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Date: Wed, 12 Mar 2008 03:53:29 +0100 (CET)
From: Andi Kleen <andi@...stfloor.org>
To: andreas.herrmann3@....com, tglx@...utronix.de, mingo@...e.hu,
linux-kernel@...r.kernel.org
Subject: [PATCH] [3/7] Add set_memory_4k to pageattr.c
Add a new function to force split large pages into 4k pages.
This is needed for some followup optimizations.
I had to add a new field to cpa_data to pass down the information
that try_preserve_large_page should not run.
Right now no set_page_4k() because I didn't need it and all the
specialized users I have in mind would be more comfortable with
pure addresses. I also didn't export it because it's unlikely
external code needs it.
Signed-off-by: Andi Kleen <ak@...e.de>
Index: linux/arch/x86/mm/pageattr.c
===================================================================
--- linux.orig/arch/x86/mm/pageattr.c
+++ linux/arch/x86/mm/pageattr.c
@@ -28,6 +28,7 @@ struct cpa_data {
int numpages;
int flushtlb;
unsigned long pfn;
+ unsigned force_split : 1;
};
#ifdef CONFIG_X86_64
@@ -259,6 +260,9 @@ try_preserve_large_page(pte_t *kpte, uns
int i, do_split = 1;
unsigned int level;
+ if (cpa->force_split)
+ return 1;
+
spin_lock_irqsave(&pgd_lock, flags);
/*
* Check for races, another CPU might have split this page
@@ -693,7 +697,8 @@ static inline int cache_attr(pgprot_t at
}
static int change_page_attr_set_clr(unsigned long addr, int numpages,
- pgprot_t mask_set, pgprot_t mask_clr)
+ pgprot_t mask_set, pgprot_t mask_clr,
+ int force_split)
{
struct cpa_data cpa;
int ret, cache, checkalias;
@@ -704,7 +709,7 @@ static int change_page_attr_set_clr(unsi
*/
mask_set = canon_pgprot(mask_set);
mask_clr = canon_pgprot(mask_clr);
- if (!pgprot_val(mask_set) && !pgprot_val(mask_clr))
+ if (!pgprot_val(mask_set) && !pgprot_val(mask_clr) && !force_split)
return 0;
/* Ensure we are PAGE_SIZE aligned */
@@ -721,6 +726,7 @@ static int change_page_attr_set_clr(unsi
cpa.mask_set = mask_set;
cpa.mask_clr = mask_clr;
cpa.flushtlb = 0;
+ cpa.force_split = force_split;
/* No alias checking for _NX bit modifications */
checkalias = (pgprot_val(mask_set) | pgprot_val(mask_clr)) != _PAGE_NX;
@@ -759,13 +765,13 @@ out:
static inline int change_page_attr_set(unsigned long addr, int numpages,
pgprot_t mask)
{
- return change_page_attr_set_clr(addr, numpages, mask, __pgprot(0));
+ return change_page_attr_set_clr(addr, numpages, mask, __pgprot(0), 0);
}
static inline int change_page_attr_clear(unsigned long addr, int numpages,
pgprot_t mask)
{
- return change_page_attr_set_clr(addr, numpages, __pgprot(0), mask);
+ return change_page_attr_set_clr(addr, numpages, __pgprot(0), mask, 0);
}
int set_memory_uc(unsigned long addr, int numpages)
@@ -809,6 +815,12 @@ int set_memory_np(unsigned long addr, in
return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_PRESENT));
}
+int set_memory_4k(unsigned long addr, int numpages)
+{
+ return change_page_attr_set_clr(addr, numpages, __pgprot(0),
+ __pgprot(0), 1);
+}
+
int set_pages_uc(struct page *page, int numpages)
{
unsigned long addr = (unsigned long)page_address(page);
Index: linux/include/asm-x86/cacheflush.h
===================================================================
--- linux.orig/include/asm-x86/cacheflush.h
+++ linux/include/asm-x86/cacheflush.h
@@ -41,6 +41,7 @@ int set_memory_nx(unsigned long addr, in
int set_memory_ro(unsigned long addr, int numpages);
int set_memory_rw(unsigned long addr, int numpages);
int set_memory_np(unsigned long addr, int numpages);
+int set_memory_4k(unsigned long addr, int numpages);
void clflush_cache_range(void *addr, unsigned int size);
--
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