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

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Date:	Thu, 01 Jul 2010 10:42:51 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Li Yang <leoli@...escale.com>, Jin Qing <b24347@...escale.com>,
	Kumar Gala <galak@...nel.crashing.org>
Subject: [081/200] powerpc/fsl-booke: Fix InstructionTLBError execute permission check

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

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

From: Li Yang <leoli@...escale.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@...escale.com>
Signed-off-by: Jin Qing <b24347@...escale.com>
Signed-off-by: Kumar Gala <galak@...nel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.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 */
 


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