[081/200] powerpc/fsl-booke: Fix InstructionTLBError execute permission check

Greg KH
2010-07-01T21:16:11Z

2.6.34-stable review patch. If anyone has any objections, please let me know.

------------------

From: Li Yang <leoli@freescale.com>

commit 78e2e68a2b79f394b7cd61e07987a8a89af907f7 upstream.

In CONFIG_PTE_64BIT the PTE format has unique permission bits for user
and supervisor execute. However on !CONFIG_PTE_64BIT we overload the
supervisor bit to imply user execute with _PAGE_USER set. This allows
us to use the same permission check mask for user or supervisor code on
!CONFIG_PTE_64BIT.

However, on CONFIG_PTE_64BIT we map _PAGE_EXEC to _PAGE_BAP_UX so we
need a different permission mask based on the fault coming from a kernel
address or user space.

Without unique permission masks we see issues like the following with
modules:

Unable to handle kernel paging request for instruction fetch
Faulting instruction address: 0xf938d040
Oops: Kernel access of bad area, sig: 11 [#1]

Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Jin Qing <b24347@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
arch/powerpc/kernel/head_fsl_booke.S | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

--- a/arch/powerpc/kernel/head_fsl_booke.S
+++ b/arch/powerpc/kernel/head_fsl_booke.S
@@ -639,6 +639,13 @@ interrupt_base:
rlwinm r12,r12,0,16,1
mtspr SPRN_MAS1,r12

+ /* Make up the required permissions for kernel code */
+#ifdef CONFIG_PTE_64BIT
+ li r13,_PAGE_PRESENT | _PAGE_BAP_SX
+ oris r13,r13,_PAGE_ACCESSED@h
+#else
+ li r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
+#endif
b 4f

/* Get the PGD for the current thread */
@@ -646,15 +653,15 @@ interrupt_base:
mfspr r11,SPRN_SPRG_THREAD
lwz r11,PGDIR(r11)

-4:
- /* Make up the required permissions */
+ /* Make up the required permissions for user code */
#ifdef CONFIG_PTE_64BIT
- li r13,_PAGE_PRESENT | _PAGE_EXEC
+ li r13,_PAGE_PRESENT | _PAGE_BAP_UX
oris r13,r13,_PAGE_ACCESSED@h
#else
li r13,_PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_EXEC
#endif

+4:
FIND_PTE
andc. r13,r13,r11 /* Check permission */