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syssem*: eleminate redundant validaddr() checks

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validaddr looks up the segments for an address range
and checks the flags and if the address range lies
within bounds on the segments.

as we'r going to lookup the segment in the syssem*
syscalls anyway, we can do the checks ourselfs avoiding
the double segment array lookups.

the implication of this tho is that now a semaphore cannot
span multiple segments. but this would be highly unusual
given that segments are page aligned.
This commit is contained in:
cinap_lenrek 2013-09-24 01:52:20 +02:00
parent 365fd745d6
commit 62b3eea271
1 changed files with 13 additions and 7 deletions
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20
sys/src/9/port/sysproc.c
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@ -1109,13 +1109,15 @@ syssemacquire(ulong *arg)
long *addr;
Segment *s;
validaddr(arg[0], sizeof(long), 1);
evenaddr(arg[0]);
addr = (long*)arg[0];
block = arg[1];
if((s = seg(up, (ulong)addr, 0)) == nil)
s = seg(up, (ulong)addr, 0);
if(s == nil || (s->type&SG_RONLY) != 0 || (ulong)addr+sizeof(long) > s->top){
validaddr((ulong)addr, sizeof(long), 1);
error(Ebadarg);
}
if(*addr < 0)
error(Ebadarg);
return semacquire(s, addr, block);
@ -1128,13 +1130,15 @@ systsemacquire(ulong *arg)
ulong ms;
Segment *s;
validaddr(arg[0], sizeof(long), 1);
evenaddr(arg[0]);
addr = (long*)arg[0];
ms = arg[1];
if((s = seg(up, (ulong)addr, 0)) == nil)
s = seg(up, (ulong)addr, 0);
if(s == nil || (s->type&SG_RONLY) != 0 || (ulong)addr+sizeof(long) > s->top){
validaddr((ulong)addr, sizeof(long), 1);
error(Ebadarg);
}
if(*addr < 0)
error(Ebadarg);
return tsemacquire(s, addr, ms);
@ -1146,13 +1150,15 @@ syssemrelease(ulong *arg)
long *addr, delta;
Segment *s;
validaddr(arg[0], sizeof(long), 1);
evenaddr(arg[0]);
addr = (long*)arg[0];
delta = arg[1];
if((s = seg(up, (ulong)addr, 0)) == nil)
s = seg(up, (ulong)addr, 0);
if(s == nil || (s->type&SG_RONLY) != 0 || (ulong)addr+sizeof(long) > s->top){
validaddr((ulong)addr, sizeof(long), 1);
error(Ebadarg);
}
/* delta == 0 is a no-op, not a release */
if(delta < 0 || *addr < 0)
error(Ebadarg);