ref: 37e65b331bdf98f409be1bd2fbb55aec158c7877
dir: /sys/src/9/pc/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 fault386(Ureg*, void*); static void doublefault(Ureg*, void*); static void unexpected(Ureg*, void*); static void _dumpstack(Ureg*); /* * Minimal trap setup. Just enough so that we can panic * on traps (bugs) during kernel initialization. * Called very early - malloc is not yet available. */ void trapinit0(void) { int d1, v; ulong vaddr; Segdesc *idt; ushort ptr[3]; idt = (Segdesc*)IDTADDR; vaddr = (ulong)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[v].d0 = (vaddr & 0xFFFF)|(KESEL<<16); idt[v].d1 = d1; vaddr += 6; } ptr[0] = sizeof(Segdesc)*256-1; ptr[1] = IDTADDR & 0xFFFF; ptr[2] = IDTADDR >> 16; lidt(ptr); } 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, fault386, 0, "fault386"); 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(); sprint(buf, "sys: trap: %s", excname[vno]); postnote(up, 1, buf, NDebug); return 1; } return 0; } /* * All traps come here. It is slower to have all traps call trap() * rather than directly vectoring the handler. However, this avoids a * lot of code duplication and possible bugs. The only exception is * VectorSYSCALL. * Trap is called with interrupts disabled via interrupt-gates. */ void trap(Ureg* ureg) { int vno, user; user = kenter(ureg); vno = ureg->trap; if(!irqhandled(ureg, vno) && (!user || !usertrap(vno))){ if(!user){ void (*pc)(void); ulong *sp; extern void _forkretpopgs(void); extern void _forkretpopfs(void); extern void _forkretpopes(void); extern void _forkretpopds(void); extern void _forkretiret(void); extern void _rdmsrinst(void); extern void _wrmsrinst(void); extern void _peekinst(void); extern void load_fs(ulong); extern void load_gs(ulong); load_fs(NULLSEL); load_gs(NULLSEL); sp = (ulong*)&ureg->sp; /* kernel stack */ pc = (void*)ureg->pc; if(pc == _forkretpopgs || pc == _forkretpopfs || pc == _forkretpopes || pc == _forkretpopds){ if(vno == VectorGPF || vno == VectorSNP){ sp[0] = NULLSEL; return; } } else if(pc == _forkretiret){ if(vno == VectorGPF || vno == VectorSNP){ sp[1] = UESEL; /* CS */ sp[4] = UDSEL; /* SS */ return; } } else if(pc == _rdmsrinst || pc == _wrmsrinst){ if(vno == VectorGPF){ ureg->bp = -1; ureg->pc += 2; return; } } else if(pc == _peekinst){ if(vno == VectorGPF){ ureg->pc += 2; return; } } /* early fault before trapinit() */ if(vno == VectorPF) fault386(ureg, 0); } dumpregs(ureg); if(!user){ ureg->sp = (ulong)&ureg->sp; _dumpstack(ureg); } if(vno < nelem(excname)) panic("%s", excname[vno]); panic("unknown trap/intr: %d", vno); } splhi(); if(user){ if(up->procctl || up->nnote) notify(ureg); kexit(ureg); } } /* * dump registers */ void dumpregs2(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("FLAGS=%luX TRAP=%luX ECODE=%luX PC=%luX", ureg->flags, ureg->trap, ureg->ecode, ureg->pc); if(userureg(ureg)) iprint(" SS=%4.4luX USP=%luX\n", ureg->ss & 0xFFFF, ureg->usp); else iprint(" SP=%luX\n", (ulong)&ureg->sp); iprint(" AX %8.8luX BX %8.8luX CX %8.8luX DX %8.8luX\n", ureg->ax, ureg->bx, ureg->cx, ureg->dx); iprint(" SI %8.8luX DI %8.8luX BP %8.8luX\n", ureg->si, ureg->di, ureg->bp); iprint(" CS %4.4luX DS %4.4luX ES %4.4luX FS %4.4luX GS %4.4luX\n", ureg->cs & 0xFFFF, ureg->ds & 0xFFFF, ureg->es & 0xFFFF, ureg->fs & 0xFFFF, ureg->gs & 0xFFFF); } void dumpregs(Ureg* ureg) { dumpregs2(ureg); /* * 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 %8.8lux CR2 %8.8lux CR3 %8.8lux", getcr0(), getcr2(), getcr3()); if(m->cpuiddx & (Mce|Tsc|Pse|Vmex)){ iprint(" CR4 %8.8lux\n", getcr4()); if(ureg->trap == 18) dumpmcregs(); } iprint("\n 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 = (ulong)&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 %.8lux %.8lux <<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("%.8p=%.8p ", l, v); i++; } if(i == 4){ i = 0; x += iprint("\n"); } } if(i) iprint("\n"); iprint("EOF\n"); if(ureg->trap != 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 *) { u32int dr6, m; char buf[ERRMAX]; char *p, *e; int i; dr6 = getdr6(); if(up == nil) panic("kernel debug exception dr6=%#.8ux", 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){ sprint(buf, "sys: debug exception dr6=%#.8ux", 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 %lud; ignoring\n", ureg->trap); } extern void checkpages(void); extern void checkfault(ulong, ulong); static void fault386(Ureg* ureg, void*) { ulong addr; int read, user, n, insyscall; char buf[ERRMAX]; addr = getcr2(); read = !(ureg->ecode & 2); user = userureg(ureg); if(!user){ if(vmapsync(addr)) return; { extern void _peekinst(void); if((void(*)(void))ureg->pc == _peekinst){ ureg->pc += 2; return; } } if(addr >= USTKTOP) panic("kernel fault: bad address pc=0x%.8lux addr=0x%.8lux", ureg->pc, addr); if(up == nil) panic("kernel fault: no user process pc=0x%.8lux addr=0x%.8lux", ureg->pc, addr); } if(up == nil) panic("user fault: up=0 pc=0x%.8lux addr=0x%.8lux", ureg->pc, addr); insyscall = up->insyscall; up->insyscall = 1; n = fault(addr, ureg->pc, read); if(n < 0){ if(!user){ dumpregs(ureg); panic("fault: 0x%lux", addr); } checkpages(); checkfault(addr, ureg->pc); sprint(buf, "sys: trap: fault %s addr=0x%lux", read ? "read" : "write", addr); postnote(up, 1, buf, NDebug); } up->insyscall = insyscall; } /* * system calls */ #include "../port/systab.h" /* * Syscall is called directly from assembler without going through trap(). */ void syscall(Ureg* ureg) { char *e; ulong sp; long ret; int i, s; ulong scallnr; vlong startns, stopns; if(!kenter(ureg)) panic("syscall: cs 0x%4.4luX", ureg->cs); m->syscall++; up->insyscall = 1; up->pc = ureg->pc; sp = ureg->usp; scallnr = ureg->ax; up->scallnr = scallnr; spllo(); ret = -1; if(!waserror()){ if(sp<(USTKTOP-BY2PG) || sp>(USTKTOP-sizeof(Sargs)-BY2WD)) validaddr(sp, sizeof(Sargs)+BY2WD, 0); up->s = *((Sargs*)(sp+BY2WD)); 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=%lux pc=%lux\n", up->errlab[i].sp, up->errlab[i].pc); panic("error stack"); } /* * Put return value in frame. On the x86 the syscall is * just another trap and the return value from syscall is * ignored. On other machines the return value is put into * the results register by caller of syscall. */ ureg->ax = 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); } up->insyscall = 0; up->psstate = 0; if(scallnr == NOTED) noted(ureg, *((ulong*)up->s.args)); splhi(); if(scallnr!=RFORK && (up->procctl || up->nnote)) notify(ureg); /* if we delayed sched because we held a lock, sched now */ if(up->delaysched){ sched(); splhi(); } kexit(ureg); } /* * Call user, if necessary, with note. * Pass user the Ureg struct and the note on his stack. */ int notify(Ureg* ureg) { ulong s, sp; char *msg; if(up->procctl) procctl(); if(up->nnote == 0) return 0; if(up->fpstate == FPactive){ fpsave(up->fpsave); up->fpstate = FPinactive; } up->fpstate |= FPillegal; s = spllo(); qlock(&up->debug); msg = popnote(ureg); if(msg == nil){ qunlock(&up->debug); splhi(); return 0; } sp = ureg->usp; sp -= 256; /* debugging: preserve context causing problem */ sp -= sizeof(Ureg); if(0) print("%s %lud: notify %.8lux %.8lux %.8lux %s\n", up->text, up->pid, ureg->pc, ureg->usp, 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; *(ulong*)(sp+2*BY2WD) = sp+3*BY2WD; /* arg 2 is string */ *(ulong*)(sp+1*BY2WD) = (ulong)up->ureg; /* arg 1 is ureg* */ *(ulong*)(sp+0*BY2WD) = 0; /* arg 0 is pc */ ureg->usp = sp; ureg->pc = (ulong)up->notify; ureg->cs = UESEL; ureg->ss = ureg->ds = ureg->es = UDSEL; qunlock(&up->debug); splx(s); return 1; } /* * Return user to state before notify() */ void noted(Ureg* ureg, ulong arg0) { Ureg *nureg; ulong 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 */ up->fpstate &= ~FPillegal; /* sanity clause */ oureg = (ulong)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 */ nureg->flags = (ureg->flags & ~0xCD5) | (nureg->flags & 0xCD5); nureg->cs |= 3; nureg->ss |= 3; memmove(ureg, nureg, sizeof(Ureg)); switch(arg0){ case NCONT: case NRSTR: if(0) print("%s %lud: noted %.8lux %.8lux\n", up->text, up->pid, nureg->pc, nureg->usp); if(!okaddr(nureg->pc, 1, 0) || !okaddr(nureg->usp, BY2WD, 0)){ qunlock(&up->debug); pprint("suicide: trap in noted\n"); pexit("Suicide", 0); } up->ureg = (Ureg*)(*(ulong*)(oureg-BY2WD)); qunlock(&up->debug); break; case NSAVE: if(!okaddr(nureg->pc, BY2WD, 0) || !okaddr(nureg->usp, BY2WD, 0)){ qunlock(&up->debug); pprint("suicide: trap in noted\n"); pexit("Suicide", 0); } qunlock(&up->debug); sp = oureg-4*BY2WD-ERRMAX; splhi(); ureg->sp = sp; ((ulong*)sp)[1] = oureg; /* arg 1 0(FP) is ureg* */ ((ulong*)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) { ulong *sp; Ureg *ureg; sp = (ulong*)(USTKTOP - ssize); *--sp = nargs; ureg = up->dbgreg; ureg->usp = (ulong)sp; ureg->pc = entry; ureg->cs = UESEL; ureg->ss = ureg->ds = ureg->es = UDSEL; ureg->fs = ureg->gs = NULLSEL; return 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 then restore the saved values before returning. */ void setregisters(Ureg* ureg, char* pureg, char* uva, int n) { ulong flags; flags = ureg->flags; memmove(pureg, uva, n); ureg->flags = (ureg->flags & 0xCD5) | (flags & ~0xCD5); ureg->cs |= 3; ureg->ss |= 3; } 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 = (ulong)entry; p->sched.sp = (ulong)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 = (ulong)p - (sizeof(Ureg)+2*BY2WD); p->sched.pc = (ulong)forkret; cureg = (Ureg*)(p->sched.sp+2*BY2WD); memmove(cureg, ureg, sizeof(Ureg)); /* return value of syscall in child */ 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+4; } ulong dbgpc(Proc *p) { Ureg *ureg; ureg = p->dbgreg; if(ureg == 0) return 0; return ureg->pc; }