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Code Issues Releases Activity

Simplify and clean up pmap_clearbit()

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There is no need for calling vm_page_dirty() when clearing "modified" flag as
it is already set for that page in pmap_fault_fixup() or pmap_enter() thanks
to "modified" bit emulation.

Also, there is no need for checking PTE "referenced" or "writeable" flags.  If
there is a request to clear a particular flag we should just do it.

Submitted by:	Zbigniew Bodek <zbb@semihalf.com>
Reviewed by:	gber
Sponsored by:	The FreeBSD Foundation, Semihalf
This commit is contained in:
Rafal Jaworowski 2013-08-19 15:58:39 +00:00
parent 1662b00871
commit ec34d19b9d
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=254535
1 changed files with 2 additions and 7 deletions
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9
sys/arm/arm/pmap-v6.c
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@ -900,9 +900,6 @@ pmap_clearbit(struct vm_page *m, u_int maskbits)
rw_wlock(&pvh_global_lock);
if (maskbits & PVF_WRITE)
maskbits |= PVF_MOD;
if (TAILQ_EMPTY(&m->md.pv_list)) {
rw_wunlock(&pvh_global_lock);
return (0);
@ -924,14 +921,12 @@ pmap_clearbit(struct vm_page *m, u_int maskbits)
ptep = &l2b->l2b_kva[l2pte_index(va)];
npte = opte = *ptep;
if ((maskbits & (PVF_WRITE|PVF_MOD)) && L2_S_WRITABLE(opte)) {
vm_page_dirty(m);
if (maskbits & (PVF_WRITE | PVF_MOD)) {
/* make the pte read only */
npte |= L2_APX;
}
if ((maskbits & PVF_REF) && L2_S_REFERENCED(opte)) {
if (maskbits & PVF_REF) {
/*
* Clear referenced flag in PTE so that we
* will take a flag fault the next time the mapping