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- Make pmap_emulate_reference() MP and preemption safe. Previously, it

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contained "sanity" checks that could be violated if another CPU modified
   the pmap between the emulation trap and locking the pmap in
   pmap_emulate_reference().  As a result, the pte could be inconsistent
   with the access that caused the emulation trap.  In such cases,
   pmap_emulate_reference() now flushes the current CPU's TLB entry and
   returns.
 - Make pmap_changebit() an inline function, reducing object code size.
This commit is contained in:
alc 2004-08-15 20:54:25 +00:00
parent f00617cc7c
commit 9c821fd980
1 changed files with 20 additions and 30 deletions
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50
sys/alpha/alpha/pmap.c
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@ -2173,7 +2173,7 @@ pmap_remove_pages(pmap, sva, eva)
/*
* this routine is used to modify bits in ptes
*/
static void
static __inline void
pmap_changebit(vm_page_t m, int bit, boolean_t setem)
{
pv_entry_t pv;
@ -2410,7 +2410,7 @@ void
pmap_emulate_reference(struct vmspace *vm, vm_offset_t v, int user, int write)
{
pmap_t pmap;
pt_entry_t faultoff, *pte;
pt_entry_t *pte;
/*
* Convert process and virtual address to physical address.
@ -2427,32 +2427,15 @@ pmap_emulate_reference(struct vmspace *vm, vm_offset_t v, int user, int write)
PMAP_LOCK(pmap);
pte = pmap_lev3pte(pmap, v);
}
#ifdef DEBUG /* These checks are more expensive */
if (!pmap_pte_v(pte))
panic("pmap_emulate_reference: invalid pte");
#if 0
/*
* Can't do these, because cpu_fork and cpu_swapin call
* pmap_emulate_reference(), and the bits aren't guaranteed,
* for them...
* Another CPU can modify the pmap between the emulation trap and this
* CPU locking the pmap. As a result, the pte may be inconsistent
* with the access that caused the emulation trap. In such cases,
* invalidate this CPU's TLB entry and return.
*/
if (write) {
if (!(*pte & (user ? PG_UWE : PG_UWE | PG_KWE)))
panic("pmap_emulate_reference: write but unwritable");
if (!(*pte & PG_FOW))
panic("pmap_emulate_reference: write but not FOW");
} else {
if (!(*pte & (user ? PG_URE : PG_URE | PG_KRE)))
panic("pmap_emulate_reference: !write but unreadable");
if (!(*pte & (PG_FOR | PG_FOE)))
panic("pmap_emulate_reference: !write but not FOR|FOE");
}
#endif
/* Other diagnostics? */
#endif
KASSERT((*pte & PG_MANAGED) != 0,
("pmap_emulate_reference(%p, 0x%lx, %d, %d): pa 0x%lx not managed",
curthread, v, user, write, pmap_pte_pa(pte)));
if (!pmap_pte_v(pte))
goto tbis;
/*
* Twiddle the appropriate bits to reflect the reference
@ -2463,12 +2446,19 @@ pmap_emulate_reference(struct vmspace *vm, vm_offset_t v, int user, int write)
* (2) if it was a write fault, mark page as modified.
*/
if (write) {
faultoff = PG_FOR | PG_FOE | PG_FOW;
if (!(*pte & (user ? PG_UWE : PG_UWE | PG_KWE)))
goto tbis;
if (!(*pte & PG_FOW))
goto tbis;
*pte &= ~(PG_FOR | PG_FOE | PG_FOW);
} else {
faultoff = PG_FOR | PG_FOE;
if (!(*pte & (user ? PG_URE : PG_URE | PG_KRE)))
goto tbis;
if (!(*pte & (PG_FOR | PG_FOE)))
goto tbis;
*pte &= ~(PG_FOR | PG_FOE);
}
*pte = (*pte & ~faultoff);
tbis:
ALPHA_TBIS(v);
PMAP_UNLOCK(pmap);
}