From: "Eugene (jno) Dvurechenski" <j...@linux.vnet.ibm.com>
We need to interpret the last entry of the bootmap with zero
block count as "continuation pointer".
The "last entry" is being detected by pre-filling of the scratch
space with known values and respective look-ahead.
Signed-off-by: Eugene (jno) Dvurechenski <j...@linux.vnet.ibm.com>
Signed-off-by: Jens Freimann <jf...@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntrae...@de.ibm.com>
Reviewed-by: David Hildenbrand <d...@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.h...@de.ibm.com>
Reviewed-by: Alexander Graf <ag...@suse.de>
Signed-off-by: Cornelia Huck <cornelia.h...@de.ibm.com>
---
pc-bios/s390-ccw/bootmap.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index c07553b..5ee3fcb 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -118,10 +118,26 @@ static int zipl_magic(uint8_t *ptr)
return 1;
}
+#define FREE_SPACE_FILLER '\xAA'
+
+static inline bool unused_space(const void *p, unsigned int size)
+{
+ int i;
+ const unsigned char *m = p;
+
+ for (i = 0; i < size; i++) {
+ if (m[i] != FREE_SPACE_FILLER) {
+ return false;
+ }
+ }
+ return true;
+}
+
static int zipl_load_segment(struct component_entry *entry)
{
const int max_entries = (SECTOR_SIZE / sizeof(struct scsi_blockptr));
struct scsi_blockptr *bprs = (void*)sec;
+ const int bprs_size = sizeof(sec);
uint64_t blockno;
long address;
int i;
@@ -133,6 +149,7 @@ static int zipl_load_segment(struct component_entry *entry)
debug_print_int("addr", address);
do {
+ memset(bprs, FREE_SPACE_FILLER, bprs_size);
if (virtio_read(blockno, (uint8_t *)bprs)) {
debug_print_int("failed reading bprs at", blockno);
goto fail;
@@ -150,6 +167,16 @@ static int zipl_load_segment(struct component_entry *entry)
if (i == (max_entries - 1))
break;
+ if (bprs[i].blockct == 0 && unused_space(&bprs[i + 1],
+ sizeof(struct scsi_blockptr))) {
+ /* This is a "continue" pointer.
+ * This ptr is the last one in the current script section.
+ * I.e. the next ptr must point to the unused memory area.
+ * The blockno is not zero, so the upper loop must continue
+ * reading next section of BPRS.
+ */
+ break;
+ }
address = virtio_load_direct(cur_desc[0], cur_desc[1], 0,
(void*)address);
if (address == -1)
--
1.7.9.5
