Re: [PATCH 1/5] Add pagetable allocation notifiers

[Chris Wright <chrisw@osdl.org>]

* Zachary Amsden (zach@vmware.com) wrote:
> --- linux-2.6.13.orig/arch/i386/mm/init.c	2005-08-24 09:31:05.000000000 -0700
> +++ linux-2.6.13/arch/i386/mm/init.c	2005-08-24 09:31:31.000000000 -0700
> @@ -79,6 +79,7 @@ static pte_t * __init one_page_table_ini
>  {
>  	if (pmd_none(*pmd)) {
>  		pte_t *page_table = (pte_t *) alloc_bootmem_low_pages(PAGE_SIZE);
> +		SetPagePTE(virt_to_page(page_table));

Xen has this on one_md_table_init() as well for pmd.

>  		set_pmd(pmd, __pmd(__pa(page_table) | _PAGE_TABLE));
>  		if (page_table != pte_offset_kernel(pmd, 0))
>  			BUG();	
> Index: linux-2.6.13/arch/i386/mm/pageattr.c
> ===================================================================
> --- linux-2.6.13.orig/arch/i386/mm/pageattr.c	2005-08-24 09:31:05.000000000 -0700
> +++ linux-2.6.13/arch/i386/mm/pageattr.c	2005-08-24 09:31:31.000000000 -0700
> @@ -52,8 +52,9 @@ static struct page *split_large_page(uns
>  	address = __pa(address);
>  	addr = address & LARGE_PAGE_MASK; 
>  	pbase = (pte_t *)page_address(base);
> +	SetPagePTE(virt_to_page(pbase));
>  	for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) {
> -               set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,
> +		set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT,

No need to intersperse whitespace cleanups.

>                                            addr == address ? prot : PAGE_KERNEL));
>  	}
>  	return base;
> @@ -146,6 +147,7 @@ __change_page_attr(struct page *page, pg
>  		BUG_ON(!page_count(kpte_page));
>  
>  		if (cpu_has_pse && (page_count(kpte_page) == 1)) {
> +			ClearPagePTE(virt_to_page(kpte));
>  			list_add(&kpte_page->lru, &df_list);
>  			revert_page(kpte_page, address);
>  		}
> Index: linux-2.6.13/arch/i386/mm/pgtable.c
> ===================================================================
> --- linux-2.6.13.orig/arch/i386/mm/pgtable.c	2005-08-24 09:31:05.000000000 -0700
> +++ linux-2.6.13/arch/i386/mm/pgtable.c	2005-08-24 09:40:22.000000000 -0700
> @@ -209,6 +209,7 @@ void pgd_ctor(void *pgd, kmem_cache_t *c
>  
>  	if (PTRS_PER_PMD == 1) {
>  		memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
> +		SetPagePDE(virt_to_page(pgd));
>  		spin_lock_irqsave(&pgd_lock, flags);
>  	}
>  
> @@ -227,6 +228,7 @@ void pgd_dtor(void *pgd, kmem_cache_t *c
>  {
>  	unsigned long flags; /* can be called from interrupt context */
>  
> +	ClearPagePDE(virt_to_page(pgd));

This reminds me, Xen had some unconditional use of pgd_dtor I need
to go back and look at.

>  	spin_lock_irqsave(&pgd_lock, flags);
>  	pgd_list_del(pgd);
>  	spin_unlock_irqrestore(&pgd_lock, flags);
> @@ -244,13 +246,16 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
>  		pmd_t *pmd = kmem_cache_alloc(pmd_cache, GFP_KERNEL);
>  		if (!pmd)
>  			goto out_oom;
> +		SetPagePDE(virt_to_page(pmd));
>  		set_pgd(&pgd[i], __pgd(1 + __pa(pmd)));
>  	}
>  	return pgd;
>  
>  out_oom:
> -	for (i--; i >= 0; i--)
> +	for (i--; i >= 0; i--) {
> +		ClearPagePDE(pfn_to_page(pgd_val(pgd[i]) >> PAGE_SHIFT));

Is that the right pfn?  That -1 throws me off.

>  		kmem_cache_free(pmd_cache, (void *)__va(pgd_val(pgd[i])-1));
> +	}
>  	kmem_cache_free(pgd_cache, pgd);
>  	return NULL;
>  }
> @@ -261,8 +266,10 @@ void pgd_free(pgd_t *pgd)
>  
>  	/* in the PAE case user pgd entries are overwritten before usage */
>  	if (PTRS_PER_PMD > 1)
> -		for (i = 0; i < USER_PTRS_PER_PGD; ++i)
> -			kmem_cache_free(pmd_cache, (void *)__va(pgd_val(pgd[i])-1));
> +		for (i = 0; i < USER_PTRS_PER_PGD; ++i) {
> +			ClearPagePDE(pfn_to_page(pgd_val(pgd[i]) >> PAGE_SHIFT));
> +			kmem_cache_free(pmd_cache, (void *)__va(pgd_val(pgd[i]) & PAGE_MASK));

Why the switch of kmem_cache_free call?

> +		}
>  	/* in the non-PAE case, free_pgtables() clears user pgd entries */
>  	kmem_cache_free(pgd_cache, pgd);
>  }
> Index: linux-2.6.13/include/asm-i386/pgalloc.h
> ===================================================================
> --- linux-2.6.13.orig/include/asm-i386/pgalloc.h	2005-08-24 09:31:05.000000000 -0700
> +++ linux-2.6.13/include/asm-i386/pgalloc.h	2005-08-24 09:34:17.000000000 -0700
> @@ -5,14 +5,22 @@
>  #include <asm/fixmap.h>
>  #include <linux/threads.h>
>  #include <linux/mm.h>		/* for struct page */
> +#include <mach_pgalloc.h>
>  
> -#define pmd_populate_kernel(mm, pmd, pte) \
> -		set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte)))
> +#define pmd_populate_kernel(mm, pmd, pte) 			\
> +do {								\
> +	SetPagePTE(virt_to_page(pte));				\
> +	set_pmd(pmd, __pmd(_PAGE_TABLE + __pa(pte)));		\
> +} while (0)
>  
>  #define pmd_populate(mm, pmd, pte) 				\
> +do {								\
> +	SetPagePTE(pte);					\
>  	set_pmd(pmd, __pmd(_PAGE_TABLE +			\
>  		((unsigned long long)page_to_pfn(pte) <<	\
> -			(unsigned long long) PAGE_SHIFT)))
> +			(unsigned long long) PAGE_SHIFT)));	\
> +} while (0)
> +
>  /*
>   * Allocate and free page tables.
>   */
> @@ -33,7 +41,11 @@ static inline void pte_free(struct page 
>  }
>  
>  
> -#define __pte_free_tlb(tlb,pte) tlb_remove_page((tlb),(pte))
> +#define __pte_free_tlb(tlb,pte) 		\
> +do {						\
> +	tlb_remove_page((tlb),(pte));		\
> +	ClearPagePTE(pte);			\
> +} while (0)
>  
>  #ifdef CONFIG_X86_PAE
>  /*
> Index: linux-2.6.13/include/asm-i386/mach-default/mach_pgalloc.h
> ===================================================================
> --- linux-2.6.13.orig/include/asm-i386/mach-default/mach_pgalloc.h	2005-08-24 09:31:05.000000000 -0700
> +++ linux-2.6.13/include/asm-i386/mach-default/mach_pgalloc.h	2005-08-24 09:31:31.000000000 -0700
> @@ -1,7 +1,40 @@
> +/*
> + * Copyright (C) 2005, VMware, Inc.
> + *
> + * All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
> + * NON INFRINGEMENT.  See the GNU General Public License for more
> + * details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + *
> + * Send feedback to zach@vmware.com
> + *
> + */
>  #ifndef __ASM_MACH_PGALLOC_H
>  #define __ASM_MACH_PGALLOC_H
>  
> +/*
> + * These hooks allow the hypervisor to be notified about page type
> + * transition events.
> + */
> +
> +#define SetPagePTE(_page)
> +#define ClearPagePTE(_page)
> +#define SetPagePDE(_page)
> +#define ClearPagePDE(_page)
> +
>  #define SetPagesLDT(_va, _pages)
>  #define ClearPagesLDT(_va, _pages)
>  
> -#endif
> +#endif /* _ASM_MACH_PGALLOC_H */