[PARISC] only make executable areas executable

Currently parisc has the whole kernel marked as RWX, meaning any
kernel page at all is eligible to be executed.  This can cause a
theoretical problem on systems with combined I/D TLB because the act
of referencing a page causes a TLB insertion with an executable bit.
This TLB entry may be used by the CPU as the basis for speculating the
page into the I-Cache.  If this speculated page is subsequently used
for a user process, there is the possibility we will get a stale
I-cache line picked up as the binary executes.

As a point of good practise, only mark actual kernel text pages as
executable.  The same has to be done for init_text pages, but they're
converted to data pages (and the I-Cache flushed) when the init memory
is released.

Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 9 insertions, 1 deletions

diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
index 6e81bb596e5b..cedbbb8b18d9 100644
--- a/arch/parisc/kernel/module.c
+++ b/arch/parisc/kernel/module.c
@@ -61,8 +61,10 @@
 #include <linux/string.h>
 #include <linux/kernel.h>
 #include <linux/bug.h>
+#include <linux/mm.h>
 #include <linux/slab.h>
 
+#include <asm/pgtable.h>
 #include <asm/unwind.h>
 
 #if 0
@@ -214,7 +216,13 @@ void *module_alloc(unsigned long size)
 {
 	if (size == 0)
 		return NULL;
-	return vmalloc(size);
+	/* using RWX means less protection for modules, but it's
+	 * easier than trying to map the text, data, init_text and
+	 * init_data correctly */
+	return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
+				    GFP_KERNEL | __GFP_HIGHMEM,
+				    PAGE_KERNEL_RWX, -1,
+				    __builtin_return_address(0));
 }
 
 #ifndef CONFIG_64BIT