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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.
- */
- /*
- * EPISODE 12B
- * How to recognise different types of trees from quite a long way away.
- * NO. 1
- * THE LARCH
- */
- #include "u.h"
- #include "../port/lib.h"
- #include "mem.h"
- #include "dat.h"
- #include "fns.h"
- #include "../port/error.h"
- /* the rules are different for different compilers. We need to define up. */
- // Initialize it to force it into data.
- // That way, if we set them in assembly, they won't get zero'd by the bss init in main
- // N.B. There was an interesting hack in plan 9 c. You could grab up to two registers for your
- // program. In the case of Plan 9, m was r15, and up was r14. Very slick, and if there is a way to do
- // this in gcc or clang I don't know it. This also nicely handled per cpu info; R15/14 were always right for
- // your core and context.
- //Mach *m = (void *)0;
- int
- incref(Ref *r)
- {
- int x;
- lock(r);
- x = ++r->ref;
- unlock(r);
- return x;
- }
- int
- decref(Ref *r)
- {
- int x;
- lock(r);
- x = --r->ref;
- unlock(r);
- if(x < 0)
- panic("decref pc=%#p", getcallerpc(&r));
- return x;
- }
- void
- procrestore(Proc *p)
- {
- uint64_t t;
- if(p->kp)
- return;
- cycles(&t);
- p->pcycles -= t;
- fpuprocrestore(p);
- }
- /*
- * Save the mach dependent part of the process state.
- * NB: the caller should mmuflushtlb after procsave().
- * procsave/procrestore don't touch the mmu, they
- * care about fpu, mostly.
- */
- void
- procsave(Proc *p)
- {
- uint64_t t;
- cycles(&t);
- p->pcycles += t;
- fpuprocsave(p);
- }
- static void
- linkproc(void)
- {
- Proc *up = externup();
- spllo();
- up->kpfun(up->kparg);
- pexit("kproc dying", 0);
- }
- void
- kprocchild(Proc* p, void (*func)(void*), void* arg)
- {
- /*
- * gotolabel() needs a word on the stack in
- * which to place the return PC used to jump
- * to linkproc().
- */
- p->sched.pc = PTR2UINT(linkproc);
- p->sched.sp = PTR2UINT(p->kstack+KSTACK-BY2SE);
- p->sched.sp = STACKALIGN(p->sched.sp);
- p->kpfun = func;
- p->kparg = arg;
- }
- /*
- * put the processor in the halt state if we've no processes to run.
- * an interrupt will get us going again.
- * The boot TC in nix can't halt, because it must stay alert in
- * case an AC makes a handler process ready.
- * We should probably use mwait in that case.
- */
- void
- idlehands(void)
- {
- if(machp()->nixtype != NIXAC)
- halt();
- }
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