault_flags); panic("held tokens"); } PRELE(lp->lwp_proc); } else { /* * Don't have to worry about process locking or stacks in the * kernel. */ fault_flags = VM_FAULT_NORMAL; rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); if (td->td_toks_stop != stop) { stop = td->td_toks_stop - 1; kprintf("B-HELD TOKENS DURING PFAULT td=%p(%s) map=%p va=%p ftype=%d fault_flags=%d\n", td, td->td_comm, map, (void *)va, ftype, VM_FAULT_NORMAL); panic("held tokens"); } } if (rv == KERN_SUCCESS) return (0); nogo: if (!usermode) { /* * NOTE: in 64-bit mode traps push rsp/ss * even if no ring change occurs. */ if (td->td_pcb->pcb_onfault && td->td_pcb->pcb_onfault_sp == frame->tf_rsp && td->td_gd->gd_intr_nesting_level == 0) { frame->tf_rip = (register_t)td->td_pcb->pcb_onfault; return (0); } trap_fatal(frame, frame->tf_addr); return (-1); } /* * NOTE: on x86_64 we have a tf_addr field in the trapframe, no * kludge is needed to pass the fault address to signal handlers. */ p = td->td_proc; #ifdef DDB if (td->td_lwp->lwp_vkernel == NULL) { while (freeze_on_seg_fault) { tsleep(p, 0, "freeze", hz * 20); } if (ddb_on_seg_fault) Debugger("ddb_on_seg_fault"); } #endif return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); } static void trap_fatal(struct trapframe *frame, vm_offset_t eva) { int code, ss; u_int type; long rsp; struct soft_segment_descriptor softseg; code = frame->tf_err; type = frame->tf_trapno; sdtossd(&mdcpu->gd_gdt[IDXSEL(frame->tf_cs & 0xffff)], &softseg); kprintf("\n\nFatal trap %d: ", type); if (type <= MAX_TRAP_MSG) kprintf("%s ", trap_msg[type]); else kprintf("rsvd(%d) ", type - T_RESERVED); kprintf("while in %s mode\n", ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); /* three separate prints in case of a trap on an unmapped page */ kprintf("cpuid = %d; ", mycpu->gd_cpuid); if (lapic_usable) kprintf("lapic id = %u\n", LAPIC_READID); if (type == T_PAGEFLT) { kprintf("fault virtual address = 0x%lx\n", eva); kprintf("fault code = %s %s %s, %s\n", code & PGEX_U ? "user" : "supervisor", code & PGEX_W ? "write" : "read", code & PGEX_I ? "instruction" : "data", code & PGEX_P ? "protection violation" : "page not present"); } kprintf("instruction pointer = 0x%lx:0x%lx\n", frame->tf_cs & 0xffff, frame->tf_rip); if (ISPL(frame->tf_cs) == SEL_UPL) { ss = frame->tf_ss & 0xffff; rsp = frame->tf_rsp; } else { /* * NOTE: in 64-bit mode traps push rsp/ss even if no ring * change occurs. */ ss = GSEL(GDATA_SEL, SEL_KPL); rsp = frame->tf_rsp; } kprintf("stack pointer = 0x%x:0x%lx\n", ss, rsp); kprintf("frame pointer = 0x%x:0x%lx\n", ss, frame->tf_rbp); kprintf("code segment = base 0x%lx, limit 0x%lx, type 0x%x\n", softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); kprintf(" = DPL %d, pres %d, long %d, def32 %d, gran %d\n", softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_long, softseg.ssd_def32, softseg.ssd_gran); kprintf("processor eflags = "); if (frame->tf_rflags & PSL_T) kprintf("trace trap, "); if (frame->tf_rflags & PSL_I) kprintf("interrupt enabled, "); if (frame->tf_rflags & PSL_NT) kprintf("nested task, "); if (frame->tf_rflags & PSL_RF) kprintf("resume, "); if (frame->tf_rflags & PSL_AC) kprintf("smap_open, "); kprintf("IOPL = %ld\n", (frame->tf_rflags & PSL_IOPL) >> 12); kprintf("current process = "); if (curproc) { kprintf("%lu\n", (u_long)curproc->p_pid); } else { kprintf("Idle\n"); } kprintf("current thread = pri %d ", curthread->td_pri); if (curthread->td_critcount) kprintf("(CRIT)"); kprintf("\n"); #ifdef DDB if ((debugger_on_panic || db_active) && kdb_trap(type, code, frame)) return; #endif kprintf("trap number = %d\n", type); if (type <= MAX_TRAP_MSG) panic("%s", trap_msg[type]); else panic("unknown/reserved trap"); } /* * Double fault handler. Called when a fault occurs while writing * a frame for a trap/exception onto the stack. This usually occurs * when the stack overflows (such is the case with infinite recursion, * for example). */ static __inline int in_kstack_guard(register_t rptr) { thread_t td = curthread; if ((char *)rptr >= td->td_kstack && (char *)rptr < td->td_kstack + PAGE_SIZE) { return 1; } return 0; } void dblfault_handler(struct trapframe *frame) { thread_t td = curthread; if (in_kstack_guard(frame->tf_rsp) || in_kstack_guard(frame->tf_rbp)) { kprintf("DOUBLE FAULT - KERNEL STACK GUARD HIT!\n"); if (in_kstack_guard(frame->tf_rsp)) frame->tf_rsp = (register_t)(td->td_kstack + PAGE_SIZE); if (in_kstack_guard(frame->tf_rbp)) frame->tf_rbp = (register_t)(td->td_kstack + PAGE_SIZE); } else { kprintf("DOUBLE FAULT\n"); } kprintf("\nFatal double fault\n"); kprintf("rip = 0x%lx\n", frame->tf_rip); kprintf("rsp = 0x%lx\n", frame->tf_rsp); kprintf("rbp = 0x%lx\n", frame->tf_rbp); /* three separate prints in case of a trap on an unmapped page */ kprintf("cpuid = %d; ", mycpu->gd_cpuid); if (lapic_usable) kprintf("lapic id = %u\n", LAPIC_READID); panic("double fault"); } /* * syscall2 - MP aware system call request C handler * * A system call is essentially treated as a trap except that the * MP lock is not held on entry or return. We are responsible for * obtaining the MP lock if necessary and for handling ASTs * (e.g. a task switch) prior to return. */ void syscall2(struct trapframe *frame) { struct thread *td = curthread; struct proc *p = td->td_proc; struct lwp *lp = td->td_lwp; struct sysent *callp; register_t orig_tf_rflags; int sticks; int error; int narg; #ifdef INVARIANTS int crit_count = td->td_critcount; #endif struct sysmsg sysmsg; union sysunion *argp; u_int code; const int regcnt = 6; /* number of args passed in registers */ mycpu->gd_cnt.v_syscall++; #ifdef DIAGNOSTIC if (__predict_false(ISPL(frame->tf_cs) != SEL_UPL)) { panic("syscall"); /* NOT REACHED */ } #endif KTR_LOG(kernentry_syscall, p->p_pid, lp->lwp_tid, frame->tf_rax); userenter(td, p); /* lazy raise our priority */ /* * Misc */ sticks = (int)td->td_sticks; orig_tf_rflags = frame->tf_rflags; /* * Virtual kernel intercept - if a VM context managed by a virtual * kernel issues a system call the virtual kernel handles it, not us. * Restore the virtual kernel context and return from its system * call. The current frame is copied out to the virtual kernel. */ if (__predict_false(lp->lwp_vkernel && lp->lwp_vkernel->ve)) { vkernel_trap(lp, frame); error = EJUSTRETURN; callp = NULL; code = 0; goto out; } /* * Get the system call parameters and account for time */ #ifdef DIAGNOSTIC KASSERT(lp->lwp_md.md_regs == frame, ("Frame mismatch %p %p", lp->lwp_md.md_regs, frame)); #endif code = (u_int)frame->tf_rax; if (code >= p->p_sysent->sv_size) code = SYS___nosys; argp = (union sysunion *)&frame->tf_rdi; callp = &p->p_sysent->sv_table[code]; /* * On x86_64 we get up to six arguments in registers. The rest are * on the stack. The first six members of 'struct trapframe' happen * to be the registers used to pass arguments, in exactly the right * order. * * Any arguments beyond available argument-passing registers must * be copyin()'d from the user stack. */ narg = callp->sy_narg; if (__predict_false(narg > regcnt)) { register_t *argsdst; caddr_t params; argsdst = (register_t *)&sysmsg.extargs; bcopy(argp, argsdst, sizeof(register_t) * regcnt); params = (caddr_t)frame->tf_rsp + sizeof(register_t); error = copyin(params, &argsdst[regcnt], (narg - regcnt) * sizeof(register_t)); argp = (void *)argsdst; if (error) { #ifdef KTRACE if (KTRPOINTP(p, td, KTR_SYSCALL)) { ktrsyscall(lp, code, narg, argp); } #endif goto bad; } } #ifdef KTRACE if (KTRPOINTP(p, td, KTR_SYSCALL)) { ktrsyscall(lp, code, narg, argp); } #endif /* * Default return value is 0 (will be copied to %rax). Double-value * returns use %rax and %rdx. %rdx is left unchanged for system * calls which return only one result. */ sysmsg.sysmsg_fds[0] = 0; sysmsg.sysmsg_fds[1] = frame->tf_rdx; /* * The syscall might manipulate the trap frame. If it does it * will probably return EJUSTRETURN. */ sysmsg.sysmsg_frame = frame; STOPEVENT(p, S_SCE, narg); /* MP aware */ /* * NOTE: All system calls run MPSAFE now. The system call itself * is responsible for getting the MP lock. */ #ifdef SYSCALL_DEBUG tsc_uclock_t tscval = rdtsc(); #endif error = (*callp->sy_call)(&sysmsg, argp); #ifdef SYSCALL_DEBUG tscval = rdtsc() - tscval; tscval = tscval * 1000000 / (tsc_frequency / 1000); /* ns */ { struct syscallwc *scwc = &SysCallsWorstCase[mycpu->gd_cpuid]; int idx = scwc->idx++ % SCWC_MAXT; scwc->tot[code] += tscval - scwc->timings[code][idx]; scwc->timings[code][idx] = tscval; } #endif out: /* * MP SAFE (we may or may not have the MP lock at this point) */ //kprintf("SYSMSG %d ", error); if (__predict_true(error == 0)) { /* * Reinitialize proc pointer `p' as it may be different * if this is a child returning from fork syscall. */ p = curproc; lp = curthread->td_lwp; frame->tf_rax = sysmsg.sysmsg_fds[0]; frame->tf_rdx = sysmsg.sysmsg_fds[1]; frame->tf_rflags &= ~PSL_C; } else if (error == ERESTART) { /* * Reconstruct pc, we know that 'syscall' is 2 bytes. * We have to do a full context restore so that %r10 * (which was holding the value of %rcx) is restored for * the next iteration. */ if (frame->tf_err != 0 && frame->tf_err != 2) kprintf("lp %s:%d frame->tf_err is weird %ld\n", td->td_comm, lp->lwp_proc->p_pid, frame->tf_err); frame->tf_rip -= frame->tf_err; frame->tf_r10 = frame->tf_rcx; } else if (error == EJUSTRETURN) { /* do nothing */ } else if (error == EASYNC) { panic("Unexpected EASYNC return value (for now)"); } else { bad: if (p->p_sysent->sv_errsize) { if (error >= p->p_sysent->sv_errsize) error = -1; /* XXX */ else error = p->p_sysent->sv_errtbl[error]; } frame->tf_rax = error; frame->tf_rflags |= PSL_C; } /* * Traced syscall. trapsignal() should now be MP aware */ if (__predict_false(orig_tf_rflags & PSL_T)) { frame->tf_rflags &= ~PSL_T; trapsignal(lp, SIGTRAP, TRAP_TRACE); } /* * Handle reschedule and other end-of-syscall issues */ userret(lp, frame, sticks); #ifdef KTRACE if (KTRPOINTP(p, td, KTR_SYSRET)) { ktrsysret(lp, code, error, sysmsg.sysmsg_result); } #endif /* * This works because errno is findable through the * register set. If we ever support an emulation where this * is not the case, this code will need to be revisited. */ STOPEVENT(p, S_SCX, code); userexit(lp); KTR_LOG(kernentry_syscall_ret, p->p_pid, lp->lwp_tid, error); #ifdef INVARIANTS KASSERT(crit_count == td->td_critcount, ("syscall: critical section count mismatch! " "%d/%d in %s sysno=%d", crit_count, td->td_critcount, td->td_comm, code)); KASSERT(&td->td_toks_base == td->td_toks_stop, ("syscall: %ld extra tokens held after trap! syscall %p", td->td_toks_stop - &td->td_toks_base, callp->sy_call)); #endif } /* * Handles the syscall() and __syscall() API */ void xsyscall(struct sysmsg *sysmsg, struct nosys_args *uap); int sys_xsyscall(struct sysmsg *sysmsg, const struct nosys_args *uap) { struct trapframe *frame; struct sysent *callp; union sysunion *argp; struct thread *td; struct proc *p; const int regcnt = 5; /* number of args passed in registers */ u_int code; int error; int narg; td = curthread; p = td->td_proc; frame = sysmsg->sysmsg_frame; code = (u_int)frame->tf_rdi; if (code >= p->p_sysent->sv_size) code = SYS___nosys; argp = (union sysunion *)(&frame->tf_rdi + 1); callp = &p->p_sysent->sv_table[code]; narg = callp->sy_narg; /* * On x86_64 we get up to six arguments in registers. The rest are * on the stack. However, for syscall() and __syscall() the syscall * number is inserted as the first argument, so the limit is reduced * by one to five. */ if (__predict_false(narg > regcnt)) { register_t *argsdst; caddr_t params; argsdst = (register_t *)&sysmsg->extargs; bcopy(argp, argsdst, sizeof(register_t) * regcnt); params = (caddr_t)frame->tf_rsp + sizeof(register_t); error = copyin(params, &argsdst[regcnt], (narg - regcnt) * sizeof(register_t)); argp = (void *)argsdst; if (error) { #ifdef KTRACE if (KTRPOINTP(p, td, KTR_SYSCALL)) { ktrsyscall(td->td_lwp, code, narg, argp); } if (KTRPOINTP(p, td, KTR_SYSRET)) { ktrsysret(td->td_lwp, code, error, sysmsg->sysmsg_result); } #endif return error; } } #ifdef KTRACE if (KTRPOINTP(p, td, KTR_SYSCALL)) { ktrsyscall(td->td_lwp, code, narg, argp); } #endif error = (*callp->sy_call)(sysmsg, argp); #ifdef KTRACE if (KTRPOINTP(p, td, KTR_SYSRET)) { register_t rval; rval = (callp->sy_rsize <= 4) ? sysmsg->sysmsg_result : sysmsg->sysmsg_lresult; ktrsysret(td->td_lwp, code, error, rval); } #endif return error; } void fork_return(struct lwp *lp, struct trapframe *frame) { frame->tf_rax = 0; /* Child returns zero */ frame->tf_rflags &= ~PSL_C; /* success */ frame->tf_rdx = 1; generic_lwp_return(lp, frame); KTR_LOG(kernentry_fork_ret, lp->lwp_proc->p_pid, lp->lwp_tid); } /* * Simplified back end of syscall(), used when returning from fork() * directly into user mode. * * This code will return back into the fork trampoline code which then * runs doreti. */ void generic_lwp_return(struct lwp *lp, struct trapframe *frame) { struct proc *p = lp->lwp_proc; /* * Check for exit-race. If one lwp exits the process concurrent with * another lwp creating a new thread, the two operations may cross * each other resulting in the newly-created lwp not receiving a * KILL signal. */ if (p->p_flags & P_WEXIT) { lwpsignal(p, lp, SIGKILL); } /* * Newly forked processes are given a kernel priority. We have to * adjust the priority to a normal user priority and fake entry * into the kernel (call userenter()) to install a passive release * function just in case userret() decides to stop the process. This * can occur when ^Z races a fork. If we do not install the passive * release function the current process designation will not be * released when the thread goes to sleep. */ lwkt_setpri_self(TDPRI_USER_NORM); userenter(lp->lwp_thread, p); userret(lp, frame, 0); #ifdef KTRACE if (KTRPOINTP(p, lp->lwp_thread, KTR_SYSRET)) ktrsysret(lp, SYS_fork, 0, 0); #endif lp->lwp_flags |= LWP_PASSIVE_ACQ; userexit(lp); lp->lwp_flags &= ~LWP_PASSIVE_ACQ; } /* * If PGEX_FPFAULT is set then set FP_VIRTFP in the PCB to force a T_DNA * fault (which is then passed back to the virtual kernel) if an attempt is * made to use the FP unit. * * XXX this is a fairly big hack. */ void set_vkernel_fp(struct trapframe *frame) { struct thread *td = curthread; if (frame->tf_xflags & PGEX_FPFAULT) { td->td_pcb->pcb_flags |= FP_VIRTFP; if (mdcpu->gd_npxthread == td) npxexit(); } else { td->td_pcb->pcb_flags &= ~FP_VIRTFP; } } /* * Called from vkernel_trap() to fixup the vkernel's syscall * frame for vmspace_ctl() return. */ void cpu_vkernel_trap(struct trapframe *frame, int error) { frame->tf_rax = error; if (error) frame->tf_rflags |= PSL_C; else frame->tf_rflags &= ~PSL_C; }