diff options
| author | Alan Cox <alc@FreeBSD.org> | 2003-10-13 03:28:31 +0000 |
|---|---|---|
| committer | Alan Cox <alc@FreeBSD.org> | 2003-10-13 03:28:31 +0000 |
| commit | 50ac3f993968514dce23433facb14591cd7bbb29 (patch) | |
| tree | 5c56abcbe24b6c939aae49507c8c4cf5b0c44b33 /sys | |
| parent | 0986ab12e44caea472245845f9a89ced4f137d73 (diff) | |
Notes
Diffstat (limited to 'sys')
| -rw-r--r-- | sys/i386/i386/pmap.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/sys/i386/i386/pmap.c b/sys/i386/i386/pmap.c index 3cd0bdd4dcf8..835b895ca552 100644 --- a/sys/i386/i386/pmap.c +++ b/sys/i386/i386/pmap.c @@ -739,13 +739,17 @@ pmap_invalidate_all(pmap_t pmap) #endif /* !I386_CPU */ /* - * Are we current address space or kernel? + * Are we current address space or kernel? N.B. We return FALSE when + * a pmap's page table is in use because a kernel thread is borrowing + * it. The borrowed page table can change spontaneously, making any + * dependence on its continued use subject to a race condition. */ -static __inline int +static int pmap_is_current(pmap_t pmap) { return (pmap == kernel_pmap || - (pmap->pm_pdir[PTDPTDI] & PG_FRAME) == (PTDpde[0] & PG_FRAME)); + (pmap == vmspace_pmap(curthread->td_proc->p_vmspace) && + (pmap->pm_pdir[PTDPTDI] & PG_FRAME) == (PTDpde[0] & PG_FRAME))); } /* @@ -958,7 +962,11 @@ _pmap_unwire_pte_hold(pmap_t pmap, vm_page_t m) */ pmap->pm_pdir[m->pindex] = 0; --pmap->pm_stats.resident_count; - if (pmap_is_current(pmap)) { + /* + * We never unwire a kernel page table page, making a + * check for the kernel_pmap unnecessary. + */ + if ((pmap->pm_pdir[PTDPTDI] & PG_FRAME) == (PTDpde[0] & PG_FRAME)) { /* * Do an invltlb to make the invalidated mapping * take effect immediately. |