ARM: 7649/1: mm: mm->context.id fix for big-endian
Since the new ASID code in b5466f8728527a05a493cc4abe9e6f034a1bbaab
("ARM: mm: remove IPI broadcasting on ASID rollover") was changed to
use 64bit operations it has broken the BE operation due to an issue
with the MM code accessing sub-fields of mm->context.id.
When running in BE mode we see the values in mm->context.id are stored
with the highest value first, so the LDR in the arch/arm/mm/proc-macros.S
reads the wrong part of this field. To resolve this, change the LDR in
the mmid macro to load from +4.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Ben Dooks <ben.dooks@codethink.co.uk>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
diff --git a/arch/arm/mm/context.c b/arch/arm/mm/context.c
index bc4a5e9..7a05111 100644
--- a/arch/arm/mm/context.c
+++ b/arch/arm/mm/context.c
@@ -34,6 +34,9 @@
* The ASID is used to tag entries in the CPU caches and TLBs.
* The context ID is used by debuggers and trace logic, and
* should be unique within all running processes.
+ *
+ * In big endian operation, the two 32 bit words are swapped if accesed by
+ * non 64-bit operations.
*/
#define ASID_FIRST_VERSION (1ULL << ASID_BITS)
#define NUM_USER_ASIDS (ASID_FIRST_VERSION - 1)
diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S
index eb6aa73..f9a0aa7 100644
--- a/arch/arm/mm/proc-macros.S
+++ b/arch/arm/mm/proc-macros.S
@@ -38,9 +38,14 @@
/*
* mmid - get context id from mm pointer (mm->context.id)
+ * note, this field is 64bit, so in big-endian the two words are swapped too.
*/
.macro mmid, rd, rn
+#ifdef __ARMEB__
+ ldr \rd, [\rn, #MM_CONTEXT_ID + 4 ]
+#else
ldr \rd, [\rn, #MM_CONTEXT_ID]
+#endif
.endm
/*