Blackfin arch: Fix bug - KGDB single step into the middle of a 4 bytes instruction on bf561 after soft bp is hit

Run IFLUSH twice to avoid loading wrong instruction
after invalidating icache and following sequence is met.

1) The one instruction address is cached in the icache.
2) This instruction in SDRAM is changed.
3) IFLASH[P0] is executed only once in lackfin_icache_flush_range().
4) This instruction is executed again, but not the changed new one.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/arch/blackfin/mach-common/cache.S b/arch/blackfin/mach-common/cache.S
index 3c98dacbf289..aa0648c6a9fe 100644
--- a/arch/blackfin/mach-common/cache.S
+++ b/arch/blackfin/mach-common/cache.S
@@ -66,11 +66,33 @@
 
 /* Invalidate all instruction cache lines assocoiated with this memory area */
 ENTRY(_blackfin_icache_flush_range)
+/*
+ * Walkaround to avoid loading wrong instruction after invalidating icache
+ * and following sequence is met.
+ *
+ * 1) One instruction address is cached in the instruction cache.
+ * 2) This instruction in SDRAM is changed.
+ * 3) IFLASH[P0] is executed only once in blackfin_icache_flush_range().
+ * 4) This instruction is executed again, but the old one is loaded.
+ */
+        P0 = R0;
+        IFLUSH[P0];
         do_flush IFLUSH, , nop
 ENDPROC(_blackfin_icache_flush_range)
 
 /* Flush all cache lines assocoiated with this area of memory. */
 ENTRY(_blackfin_icache_dcache_flush_range)
+/*
+ * Walkaround to avoid loading wrong instruction after invalidating icache
+ * and following sequence is met.
+ *
+ * 1) One instruction address is cached in the instruction cache.
+ * 2) This instruction in SDRAM is changed.
+ * 3) IFLASH[P0] is executed only once in blackfin_icache_flush_range().
+ * 4) This instruction is executed again, but the old one is loaded.
+ */
+        P0 = R0;
+        IFLUSH[P0];
         do_flush FLUSH, IFLUSH
 ENDPROC(_blackfin_icache_dcache_flush_range)