From: kfraser@localhost.localdomain <kfraser@localhost.localdomain>
Date: Mon, 13 Nov 2006 13:37:54 +0000 (+0000)
Subject: [LINUX] Fix clear_fixmap().
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~15551^2~10
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=8f3784dc2b4aee97736a38c504d89da16e1db41f;p=xen.git

[LINUX] Fix clear_fixmap().

On i386-PAE, clear_fixmap() results in ill use of set_pte(). In all
contexts, p2m translations shouldn't occur here. Note that this is not
really an issue on native linux, as there is
(a) no pfn-to-mfn translation and
(b) __set_fixmap() takes an unsigned long physical address rather than
    a paddr_t, which makes it so that bits 32 and up of the physical
    address are always zero, permitting either order store when
    clearing the entry.

Signed-off-by: Jan Beulich <jbeulich@novell.com>
---

diff --git a/linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c b/linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c
index d843538917..0ff01f52f8 100644
--- a/linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c
+++ b/linux-2.6-xen-sparse/arch/i386/mm/pgtable-xen.c
@@ -102,8 +102,11 @@ static void set_pte_pfn(unsigned long vaddr, unsigned long pfn, pgprot_t flags)
 		return;
 	}
 	pte = pte_offset_kernel(pmd, vaddr);
-	/* <pfn,flags> stored as-is, to permit clearing entries */
-	set_pte(pte, pfn_pte(pfn, flags));
+	if (pgprot_val(flags))
+		/* <pfn,flags> stored as-is, to permit clearing entries */
+		set_pte(pte, pfn_pte(pfn, flags));
+	else
+		pte_clear(&init_mm, vaddr, pte);
 
 	/*
 	 * It's enough to flush this one mapping.
@@ -140,8 +143,11 @@ static void set_pte_pfn_ma(unsigned long vaddr, unsigned long pfn,
 		return;
 	}
 	pte = pte_offset_kernel(pmd, vaddr);
-	/* <pfn,flags> stored as-is, to permit clearing entries */
-	set_pte(pte, pfn_pte_ma(pfn, flags));
+	if (pgprot_val(flags))
+		/* <pfn,flags> stored as-is, to permit clearing entries */
+		set_pte(pte, pfn_pte_ma(pfn, flags));
+	else
+		pte_clear(&init_mm, vaddr, pte);
 
 	/*
 	 * It's enough to flush this one mapping.
diff --git a/linux-2.6-xen-sparse/arch/x86_64/mm/init-xen.c b/linux-2.6-xen-sparse/arch/x86_64/mm/init-xen.c
index 61c75c08a6..455b20b47e 100644
--- a/linux-2.6-xen-sparse/arch/x86_64/mm/init-xen.c
+++ b/linux-2.6-xen-sparse/arch/x86_64/mm/init-xen.c
@@ -260,7 +260,10 @@ static void set_pte_phys(unsigned long vaddr,
 			return;
 		}
 	}
-	new_pte = pfn_pte(phys >> PAGE_SHIFT, prot);
+	if (pgprot_val(prot))
+		new_pte = pfn_pte(phys >> PAGE_SHIFT, prot);
+	else
+		new_pte = __pte(0);
 
 	pte = pte_offset_kernel(pmd, vaddr);
 	if (!pte_none(*pte) &&