[PATCH] ARM: 2698/1: Enable kernel r/w access to user pages on ARMv6

Patch from Catalin Marinas

cpu_v6_set_pte() sets the kernel access rights to r/o for user
pages (L_PTE_USER) when neither L_PTE_WRITE nor L_PTE_DIRTY are
set. This causes a kernel data abort when writing the TLS value
in the 0xffff0000 page. This patch enables the kernel r/w access.

Signed-off-by: Catalin Marinas
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mm/proc-v6.S

@@ -132,8 +132,8 @@ ENTRY(cpu_v6_switch_mm)
  *	  100x   1   0   1	r/o	no acc
  *	  10x0   1   0   1	r/o	no acc
  *	  1011   0   0   1	r/w	no acc
- *	  110x   1   1   0	r/o	r/o
- *	  11x0   1   1   0	r/o	r/o
+ *	  110x   0   1   0	r/w	r/o
+ *	  11x0   0   1   0	r/w	r/o
  *	  1111   0   1   1	r/w	r/w
  */
 ENTRY(cpu_v6_set_pte)
@@ -150,7 +150,7 @@ ENTRY(cpu_v6_set_pte)
 	tst	r1, #L_PTE_USER
 	orrne	r2, r2, #AP1 | nG
 	tstne	r2, #APX
-	eorne	r2, r2, #AP0
+	bicne	r2, r2, #APX | AP0
 
 	tst	r1, #L_PTE_YOUNG
 	biceq	r2, r2, #APX | AP1 | AP0