[Blackfin] arch: fix bug - a crash on bootup with CONFIG_MPU on the BF548
The function flush_switched_dcplbs was clearing the CPLB entries covering
the process permission bitmasks. This means that the sequence
flush_switched_dcplbs ();
set_mask_dcplbs(mm->context.page_rwx_mask);
has a problem: if kernel code (such as an interrupt) causes a CPLB miss before
set_mask_dcplbs completes, the CPLB handler function causes a double fault,
with an instantaneous reboot.
This bug fix is dedicated to Michael Hennerich, the only person in the world
capable of providing working JTAG hardware.
Signed-off-by: Bernd Schmidt <bernds_cb1@t-online.de>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
diff --git a/arch/blackfin/kernel/cplb-mpu/cplbmgr.c b/arch/blackfin/kernel/cplb-mpu/cplbmgr.c
index 6f1c053..f23bba5 100644
--- a/arch/blackfin/kernel/cplb-mpu/cplbmgr.c
+++ b/arch/blackfin/kernel/cplb-mpu/cplbmgr.c
@@ -307,7 +307,7 @@
enable_icplb();
disable_dcplb();
- for (i = first_mask_dcplb; i < MAX_CPLBS; i++) {
+ for (i = first_switched_dcplb; i < MAX_CPLBS; i++) {
dcplb_tbl[i].data = 0;
bfin_write32(DCPLB_DATA0 + i * 4, 0);
}