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u3: updates memory protections and page metadata when moving guard page

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This commit is contained in:
Joe Bryan 2022-11-30 18:24:21 -05:00
parent dac240bdfa
commit 7ca9ebaa4d
1 changed files with 20 additions and 1 deletions
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21
pkg/urbit/noun/events.c
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@ -1240,8 +1240,27 @@ void
u3e_ward(u3_post low_p, u3_post hig_p)
{
#ifdef U3_GUARD_PAGE
if ( (low_p > gar_pag_p) || (hig_p < gar_pag_p) ) {
const u3p(c3_w) gar_p = gar_pag_p;
if ( (low_p > gar_p) || (hig_p < gar_p) ) {
_ce_center_guard_page();
if ( 0 != mprotect(u3a_into(gar_p),
pag_siz_i,
(PROT_READ | PROT_WRITE)) )
{
fprintf(stderr, "loom: failed to unprotect old guard page: %s\r\n",
strerror(errno));
c3_assert(0);
}
{
c3_w pag_w = gar_p >> u3a_page;
c3_w blk_w = (pag_w >> 5);
c3_w bit_w = (pag_w & 31);
u3P.dit_w[blk_w] |= (1 << bit_w);
}
}
#endif
}