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>

1 files changed, 9 insertions, 12 deletions

diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index 0efd5f5b7ba0..fae774651374 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -112,24 +112,21 @@ ENTRY(_ex_dcplb_viol)
 ENTRY(_ex_dcplb_miss)
 ENTRY(_ex_icplb_miss)
         (R7:6,P5:4) = [sp++];
-        ASTAT = [sp++];
-        SAVE_ALL_SYS
-#ifdef CONFIG_MPU
+        /* We leave the previously pushed ASTAT on the stack.  */
+        SAVE_CONTEXT_CPLB
+
         /* We must load R1 here, _before_ DEBUG_HWTRACE_SAVE, since that
          * will change the stack pointer.  */
         R0 = SEQSTAT;
         R1 = SP;
-#endif
+
         DEBUG_HWTRACE_SAVE(p5, r7)
-#ifdef CONFIG_MPU
+
         sp += -12;
         call _cplb_hdr;
         sp += 12;
         CC = R0 == 0;
         IF !CC JUMP _handle_bad_cplb;
-#else
-        call __cplb_hdr;
-#endif
 
 #ifdef CONFIG_DEBUG_DOUBLEFAULT
         /* While we were processing this, did we double fault? */
@@ -143,7 +140,8 @@ ENTRY(_ex_icplb_miss)
 #endif
 
         DEBUG_HWTRACE_RESTORE(p5, r7)
-        RESTORE_ALL_SYS
+        RESTORE_CONTEXT_CPLB
+        ASTAT = [SP++];
         SP = EX_SCRATCH_REG;
         rtx;
 ENDPROC(_ex_icplb_miss)
@@ -298,9 +296,8 @@ ENTRY(_handle_bad_cplb)
          * the stack to get ready so, we can fall through - we
          * need to make a CPLB exception look like a normal exception
          */
-
-        RESTORE_ALL_SYS
-        [--sp] = ASTAT;
+        RESTORE_CONTEXT_CPLB
+        /* ASTAT is still on the stack, where it is needed.  */
         [--sp] = (R7:6,P5:4);
 
 ENTRY(_ex_replaceable)