powerpc ioremap_prot

This adds ioremap_prot and pte_pgprot() so that one can extract protection
bits from a PTE and use them to ioremap_prot() (in order to support ptrace
of VM_IO | VM_PFNMAP as per Rik's patch).

This moves a couple of flag checks around in the ioremap implementations
of arch/powerpc.  There's a side effect of allowing non-cacheable and
non-guarded mappings on ppc32 which before would always have _PAGE_GUARDED
set whenever _PAGE_NO_CACHE is.

(standard ioremap will still set _PAGE_GUARDED, but ioremap_prot will be
capable of setting such a non guarded mapping).

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Dave Airlie <airlied@linux.ie>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 33 insertions, 6 deletions

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 4d7e2ba10ba..a487671c282 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -111,6 +111,7 @@ config PPC
 	select HAVE_DYNAMIC_FTRACE
 	select HAVE_FTRACE
 	select HAVE_IDE
+	select HAVE_IOREMAP_PROT
 	select HAVE_KPROBES
 	select HAVE_ARCH_KGDB
 	select HAVE_KRETPROBES
diff --git a/arch/powerpc/mm/pgtable_32.c b/arch/powerpc/mm/pgtable_32.c
index c7584072dfc..2001abdb191 100644
--- a/arch/powerpc/mm/pgtable_32.c
+++ b/arch/powerpc/mm/pgtable_32.c
@@ -145,13 +145,20 @@ void pte_free(struct mm_struct *mm, pgtable_t ptepage)
 void __iomem *
 ioremap(phys_addr_t addr, unsigned long size)
 {
-	return __ioremap(addr, size, _PAGE_NO_CACHE);
+	return __ioremap(addr, size, _PAGE_NO_CACHE | _PAGE_GUARDED);
 }
 EXPORT_SYMBOL(ioremap);
 
 void __iomem *
 ioremap_flags(phys_addr_t addr, unsigned long size, unsigned long flags)
 {
+	/* writeable implies dirty for kernel addresses */
+	if (flags & _PAGE_RW)
+		flags |= _PAGE_DIRTY | _PAGE_HWWRITE;
+
+	/* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
+	flags &= ~(_PAGE_USER | _PAGE_EXEC | _PAGE_HWEXEC);
+
 	return __ioremap(addr, size, flags);
 }
 EXPORT_SYMBOL(ioremap_flags);
@@ -163,6 +170,14 @@ __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
 	phys_addr_t p;
 	int err;
 
+	/* Make sure we have the base flags */
+	if ((flags & _PAGE_PRESENT) == 0)
+		flags |= _PAGE_KERNEL;
+
+	/* Non-cacheable page cannot be coherent */
+	if (flags & _PAGE_NO_CACHE)
+		flags &= ~_PAGE_COHERENT;
+
 	/*
 	 * Choose an address to map it to.
 	 * Once the vmalloc system is running, we use it.
@@ -219,11 +234,6 @@ __ioremap(phys_addr_t addr, unsigned long size, unsigned long flags)
 		v = (ioremap_bot -= size);
 	}
 
-	if ((flags & _PAGE_PRESENT) == 0)
-		flags |= _PAGE_KERNEL;
-	if (flags & _PAGE_NO_CACHE)
-		flags |= _PAGE_GUARDED;
-
 	/*
 	 * Should check if it is a candidate for a BAT mapping
 	 */
diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c
index 3ef0ad2f9ca..365e61ae5db 100644
--- a/arch/powerpc/mm/pgtable_64.c
+++ b/arch/powerpc/mm/pgtable_64.c
@@ -107,9 +107,18 @@ void __iomem * __ioremap_at(phys_addr_t pa, void *ea, unsigned long size,
 {
 	unsigned long i;
 
+	/* Make sure we have the base flags */
 	if ((flags & _PAGE_PRESENT) == 0)
 		flags |= pgprot_val(PAGE_KERNEL);
 
+	/* Non-cacheable page cannot be coherent */
+	if (flags & _PAGE_NO_CACHE)
+		flags &= ~_PAGE_COHERENT;
+
+	/* We don't support the 4K PFN hack with ioremap */
+	if (flags & _PAGE_4K_PFN)
+		return NULL;
+
 	WARN_ON(pa & ~PAGE_MASK);
 	WARN_ON(((unsigned long)ea) & ~PAGE_MASK);
 	WARN_ON(size & ~PAGE_MASK);
@@ -190,6 +199,13 @@ void __iomem * ioremap(phys_addr_t addr, unsigned long size)
 void __iomem * ioremap_flags(phys_addr_t addr, unsigned long size,
 			     unsigned long flags)
 {
+	/* writeable implies dirty for kernel addresses */
+	if (flags & _PAGE_RW)
+		flags |= _PAGE_DIRTY;
+
+	/* we don't want to let _PAGE_USER and _PAGE_EXEC leak out */
+	flags &= ~(_PAGE_USER | _PAGE_EXEC);
+
 	if (ppc_md.ioremap)
 		return ppc_md.ioremap(addr, size, flags);
 	return __ioremap(addr, size, flags);