[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>
diff --git a/arch/parisc/kernel/head.S b/arch/parisc/kernel/head.S
index 145c5e4..37aabd7 100644
--- a/arch/parisc/kernel/head.S
+++ b/arch/parisc/kernel/head.S
@@ -106,8 +106,9 @@
#endif
- /* Now initialize the PTEs themselves */
- ldo 0+_PAGE_KERNEL(%r0),%r3 /* Hardwired 0 phys addr start */
+ /* Now initialize the PTEs themselves. We use RWX for
+ * everything ... it will get remapped correctly later */
+ ldo 0+_PAGE_KERNEL_RWX(%r0),%r3 /* Hardwired 0 phys addr start */
ldi (1<<(KERNEL_INITIAL_ORDER-PAGE_SHIFT)),%r11 /* PFN count */
load32 PA(pg0),%r1