Date: Sat, 19 Nov 2005 05:06:32 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/amd64/amd64 pmap.c Message-ID: <200511190506.jAJ56WD5072539@repoman.freebsd.org>
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alc 2005-11-19 05:06:32 UTC
FreeBSD src repository
Modified files: (Branch: RELENG_6)
sys/amd64/amd64 pmap.c
Log:
MFC revision 1.517
When support for 2MB/4MB pages was added in revision 1.148 an error was
made in pmap_protect(): The pmap's resident count should not be reduced
unless mappings are removed.
The errant change to the pmap's resident count could result in a later
pmap_remove() failing to remove any mappings if the errant change has set
the pmap's resident count to zero.
MFC revision 1.518
Decouple the unrefing of a page table page from the removal of a pv entry.
In other words, change pmap_remove_entry() such that it no longer unrefs
the page table page. Now, it only removes the pv entry.
MFC revision 1.519
Eliminate unneeded diagnostic code.
MFC revision 1.520
Eliminate unneeded diagnostic code.
Eliminate an unused #include. (Kernel stack allocation and deallocation
long ago migrated to the machine-independent code.)
MFC revision 1.521
Simplify the page table page reference counting by pmap_enter()'s change of
mapping case.
Eliminate a stale comment from pmap_enter().
MFC revision 1.522
Correct a performance bug in revision 1.462. The effect of the bug is to
execute the outer loop in procedures such as pmap_protect() many more times
than necessary.
MFC revision 1.523
Introduce pmap_pml4e_to_pdpe() and pmap_pdpe_to_pde() and use them to avoid
recomputation of the pml4e and pdpe in pmap_copy(), pmap_protect(), and
pmap_remove().
MFC revision 1.524
Change pmap_extract() and pmap_extract_and_hold() to use PG_FRAME rather
than ~PDRMASK to extract the physical address of a superpage from a PDE.
The use of ~PDRMASK is problematic if the PDE has PG_NX set. Specifically,
the PG_NX bit will be included in the physical address if ~PDRMASK is used.
MFC revision 1.525
Pass the PDE from pmap_remove() to pmap_remove_page() so that the latter
procedure doesn't have to recompute it.
MFC revision 1.526
Remedy the following three problems:
1. The amd64 pmap, unlike the i386 pmap, maintains a reference count
for each page directory (PD) page. However, in the transformation
of the i386 pmap into the amd64 pmap, operations, such as
pmap_copy() and pmap_object_init_pt(), that create 2MB "superpage"
mappings by setting the PG_PS bit in a PD entry were not modified
to adjust the underlying PD page's reference count. Consequently,
superpage mappings could disappear prematurely.
2. pmap_object_init_pt() could crash or corrupt memory if either the
virtual address range being mapped crosses a 1GB boundary in the
virtual address space or nothing is mapped in the 1GB area.
3. When pmap_allocpte() destroys a 2MB "superpage" mapping it does not
reduce the pmap's resident count accordingly. It should. (This
bug is inherited from i386.)
MFC revision 1.528
Eliminate unnecessary TLB invalidations by pmap_enter(). Specifically,
eliminate TLB invalidations when permissions are relaxed, such as when a
read-only mapping is changed to a read/write mapping. Additionally,
eliminate TLB invalidations when bits that are ignored by the hardware,
such as PG_W ("wired mapping"), are changed.
Revision Changes Path
1.516.2.3 +166 -117 src/sys/amd64/amd64/pmap.c
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