ref: c220d0acc67b3f5e0e8af2bbe41fa8e367e6aa60
dir: /sys/src/9/pc64/trap.c/
#include "u.h" #include "tos.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "io.h" #include "ureg.h" #include "../port/error.h" #include <trace.h> extern int irqhandled(Ureg*, int); extern void irqinit(void); void noted(Ureg*, ulong); static void debugexc(Ureg*, void*); static void debugbpt(Ureg*, void*); static void faultamd64(Ureg*, void*); static void doublefault(Ureg*, void*); static void unexpected(Ureg*, void*); static void _dumpstack(Ureg*); void trapinit0(void) { u32int d1, v; uintptr vaddr; Segdesc *idt; uintptr ptr[2]; idt = (Segdesc*)IDTADDR; vaddr = (uintptr)vectortable; for(v = 0; v < 256; v++){ d1 = (vaddr & 0xFFFF0000)|SEGP; switch(v){ case VectorBPT: d1 |= SEGPL(3)|SEGIG; break; case VectorSYSCALL: d1 |= SEGPL(3)|SEGIG; break; default: d1 |= SEGPL(0)|SEGIG; break; } idt->d0 = (vaddr & 0xFFFF)|(KESEL<<16); idt->d1 = d1; idt++; idt->d0 = (vaddr >> 32); idt->d1 = 0; idt++; vaddr += 6; } ((ushort*)&ptr[1])[-1] = sizeof(Segdesc)*512-1; ptr[1] = IDTADDR; lidt(&((ushort*)&ptr[1])[-1]); } void trapinit(void) { irqinit(); nmienable(); /* * Special traps. * Syscall() is called directly without going through trap(). */ trapenable(VectorDE, debugexc, 0, "debugexc"); trapenable(VectorBPT, debugbpt, 0, "debugpt"); trapenable(VectorPF, faultamd64, 0, "faultamd64"); trapenable(Vector2F, doublefault, 0, "doublefault"); trapenable(Vector15, unexpected, 0, "unexpected"); } static char* excname[32] = { "divide error", "debug exception", "nonmaskable interrupt", "breakpoint", "overflow", "bounds check", "invalid opcode", "coprocessor not available", "double fault", "coprocessor segment overrun", "invalid TSS", "segment not present", "stack exception", "general protection violation", "page fault", "15 (reserved)", "coprocessor error", "alignment check", "machine check", "simd error", "20 (reserved)", "21 (reserved)", "22 (reserved)", "23 (reserved)", "24 (reserved)", "25 (reserved)", "26 (reserved)", "27 (reserved)", "28 (reserved)", "29 (reserved)", "30 (reserved)", "31 (reserved)", }; static int usertrap(int vno) { char buf[ERRMAX]; if(vno < nelem(excname)){ spllo(); snprint(buf, sizeof(buf), "sys: trap: %s", excname[vno]); postnote(up, 1, buf, NDebug); return 1; } return 0; } void trap(Ureg *ureg) { int vno, user; FPsave *f = nil; vno = ureg->type; user = kenter(ureg); if(vno != VectorCNA) f = fpukenter(ureg); if(!irqhandled(ureg, vno) && (!user || !usertrap(vno))){ if(!user){ void (*pc)(void); extern void _rdmsrinst(void); extern void _wrmsrinst(void); extern void _peekinst(void); pc = (void*)ureg->pc; if(pc == _rdmsrinst || pc == _wrmsrinst){ if(vno == VectorGPF){ ureg->bp = -1; ureg->pc += 2; goto out; } } else if(pc == _peekinst){ if(vno == VectorGPF || vno == VectorPF){ ureg->pc += 2; goto out; } } /* early fault before trapinit() */ if(vno == VectorPF) faultamd64(ureg, 0); } dumpregs(ureg); if(!user){ ureg->sp = (uintptr)&ureg->sp; _dumpstack(ureg); } if(vno < nelem(excname)) panic("%s", excname[vno]); panic("unknown trap/intr: %d", vno); } out: splhi(); if(user){ if(up->procctl || up->nnote) notify(ureg); kexit(ureg); } if(vno != VectorCNA) fpukexit(ureg, f); } void dumpregs(Ureg* ureg) { if(up) iprint("cpu%d: registers for %s %lud\n", m->machno, up->text, up->pid); else iprint("cpu%d: registers for kernel\n", m->machno); iprint(" AX %.16lluX BX %.16lluX CX %.16lluX\n", ureg->ax, ureg->bx, ureg->cx); iprint(" DX %.16lluX SI %.16lluX DI %.16lluX\n", ureg->dx, ureg->si, ureg->di); iprint(" BP %.16lluX R8 %.16lluX R9 %.16lluX\n", ureg->bp, ureg->r8, ureg->r9); iprint(" R10 %.16lluX R11 %.16lluX R12 %.16lluX\n", ureg->r10, ureg->r11, ureg->r12); iprint(" R13 %.16lluX R14 %.16lluX R15 %.16lluX\n", ureg->r13, ureg->r14, ureg->r15); iprint(" CS %.4lluX SS %.4lluX PC %.16lluX SP %.16lluX\n", ureg->cs & 0xffff, ureg->ss & 0xffff, ureg->pc, ureg->sp); iprint("TYPE %.2lluX ERROR %.4lluX FLAGS %.8lluX\n", ureg->type & 0xff, ureg->error & 0xffff, ureg->flags & 0xffffffff); /* * Processor control registers. * If machine check exception, time stamp counter, page size extensions * or enhanced virtual 8086 mode extensions are supported, there is a * CR4. If there is a CR4 and machine check extensions, read the machine * check address and machine check type registers if RDMSR supported. */ iprint(" CR0 %8.8llux CR2 %16.16llux CR3 %16.16llux", getcr0(), getcr2(), getcr3()); if(m->cpuiddx & (Mce|Tsc|Pse|Vmex)){ iprint(" CR4 %16.16llux\n", getcr4()); if(ureg->type == 18) dumpmcregs(); } iprint(" ur %#p up %#p\n", ureg, up); } /* * Fill in enough of Ureg to get a stack trace, and call a function. * Used by debugging interface rdb. */ void callwithureg(void (*fn)(Ureg*)) { Ureg ureg; ureg.pc = getcallerpc(&fn); ureg.sp = (uintptr)&fn; fn(&ureg); } static void _dumpstack(Ureg *ureg) { uintptr l, v, i, estack; extern ulong etext; int x; char *s; if((s = getconf("*nodumpstack")) != nil && strcmp(s, "0") != 0){ iprint("dumpstack disabled\n"); return; } iprint("dumpstack\n"); x = 0; x += iprint("ktrace /kernel/path %#p %#p <<EOF\n", ureg->pc, ureg->sp); i = 0; if(up && (uintptr)&l >= (uintptr)up - KSTACK && (uintptr)&l <= (uintptr)up) estack = (uintptr)up; else if((uintptr)&l >= (uintptr)m->stack && (uintptr)&l <= (uintptr)m+MACHSIZE) estack = (uintptr)m+MACHSIZE; else return; x += iprint("estackx %p\n", estack); for(l = (uintptr)&l; l < estack; l += sizeof(uintptr)){ v = *(uintptr*)l; if((KTZERO < v && v < (uintptr)&etext) || estack-l < 32){ /* * Could Pick off general CALL (((uchar*)v)[-5] == 0xE8) * and CALL indirect through AX * (((uchar*)v)[-2] == 0xFF && ((uchar*)v)[-2] == 0xD0), * but this is too clever and misses faulting address. */ x += iprint("%.8lux=%.8lux ", (ulong)l, (ulong)v); i++; } if(i == 4){ i = 0; x += iprint("\n"); } } if(i) iprint("\n"); iprint("EOF\n"); if(ureg->type != VectorNMI) return; i = 0; for(l = (uintptr)&l; l < estack; l += sizeof(uintptr)){ iprint("%.8p ", *(uintptr*)l); if(++i == 8){ i = 0; iprint("\n"); } } if(i) iprint("\n"); } void dumpstack(void) { callwithureg(_dumpstack); } static void debugexc(Ureg *ureg, void *) { u64int dr6, m; char buf[ERRMAX]; char *p, *e; int i; dr6 = getdr6(); if(up == nil) panic("kernel debug exception dr6=%#.8ullx", dr6); putdr6(up->dr[6]); if(userureg(ureg)) qlock(&up->debug); else if(!canqlock(&up->debug)) return; m = up->dr[7]; m = (m >> 4 | m >> 3) & 8 | (m >> 3 | m >> 2) & 4 | (m >> 2 | m >> 1) & 2 | (m >> 1 | m) & 1; m &= dr6; if(m == 0){ snprint(buf, sizeof(buf), "sys: debug exception dr6=%#.8ullx", dr6); postnote(up, 0, buf, NDebug); }else{ p = buf; e = buf + sizeof(buf); p = seprint(p, e, "sys: watchpoint "); for(i = 0; i < 4; i++) if((m & 1<<i) != 0) p = seprint(p, e, "%d%s", i, (m >> i + 1 != 0) ? "," : ""); postnote(up, 0, buf, NDebug); } qunlock(&up->debug); } static void debugbpt(Ureg* ureg, void*) { if(up == 0) panic("kernel bpt"); /* restore pc to instruction that caused the trap */ ureg->pc--; postnote(up, 1, "sys: breakpoint", NDebug); } static void doublefault(Ureg*, void*) { panic("double fault"); } static void unexpected(Ureg* ureg, void*) { print("unexpected trap %llud; ignoring\n", ureg->type); } static void faultnote(Ureg *ureg, char *access, uintptr addr) { extern void checkpages(void); char buf[ERRMAX]; if(!userureg(ureg)){ dumpregs(ureg); panic("fault: %s addr=%#p", access, addr); } checkpages(); snprint(buf, sizeof(buf), "sys: trap: fault %s addr=%#p", access, addr); postnote(up, 1, buf, NDebug); } static void faultamd64(Ureg* ureg, void*) { uintptr addr; int read, user; addr = getcr2(); read = !(ureg->error & 2); user = userureg(ureg); if(user) up->insyscall = 1; else { extern void _peekinst(void); if((void(*)(void))ureg->pc == _peekinst){ ureg->pc += 2; return; } if(addr >= USTKTOP) panic("kernel fault: bad address pc=%#p addr=%#p", ureg->pc, addr); if(up == nil) panic("kernel fault: no user process pc=%#p addr=%#p", ureg->pc, addr); if(waserror()){ if(up->nerrlab == 0){ pprint("suicide: sys: %s\n", up->errstr); pexit(up->errstr, 1); } nexterror(); } } if(fault(addr, ureg->pc, read)) faultnote(ureg, read? "read": "write", addr); if(user) up->insyscall = 0; else poperror(); } /* * system calls */ #include "../port/systab.h" /* * Syscall is called directly from assembler without going through trap(). */ void syscall(Ureg* ureg) { char *e; uintptr sp; long long ret; int i, s; ulong scallnr; vlong startns, stopns; if(!kenter(ureg)) panic("syscall: cs 0x%4.4lluX", ureg->cs); fpukenter(ureg); m->syscall++; up->insyscall = 1; up->pc = ureg->pc; sp = ureg->sp; scallnr = ureg->bp; /* RARG */ up->scallnr = scallnr; spllo(); ret = -1; startns = 0; if(!waserror()){ if(sp<(USTKTOP-BY2PG) || sp>(USTKTOP-sizeof(Sargs)-BY2WD)) validaddr(sp, sizeof(Sargs)+BY2WD, 0); up->s = *((Sargs*)(sp+BY2WD)); if(0){ syscallfmt(scallnr, ureg->pc, (va_list)up->s.args); print("syscall: %s\n", up->syscalltrace); } if(up->procctl == Proc_tracesyscall){ syscallfmt(scallnr, ureg->pc, (va_list)up->s.args); s = splhi(); up->procctl = Proc_stopme; procctl(); splx(s); startns = todget(nil); } if(scallnr >= nsyscall || systab[scallnr] == nil){ postnote(up, 1, "sys: bad sys call", NDebug); error(Ebadarg); } up->psstate = sysctab[scallnr]; ret = systab[scallnr]((va_list)up->s.args); poperror(); }else{ /* failure: save the error buffer for errstr */ e = up->syserrstr; up->syserrstr = up->errstr; up->errstr = e; if(0 && up->pid == 1) print("syscall %lud error %s\n", scallnr, up->syserrstr); } if(up->nerrlab){ print("bad errstack [%lud]: %d extra\n", scallnr, up->nerrlab); for(i = 0; i < NERR; i++) print("sp=%#p pc=%#p\n", up->errlab[i].sp, up->errlab[i].pc); panic("error stack"); } ureg->ax = ret; if(0){ print("syscallret: %lud %s %s ret=%lld\n", up->pid, up->text, sysctab[scallnr], ret); } if(up->procctl == Proc_tracesyscall){ stopns = todget(nil); sysretfmt(scallnr, (va_list)up->s.args, ret, startns, stopns); s = splhi(); up->procctl = Proc_stopme; procctl(); splx(s); } if(scallnr == NOTED){ /* * normally, syscall() returns to forkret() * not restoring general registers when going * to userspace. to completely restore the * interrupted context, we have to return thru * noteret(). we override return pc to jump to * to it when returning form syscall() */ ((void**)&ureg)[-1] = (void*)noteret; noted(ureg, *((ulong*)up->s.args)); splhi(); up->fpstate &= ~FPillegal; } else splhi(); if(scallnr != RFORK && (up->procctl || up->nnote) && notify(ureg)) ((void**)&ureg)[-1] = (void*)noteret; /* loads RARG */ up->insyscall = 0; up->psstate = nil; /* if we delayed sched because we held a lock, sched now */ if(up->delaysched) sched(); kexit(ureg); fpukexit(ureg, nil); } /* * Call user, if necessary, with note. * Pass user the Ureg struct and the note on his stack. */ int notify(Ureg* ureg) { uintptr sp; char *msg; if(up->procctl) procctl(); if(up->nnote == 0) return 0; spllo(); qlock(&up->debug); msg = popnote(ureg); if(msg == nil){ qunlock(&up->debug); splhi(); return 0; } sp = ureg->sp; sp -= 256; /* debugging: preserve context causing problem */ sp -= sizeof(Ureg); if(0) print("%s %lud: notify %#p %#p %#p %s\n", up->text, up->pid, ureg->pc, ureg->sp, sp, msg); if(!okaddr((uintptr)up->notify, 1, 0) || !okaddr(sp-ERRMAX-4*BY2WD, sizeof(Ureg)+ERRMAX+4*BY2WD, 1)){ qunlock(&up->debug); pprint("suicide: bad address in notify\n"); pexit("Suicide", 0); } memmove((Ureg*)sp, ureg, sizeof(Ureg)); *(Ureg**)(sp-BY2WD) = up->ureg; /* word under Ureg is old up->ureg */ up->ureg = (void*)sp; sp -= BY2WD+ERRMAX; memmove((char*)sp, msg, ERRMAX); sp -= 3*BY2WD; ((uintptr*)sp)[2] = sp + 3*BY2WD; /* arg2 string */ ((uintptr*)sp)[1] = (uintptr)up->ureg; /* arg1 is ureg* */ ((uintptr*)sp)[0] = 0; /* arg0 is pc */ ureg->sp = sp; ureg->pc = (uintptr)up->notify; ureg->bp = (uintptr)up->ureg; /* arg1 passed in RARG */ ureg->cs = UESEL; ureg->ss = UDSEL; qunlock(&up->debug); splhi(); fpuprocsave(up); up->fpstate |= FPillegal; return 1; } /* * Return user to state before notify() */ void noted(Ureg* ureg, ulong arg0) { Ureg *nureg; uintptr oureg, sp; qlock(&up->debug); if(arg0!=NRSTR && !up->notified) { qunlock(&up->debug); pprint("call to noted() when not notified\n"); pexit("Suicide", 0); } up->notified = 0; nureg = up->ureg; /* pointer to user returned Ureg struct */ /* sanity clause */ oureg = (uintptr)nureg; if(!okaddr(oureg-BY2WD, BY2WD+sizeof(Ureg), 0)){ qunlock(&up->debug); pprint("bad ureg in noted or call to noted when not notified\n"); pexit("Suicide", 0); } /* don't let user change system flags or segment registers */ setregisters(ureg, (char*)ureg, (char*)nureg, sizeof(Ureg)); switch(arg0){ case NCONT: case NRSTR: if(0) print("%s %lud: noted %#p %#p\n", up->text, up->pid, nureg->pc, nureg->sp); if(!okaddr(nureg->pc, 1, 0) || !okaddr(nureg->sp, BY2WD, 0)){ qunlock(&up->debug); pprint("suicide: trap in noted\n"); pexit("Suicide", 0); } up->ureg = (Ureg*)(*(uintptr*)(oureg-BY2WD)); qunlock(&up->debug); break; case NSAVE: if(!okaddr(nureg->pc, 1, 0) || !okaddr(nureg->sp, BY2WD, 0)){ qunlock(&up->debug); pprint("suicide: trap in noted\n"); pexit("Suicide", 0); } qunlock(&up->debug); sp = oureg-4*BY2WD-ERRMAX; ureg->sp = sp; ureg->bp = oureg; /* arg 1 passed in RARG */ ((uintptr*)sp)[1] = oureg; /* arg 1 0(FP) is ureg* */ ((uintptr*)sp)[0] = 0; /* arg 0 is pc */ break; default: up->lastnote->flag = NDebug; /* fall through */ case NDFLT: qunlock(&up->debug); if(up->lastnote->flag == NDebug) pprint("suicide: %s\n", up->lastnote->msg); pexit(up->lastnote->msg, up->lastnote->flag!=NDebug); } } uintptr execregs(uintptr entry, ulong ssize, ulong nargs) { uintptr *sp; Ureg *ureg; sp = (uintptr*)(USTKTOP - ssize); *--sp = nargs; ureg = up->dbgreg; ureg->sp = (uintptr)sp; ureg->pc = entry; ureg->cs = UESEL; ureg->ss = UDSEL; ureg->r14 = ureg->r15 = 0; /* extern user registers */ return (uintptr)USTKTOP-sizeof(Tos); /* address of kernel/user shared data */ } /* * return the userpc the last exception happened at */ uintptr userpc(void) { Ureg *ureg; ureg = (Ureg*)up->dbgreg; return ureg->pc; } /* This routine must save the values of registers the user is not permitted * to write from devproc and noted() and then restore the saved values before returning. */ void setregisters(Ureg* ureg, char* pureg, char* uva, int n) { u64int flags; flags = ureg->flags; memmove(pureg, uva, n); ureg->cs = UESEL; ureg->ss = UDSEL; ureg->flags = (ureg->flags & 0x00ff) | (flags & 0xff00); ureg->pc &= UADDRMASK; } void kprocchild(Proc *p, void (*entry)(void)) { /* * gotolabel() needs a word on the stack in * which to place the return PC used to jump * to linkproc(). */ p->sched.pc = (uintptr)entry; p->sched.sp = (uintptr)p - BY2WD; } void forkchild(Proc *p, Ureg *ureg) { Ureg *cureg; /* * Add 2*BY2WD to the stack to account for * - the return PC * - trap's argument (ur) */ p->sched.sp = (uintptr)p - (sizeof(Ureg)+2*BY2WD); p->sched.pc = (uintptr)forkret; cureg = (Ureg*)(p->sched.sp+2*BY2WD); memmove(cureg, ureg, sizeof(Ureg)); cureg->ax = 0; } /* Give enough context in the ureg to produce a kernel stack for * a sleeping process */ void setkernur(Ureg* ureg, Proc* p) { ureg->pc = p->sched.pc; ureg->sp = p->sched.sp+8; ureg->r14 = (uintptr)p; } uintptr dbgpc(Proc *p) { Ureg *ureg; ureg = p->dbgreg; if(ureg == nil) return 0; return ureg->pc; }