/*- * Copyright (C) 1994, David Greenman * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * * 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 * $FreeBSD$ */ /* * 386 Trap and System call handling */ #include "opt_cpu.h" #include "opt_ddb.h" #include "opt_ktrace.h" #include "opt_clock.h" #include "opt_trap.h" #include #include #include #include #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 #ifdef SMP #include #endif #include #include #include #ifdef POWERFAIL_NMI #include #include #endif #include #include #include "isa.h" #include "npx.h" #include int (*pmath_emulate) __P((struct trapframe *)); extern void trap __P((struct trapframe frame)); extern int trapwrite __P((unsigned addr)); extern void syscall2 __P((struct trapframe frame)); extern void ast __P((struct trapframe frame)); static int trap_pfault __P((struct trapframe *, int, vm_offset_t)); static void trap_fatal __P((struct trapframe *, vm_offset_t)); void dblfault_handler __P((void)); extern inthand_t IDTVEC(syscall); #define MAX_TRAP_MSG 28 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 */ }; static __inline int userret __P((struct proc *p, struct trapframe *frame, u_quad_t oticks, int have_giant)); #if defined(I586_CPU) && !defined(NO_F00F_HACK) extern int has_f00f_bug; #endif #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"); #endif static int panic_on_nmi = 1; SYSCTL_INT(_machdep, OID_AUTO, panic_on_nmi, CTLFLAG_RW, &panic_on_nmi, 0, "Panic on NMI"); static __inline int userret(p, frame, oticks, have_giant) struct proc *p; struct trapframe *frame; u_quad_t oticks; int have_giant; { int sig, s; while ((sig = CURSIG(p)) != 0) { if (have_giant == 0) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; } postsig(sig); } p->p_priority = p->p_usrpri; if (resched_wanted()) { /* * Since we are curproc, clock will normally just change * our priority without moving us from one queue to another * (since the running process is not on a queue.) * If that happened after we setrunqueue ourselves but before we * mi_switch()'ed, we might not be on the queue indicated by * our priority. */ s = splhigh(); mtx_enter(&sched_lock, MTX_SPIN); DROP_GIANT_NOSWITCH(); setrunqueue(p); p->p_stats->p_ru.ru_nivcsw++; mi_switch(); mtx_exit(&sched_lock, MTX_SPIN); PICKUP_GIANT(); splx(s); while ((sig = CURSIG(p)) != 0) { if (have_giant == 0) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; } postsig(sig); } } /* * Charge system time if profiling. */ if (p->p_flag & P_PROFIL) { if (have_giant == 0) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; } addupc_task(p, frame->tf_eip, (u_int)(p->p_sticks - oticks) * psratio); } curpriority = p->p_priority; return(have_giant); } /* * Exception, fault, and trap interface to the FreeBSD 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. */ void trap(frame) struct trapframe frame; { struct proc *p = curproc; u_quad_t sticks = 0; int i = 0, ucode = 0, type, code; vm_offset_t eva; #ifdef POWERFAIL_NMI static int lastalert = 0; #endif atomic_add_int(&cnt.v_trap, 1); if ((frame.tf_eflags & 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. XXX Consider whether is this still * correct. */ type = frame.tf_trapno; if (ISPL(frame.tf_cs) == SEL_UPL || (frame.tf_eflags & PSL_VM)) printf( "pid %ld (%s): trap %d with interrupts disabled\n", (long)curproc->p_pid, curproc->p_comm, type); else if (type != T_BPTFLT && type != T_TRCTRAP) /* * XXX not quite right, since this may be for a * multiple fault in user mode. */ printf("kernel trap %d with interrupts disabled\n", type); enable_intr(); } eva = 0; if (frame.tf_trapno == T_PAGEFLT) { /* * For some Cyrix CPUs, %cr2 is clobbered by * interrupts. This problem is worked around by using * an interrupt gate for the pagefault handler. We * are finally ready to read %cr2 and then must * reenable interrupts. */ eva = rcr2(); enable_intr(); } mtx_enter(&Giant, MTX_DEF); #if defined(I586_CPU) && !defined(NO_F00F_HACK) restart: #endif type = frame.tf_trapno; code = frame.tf_err; if ((ISPL(frame.tf_cs) == SEL_UPL) || ((frame.tf_eflags & PSL_VM) && !in_vm86call)) { /* user trap */ sticks = p->p_sticks; p->p_md.md_regs = &frame; switch (type) { case T_PRIVINFLT: /* privileged instruction fault */ ucode = type; i = SIGILL; break; case T_BPTFLT: /* bpt instruction fault */ case T_TRCTRAP: /* trace trap */ frame.tf_eflags &= ~PSL_T; i = SIGTRAP; break; case T_ARITHTRAP: /* arithmetic trap */ ucode = code; i = SIGFPE; break; /* * The following two traps can happen in * vm86 mode, and, if so, we want to handle * them specially. */ case T_PROTFLT: /* general protection fault */ case T_STKFLT: /* stack fault */ if (frame.tf_eflags & PSL_VM) { i = vm86_emulate((struct vm86frame *)&frame); if (i == 0) goto user; break; } /* FALL THROUGH */ case T_SEGNPFLT: /* segment not present fault */ case T_TSSFLT: /* invalid TSS fault */ case T_DOUBLEFLT: /* double fault */ default: ucode = code + BUS_SEGM_FAULT ; i = SIGBUS; break; case T_PAGEFLT: /* page fault */ i = trap_pfault(&frame, TRUE, eva); #if defined(I586_CPU) && !defined(NO_F00F_HACK) if (i == -2) { /* * f00f hack workaround has triggered, treat * as illegal instruction not page fault. */ frame.tf_trapno = T_PRIVINFLT; goto restart; } #endif if (i == -1) goto out; if (i == 0) goto user; ucode = T_PAGEFLT; break; case T_DIVIDE: /* integer divide fault */ ucode = FPE_INTDIV; i = SIGFPE; break; #if NISA > 0 case T_NMI: #ifdef POWERFAIL_NMI #ifndef TIMER_FREQ # define TIMER_FREQ 1193182 #endif if (time_second - lastalert > 10) { log(LOG_WARNING, "NMI: power fail\n"); sysbeep(TIMER_FREQ/880, hz); lastalert = time_second; } goto out; #else /* !POWERFAIL_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) { printf ("NMI ... going to debugger\n"); kdb_trap (type, 0, &frame); } #endif /* DDB */ goto out; } else if (panic_on_nmi) panic("NMI indicates hardware failure"); break; #endif /* POWERFAIL_NMI */ #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: #if NNPX > 0 /* transparent fault (due to context switch "late") */ if (npxdna()) goto out; #endif if (!pmath_emulate) { i = SIGFPE; ucode = FPE_FPU_NP_TRAP; break; } i = (*pmath_emulate)(&frame); if (i == 0) { if (!(frame.tf_eflags & PSL_T)) goto out; frame.tf_eflags &= ~PSL_T; i = SIGTRAP; } /* else ucode = emulator_only_knows() XXX */ break; case T_FPOPFLT: /* FPU operand fetch fault */ ucode = T_FPOPFLT; i = SIGILL; break; } } else { /* kernel trap */ switch (type) { case T_PAGEFLT: /* page fault */ (void) trap_pfault(&frame, FALSE, eva); goto out; case T_DNA: #if NNPX > 0 /* * The kernel is apparently using npx for copying. * XXX this should be fatal unless the kernel has * registered such use. */ if (npxdna()) goto out; #endif break; /* * The following two traps can happen in * vm86 mode, and, if so, we want to handle * them specially. */ case T_PROTFLT: /* general protection fault */ case T_STKFLT: /* stack fault */ if (frame.tf_eflags & PSL_VM) { i = vm86_emulate((struct vm86frame *)&frame); if (i != 0) /* * returns to original process */ vm86_trap((struct vm86frame *)&frame); goto out; } if (type == T_STKFLT) break; /* FALL THROUGH */ case T_SEGNPFLT: /* segment not present fault */ if (in_vm86call) break; if (intr_nesting_level != 0) break; /* * Invalid %fs's and %gs's can be created using * procfs or PT_SETREGS or by invalidating the * underlying LDT entry. This causes a fault * in kernel mode when the kernel attempts to * switch contexts. Lose the bad context * (XXX) so that we can continue, and generate * a signal. */ if (frame.tf_eip == (int)cpu_switch_load_gs) { curpcb->pcb_gs = 0; psignal(p, SIGBUS); goto out; } /* * Invalid segment selectors and out of bounds * %eip's and %esp'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 (frame.tf_eip == (int)doreti_iret) { frame.tf_eip = (int)doreti_iret_fault; goto out; } if (frame.tf_eip == (int)doreti_popl_ds) { frame.tf_eip = (int)doreti_popl_ds_fault; goto out; } if (frame.tf_eip == (int)doreti_popl_es) { frame.tf_eip = (int)doreti_popl_es_fault; goto out; } if (frame.tf_eip == (int)doreti_popl_fs) { frame.tf_eip = (int)doreti_popl_fs_fault; goto out; } if (curpcb && curpcb->pcb_onfault) { frame.tf_eip = (int)curpcb->pcb_onfault; goto out; } 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_eflags & PSL_NT) { frame.tf_eflags &= ~PSL_NT; goto out; } break; case T_TRCTRAP: /* trace trap */ if (frame.tf_eip == (int)IDTVEC(syscall)) { /* * We've just entered system mode via the * syscall lcall. Continue single stepping * silently until the syscall handler has * saved the flags. */ goto out; } if (frame.tf_eip == (int)IDTVEC(syscall) + 1) { /* * The syscall handler has now saved the * flags. Stop single stepping it. */ frame.tf_eflags &= ~PSL_T; goto out; } /* * 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() && !in_vm86call) { /* * Reset breakpoint bits because the * processor doesn't */ load_dr6(rdr6() & 0xfffffff0); goto out; } /* * Fall through (TRCTRAP kernel mode, kernel address) */ case T_BPTFLT: /* * If DDB is enabled, let it handle the debugger trap. * Otherwise, debugger traps "can't happen". */ #ifdef DDB if (kdb_trap (type, 0, &frame)) goto out; #endif break; #if NISA > 0 case T_NMI: #ifdef POWERFAIL_NMI if (time_second - lastalert > 10) { log(LOG_WARNING, "NMI: power fail\n"); sysbeep(TIMER_FREQ/880, hz); lastalert = time_second; } goto out; #else /* !POWERFAIL_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) { printf ("NMI ... going to debugger\n"); kdb_trap (type, 0, &frame); } #endif /* DDB */ goto out; } else if (panic_on_nmi == 0) goto out; /* FALL THROUGH */ #endif /* POWERFAIL_NMI */ #endif /* NISA > 0 */ } trap_fatal(&frame, eva); goto out; } /* Translate fault for emulators (e.g. Linux) */ if (*p->p_sysent->sv_transtrap) i = (*p->p_sysent->sv_transtrap)(i, type); trapsignal(p, 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", (u_long)eva); uprintf("\n"); } #endif user: userret(p, &frame, sticks, 1); out: mtx_exit(&Giant, MTX_DEF); } #ifdef notyet /* * This version doesn't allow a page fault to user space while * in the kernel. The rest of the kernel needs to be made "safe" * before this can be used. I think the only things remaining * to be made safe are the iBCS2 code and the process tracing/ * debugging code. */ static int trap_pfault(frame, usermode, eva) struct trapframe *frame; int usermode; vm_offset_t eva; { vm_offset_t va; struct vmspace *vm = NULL; vm_map_t map = 0; int rv = 0; vm_prot_t ftype; struct proc *p = curproc; if (frame->tf_err & PGEX_W) ftype = VM_PROT_WRITE; else ftype = VM_PROT_READ; va = trunc_page(eva); if (va < VM_MIN_KERNEL_ADDRESS) { vm_offset_t v; vm_page_t mpte; if (p == NULL || (!usermode && va < VM_MAXUSER_ADDRESS && (intr_nesting_level != 0 || curpcb == NULL || curpcb->pcb_onfault == NULL))) { trap_fatal(frame, eva); return (-1); } /* * 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. */ vm = p->p_vmspace; if (vm == NULL) goto nogo; map = &vm->vm_map; /* * Keep swapout from messing with us during this * critical time. */ ++p->p_lock; /* * Grow the stack if necessary */ /* grow_stack returns false only if va falls into * a growable stack region and the stack growth * fails. It returns true if va was not within * a growable stack region, or if the stack * growth succeeded. */ if (!grow_stack (p, va)) { rv = KERN_FAILURE; --p->p_lock; goto nogo; } /* Fault in the user page: */ rv = vm_fault(map, va, ftype, (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY : VM_FAULT_NORMAL); --p->p_lock; } else { /* * Don't allow user-mode faults in kernel address space. */ if (usermode) goto nogo; /* * Since we know that kernel virtual address addresses * always have pte pages mapped, we just have to fault * the page. */ rv = vm_fault(kernel_map, va, ftype, VM_FAULT_NORMAL); } if (rv == KERN_SUCCESS) return (0); nogo: if (!usermode) { if (intr_nesting_level == 0 && curpcb && curpcb->pcb_onfault) { frame->tf_eip = (int)curpcb->pcb_onfault; return (0); } trap_fatal(frame, eva); return (-1); } /* kludge to pass faulting virtual address to sendsig */ frame->tf_err = eva; return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); } #endif int trap_pfault(frame, usermode, eva) struct trapframe *frame; int usermode; vm_offset_t eva; { vm_offset_t va; struct vmspace *vm = NULL; vm_map_t map = 0; int rv = 0; vm_prot_t ftype; struct proc *p = curproc; va = trunc_page(eva); if (va >= KERNBASE) { /* * Don't allow user-mode faults in kernel address space. * An exception: if the faulting address is the invalid * instruction entry in the IDT, then the Intel Pentium * F00F bug workaround was triggered, and we need to * treat it is as an illegal instruction, and not a page * fault. */ #if defined(I586_CPU) && !defined(NO_F00F_HACK) if ((eva == (unsigned int)&idt[6]) && has_f00f_bug) return -2; #endif if (usermode) 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 (p != NULL) vm = p->p_vmspace; if (vm == NULL) goto nogo; map = &vm->vm_map; } if (frame->tf_err & PGEX_W) ftype = VM_PROT_WRITE; else ftype = VM_PROT_READ; if (map != kernel_map) { /* * Keep swapout from messing with us during this * critical time. */ ++p->p_lock; /* * Grow the stack if necessary */ /* grow_stack returns false only if va falls into * a growable stack region and the stack growth * fails. It returns true if va was not within * a growable stack region, or if the stack * growth succeeded. */ if (!grow_stack (p, va)) { rv = KERN_FAILURE; --p->p_lock; goto nogo; } /* Fault in the user page: */ rv = vm_fault(map, va, ftype, (ftype & VM_PROT_WRITE) ? VM_FAULT_DIRTY : VM_FAULT_NORMAL); --p->p_lock; } else { /* * Don't have to worry about process locking or stacks in the kernel. */ rv = vm_fault(map, va, ftype, VM_FAULT_NORMAL); } if (rv == KERN_SUCCESS) return (0); nogo: if (!usermode) { if (intr_nesting_level == 0 && curpcb && curpcb->pcb_onfault) { frame->tf_eip = (int)curpcb->pcb_onfault; return (0); } trap_fatal(frame, eva); return (-1); } /* kludge to pass faulting virtual address to sendsig */ frame->tf_err = eva; return((rv == KERN_PROTECTION_FAILURE) ? SIGBUS : SIGSEGV); } static void trap_fatal(frame, eva) struct trapframe *frame; vm_offset_t eva; { int code, type, ss, esp; struct soft_segment_descriptor softseg; code = frame->tf_err; type = frame->tf_trapno; sdtossd(&gdt[IDXSEL(frame->tf_cs & 0xffff)].sd, &softseg); if (type <= MAX_TRAP_MSG) printf("\n\nFatal trap %d: %s while in %s mode\n", type, trap_msg[type], frame->tf_eflags & PSL_VM ? "vm86" : ISPL(frame->tf_cs) == SEL_UPL ? "user" : "kernel"); #ifdef SMP /* two seperate prints in case of a trap on an unmapped page */ printf("cpuid = %d; ", cpuid); printf("lapic.id = %08x\n", lapic.id); #endif if (type == T_PAGEFLT) { printf("fault virtual address = 0x%x\n", eva); printf("fault code = %s %s, %s\n", code & PGEX_U ? "user" : "supervisor", code & PGEX_W ? "write" : "read", code & PGEX_P ? "protection violation" : "page not present"); } printf("instruction pointer = 0x%x:0x%x\n", frame->tf_cs & 0xffff, frame->tf_eip); if ((ISPL(frame->tf_cs) == SEL_UPL) || (frame->tf_eflags & PSL_VM)) { ss = frame->tf_ss & 0xffff; esp = frame->tf_esp; } else { ss = GSEL(GDATA_SEL, SEL_KPL); esp = (int)&frame->tf_esp; } printf("stack pointer = 0x%x:0x%x\n", ss, esp); printf("frame pointer = 0x%x:0x%x\n", ss, frame->tf_ebp); printf("code segment = base 0x%x, limit 0x%x, type 0x%x\n", softseg.ssd_base, softseg.ssd_limit, softseg.ssd_type); printf(" = DPL %d, pres %d, def32 %d, gran %d\n", softseg.ssd_dpl, softseg.ssd_p, softseg.ssd_def32, softseg.ssd_gran); printf("processor eflags = "); if (frame->tf_eflags & PSL_T) printf("trace trap, "); if (frame->tf_eflags & PSL_I) printf("interrupt enabled, "); if (frame->tf_eflags & PSL_NT) printf("nested task, "); if (frame->tf_eflags & PSL_RF) printf("resume, "); if (frame->tf_eflags & PSL_VM) printf("vm86, "); printf("IOPL = %d\n", (frame->tf_eflags & PSL_IOPL) >> 12); printf("current process = "); if (curproc) { printf("%lu (%s)\n", (u_long)curproc->p_pid, curproc->p_comm ? curproc->p_comm : ""); } else { printf("Idle\n"); } #ifdef KDB if (kdb_trap(&psl)) return; #endif #ifdef DDB if ((debugger_on_panic || db_active) && kdb_trap(type, 0, frame)) return; #endif printf("trap number = %d\n", type); if (type <= MAX_TRAP_MSG) panic(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). * * XXX Note that the current PTD gets replaced by IdlePTD when the * task switch occurs. This means that the stack that was active at * the time of the double fault is not available at unless * the machine was idle when the double fault occurred. The downside * of this is that "trace " in ddb won't work. */ void dblfault_handler() { printf("\nFatal double fault:\n"); printf("eip = 0x%x\n", common_tss.tss_eip); printf("esp = 0x%x\n", common_tss.tss_esp); printf("ebp = 0x%x\n", common_tss.tss_ebp); #ifdef SMP /* two seperate prints in case of a trap on an unmapped page */ printf("cpuid = %d; ", cpuid); printf("lapic.id = %08x\n", lapic.id); #endif panic("double fault"); } /* * Compensate for 386 brain damage (missing URKR). * This is a little simpler than the pagefault handler in trap() because * it the page tables have already been faulted in and high addresses * are thrown out early for other reasons. */ int trapwrite(addr) unsigned addr; { struct proc *p; vm_offset_t va; struct vmspace *vm; int rv; va = trunc_page((vm_offset_t)addr); /* * XXX - MAX is END. Changed > to >= for temp. fix. */ if (va >= VM_MAXUSER_ADDRESS) return (1); p = curproc; vm = p->p_vmspace; ++p->p_lock; if (!grow_stack (p, va)) { --p->p_lock; return (1); } /* * fault the data page */ rv = vm_fault(&vm->vm_map, va, VM_PROT_WRITE, VM_FAULT_DIRTY); --p->p_lock; if (rv != KERN_SUCCESS) return 1; return (0); } /* * 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. * * In general, only simple access and manipulation of curproc and * the current stack is allowed without having to hold MP lock. */ void syscall2(frame) struct trapframe frame; { caddr_t params; int i; struct sysent *callp; struct proc *p = curproc; u_quad_t sticks; int error; int narg; int args[8]; int have_giant = 0; u_int code; atomic_add_int(&cnt.v_syscall, 1); #ifdef DIAGNOSTIC if (ISPL(frame.tf_cs) != SEL_UPL) { mtx_enter(&Giant, MTX_DEF); panic("syscall"); /* NOT REACHED */ } #endif /* * handle atomicy by looping since interrupts are enabled and the * MP lock is not held. */ sticks = ((volatile struct proc *)p)->p_sticks; while (sticks != ((volatile struct proc *)p)->p_sticks) sticks = ((volatile struct proc *)p)->p_sticks; p->p_md.md_regs = &frame; params = (caddr_t)frame.tf_esp + sizeof(int); code = frame.tf_eax; if (p->p_sysent->sv_prepsyscall) { /* * The prep code is not MP aware. */ mtx_enter(&Giant, MTX_DEF); (*p->p_sysent->sv_prepsyscall)(&frame, args, &code, ¶ms); mtx_exit(&Giant, MTX_DEF); } else { /* * Need to check if this is a 32 bit or 64 bit syscall. * fuword is MP aware. */ if (code == SYS_syscall) { /* * Code is first argument, followed by actual args. */ code = fuword(params); params += sizeof(int); } else if (code == SYS___syscall) { /* * Like syscall, but code is a quad, so as to maintain * quad alignment for the rest of the arguments. */ code = fuword(params); params += sizeof(quad_t); } } if (p->p_sysent->sv_mask) code &= p->p_sysent->sv_mask; if (code >= p->p_sysent->sv_size) callp = &p->p_sysent->sv_table[0]; else callp = &p->p_sysent->sv_table[code]; narg = callp->sy_narg & SYF_ARGMASK; /* * copyin is MP aware, but the tracing code is not */ if (params && (i = narg * sizeof(int)) && (error = copyin(params, (caddr_t)args, (u_int)i))) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; #ifdef KTRACE if (KTRPOINT(p, KTR_SYSCALL)) ktrsyscall(p->p_tracep, code, narg, args); #endif goto bad; } /* * Try to run the syscall without the MP lock if the syscall * is MP safe. We have to obtain the MP lock no matter what if * we are ktracing */ if ((callp->sy_narg & SYF_MPSAFE) == 0) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; } #ifdef KTRACE if (KTRPOINT(p, KTR_SYSCALL)) { if (have_giant == 0) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; } ktrsyscall(p->p_tracep, code, narg, args); } #endif p->p_retval[0] = 0; p->p_retval[1] = frame.tf_edx; STOPEVENT(p, S_SCE, narg); /* MP aware */ error = (*callp->sy_call)(p, args); /* * MP SAFE (we may or may not have the MP lock at this point) */ switch (error) { case 0: /* * Reinitialize proc pointer `p' as it may be different * if this is a child returning from fork syscall. */ p = curproc; frame.tf_eax = p->p_retval[0]; frame.tf_edx = p->p_retval[1]; frame.tf_eflags &= ~PSL_C; break; case ERESTART: /* * Reconstruct pc, assuming lcall $X,y is 7 bytes, * int 0x80 is 2 bytes. We saved this in tf_err. */ frame.tf_eip -= frame.tf_err; break; case EJUSTRETURN: break; default: 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_eax = error; frame.tf_eflags |= PSL_C; break; } /* * Traced syscall. trapsignal() is not MP aware. */ if ((frame.tf_eflags & PSL_T) && !(frame.tf_eflags & PSL_VM)) { if (have_giant == 0) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; } frame.tf_eflags &= ~PSL_T; trapsignal(p, SIGTRAP, 0); } /* * Handle reschedule and other end-of-syscall issues */ have_giant = userret(p, &frame, sticks, have_giant); #ifdef KTRACE if (KTRPOINT(p, KTR_SYSRET)) { if (have_giant == 0) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; } ktrsysret(p->p_tracep, code, error, p->p_retval[0]); } #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); /* * Release the MP lock if we had to get it */ if (have_giant) mtx_exit(&Giant, MTX_DEF); mtx_assert(&sched_lock, MA_NOTOWNED); mtx_assert(&Giant, MA_NOTOWNED); } void ast(frame) struct trapframe frame; { struct proc *p = CURPROC; u_quad_t sticks; /* * handle atomicy by looping since interrupts are enabled and the * MP lock is not held. */ sticks = ((volatile struct proc *)p)->p_sticks; while (sticks != ((volatile struct proc *)p)->p_sticks) sticks = ((volatile struct proc *)p)->p_sticks; astoff(); atomic_add_int(&cnt.v_soft, 1); if (p->p_flag & P_OWEUPC) { mtx_enter(&Giant, MTX_DEF); p->p_flag &= ~P_OWEUPC; addupc_task(p, p->p_stats->p_prof.pr_addr, p->p_stats->p_prof.pr_ticks); } if (p->p_flag & P_ALRMPEND) { if (!mtx_owned(&Giant)) mtx_enter(&Giant, MTX_DEF); p->p_flag &= ~P_ALRMPEND; psignal(p, SIGVTALRM); } if (p->p_flag & P_PROFPEND) { if (!mtx_owned(&Giant)) mtx_enter(&Giant, MTX_DEF); p->p_flag &= ~P_PROFPEND; psignal(p, SIGPROF); } if (userret(p, &frame, sticks, mtx_owned(&Giant)) != 0) mtx_exit(&Giant, MTX_DEF); } /* * Simplified back end of syscall(), used when returning from fork() * directly into user mode. Giant is not held on entry, and must not * be held on return. */ void fork_return(p, frame) struct proc *p; struct trapframe frame; { int have_giant; frame.tf_eax = 0; /* Child returns zero */ frame.tf_eflags &= ~PSL_C; /* success */ frame.tf_edx = 1; have_giant = userret(p, &frame, 0, mtx_owned(&Giant)); #ifdef KTRACE if (KTRPOINT(p, KTR_SYSRET)) { if (have_giant == 0) { mtx_enter(&Giant, MTX_DEF); have_giant = 1; } ktrsysret(p->p_tracep, SYS_fork, 0, 0); } #endif if (have_giant) mtx_exit(&Giant, MTX_DEF); }