From: Maxim Samoylov <max7...@linux.vnet.ibm.com>
Boot entry is considered compatible if boot image is Linux kernel
with matching S390 Linux magic string.
Empty boot images with sector_count == 0 are considered broken.
Signed-off-by: Maxim Samoylov <max7...@linux.vnet.ibm.com>
Reviewed-by: David Hildenbrand <d...@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.h...@de.ibm.com>
---
pc-bios/s390-ccw/bootmap.c | 11 ++++++++++-
pc-bios/s390-ccw/bootmap.h | 8 ++++++++
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 7c8dce1..82cca9c 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -450,7 +450,16 @@ static void ipl_scsi(void)
static bool is_iso_bc_entry_compatible(IsoBcSection *s)
{
- return true;
+ uint8_t *magic_sec = (uint8_t *)(sec + ISO_SECTOR_SIZE);
+
+ if (s->unused || !s->sector_count) {
+ return false;
+ }
+ read_iso_sector(bswap32(s->load_rba), magic_sec,
+ "Failed to read image sector 0");
+
+ /* Checking bytes 8 - 32 for S390 Linux magic */
+ return !_memcmp(magic_sec + 8, linux_s390_magic, 24);
}
static void load_iso_bc_entry(IsoBcSection *load)
diff --git a/pc-bios/s390-ccw/bootmap.h b/pc-bios/s390-ccw/bootmap.h
index 4f6f767..cc77fd7 100644
--- a/pc-bios/s390-ccw/bootmap.h
+++ b/pc-bios/s390-ccw/bootmap.h
@@ -495,6 +495,14 @@ typedef struct IsoBcHdr {
uint8_t id[28];
} __attribute__((packed)) IsoBcHdr;
+/*
+ * Match two CCWs located after PSW and eight filler bytes.
+ * From libmagic and arch/s390/kernel/head.S.
+ */
+const uint8_t linux_s390_magic[] = "\x02\x00\x00\x18\x60\x00\x00\x50\x02\x00"
+ "\x00\x68\x60\x00\x00\x50\x40\x40\x40\x40"
+ "\x40\x40\x40\x40";
+
typedef struct IsoBcEntry {
uint8_t id;
union {
--
2.6.3
