Attachment 299460 Details for Bug 437412 – Fix xen mprotect(PROT_NONE) handling on ioremap()ed memory

[patch] Fix xen mprotect(PROT_NONE) handling on ioremap()ed memory

linux-2.6-xen-fix-ioremap-mprotect.patch (text/plain), 9.82 KB, created by Stephen Tweedie on 2008-03-28 13:08:48 UTC

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Creator: Stephen Tweedie

Created: 2008-03-28 13:08:48 UTC

Size: 9.82 KB

patch

obsolete

>commit dd649b84b42b60261c093f7d74065378cf49c273
>Author: Stephen Tweedie <sct@redhat.com>
>Date:   Thu Mar 27 21:35:20 2008 +0000
>
>    Xen: Fix mprotect on ioremaped regions.
>    
>    Fixes bug 437412: system crashes when X starts.
>    
>    This patch fixes a regression caused by patch
>    linux-2.6-xen-save-restore-pv-oops-when-mmap-prot_none.patch.
>    
>    When Xen PV guests migrate, the HV updates the hardware frame numbers
>    in all valid ptes automatically to reflect the layout of the guest on
>    the new host.  But it skips over ptes which are not marked as present.
>    
>    On Linux x86, the mmu has no way to make a present page unreadable,
>    so to implement PROT_NONE, the mmu clears the present bit.  This
>    prevents the hypervisor from translating the ptes correctly on migrate,
>    which leaves the ptes pointing to the wrong page on the new host.
>    
>    The above patch fixed this by storing the hardware frame numbers
>    for PROT_NONE pages as guest-relative pseudopage frame references
>    instead.  Unfortunately, that breaks mprotect(PROT_NONE) on
>    ioremap()ed memory regions, which do not have any guest-relative
>    frame numbers --- such pages are always specific to the host.
>    
>    Fix this by introducing a new pte flag, _PAGE_IO, for ioremap()ed
>    pages and exempting such ptes from PROT_NONE translation.
>    
>    Based on upstream linux-2.6.18-xen.hg changesets 488 and 492:
>    
>      xen, x86: Track foreign and I/O mappings with a new pte flag, and do
>      not subject such ptes to conversions to/from pseudophysical addresses.
>    
>    and
>    
>      xen, i386: Fix non-PAE build failure.
>    
>    but modified on x86_64 to use the second os-available pte bit, 0x400
>    instead of 0x200, for _PAGE_IO --- the bit used upstream is already used
>    for _PAGE_SOFTDIRTY in the non-upstream RHEL-specific patch,
>    linux-2.6-x86_64-dirty-page-tracking.patch.
>    
>    Signed-off-by: Stephen Tweedie <sct@redhat.com>
>
>diff --git a/arch/i386/mm/ioremap-xen.c b/arch/i386/mm/ioremap-xen.c
>index b9d379a..5f69a4c 100644
>--- a/arch/i386/mm/ioremap-xen.c
>+++ b/arch/i386/mm/ioremap-xen.c
>@@ -76,7 +76,7 @@ static int __direct_remap_pfn_range(struct mm_struct *mm,
> 		 * Fill in the machine address: PTE ptr is done later by
> 		 * apply_to_page_range(). 
> 		 */
>-		v->val = pte_val_ma(pfn_pte_ma(mfn, prot));
>+		v->val = pte_val_ma(pfn_pte_ma(mfn, prot)) | _PAGE_IO;
> 
> 		mfn++;
> 		address += PAGE_SIZE; 
>diff --git a/include/asm-i386/mach-xen/asm/page.h b/include/asm-i386/mach-xen/asm/page.h
>index b16b28b..4756ccc 100644
>--- a/include/asm-i386/mach-xen/asm/page.h
>+++ b/include/asm-i386/mach-xen/asm/page.h
>@@ -36,6 +36,7 @@
>  * below. The preprocessor will warn if the two definitions aren't identical.
>  */
> #define _PAGE_PRESENT	0x001
>+#define _PAGE_IO	0x200
> 
> #define arch_free_page(_page,_order)			\
> ({	int foreign = PageForeign(_page);		\
>@@ -88,8 +89,9 @@ typedef struct { unsigned long long pgd; } pgd_t;
> typedef struct { unsigned long long pgprot; } pgprot_t;
> #define pgprot_val(x)	((x).pgprot)
> #include <asm/maddr.h>
>-#define __pte(x) ({ unsigned long long _x = (x);        \
>-    if (_x & _PAGE_PRESENT) _x = pte_phys_to_machine(_x);   \
>+#define __pte(x) ({ unsigned long long _x = (x);			\
>+    if ((_x & (_PAGE_PRESENT|_PAGE_IO)) == _PAGE_PRESENT)		\
>+        _x = pte_phys_to_machine(_x);					\
>     ((pte_t) {(unsigned long)(_x), (unsigned long)(_x>>32)}); })
> #define __pgd(x) ({ unsigned long long _x = (x); \
>     (pgd_t) {((_x) & _PAGE_PRESENT) ? pte_phys_to_machine(_x) : (_x)}; })
>@@ -103,7 +105,8 @@ static inline unsigned long long pte_val_ma(pte_t x)
> static inline unsigned long long pte_val(pte_t x)
> {
> 	unsigned long long ret = pte_val_ma(x);
>-	if (x.pte_low & _PAGE_PRESENT) ret = pte_machine_to_phys(ret);
>+	if ((x.pte_low & (_PAGE_PRESENT|_PAGE_IO)) == _PAGE_PRESENT)
>+		ret = pte_machine_to_phys(ret);
> 	return ret;
> }
> static inline unsigned long long pmd_val(pmd_t x)
>@@ -130,13 +133,16 @@ typedef struct { unsigned long pgprot; } pgprot_t;
> #define pgprot_val(x)	((x).pgprot)
> #include <asm/maddr.h>
> #define boot_pte_t pte_t /* or would you rather have a typedef */
>-#define pte_val(x)	(((x).pte_low & _PAGE_PRESENT) ? \
>-			 machine_to_phys((x).pte_low) : \
>+#define pte_val(x)	((((x).pte_low & (_PAGE_PRESENT|_PAGE_IO)) \
>+			 == _PAGE_PRESENT) ?			   \
>+			 machine_to_phys((x).pte_low) :		   \
> 			 (x).pte_low)
> #define pte_val_ma(x)	((x).pte_low)
> #define __pte_val(x)	pte_val_ma(x)
>-#define __pte(x) ({ unsigned long _x = (x); \
>-    (pte_t) {((_x) & _PAGE_PRESENT) ? phys_to_machine(_x) : (_x)}; })
>+#define __pte(x) ({ unsigned long _x = (x);			\
>+    if ((_x & (_PAGE_PRESENT|_PAGE_IO)) == _PAGE_PRESENT)	\
>+        _x = phys_to_machine(_x);				\
>+    ((pte_t) { _x }); })
> #define __pgd(x) ({ unsigned long _x = (x); \
>     (pgd_t) {((_x) & _PAGE_PRESENT) ? phys_to_machine(_x) : (_x)}; })
> static inline unsigned long pgd_val(pgd_t x)
>diff --git a/include/asm-i386/mach-xen/asm/pgtable-2level.h b/include/asm-i386/mach-xen/asm/pgtable-2level.h
>index f7250a3..2694758 100644
>--- a/include/asm-i386/mach-xen/asm/pgtable-2level.h
>+++ b/include/asm-i386/mach-xen/asm/pgtable-2level.h
>@@ -41,8 +41,10 @@
> #define __pte_mfn(_pte) ((_pte).pte_low >> PAGE_SHIFT)
> #define pte_mfn(_pte) ((_pte).pte_low & _PAGE_PRESENT ? \
> 	__pte_mfn(_pte) : pfn_to_mfn(__pte_mfn(_pte)))
>-#define pte_pfn(_pte) ((_pte).pte_low & _PAGE_PRESENT ? \
>-	mfn_to_local_pfn(__pte_mfn(_pte)) : __pte_mfn(_pte))
>+#define pte_pfn(_pte) ((_pte).pte_low & _PAGE_IO ? max_mapnr :	\
>+		       (_pte).pte_low & _PAGE_PRESENT ?		\
>+		       mfn_to_local_pfn(__pte_mfn(_pte)) :	\
>+		       __pte_mfn(_pte))
> 
> #define pte_page(_pte) pfn_to_page(pte_pfn(_pte))
> 
>diff --git a/include/asm-i386/mach-xen/asm/pgtable-3level.h b/include/asm-i386/mach-xen/asm/pgtable-3level.h
>index 8747c52..84f787f 100644
>--- a/include/asm-i386/mach-xen/asm/pgtable-3level.h
>+++ b/include/asm-i386/mach-xen/asm/pgtable-3level.h
>@@ -149,8 +149,10 @@ static inline int pte_none(pte_t pte)
> 			 ((_pte).pte_high << (32-PAGE_SHIFT)))
> #define pte_mfn(_pte) ((_pte).pte_low & _PAGE_PRESENT ? \
> 	__pte_mfn(_pte) : pfn_to_mfn(__pte_mfn(_pte)))
>-#define pte_pfn(_pte) ((_pte).pte_low & _PAGE_PRESENT ? \
>-	mfn_to_local_pfn(__pte_mfn(_pte)) : __pte_mfn(_pte))
>+#define pte_pfn(_pte) ((_pte).pte_low & _PAGE_IO ? max_mapnr :	\
>+		       (_pte).pte_low & _PAGE_PRESENT ?		\
>+		       mfn_to_local_pfn(__pte_mfn(_pte)) :	\
>+		       __pte_mfn(_pte))
> 
> extern unsigned long long __supported_pte_mask;
> 
>diff --git a/include/asm-i386/mach-xen/asm/pgtable.h b/include/asm-i386/mach-xen/asm/pgtable.h
>index 8e03275..05b6e71 100644
>--- a/include/asm-i386/mach-xen/asm/pgtable.h
>+++ b/include/asm-i386/mach-xen/asm/pgtable.h
>@@ -130,9 +130,12 @@ void paging_init(void);
> #define _PAGE_NX	0
> #endif
> 
>+/* Mapped page is I/O or foreign and has no associated page struct. */
>+#define _PAGE_IO	0x200
>+
> #define _PAGE_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_DIRTY)
> #define _KERNPG_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
>-#define _PAGE_CHG_MASK	(PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY)
>+#define _PAGE_CHG_MASK	(PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_IO)
> 
> #define PAGE_NONE \
> 	__pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
>diff --git a/include/asm-x86_64/mach-xen/asm/page.h b/include/asm-x86_64/mach-xen/asm/page.h
>index 50ad81d..084a3bc 100644
>--- a/include/asm-x86_64/mach-xen/asm/page.h
>+++ b/include/asm-x86_64/mach-xen/asm/page.h
>@@ -18,6 +18,7 @@
>  * below. The preprocessor will warn if the two definitions aren't identical.
>  */
> #define _PAGE_PRESENT	0x001
>+#define _PAGE_IO	0x400
> 
> #define arch_free_page(_page,_order)			\
> ({	int foreign = PageForeign(_page);		\
>@@ -101,8 +102,9 @@ typedef struct { unsigned long pgd; } pgd_t;
> 
> typedef struct { unsigned long pgprot; } pgprot_t;
> 
>-#define pte_val(x)	(((x).pte & _PAGE_PRESENT) ? \
>-			 pte_machine_to_phys((x).pte) : \
>+#define pte_val(x)	((((x).pte & (_PAGE_PRESENT|_PAGE_IO)) \
>+			  == _PAGE_PRESENT) ?		       \
>+			 pte_machine_to_phys((x).pte) :	       \
> 			 (x).pte)
> #define pte_val_ma(x)	((x).pte)
> 
>@@ -135,7 +137,8 @@ static inline unsigned long pgd_val(pgd_t x)
> 
> static inline pte_t __pte(unsigned long x)
> {
>-	if (x & _PAGE_PRESENT) x = pte_phys_to_machine(x);
>+	if ((x & (_PAGE_PRESENT|_PAGE_IO)) == _PAGE_PRESENT)
>+		x = pte_phys_to_machine(x);
> 	return ((pte_t) { (x) });
> }
> 
>diff --git a/include/asm-x86_64/mach-xen/asm/pgtable.h b/include/asm-x86_64/mach-xen/asm/pgtable.h
>index c740ff9..e35ffe3 100644
>--- a/include/asm-x86_64/mach-xen/asm/pgtable.h
>+++ b/include/asm-x86_64/mach-xen/asm/pgtable.h
>@@ -229,10 +229,13 @@ static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, unsigned long
> #define _PAGE_PROTNONE	0x080	/* If not present */
> #define _PAGE_NX        (_AC(1,UL)<<_PAGE_BIT_NX)
> 
>+/* Mapped page is I/O or foreign and has no associated page struct. */
>+#define _PAGE_IO	0x400
>+
> #define _PAGE_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_DIRTY)
> #define _KERNPG_TABLE	(_PAGE_PRESENT | _PAGE_RW | _PAGE_ACCESSED | _PAGE_DIRTY)
> 
>-#define _PAGE_CHG_MASK	(PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_SOFTDIRTY)
>+#define _PAGE_CHG_MASK	(PTE_MASK | _PAGE_ACCESSED | _PAGE_DIRTY | _PAGE_SOFTDIRTY | _PAGE_IO)
> 
> #define PAGE_NONE	__pgprot(_PAGE_PROTNONE | _PAGE_ACCESSED)
> #define PAGE_SHARED	__pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_USER | _PAGE_ACCESSED | _PAGE_NX)
>@@ -325,8 +328,10 @@ static inline unsigned long pud_bad(pud_t pud)
> #define __pte_mfn(_pte) (((_pte).pte & PTE_MASK) >> PAGE_SHIFT)
> #define pte_mfn(_pte) ((_pte).pte & _PAGE_PRESENT ? \
> 	__pte_mfn(_pte) : pfn_to_mfn(__pte_mfn(_pte)))
>-#define pte_pfn(_pte) ((_pte).pte & _PAGE_PRESENT ? \
>-	mfn_to_local_pfn(__pte_mfn(_pte)) : __pte_mfn(_pte))
>+#define pte_pfn(_pte) ((_pte).pte & _PAGE_IO ? end_pfn :	\
>+		       (_pte).pte & _PAGE_PRESENT ?		\
>+		       mfn_to_local_pfn(__pte_mfn(_pte)) :	\
>+		       __pte_mfn(_pte))
> 
> #define pte_page(x)	pfn_to_page(pte_pfn(x))
>

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Attachments on bug 437412: 297993 | 298069 | 299460