Blackfin arch: Faster C implementation of no-MPU CPLB handler

This is a mixture ofcMichael McTernan's patch and the existing cplb-mpu code.

We ditch the old cplb-nompu implementation, which is a good example of
why a good algorithm in a HLL is preferrable to a bad algorithm written in
assembly.  Rather than try to construct a table of all posible CPLBs and
search it, we just create a (smaller) table of memory regions and
their attributes.  Some of the data structures are now unified for both
the mpu and nompu cases.  A lot of needless complexity in cplbinit.c is
removed.

Further optimizations:
  * compile cplbmgr.c with a lot of -ffixed-reg options, and omit saving
    these registers on the stack when entering a CPLB exception.
  * lose cli/nop/nop/sti sequences for some workarounds - these don't
  * make
    sense in an exception context

Additional code unification should be possible after this.

[Mike Frysinger <vapier.adi@gmail.com>:
 - convert CPP if statements to C if statements
 - remove redundant statements
 - use a do...while loop rather than a for loop to get slightly better
   optimization and to avoid gcc "may be used uninitialized" warnings ...
   we know that the [id]cplb_nr_bounds variables will never be 0, so this
   is OK
 - the no-mpu code was the last user of MAX_MEM_SIZE and with that rewritten,
   we can punt it
 - add some BUG_ON() checks to make sure we dont overflow the small
   cplb_bounds array
 - add i/d cplb entries for the bootrom because there is functions/data in
   there we want to access
 - we do not need a NULL trailing entry as any time we access the bounds
   arrays, we use the nr_bounds variable
]

Signed-off-by: Michael McTernan <mmcternan@airvana.com>
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

3 files changed, 16 insertions, 2 deletions

diff --git a/arch/blackfin/kernel/cplb-mpu/Makefile b/arch/blackfin/kernel/cplb-mpu/Makefile
index bd92301a704b..7d70d3bf3212 100644
--- a/arch/blackfin/kernel/cplb-mpu/Makefile
+++ b/arch/blackfin/kernel/cplb-mpu/Makefile
@@ -3,3 +3,8 @@
 #
 
 obj-y := cplbinit.o cacheinit.o cplbmgr.o
+
+CFLAGS_cplbmgr.o := -ffixed-I0 -ffixed-I1 -ffixed-I2 -ffixed-I3 \
+                    -ffixed-L0 -ffixed-L1 -ffixed-L2 -ffixed-L3 \
+                    -ffixed-M0 -ffixed-M1 -ffixed-M2 -ffixed-M3 \
+                    -ffixed-B0 -ffixed-B1 -ffixed-B2 -ffixed-B3
diff --git a/arch/blackfin/kernel/cplb-mpu/cplbinit.c b/arch/blackfin/kernel/cplb-mpu/cplbinit.c
index 1ea7c18435ae..bdb958486e76 100644
--- a/arch/blackfin/kernel/cplb-mpu/cplbinit.c
+++ b/arch/blackfin/kernel/cplb-mpu/cplbinit.c
@@ -107,3 +107,7 @@ void __init generate_cplb_tables_cpu(unsigned int cpu)
         while (i_i < MAX_CPLBS)
                 icplb_tbl[cpu][i_i++].data = 0;
 }
+
+void generate_cplb_tables_all(void)
+{
+}
diff --git a/arch/blackfin/kernel/cplb-mpu/cplbmgr.c b/arch/blackfin/kernel/cplb-mpu/cplbmgr.c
index 76bd99177de5..5ef5d1a787fc 100644
--- a/arch/blackfin/kernel/cplb-mpu/cplbmgr.c
+++ b/arch/blackfin/kernel/cplb-mpu/cplbmgr.c
@@ -25,8 +25,13 @@
 #include <asm/cplbinit.h>
 #include <asm/mmu_context.h>
 
-#define FAULT_RW        (1 << 16)
-#define FAULT_USERSUPV  (1 << 17)
+/*
+ * WARNING
+ *
+ * This file is compiled with certain -ffixed-reg options.  We have to
+ * make sure not to call any functions here that could clobber these
+ * registers.
+ */
 
 int page_mask_nelts;
 int page_mask_order;