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- /*
- * This file is part of the UCB release of Plan 9. It is subject to the license
- * terms in the LICENSE file found in the top-level directory of this
- * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No
- * part of the UCB release of Plan 9, including this file, may be copied,
- * modified, propagated, or distributed except according to the terms contained
- * in the LICENSE file.
- */
- #include "u.h"
- #include "tos.h"
- #include "../port/lib.h"
- #include "mem.h"
- #include "dat.h"
- #include "fns.h"
- #include "../port/error.h"
- #include "../port/edf.h"
- #include <a.out.h>
- #include <trace.h>
- void
- sysrfork(Ar0* ar0, va_list list)
- {
- Proc *p;
- int flag, i, n, pid;
- Fgrp *ofg;
- Pgrp *opg;
- Rgrp *org;
- Egrp *oeg;
- Mach *wm;
- /*
- * int rfork(int);
- */
- flag = va_arg(list, int);
- /* Check flags before we commit */
- if((flag & (RFFDG|RFCFDG)) == (RFFDG|RFCFDG))
- error(Ebadarg);
- if((flag & (RFNAMEG|RFCNAMEG)) == (RFNAMEG|RFCNAMEG))
- error(Ebadarg);
- if((flag & (RFENVG|RFCENVG)) == (RFENVG|RFCENVG))
- error(Ebadarg);
- if((flag & (RFPREPAGE|RFCPREPAGE)) == (RFPREPAGE|RFCPREPAGE))
- error(Ebadarg);
- if((flag & (RFCORE|RFCCORE)) == (RFCORE|RFCCORE))
- error(Ebadarg);
- if(flag & RFCORE && up->wired != nil)
- error("wired proc cannot move to ac");
- if((flag&RFPROC) == 0) {
- if(flag & (RFMEM|RFNOWAIT))
- error(Ebadarg);
- if(flag & (RFFDG|RFCFDG)) {
- ofg = up->fgrp;
- if(flag & RFFDG)
- up->fgrp = dupfgrp(ofg);
- else
- up->fgrp = dupfgrp(nil);
- closefgrp(ofg);
- }
- if(flag & (RFNAMEG|RFCNAMEG)) {
- opg = up->pgrp;
- up->pgrp = newpgrp();
- if(flag & RFNAMEG)
- pgrpcpy(up->pgrp, opg);
- /* inherit noattach */
- up->pgrp->noattach = opg->noattach;
- closepgrp(opg);
- }
- if(flag & RFNOMNT)
- up->pgrp->noattach = 1;
- if(flag & RFREND) {
- org = up->rgrp;
- up->rgrp = newrgrp();
- closergrp(org);
- }
- if(flag & (RFENVG|RFCENVG)) {
- oeg = up->egrp;
- up->egrp = smalloc(sizeof(Egrp));
- up->egrp->ref = 1;
- if(flag & RFENVG)
- envcpy(up->egrp, oeg);
- closeegrp(oeg);
- }
- if(flag & RFNOTEG)
- up->noteid = incref(¬eidalloc);
- if(flag & (RFPREPAGE|RFCPREPAGE)){
- up->prepagemem = flag&RFPREPAGE;
- nixprepage(-1);
- }
- if(flag & RFCORE){
- up->ac = getac(up, -1);
- up->procctl = Proc_toac;
- }else if(flag & RFCCORE){
- if(up->ac != nil)
- up->procctl = Proc_totc;
- }
- ar0->i = 0;
- return;
- }
- p = newproc();
- if(flag & RFCORE){
- if(!waserror()){
- p->ac = getac(p, -1);
- p->procctl = Proc_toac;
- poperror();
- }else{
- print("warning: rfork: no available ac for the child, it runs in the tc\n");
- p->procctl = 0;
- }
- }
- if(up->trace)
- p->trace = 1;
- p->scallnr = up->scallnr;
- memmove(p->arg, up->arg, sizeof(up->arg));
- p->nerrlab = 0;
- p->slash = up->slash;
- p->dot = up->dot;
- incref(p->dot);
- memmove(p->note, up->note, sizeof(p->note));
- p->privatemem = up->privatemem;
- p->noswap = up->noswap;
- p->nnote = up->nnote;
- p->notified = 0;
- p->lastnote = up->lastnote;
- p->notify = up->notify;
- p->ureg = up->ureg;
- p->prepagemem = up->prepagemem;
- p->dbgreg = 0;
- /* Make a new set of memory segments */
- n = flag & RFMEM;
- qlock(&p->seglock);
- if(waserror()){
- qunlock(&p->seglock);
- nexterror();
- }
- for(i = 0; i < NSEG; i++)
- if(up->seg[i])
- p->seg[i] = dupseg(up->seg, i, n);
- qunlock(&p->seglock);
- poperror();
- /* File descriptors */
- if(flag & (RFFDG|RFCFDG)) {
- if(flag & RFFDG)
- p->fgrp = dupfgrp(up->fgrp);
- else
- p->fgrp = dupfgrp(nil);
- }
- else {
- p->fgrp = up->fgrp;
- incref(p->fgrp);
- }
- /* Process groups */
- if(flag & (RFNAMEG|RFCNAMEG)) {
- p->pgrp = newpgrp();
- if(flag & RFNAMEG)
- pgrpcpy(p->pgrp, up->pgrp);
- /* inherit noattach */
- p->pgrp->noattach = up->pgrp->noattach;
- }
- else {
- p->pgrp = up->pgrp;
- incref(p->pgrp);
- }
- if(flag & RFNOMNT)
- up->pgrp->noattach = 1;
- if(flag & RFREND)
- p->rgrp = newrgrp();
- else {
- incref(up->rgrp);
- p->rgrp = up->rgrp;
- }
- /* Environment group */
- if(flag & (RFENVG|RFCENVG)) {
- p->egrp = smalloc(sizeof(Egrp));
- p->egrp->ref = 1;
- if(flag & RFENVG)
- envcpy(p->egrp, up->egrp);
- }
- else {
- p->egrp = up->egrp;
- incref(p->egrp);
- }
- p->hang = up->hang;
- p->procmode = up->procmode;
- /* Craft a return frame which will cause the child to pop out of
- * the scheduler in user mode with the return register zero
- */
- sysrforkchild(p, up);
- p->parent = up;
- p->parentpid = up->pid;
- if(flag&RFNOWAIT)
- p->parentpid = 0;
- else {
- lock(&up->exl);
- up->nchild++;
- unlock(&up->exl);
- }
- if((flag&RFNOTEG) == 0)
- p->noteid = up->noteid;
- pid = p->pid;
- memset(p->time, 0, sizeof(p->time));
- p->time[TReal] = sys->ticks;
- if(flag & (RFPREPAGE|RFCPREPAGE)){
- p->prepagemem = flag&RFPREPAGE;
- /*
- * BUG: this is prepaging our memory, not
- * that of the child, but at least we
- * will do the copy on write.
- */
- nixprepage(-1);
- }
- kstrdup(&p->text, up->text);
- kstrdup(&p->user, up->user);
- /*
- * since the bss/data segments are now shareable,
- * any mmu info about this process is now stale
- * (i.e. has bad properties) and has to be discarded.
- */
- mmuflush();
- p->basepri = up->basepri;
- p->priority = up->basepri;
- p->fixedpri = up->fixedpri;
- p->mp = up->mp;
- wm = up->wired;
- if(wm)
- procwired(p, wm->machno);
- p->color = up->color;
- ready(p);
- sched();
- ar0->i = pid;
- }
- static uint64_t
- vl2be(uint64_t v)
- {
- uint8_t *p;
- p = (uint8_t*)&v;
- return ((uint64_t)((p[0]<<24)|(p[1]<<16)|(p[2]<<8)|p[3])<<32)
- |((uint64_t)(p[4]<<24)|(p[5]<<16)|(p[6]<<8)|p[7]);
- }
- static uint32_t
- l2be(int32_t l)
- {
- uint8_t *cp;
- cp = (uint8_t*)&l;
- return (cp[0]<<24) | (cp[1]<<16) | (cp[2]<<8) | cp[3];
- }
- typedef struct {
- Exec;
- uvlong hdr[1];
- } Hdr;
- /*
- * flags can ONLY specify that you want an AC for you, or
- * that you want an XC for you.
- *
- */
- static void
- execac(Ar0* ar0, int flags, char *ufile, char **argv)
- {
- Hdr hdr;
- Fgrp *f;
- Tos *tos;
- Chan *chan, *ichan;
- Image *img;
- Segment *s;
- int argc, i, n;
- char *a, *elem, *file, *p;
- char line[sizeof(Exec)], *progarg[sizeof(Exec)/2+1];
- int32_t hdrsz, magic, textsz, datasz, bsssz;
- uintptr textlim, datalim, bsslim, entry, stack;
- static int colorgen;
- file = nil;
- elem = nil;
- switch(flags){
- case EXTC:
- case EXXC:
- break;
- case EXAC:
- up->ac = getac(up, -1);
- break;
- default:
- error("unknown execac flag");
- }
- if(waserror()){
- DBG("execac: failing: %s\n", up->errstr);
- free(file);
- free(elem);
- if(flags == EXAC && up->ac != nil)
- up->ac->proc = nil;
- up->ac = nil;
- nexterror();
- }
- /*
- * Open the file, remembering the final element and the full name.
- */
- argc = 0;
- file = validnamedup(ufile, 1);
- DBG("execac: up %#p file %s\n", up, file);
- if(up->trace)
- proctracepid(up);
- ichan = namec(file, Aopen, OEXEC, 0);
- if(waserror()){
- cclose(ichan);
- nexterror();
- }
- kstrdup(&elem, up->genbuf);
- /*
- * Read the header.
- * If it's a #!, fill in progarg[] with info then read a new header
- * from the file indicated by the #!.
- * The #! line must be less than sizeof(Exec) in size,
- * including the terminating \n.
- */
- hdrsz = ichan->dev->read(ichan, &hdr, sizeof(Hdr), 0);
- if(hdrsz < 2)
- error(Ebadexec);
- p = (char*)&hdr;
- if(p[0] == '#' && p[1] == '!'){
- p = memccpy(line, (char*)&hdr, '\n',
- MIN(sizeof(Exec), hdrsz));
- if(p == nil)
- error(Ebadexec);
- *(p-1) = '\0';
- argc = tokenize(line+2, progarg, nelem(progarg));
- if(argc == 0)
- error(Ebadexec);
- /* The original file becomes an extra arg after #! line */
- progarg[argc++] = file;
- /*
- * Take the #! $0 as a file to open, and replace
- * $0 with the original path's name.
- */
- p = progarg[0];
- progarg[0] = elem;
- chan = nil; /* in case namec errors out */
- USED(chan);
- chan = namec(p, Aopen, OEXEC, 0);
- hdrsz = chan->dev->read(chan, &hdr, sizeof(Hdr), 0);
- if(hdrsz < 2)
- error(Ebadexec);
- }else{
- chan = ichan;
- incref(ichan);
- }
- /* chan is the chan to use, initial or not. ichan is irrelevant now */
- cclose(ichan);
- poperror();
- /*
- * #! has had its chance, now we need a real binary.
- */
- magic = l2be(hdr.magic);
- if(hdrsz != sizeof(Hdr) || magic != AOUT_MAGIC)
- error(Ebadexec);
- if(magic & HDR_MAGIC){
- entry = vl2be(hdr.hdr[0]);
- hdrsz = sizeof(Hdr);
- }
- else{
- entry = l2be(hdr.entry);
- hdrsz = sizeof(Exec);
- }
- textsz = l2be(hdr.text);
- datasz = l2be(hdr.data);
- bsssz = l2be(hdr.bss);
- textlim = UTROUND(UTZERO+hdrsz+textsz);
- datalim = BIGPGROUND(textlim+datasz);
- bsslim = BIGPGROUND(textlim+datasz+bsssz);
- /*
- * Check the binary header for consistency,
- * e.g. the entry point is within the text segment and
- * the segments don't overlap each other.
- */
- if(entry < UTZERO+hdrsz || entry >= UTZERO+hdrsz+textsz)
- error(Ebadexec);
- if(textsz >= textlim || datasz > datalim || bsssz > bsslim
- || textlim >= USTKTOP || datalim >= USTKTOP || bsslim >= USTKTOP
- || datalim < textlim || bsslim < datalim)
- error(Ebadexec);
- if(up->ac != nil && up->ac != m)
- up->color = corecolor(up->ac->machno);
- else
- up->color = corecolor(m->machno);
- /*
- * The new stack is created in ESEG, temporarily mapped elsewhere.
- * The stack contains, in descending address order:
- * a structure containing housekeeping and profiling data (Tos);
- * argument strings;
- * array of vectors to the argument strings with a terminating
- * nil (argv).
- * When the exec is committed, this temporary stack in ESEG will
- * become SSEG.
- * The architecture-dependent code which jumps to the new image
- * will also push a count of the argument array onto the stack (argc).
- */
- qlock(&up->seglock);
- if(waserror()){
- if(up->seg[ESEG] != nil){
- putseg(up->seg[ESEG]);
- up->seg[ESEG] = nil;
- }
- qunlock(&up->seglock);
- nexterror();
- }
- up->seg[ESEG] = newseg(SG_STACK, TSTKTOP-USTKSIZE, USTKSIZE/BIGPGSZ);
- up->seg[ESEG]->color = up->color;
- /*
- * Stack is a pointer into the temporary stack
- * segment, and will move as items are pushed.
- */
- stack = TSTKTOP-sizeof(Tos);
- /*
- * First, the top-of-stack structure.
- */
- tos = (Tos*)stack;
- tos->cyclefreq = m->cyclefreq;
- cycles((uint64_t*)&tos->pcycles);
- tos->pcycles = -tos->pcycles;
- tos->kcycles = tos->pcycles;
- tos->clock = 0;
- /*
- * Next push any arguments found from a #! header.
- */
- for(i = 0; i < argc; i++){
- n = strlen(progarg[i])+1;
- stack -= n;
- memmove(UINT2PTR(stack), progarg[i], n);
- }
- /*
- * Copy the strings pointed to by the syscall argument argv into
- * the temporary stack segment, being careful to check
- * the strings argv points to are valid.
- */
- for(i = 0;; i++, argv++){
- a = *(char**)validaddr(argv, sizeof(char**), 0);
- if(a == nil)
- break;
- a = validaddr(a, 1, 0);
- n = ((char*)vmemchr(a, 0, 0x7fffffff) - a) + 1;
- /*
- * This futzing is so argv[0] gets validated even
- * though it will be thrown away if this is a shell
- * script.
- */
- if(argc > 0 && i == 0)
- continue;
- /*
- * Before copying the string into the temporary stack,
- * which might involve a demand-page, check the string
- * will not overflow the bottom of the stack.
- */
- stack -= n;
- if(stack < TSTKTOP-USTKSIZE)
- error(Enovmem);
- p = UINT2PTR(stack);
- memmove(p, a, n);
- p[n-1] = 0;
- argc++;
- }
- if(argc < 1)
- error(Ebadexec);
- /*
- * Before pushing the argument pointers onto the temporary stack,
- * which might involve a demand-page, check there is room for the
- * terminating nil pointer, plus pointers, plus some slop for however
- * argc might be passed on the stack by sysexecregs (give a page
- * of slop, it is an overestimate, but why not).
- * Sysexecstack does any architecture-dependent stack alignment.
- * Keep a copy of the start of the argument strings before alignment
- * so up->args can be created later.
- * Although the argument vectors are being pushed onto the stack in
- * the temporary segment, the values must be adjusted to reflect
- * the segment address after it replaces the current SSEG.
- */
- a = p = UINT2PTR(stack);
- stack = sysexecstack(stack, argc);
- if(stack-(argc+1)*sizeof(char**)-BIGPGSZ < TSTKTOP-USTKSIZE)
- error(Ebadexec);
- argv = (char**)stack;
- *--argv = nil;
- for(i = 0; i < argc; i++){
- *--argv = p + (USTKTOP-TSTKTOP);
- p += strlen(p) + 1;
- }
- /*
- * Make a good faith copy of the args in up->args using the strings
- * in the temporary stack segment. The length must be > 0 as it
- * includes the \0 on the last argument and argc was checked earlier
- * to be > 0. After the memmove, compensate for any UTF character
- * boundary before placing the terminating \0.
- */
- n = p - a;
- if(n <= 0)
- error(Egreg);
- if(n > 128)
- n = 128;
- p = smalloc(n);
- if(waserror()){
- free(p);
- nexterror();
- }
- memmove(p, a, n);
- while(n > 0 && (p[n-1] & 0xc0) == 0x80)
- n--;
- p[n-1] = '\0';
- /*
- * All the argument processing is now done, ready to commit.
- */
- free(up->text);
- up->text = elem;
- elem = nil;
- free(up->args);
- up->args = p;
- up->nargs = n;
- poperror(); /* p (up->args) */
- /*
- * Close on exec
- */
- f = up->fgrp;
- for(i=0; i<=f->maxfd; i++)
- fdclose(i, CCEXEC);
- /*
- * Free old memory.
- * Special segments maintained across exec.
- */
- for(i = SSEG; i <= HSEG; i++) {
- putseg(up->seg[i]);
- up->seg[i] = nil; /* in case of error */
- }
- for(i = HSEG+1; i< NSEG; i++) {
- s = up->seg[i];
- if(s && (s->type&SG_CEXEC)) {
- putseg(s);
- up->seg[i] = nil;
- }
- }
- /* Text. Shared. Attaches to cache image if possible
- * but prepaged if EXAC
- */
- img = attachimage(SG_TEXT|SG_RONLY, chan, up->color, UTZERO, (textlim-UTZERO)/BIGPGSZ);
- s = img->s;
- up->seg[TSEG] = s;
- s->flushme = 1;
- s->fstart = 0;
- s->flen = hdrsz+textsz;
- if(img->color != up->color){
- up->color = img->color;
- }
- unlock(img);
- /* Data. Shared. */
- s = newseg(SG_DATA, textlim, (datalim-textlim)/BIGPGSZ);
- up->seg[DSEG] = s;
- s->color = up->color;
- /* Attached by hand */
- incref(img);
- s->image = img;
- s->fstart = hdrsz+textsz;
- s->flen = datasz;
- /* BSS. Zero fill on demand for TS */
- up->seg[BSEG] = newseg(SG_BSS, datalim, (bsslim-datalim)/BIGPGSZ);
- up->seg[BSEG]->color= up->color;
- /*
- * Move the stack
- */
- s = up->seg[ESEG];
- up->seg[ESEG] = nil;
- up->seg[SSEG] = s;
- /* the color of the stack was decided when we created it before,
- * it may have nothing to do with the color of other segments.
- */
- qunlock(&up->seglock);
- poperror(); /* seglock */
- s->base = USTKTOP-USTKSIZE;
- s->top = USTKTOP;
- relocateseg(s, USTKTOP-TSTKTOP);
- /*
- * '/' processes are higher priority.
- */
- if(chan->dev->dc == L'/')
- up->basepri = PriRoot;
- up->priority = up->basepri;
- poperror(); /* chan, elem, file */
- cclose(chan);
- free(file);
- /*
- * At this point, the mmu contains info about the old address
- * space and needs to be flushed
- */
- mmuflush();
- if(up->prepagemem || flags == EXAC)
- nixprepage(-1);
- qlock(&up->debug);
- up->nnote = 0;
- up->notify = 0;
- up->notified = 0;
- up->privatemem = 0;
- sysprocsetup(up);
- qunlock(&up->debug);
- if(up->hang)
- up->procctl = Proc_stopme;
- ar0->v = sysexecregs(entry, TSTKTOP - PTR2UINT(argv), argc);
- if(flags == EXAC){
- up->procctl = Proc_toac;
- up->prepagemem = 1;
- }
- DBG("execac up %#p done\n"
- "textsz %lx datasz %lx bsssz %lx hdrsz %lx\n"
- "textlim %ullx datalim %ullx bsslim %ullx\n", up,
- textsz, datasz, bsssz, hdrsz, textlim, datalim, bsslim);
- }
- void
- sysexecac(Ar0* ar0, va_list list)
- {
- int flags;
- char *file, **argv;
- /*
- * void* execac(int flags, char* name, char* argv[]);
- */
- flags = va_arg(list, unsigned int);
- file = va_arg(list, char*);
- file = validaddr(file, 1, 0);
- argv = va_arg(list, char**);
- evenaddr(PTR2UINT(argv));
- execac(ar0, flags, file, argv);
- }
- void
- sysexec(Ar0* ar0, va_list list)
- {
- char *file, **argv;
- /*
- * void* exec(char* name, char* argv[]);
- */
- file = va_arg(list, char*);
- file = validaddr(file, 1, 0);
- argv = va_arg(list, char**);
- evenaddr(PTR2UINT(argv));
- execac(ar0, EXTC, file, argv);
- }
- void
- sysr1(Ar0* , va_list )
- {
- print("sysr1() called. recompile your binary\n");
- }
- void
- sysnixsyscall(Ar0* , va_list )
- {
- print("nixsyscall() called. recompile your binary\n");
- }
- int
- return0(void*)
- {
- return 0;
- }
- void
- syssleep(Ar0* ar0, va_list list)
- {
- int32_t ms;
- /*
- * int sleep(long millisecs);
- */
- ms = va_arg(list, int32_t);
- ar0->i = 0;
- if(ms <= 0) {
- if (up->edf && (up->edf->flags & Admitted))
- edfyield();
- else
- yield();
- return;
- }
- if(ms < TK2MS(1))
- ms = TK2MS(1);
- tsleep(&up->sleep, return0, 0, ms);
- }
- void
- sysalarm(Ar0* ar0, va_list list)
- {
- unsigned long ms;
- /*
- * long alarm(unsigned long millisecs);
- * Odd argument type...
- */
- ms = va_arg(list, unsigned long);
- ar0->l = procalarm(ms);
- }
- void
- sysexits(Ar0*, va_list list)
- {
- char *status;
- char *inval = "invalid exit string";
- char buf[ERRMAX];
- /*
- * void exits(char *msg);
- */
- status = va_arg(list, char*);
- if(status){
- if(waserror())
- status = inval;
- else{
- status = validaddr(status, 1, 0);
- if(vmemchr(status, 0, ERRMAX) == 0){
- memmove(buf, status, ERRMAX);
- buf[ERRMAX-1] = 0;
- status = buf;
- }
- poperror();
- }
- }
- pexit(status, 1);
- }
- void
- sys_wait(Ar0* ar0, va_list list)
- {
- int pid;
- Waitmsg w;
- OWaitmsg *ow;
- /*
- * int wait(Waitmsg* w);
- *
- * Deprecated; backwards compatibility only.
- */
- ow = va_arg(list, OWaitmsg*);
- if(ow == nil){
- ar0->i = pwait(nil);
- return;
- }
- ow = validaddr(ow, sizeof(OWaitmsg), 1);
- evenaddr(PTR2UINT(ow));
- pid = pwait(&w);
- if(pid >= 0){
- readnum(0, ow->pid, NUMSIZE, w.pid, NUMSIZE);
- readnum(0, ow->time+TUser*NUMSIZE, NUMSIZE, w.time[TUser], NUMSIZE);
- readnum(0, ow->time+TSys*NUMSIZE, NUMSIZE, w.time[TSys], NUMSIZE);
- readnum(0, ow->time+TReal*NUMSIZE, NUMSIZE, w.time[TReal], NUMSIZE);
- strncpy(ow->msg, w.msg, sizeof(ow->msg));
- ow->msg[sizeof(ow->msg)-1] = '\0';
- }
- ar0->i = pid;
- }
- void
- sysawait(Ar0* ar0, va_list list)
- {
- int i;
- int pid;
- Waitmsg w;
- usize n;
- char *p;
- /*
- * int await(char* s, int n);
- * should really be
- * usize await(char* s, usize n);
- */
- p = va_arg(list, char*);
- n = va_arg(list, int32_t);
- p = validaddr(p, n, 1);
- pid = pwait(&w);
- if(pid < 0){
- ar0->i = -1;
- return;
- }
- i = snprint(p, n, "%d %lud %lud %lud %q",
- w.pid,
- w.time[TUser], w.time[TSys], w.time[TReal],
- w.msg);
- ar0->i = i;
- }
- void
- werrstr(char *fmt, ...)
- {
- va_list va;
- if(up == nil)
- return;
- va_start(va, fmt);
- vseprint(up->syserrstr, up->syserrstr+ERRMAX, fmt, va);
- va_end(va);
- }
- static void
- generrstr(char *buf, int32_t n)
- {
- char *p, tmp[ERRMAX];
- if(n <= 0)
- error(Ebadarg);
- p = validaddr(buf, n, 1);
- if(n > sizeof tmp)
- n = sizeof tmp;
- memmove(tmp, p, n);
- /* make sure it's NUL-terminated */
- tmp[n-1] = '\0';
- memmove(p, up->syserrstr, n);
- p[n-1] = '\0';
- memmove(up->syserrstr, tmp, n);
- }
- void
- syserrstr(Ar0* ar0, va_list list)
- {
- char *err;
- usize nerr;
- /*
- * int errstr(char* err, uint nerr);
- * should really be
- * usize errstr(char* err, usize nerr);
- * but errstr always returns 0.
- */
- err = va_arg(list, char*);
- nerr = va_arg(list, usize);
- generrstr(err, nerr);
- ar0->i = 0;
- }
- void
- sys_errstr(Ar0* ar0, va_list list)
- {
- char *p;
- /*
- * int errstr(char* err);
- *
- * Deprecated; backwards compatibility only.
- */
- p = va_arg(list, char*);
- generrstr(p, 64);
- ar0->i = 0;
- }
- void
- sysnotify(Ar0* ar0, va_list list)
- {
- void (*f)(void*, char*);
- /*
- * int notify(void (*f)(void*, char*));
- */
- f = (void (*)(void*, char*))va_arg(list, void*);
- if(f != nil)
- validaddr(f, sizeof(void (*)(void*, char*)), 0);
- up->notify = f;
- ar0->i = 0;
- }
- void
- sysnoted(Ar0* ar0, va_list list)
- {
- int v;
- /*
- * int noted(int v);
- */
- v = va_arg(list, int);
- if(v != NRSTR && !up->notified)
- error(Egreg);
- ar0->i = 0;
- }
- void
- sysrendezvous(Ar0* ar0, va_list list)
- {
- Proc *p, **l;
- uintptr tag, val;
- /*
- * void* rendezvous(void*, void*);
- */
- tag = PTR2UINT(va_arg(list, void*));
- l = &REND(up->rgrp, tag);
- up->rendval = ~0;
- lock(up->rgrp);
- for(p = *l; p; p = p->rendhash) {
- if(p->rendtag == tag) {
- *l = p->rendhash;
- val = p->rendval;
- p->rendval = PTR2UINT(va_arg(list, void*));
- while(p->mach != 0)
- ;
- ready(p);
- unlock(up->rgrp);
- ar0->v = UINT2PTR(val);
- return;
- }
- l = &p->rendhash;
- }
- /* Going to sleep here */
- up->rendtag = tag;
- up->rendval = PTR2UINT(va_arg(list, void*));
- up->rendhash = *l;
- *l = up;
- up->state = Rendezvous;
- if(up->trace)
- proctrace(up, SLock, 0);
- unlock(up->rgrp);
- sched();
- ar0->v = UINT2PTR(up->rendval);
- }
- /*
- * The implementation of semaphores is complicated by needing
- * to avoid rescheduling in syssemrelease, so that it is safe
- * to call from real-time processes. This means syssemrelease
- * cannot acquire any qlocks, only spin locks.
- *
- * Semacquire and semrelease must both manipulate the semaphore
- * wait list. Lock-free linked lists only exist in theory, not
- * in practice, so the wait list is protected by a spin lock.
- *
- * The semaphore value *addr is stored in user memory, so it
- * cannot be read or written while holding spin locks.
- *
- * Thus, we can access the list only when holding the lock, and
- * we can access the semaphore only when not holding the lock.
- * This makes things interesting. Note that sleep's condition function
- * is called while holding two locks - r and up->rlock - so it cannot
- * access the semaphore value either.
- *
- * An acquirer announces its intention to try for the semaphore
- * by putting a Sema structure onto the wait list and then
- * setting Sema.waiting. After one last check of semaphore,
- * the acquirer sleeps until Sema.waiting==0. A releaser of n
- * must wake up n acquirers who have Sema.waiting set. It does
- * this by clearing Sema.waiting and then calling wakeup.
- *
- * There are three interesting races here.
- * The first is that in this particular sleep/wakeup usage, a single
- * wakeup can rouse a process from two consecutive sleeps!
- * The ordering is:
- *
- * (a) set Sema.waiting = 1
- * (a) call sleep
- * (b) set Sema.waiting = 0
- * (a) check Sema.waiting inside sleep, return w/o sleeping
- * (a) try for semaphore, fail
- * (a) set Sema.waiting = 1
- * (a) call sleep
- * (b) call wakeup(a)
- * (a) wake up again
- *
- * This is okay - semacquire will just go around the loop
- * again. It does mean that at the top of the for(;;) loop in
- * semacquire, phore.waiting might already be set to 1.
- *
- * The second is that a releaser might wake an acquirer who is
- * interrupted before he can acquire the lock. Since
- * release(n) issues only n wakeup calls -- only n can be used
- * anyway -- if the interrupted process is not going to use his
- * wakeup call he must pass it on to another acquirer.
- *
- * The third race is similar to the second but more subtle. An
- * acquirer sets waiting=1 and then does a final canacquire()
- * before going to sleep. The opposite order would result in
- * missing wakeups that happen between canacquire and
- * waiting=1. (In fact, the whole point of Sema.waiting is to
- * avoid missing wakeups between canacquire() and sleep().) But
- * there can be spurious wakeups between a successful
- * canacquire() and the following semdequeue(). This wakeup is
- * not useful to the acquirer, since he has already acquired
- * the semaphore. Like in the previous case, though, the
- * acquirer must pass the wakeup call along.
- *
- * This is all rather subtle. The code below has been verified
- * with the spin model /sys/src/9/port/semaphore.p. The
- * original code anticipated the second race but not the first
- * or third, which were caught only with spin. The first race
- * is mentioned in /sys/doc/sleep.ps, but I'd forgotten about it.
- * It was lucky that my abstract model of sleep/wakeup still managed
- * to preserve that behavior.
- *
- * I remain slightly concerned about memory coherence
- * outside of locks. The spin model does not take
- * queued processor writes into account so we have to
- * think hard. The only variables accessed outside locks
- * are the semaphore value itself and the boolean flag
- * Sema.waiting. The value is only accessed with CAS,
- * whose job description includes doing the right thing as
- * far as memory coherence across processors. That leaves
- * Sema.waiting. To handle it, we call coherence() before each
- * read and after each write. - rsc
- */
- /* Add semaphore p with addr a to list in seg. */
- static void
- semqueue(Segment* s, int* addr, Sema* p)
- {
- memset(p, 0, sizeof *p);
- p->addr = addr;
- lock(&s->sema); /* uses s->sema.Rendez.Lock, but no one else is */
- p->next = &s->sema;
- p->prev = s->sema.prev;
- p->next->prev = p;
- p->prev->next = p;
- unlock(&s->sema);
- }
- /* Remove semaphore p from list in seg. */
- static void
- semdequeue(Segment* s, Sema* p)
- {
- lock(&s->sema);
- p->next->prev = p->prev;
- p->prev->next = p->next;
- unlock(&s->sema);
- }
- /* Wake up n waiters with addr on list in seg. */
- static void
- semwakeup(Segment* s, int* addr, int n)
- {
- Sema *p;
- lock(&s->sema);
- for(p = s->sema.next; p != &s->sema && n > 0; p = p->next){
- if(p->addr == addr && p->waiting){
- p->waiting = 0;
- coherence();
- wakeup(p);
- n--;
- }
- }
- unlock(&s->sema);
- }
- /* Add delta to semaphore and wake up waiters as appropriate. */
- static int
- semrelease(Segment* s, int* addr, int delta)
- {
- int value;
- do
- value = *addr;
- while(!CASW(addr, value, value+delta));
- semwakeup(s, addr, delta);
- return value+delta;
- }
- /* Try to acquire semaphore using compare-and-swap */
- static int
- canacquire(int* addr)
- {
- int value;
- while((value = *addr) > 0){
- if(CASW(addr, value, value-1))
- return 1;
- }
- return 0;
- }
- /* Should we wake up? */
- static int
- semawoke(void* p)
- {
- coherence();
- return !((Sema*)p)->waiting;
- }
- /* Acquire semaphore (subtract 1). */
- static int
- semacquire(Segment* s, int* addr, int block)
- {
- int acquired;
- Sema phore;
- if(canacquire(addr))
- return 1;
- if(!block)
- return 0;
- acquired = 0;
- semqueue(s, addr, &phore);
- for(;;){
- phore.waiting = 1;
- coherence();
- if(canacquire(addr)){
- acquired = 1;
- break;
- }
- if(waserror())
- break;
- sleep(&phore, semawoke, &phore);
- poperror();
- }
- semdequeue(s, &phore);
- coherence(); /* not strictly necessary due to lock in semdequeue */
- if(!phore.waiting)
- semwakeup(s, addr, 1);
- if(!acquired)
- nexterror();
- return 1;
- }
- /* Acquire semaphore or time-out */
- static int
- tsemacquire(Segment* s, int* addr, int32_t ms)
- {
- int acquired;
- uint32_t t;
- Sema phore;
- if(canacquire(addr))
- return 1;
- if(ms == 0)
- return 0;
- acquired = 0;
- semqueue(s, addr, &phore);
- for(;;){
- phore.waiting = 1;
- coherence();
- if(canacquire(addr)){
- acquired = 1;
- break;
- }
- if(waserror())
- break;
- t = sys->ticks;
- tsleep(&phore, semawoke, &phore, ms);
- ms -= TK2MS(sys->ticks-t);
- poperror();
- if(ms <= 0)
- break;
- }
- semdequeue(s, &phore);
- coherence(); /* not strictly necessary due to lock in semdequeue */
- if(!phore.waiting)
- semwakeup(s, addr, 1);
- if(ms <= 0)
- return 0;
- if(!acquired)
- nexterror();
- return 1;
- }
- void
- syssemacquire(Ar0* ar0, va_list list)
- {
- Segment *s;
- int *addr, block;
- /*
- * int semacquire(long* addr, int block);
- * should be (and will be implemented below as) perhaps
- * int semacquire(int* addr, int block);
- */
- addr = va_arg(list, int*);
- addr = validaddr(addr, sizeof(int), 1);
- evenaddr(PTR2UINT(addr));
- block = va_arg(list, int);
- if((s = seg(up, PTR2UINT(addr), 0)) == nil)
- error(Ebadarg);
- if(*addr < 0)
- error(Ebadarg);
- ar0->i = semacquire(s, addr, block);
- }
- void
- systsemacquire(Ar0* ar0, va_list list)
- {
- Segment *s;
- int *addr, ms;
- /*
- * int tsemacquire(long* addr, ulong ms);
- * should be (and will be implemented below as) perhaps
- * int tsemacquire(int* addr, ulong ms);
- */
- addr = va_arg(list, int*);
- addr = validaddr(addr, sizeof(int), 1);
- evenaddr(PTR2UINT(addr));
- ms = va_arg(list, uint32_t);
- if((s = seg(up, PTR2UINT(addr), 0)) == nil)
- error(Ebadarg);
- if(*addr < 0)
- error(Ebadarg);
- ar0->i = tsemacquire(s, addr, ms);
- }
- void
- syssemrelease(Ar0* ar0, va_list list)
- {
- Segment *s;
- int *addr, delta;
- /*
- * long semrelease(long* addr, long count);
- * should be (and will be implemented below as) perhaps
- * int semrelease(int* addr, int count);
- */
- addr = va_arg(list, int*);
- addr = validaddr(addr, sizeof(int), 1);
- evenaddr(PTR2UINT(addr));
- delta = va_arg(list, int);
- if((s = seg(up, PTR2UINT(addr), 0)) == nil)
- error(Ebadarg);
- if(delta < 0 || *addr < 0)
- error(Ebadarg);
- ar0->i = semrelease(s, addr, delta);
- }
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