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kernel: make segments non-executable when icache is not maintained

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This change makes it mandatory for programs to call segflush() on
code that is not in the text segment if they want to execute it.

As a side effect, this means that everything but the text segment
will be non-executable by default, even without the SG_NOEXEC
attribute. Segments with the SG_NOEXEC attribute never become
executable, even when segflush() is called on them.
This commit is contained in:
cinap_lenrek 2020-07-12 21:42:26 +02:00
parent 11fcf41472
commit 77ddc8c654
1 changed files with 5 additions and 3 deletions
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8
sys/src/9/port/fault.c
View file

@ -221,7 +221,7 @@ fixfault(Segment *s, uintptr addr, int read)
}
#ifdef PTENOEXEC
if((s->type & SG_NOEXEC) != 0)
if((s->type & SG_NOEXEC) != 0 || s->flushme == 0)
mmuphys |= PTENOEXEC;
#endif
@ -242,6 +242,8 @@ mapphys(Segment *s, uintptr addr, int attr)
pg.ref = 1;
pg.va = addr;
pg.pa = s->pseg->pa+(addr-s->base);
if(s->flushme)
pg.txtflush = ~0;
mmuphys = PPN(pg.pa) | PTEVALID;
if((attr & SG_RONLY) == 0)
@ -250,7 +252,7 @@ mapphys(Segment *s, uintptr addr, int attr)
mmuphys |= PTERONLY;
#ifdef PTENOEXEC
if((attr & SG_NOEXEC) != 0)
if((attr & SG_NOEXEC) != 0 || s->flushme == 0)
mmuphys |= PTENOEXEC;
#endif
@ -303,7 +305,7 @@ fault(uintptr addr, uintptr pc, int read)
attr |= s->pseg->attr;
if((attr & SG_FAULT) != 0
|| read? (attr & SG_NOEXEC) != 0 && (addr & -BY2PG) == (pc & -BY2PG):
|| read? ((attr & SG_NOEXEC) != 0 || s->flushme == 0) && (addr & -BY2PG) == (pc & -BY2PG):
(attr & SG_RONLY) != 0) {
qunlock(s);
up->psstate = sps;