[Blackfin] arch: fix bug - when using trace buffer with CONFIG_MPU enabled.
There were a couple of problems with the way the trace buffer state
is saved/restored in assembly. The DEBUG_HWTRACE_SAVE/RESTORE macros
save a value to the stack, which is not immediately obvious; the CPLB
exception code needed changes to load the correct value of the stack
pointer. The other problem is that the SAVE/RESTORE macros weren't
pushing and popping the value downwards on the stack, but rather moving
it _upwards_, which is of course completely broken.
We also need to make sure there's a matching DEBUG_HWTRACE_RESTORE in
the error case of the CPLB handler.
Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
diff --git a/arch/blackfin/mach-common/entry.S b/arch/blackfin/mach-common/entry.S
index cee54ce..a504c65 100644
--- a/arch/blackfin/mach-common/entry.S
+++ b/arch/blackfin/mach-common/entry.S
@@ -121,10 +121,14 @@
(R7:6,P5:4) = [sp++];
ASTAT = [sp++];
SAVE_ALL_SYS
- DEBUG_HWTRACE_SAVE(p5, r7)
#ifdef CONFIG_MPU
+ /* 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;
@@ -191,6 +195,7 @@
ENDPROC(_bfin_return_from_exception)
ENTRY(_handle_bad_cplb)
+ DEBUG_HWTRACE_RESTORE(p5, r7)
/* To get here, we just tried and failed to change a CPLB
* so, handle things in trap_c (C code), by lowering to
* IRQ5, just like we normally do. Since this is not a