ref: e1cd22504e26d0a732a4219d38d6e5fe3e03aa21
dir: /sys/src/9/kw/syscall.c/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "../port/error.h"
#include "../port/systab.h"
#include <tos.h>
#include "ureg.h"
#include "arm.h"
typedef struct {
uintptr ip;
Ureg* arg0;
char* arg1;
char msg[ERRMAX];
Ureg* old;
Ureg ureg;
} NFrame;
/*
* Return user to state before notify()
*/
static void
noted(Ureg* cur, uintptr arg0)
{
NFrame *nf;
Ureg *nur;
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;
fpunoted();
nf = up->ureg;
/* sanity clause */
if(!okaddr((uintptr)nf, sizeof(NFrame), 0)){
qunlock(&up->debug);
pprint("bad ureg in noted %#p\n", nf);
pexit("Suicide", 0);
}
/* don't let user change system flags */
nur = &nf->ureg;
nur->psr &= PsrMask|PsrDfiq|PsrDirq;
nur->psr |= (cur->psr & ~(PsrMask|PsrDfiq|PsrDirq));
memmove(cur, nur, sizeof(Ureg));
switch((int)arg0){
case NCONT:
case NRSTR:
if(!okaddr(nur->pc, BY2WD, 0) || !okaddr(nur->sp, BY2WD, 0)){
qunlock(&up->debug);
pprint("suicide: trap in noted\n");
pexit("Suicide", 0);
}
up->ureg = nf->old;
qunlock(&up->debug);
break;
case NSAVE:
if(!okaddr(nur->pc, BY2WD, 0) || !okaddr(nur->sp, BY2WD, 0)){
qunlock(&up->debug);
pprint("suicide: trap in noted\n");
pexit("Suicide", 0);
}
qunlock(&up->debug);
splhi();
nf->arg1 = nf->msg;
nf->arg0 = &nf->ureg;
nf->ip = 0;
cur->sp = (uintptr)nf;
cur->r0 = (uintptr)nf->arg0;
break;
default:
up->lastnote->flag = NDebug;
/*FALLTHROUGH*/
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);
}
}
/*
* Call user, if necessary, with note.
* Pass user the Ureg struct and the note on his stack.
*/
int
notify(Ureg* ureg)
{
u32int s;
uintptr sp;
NFrame *nf;
char *msg;
if(up->procctl)
procctl();
if(up->nnote == 0)
return 0;
fpunotify(ureg);
s = spllo();
qlock(&up->debug);
msg = popnote(ureg);
if(msg == nil){
qunlock(&up->debug);
splhi();
return 0;
}
if(!okaddr((uintptr)up->notify, 1, 0)){
qunlock(&up->debug);
pprint("suicide: notify function address %#p\n", up->notify);
pexit("Suicide", 0);
}
sp = ureg->sp - sizeof(NFrame);
if(!okaddr(sp, sizeof(NFrame), 1)){
qunlock(&up->debug);
pprint("suicide: notify stack address %#p\n", sp);
pexit("Suicide", 0);
}
nf = (void*)sp;
memmove(&nf->ureg, ureg, sizeof(Ureg));
nf->old = up->ureg;
up->ureg = nf;
memmove(nf->msg, msg, ERRMAX);
nf->arg1 = nf->msg;
nf->arg0 = &nf->ureg;
nf->ip = 0;
ureg->sp = sp;
ureg->pc = (uintptr)up->notify;
ureg->r0 = (uintptr)nf->arg0;
qunlock(&up->debug);
splx(s);
return 1;
}
void
syscall(Ureg* ureg)
{
char *e;
u32int s;
ulong sp;
long ret;
int i, scallnr;
vlong startns, stopns;
if(!kenter(ureg))
panic("syscall: from kernel: pc %#lux r14 %#lux psr %#lux",
ureg->pc, ureg->r14, ureg->psr);
m->syscall++;
up->insyscall = 1;
up->pc = ureg->pc;
scallnr = ureg->r0;
up->scallnr = scallnr;
spllo();
sp = ureg->sp;
up->nerrlab = 0;
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(up->nerrlab){
print("bad errstack [%d]: %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");
}
/*
* 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->r0 = 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);
}
uintptr
execregs(uintptr entry, ulong ssize, ulong nargs)
{
ulong *sp;
Ureg *ureg;
sp = (ulong*)(USTKTOP - ssize);
*--sp = nargs;
ureg = up->dbgreg;
// memset(ureg, 0, 15*sizeof(ulong));
ureg->r13 = (ulong)sp;
ureg->pc = entry;
//print("%lud: EXECREGS pc %#ux sp %#ux nargs %ld\n", up->pid, ureg->pc, ureg->r13, nargs);
/*
* return the address of kernel/user shared data
* (e.g. clock stuff)
*/
return USTKTOP-sizeof(Tos);
}
void
sysprocsetup(Proc* p)
{
fpusysprocsetup(p);
}
/*
* Craft a return frame which will cause the child to pop out of
* the scheduler in user mode with the return register zero. Set
* pc to point to a l.s return function.
*/
void
forkchild(Proc *p, Ureg *ureg)
{
Ureg *cureg;
//print("%lud setting up for forking child %lud\n", up->pid, p->pid);
p->sched.sp = (ulong)p-sizeof(Ureg);
p->sched.pc = (ulong)forkret;
cureg = (Ureg*)(p->sched.sp);
memmove(cureg, ureg, sizeof(Ureg));
/* syscall returns 0 for child */
cureg->r0 = 0;
}