ref: f35d5ee5b036b7b4fa59b1839f52fca15b7f99f9
dir: /sys/src/9/bcm/trap.c/
/*
* traps, exceptions, interrupts, system calls.
*/
#include "u.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 "arm.h"
enum {
Nvec = 8, /* # of vectors at start of lexception.s */
};
/*
* Layout at virtual address KZERO (double mapped at HVECTORS).
*/
typedef struct Vpage0 {
void (*vectors[Nvec])(void);
u32int vtable[Nvec];
} Vpage0;
static char *trapnames[PsrMask+1] = {
[ PsrMusr ] "user mode",
[ PsrMfiq ] "fiq interrupt",
[ PsrMirq ] "irq interrupt",
[ PsrMsvc ] "svc/swi exception",
[ PsrMabt ] "prefetch abort/data abort",
[ PsrMabt+1 ] "data abort",
[ PsrMund ] "undefined instruction",
[ PsrMsys ] "sys trap",
};
extern int irq(Ureg*);
extern int notify(Ureg*);
/*
* set up for exceptions
*/
void
trapinit(void)
{
Vpage0 *vpage0;
intrcpushutdown();
if (m->machno == 0) {
/* disable everything */
intrsoff();
/* set up the exception vectors */
vpage0 = (Vpage0*)HVECTORS;
memmove(vpage0->vectors, vectors, sizeof(vpage0->vectors));
memmove(vpage0->vtable, vtable, sizeof(vpage0->vtable));
cacheuwbinv();
l2cacheuwbinv();
}
/* set up the stacks for the interrupt modes */
setr13(PsrMfiq, (u32int*)(FIQSTKTOP));
setr13(PsrMirq, m->sirq);
setr13(PsrMabt, m->sabt);
setr13(PsrMund, m->sund);
setr13(PsrMsys, m->ssys);
coherence();
}
static char *
trapname(int psr)
{
char *s;
s = trapnames[psr & PsrMask];
if(s == nil)
s = "unknown trap number in psr";
return s;
}
/*
* called by trap to handle access faults
*/
static void
faultarm(Ureg *ureg, uintptr va, int user, int read)
{
int n, insyscall;
char buf[ERRMAX];
static int cnt, lastpid;
static ulong lastva;
if(up == nil) {
dumpregs(ureg);
panic("fault: nil up in faultarm, accessing %#p", va);
}
insyscall = up->insyscall;
up->insyscall = 1;
/* this is quite helpful during mmu and cache debugging */
if(va == lastva && up->pid == lastpid) {
++cnt;
if (cnt >= 2)
/* fault() isn't fixing the underlying cause */
panic("fault: %d consecutive faults for va %#lux",
cnt+1, va);
} else {
cnt = 0;
lastva = va;
lastpid = up->pid;
}
n = fault(va, read);
if(n < 0){
if(!user){
dumpregs(ureg);
panic("fault: kernel accessing %#p", va);
}
/* don't dump registers; programs suicide all the time */
snprint(buf, sizeof buf, "sys: trap: fault %s va=%#p",
read? "read": "write", va);
postnote(up, 1, buf, NDebug);
}
up->insyscall = insyscall;
}
/*
* returns 1 if the instruction writes memory, 0 otherwise
*/
int
writetomem(ulong inst)
{
/* swap always write memory */
if((inst & 0x0FC00000) == 0x01000000)
return 1;
/* loads and stores are distinguished by bit 20 */
if(inst & (1<<20))
return 0;
return 1;
}
/*
* here on all exceptions other than syscall (SWI) and fiq
*/
void
trap(Ureg *ureg)
{
int clockintr, user, x, rv, rem;
ulong inst, fsr;
uintptr va;
char buf[ERRMAX];
assert(!islo());
if(up != nil)
rem = ((char*)ureg)-up->kstack;
else
rem = ((char*)ureg)-((char*)m+sizeof(Mach));
if(rem < 256) {
iprint("trap: %d stack bytes left, up %#p ureg %#p at pc %#lux\n",
rem, up, ureg, ureg->pc);
delay(1000);
dumpstack();
panic("trap: %d stack bytes left, up %#p ureg %#p at pc %#lux",
rem, up, ureg, ureg->pc);
}
user = (ureg->psr & PsrMask) == PsrMusr;
if(user){
up->dbgreg = ureg;
cycles(&up->kentry);
}
/*
* All interrupts/exceptions should be resumed at ureg->pc-4,
* except for Data Abort which resumes at ureg->pc-8.
*/
if(ureg->type == (PsrMabt+1))
ureg->pc -= 8;
else
ureg->pc -= 4;
clockintr = 0; /* if set, may call sched() before return */
switch(ureg->type){
default:
panic("unknown trap; type %#lux, psr mode %#lux", ureg->type,
ureg->psr & PsrMask);
break;
case PsrMirq:
clockintr = irq(ureg);
break;
case PsrMabt: /* prefetch fault */
x = ifsrget();
fsr = (x>>7) & 0x8 | x & 0x7;
switch(fsr){
case 0x02: /* instruction debug event (BKPT) */
if(user){
snprint(buf, sizeof buf, "sys: breakpoint");
postnote(up, 1, buf, NDebug);
}else{
iprint("kernel bkpt: pc %#lux inst %#ux\n",
ureg->pc, *(u32int*)ureg->pc);
panic("kernel bkpt");
}
break;
default:
faultarm(ureg, ureg->pc, user, 1);
break;
}
break;
case PsrMabt+1: /* data fault */
va = farget();
inst = *(ulong*)(ureg->pc);
/* bits 12 and 10 have to be concatenated with status */
x = fsrget();
fsr = (x>>7) & 0x20 | (x>>6) & 0x10 | x & 0xf;
switch(fsr){
default:
case 0xa: /* ? was under external abort */
panic("unknown data fault, 6b fsr %#lux", fsr);
break;
case 0x0:
panic("vector exception at %#lux", ureg->pc);
break;
case 0x1: /* alignment fault */
case 0x3: /* access flag fault (section) */
if(user){
snprint(buf, sizeof buf,
"sys: alignment: pc %#lux va %#p\n",
ureg->pc, va);
postnote(up, 1, buf, NDebug);
} else
panic("kernel alignment: pc %#lux va %#p", ureg->pc, va);
break;
case 0x2:
panic("terminal exception at %#lux", ureg->pc);
break;
case 0x4: /* icache maint fault */
case 0x6: /* access flag fault (page) */
case 0x8: /* precise external abort, non-xlat'n */
case 0x28:
case 0xc: /* l1 translation, precise ext. abort */
case 0x2c:
case 0xe: /* l2 translation, precise ext. abort */
case 0x2e:
case 0x16: /* imprecise ext. abort, non-xlt'n */
case 0x36:
panic("external abort %#lux pc %#lux addr %#p",
fsr, ureg->pc, va);
break;
case 0x1c: /* l1 translation, precise parity err */
case 0x1e: /* l2 translation, precise parity err */
case 0x18: /* imprecise parity or ecc err */
panic("translation parity error %#lux pc %#lux addr %#p",
fsr, ureg->pc, va);
break;
case 0x5: /* translation fault, no section entry */
case 0x7: /* translation fault, no page entry */
faultarm(ureg, va, user, !writetomem(inst));
break;
case 0x9:
case 0xb:
/* domain fault, accessing something we shouldn't */
if(user){
snprint(buf, sizeof buf,
"sys: access violation: pc %#lux va %#p\n",
ureg->pc, va);
postnote(up, 1, buf, NDebug);
} else
panic("kernel access violation: pc %#lux va %#p",
ureg->pc, va);
break;
case 0xd:
case 0xf:
/* permission error, copy on write or real permission error */
faultarm(ureg, va, user, !writetomem(inst));
break;
}
break;
case PsrMund: /* undefined instruction */
if(user){
if(seg(up, ureg->pc, 0) != nil &&
*(u32int*)ureg->pc == 0xD1200070)
postnote(up, 1, "sys: breakpoint", NDebug);
else{
/* look for floating point instructions to interpret */
rv = fpuemu(ureg);
if(rv == 0){
snprint(buf, sizeof buf,
"undefined instruction: pc %#lux\n",
ureg->pc);
postnote(up, 1, buf, NDebug);
}
}
}else{
if (ureg->pc & 3) {
iprint("rounding fault pc %#lux down to word\n",
ureg->pc);
ureg->pc &= ~3;
}
iprint("undefined instruction: pc %#lux inst %#ux\n",
ureg->pc, *(u32int*)ureg->pc);
panic("undefined instruction");
}
break;
}
splhi();
/* delaysched set because we held a lock or because our quantum ended */
if(up && up->delaysched && clockintr){
sched(); /* can cause more traps */
splhi();
}
if(user){
if(up->procctl || up->nnote)
notify(ureg);
kexit(ureg);
}
}
int
isvalidaddr(void *v)
{
return (uintptr)v >= KZERO;
}
static void
dumplongs(char *msg, ulong *v, int n)
{
int i, l;
l = 0;
iprint("%s at %.8p: ", msg, v);
for(i=0; i<n; i++){
if(l >= 4){
iprint("\n %.8p: ", v);
l = 0;
}
if(isvalidaddr(v)){
iprint(" %.8lux", *v++);
l++;
}else{
iprint(" invalid");
break;
}
}
iprint("\n");
}
static void
dumpstackwithureg(Ureg *ureg)
{
uintptr l, i, v, estack;
u32int *p;
char *s;
if((s = getconf("*nodumpstack")) != nil && strcmp(s, "0") != 0){
iprint("dumpstack disabled\n");
return;
}
iprint("ktrace /kernel/path %#.8lux %#.8lux %#.8lux # pc, sp, link\n",
ureg->pc, ureg->sp, ureg->r14);
delay(2000);
i = 0;
if(up != nil && (uintptr)&l <= (uintptr)up->kstack+KSTACK)
estack = (uintptr)up->kstack+KSTACK;
else if((uintptr)&l >= (uintptr)m->stack
&& (uintptr)&l <= (uintptr)m+MACHSIZE)
estack = (uintptr)m+MACHSIZE;
else{
if(up != nil)
iprint("&up->kstack %#p &l %#p\n", up->kstack, &l);
else
iprint("&m %#p &l %#p\n", m, &l);
return;
}
for(l = (uintptr)&l; l < estack; l += sizeof(uintptr)){
v = *(uintptr*)l;
if(KTZERO < v && v < (uintptr)etext && !(v & 3)){
v -= sizeof(u32int); /* back up an instr */
p = (u32int*)v;
if((*p & 0x0f000000) == 0x0b000000){ /* BL instr? */
iprint("%#8.8lux=%#8.8lux ", l, v);
i++;
}
}
if(i == 4){
i = 0;
iprint("\n");
}
}
if(i)
iprint("\n");
}
/*
* 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);
}
void
dumpstack(void)
{
callwithureg(dumpstackwithureg);
}
void
dumpregs(Ureg* ureg)
{
int s;
if (ureg == nil) {
iprint("trap: no user process\n");
return;
}
s = splhi();
iprint("trap: %s", trapname(ureg->type));
if(ureg != nil && (ureg->psr & PsrMask) != PsrMsvc)
iprint(" in %s", trapname(ureg->psr));
iprint("\n");
iprint("psr %8.8lux type %2.2lux pc %8.8lux link %8.8lux\n",
ureg->psr, ureg->type, ureg->pc, ureg->link);
iprint("R14 %8.8lux R13 %8.8lux R12 %8.8lux R11 %8.8lux R10 %8.8lux\n",
ureg->r14, ureg->r13, ureg->r12, ureg->r11, ureg->r10);
iprint("R9 %8.8lux R8 %8.8lux R7 %8.8lux R6 %8.8lux R5 %8.8lux\n",
ureg->r9, ureg->r8, ureg->r7, ureg->r6, ureg->r5);
iprint("R4 %8.8lux R3 %8.8lux R2 %8.8lux R1 %8.8lux R0 %8.8lux\n",
ureg->r4, ureg->r3, ureg->r2, ureg->r1, ureg->r0);
iprint("stack is at %#p\n", ureg);
iprint("pc %#lux link %#lux\n", ureg->pc, ureg->link);
if(up)
iprint("user stack: %#p-%#p\n", up->kstack, up->kstack+KSTACK-4);
else
iprint("kernel stack: %8.8lux-%8.8lux\n",
(ulong)(m+1), (ulong)m+BY2PG-4);
dumplongs("stack", (ulong *)(ureg + 1), 16);
delay(2000);
dumpstack();
splx(s);
}