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amd64: For non-PTI mode, do not initialize PCPU kcr3 to KPML4phys.

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Non-PTI mode does not switch kcr3, which means that kcr3 is almost
always stale.  This is important for the NMI handler, which reloads
%cr3 with PCPU(kcr3) if the value is different from PMAP_NO_CR3.

The end result is that curpmap in NMI handler does not match the page
table loaded into hardware.  The manifestation was copyin(9) looping
forever when a usermode access page fault cannot be resolved by
vm_fault() updating a different page table.

Reported by:	mmacy
Reviewed by:	markj
Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Approved by:	re (gjb)
This commit is contained in:
Konstantin Belousov 2018-09-04 19:26:54 +00:00
parent 316086bd6c
commit e21c5abc2a
1 changed files with 7 additions and 3 deletions
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10
sys/amd64/amd64/pmap.c
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@ -7582,9 +7582,13 @@ pmap_activate_boot(pmap_t pmap)
CPU_SET(cpuid, &pmap->pm_active);
#endif
PCPU_SET(curpmap, pmap);
kcr3 = pmap->pm_cr3;
if (pmap_pcid_enabled)
kcr3 |= pmap->pm_pcids[cpuid].pm_pcid | CR3_PCID_SAVE;
if (pti) {
kcr3 = pmap->pm_cr3;
if (pmap_pcid_enabled)
kcr3 |= pmap->pm_pcids[cpuid].pm_pcid | CR3_PCID_SAVE;
} else {
kcr3 = PMAP_NO_CR3;
}
PCPU_SET(kcr3, kcr3);
PCPU_SET(ucr3, PMAP_NO_CR3);
}