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authorJeremy Fitzhardinge <jeremy@goop.org>2008-01-30 13:34:11 +0100
committerIngo Molnar <mingo@elte.hu>2008-01-30 13:34:11 +0100
commit6194ba6ff6ccf8d5c54c857600843c67aa82c407 (patch)
tree657dd9f452b252260fcf59959c0586920b8fe4c3 /arch/x86/mm/pgtable_32.c
parentfd40d6e3188b12c59696d6cb4a6f26333814d66f (diff)
downloadop-kernel-dev-6194ba6ff6ccf8d5c54c857600843c67aa82c407.zip
op-kernel-dev-6194ba6ff6ccf8d5c54c857600843c67aa82c407.tar.gz
x86: don't special-case pmd allocations as much
In x86 PAE mode, stop treating pmds as a special case. Previously they were always allocated and freed with the pgd. The modifies the code to be the same as 64-bit mode, where they are allocated on demand. This is a step on the way to unifying 32/64-bit pagetable allocation as much as possible. There is a complicating wart, however. When you install a new reference to a pmd in the pgd, the processor isn't guaranteed to see it unless you reload cr3. Since reloading cr3 also has the side-effect of flushing the tlb, this is an expense that we want to avoid whereever possible. This patch simply avoids reloading cr3 unless the update is to the current pagetable. Later patches will optimise this further. Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Andi Kleen <ak@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: William Irwin <wli@holomorphy.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'arch/x86/mm/pgtable_32.c')
-rw-r--r--arch/x86/mm/pgtable_32.c68
1 files changed, 0 insertions, 68 deletions
diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
index 3a6c920..5ca3552 100644
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -195,11 +195,6 @@ struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
return pte;
}
-void pmd_ctor(struct kmem_cache *cache, void *pmd)
-{
- memset(pmd, 0, PTRS_PER_PMD*sizeof(pmd_t));
-}
-
/*
* List of all pgd's needed for non-PAE so it can invalidate entries
* in both cached and uncached pgd's; not needed for PAE since the
@@ -285,7 +280,6 @@ static void pgd_dtor(void *pgd)
if (SHARED_KERNEL_PMD)
return;
- paravirt_release_pd(__pa(pgd) >> PAGE_SHIFT);
spin_lock_irqsave(&pgd_lock, flags);
pgd_list_del(pgd);
spin_unlock_irqrestore(&pgd_lock, flags);
@@ -367,84 +361,22 @@ static void pgd_mop_up_pmds(pgd_t *pgd)
}
#endif /* CONFIG_X86_PAE */
-/* If we allocate a pmd for part of the kernel address space, then
- make sure its initialized with the appropriate kernel mappings.
- Otherwise use a cached zeroed pmd. */
-static pmd_t *pmd_cache_alloc(int idx)
-{
- pmd_t *pmd;
-
- if (idx >= USER_PTRS_PER_PGD) {
- pmd = (pmd_t *)__get_free_page(GFP_KERNEL);
-
- if (pmd)
- memcpy(pmd,
- (void *)pgd_page_vaddr(swapper_pg_dir[idx]),
- sizeof(pmd_t) * PTRS_PER_PMD);
- } else
- pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
-
- return pmd;
-}
-
-static void pmd_cache_free(pmd_t *pmd, int idx)
-{
- if (idx >= USER_PTRS_PER_PGD)
- free_page((unsigned long)pmd);
- else
- kmem_cache_free(pmd_cache, pmd);
-}
-
pgd_t *pgd_alloc(struct mm_struct *mm)
{
- int i;
pgd_t *pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
- if (PTRS_PER_PMD == 1 || !pgd)
- return pgd;
-
mm->pgd = pgd; /* so that alloc_pd can use it */
- for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
- pmd_t *pmd = pmd_cache_alloc(i);
-
- if (!pmd)
- goto out_oom;
-
- paravirt_alloc_pd(mm, __pa(pmd) >> PAGE_SHIFT);
- set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
- }
if (pgd && !pgd_prepopulate_pmd(mm, pgd)) {
quicklist_free(0, pgd_dtor, pgd);
pgd = NULL;
}
return pgd;
-
-out_oom:
- for (i--; i >= 0; i--) {
- pgd_t pgdent = pgd[i];
- void* pmd = (void *)__va(pgd_val(pgdent)-1);
- paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
- pmd_cache_free(pmd, i);
- }
- quicklist_free(0, pgd_dtor, pgd);
- return NULL;
}
void pgd_free(pgd_t *pgd)
{
- int i;
-
- /* in the PAE case user pgd entries are overwritten before usage */
- if (PTRS_PER_PMD > 1)
- for (i = 0; i < UNSHARED_PTRS_PER_PGD; ++i) {
- pgd_t pgdent = pgd[i];
- void* pmd = (void *)__va(pgd_val(pgdent)-1);
- paravirt_release_pd(__pa(pmd) >> PAGE_SHIFT);
- pmd_cache_free(pmd, i);
- }
- /* in the non-PAE case, free_pgtables() clears user pgd entries */
pgd_mop_up_pmds(pgd);
quicklist_free(0, pgd_dtor, pgd);
}
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