1 files changed, 91 insertions, 0 deletions
diff --git a/pc-bios/s390-ccw/jump2ipl.c b/pc-bios/s390-ccw/jump2ipl.c
new file mode 100644
index 0000000000..266f1502b9
--- /dev/null
+++ b/pc-bios/s390-ccw/jump2ipl.c
@@ -0,0 +1,91 @@
+/*
+ * QEMU s390-ccw firmware - jump to IPL code
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#include "libc.h"
+#include "s390-ccw.h"
+
+#define KERN_IMAGE_START 0x010000UL
+#define PSW_MASK_64 0x0000000100000000ULL
+#define PSW_MASK_32 0x0000000080000000ULL
+#define IPL_PSW_MASK (PSW_MASK_32 | PSW_MASK_64)
+
+typedef struct ResetInfo {
+    uint32_t ipl_mask;
+    uint32_t ipl_addr;
+    uint32_t ipl_continue;
+} ResetInfo;
+
+static ResetInfo save;
+
+static void jump_to_IPL_2(void)
+{
+    ResetInfo *current = 0;
+
+    void (*ipl)(void) = (void *) (uint64_t) current->ipl_continue;
+    *current = save;
+    ipl(); /* should not return */
+}
+
+void jump_to_IPL_code(uint64_t address)
+{
+    /* store the subsystem information _after_ the bootmap was loaded */
+    write_subsystem_identification();
+
+    /* prevent unknown IPL types in the guest */
+    if (iplb.pbt == S390_IPL_TYPE_QEMU_SCSI) {
+        iplb.pbt = S390_IPL_TYPE_CCW;
+        set_iplb(&iplb);
+    }
+
+    /*
+     * The IPL PSW is at address 0. We also must not overwrite the
+     * content of non-BIOS memory after we loaded the guest, so we
+     * save the original content and restore it in jump_to_IPL_2.
+     */
+    ResetInfo *current = 0;
+
+    save = *current;
+    current->ipl_addr = (uint32_t) (uint64_t) &jump_to_IPL_2;
+    current->ipl_continue = address & 0x7fffffff;
+
+    debug_print_int("set IPL addr to", current->ipl_continue);
+
+    /* Ensure the guest output starts fresh */
+    sclp_print("\n");
+
+    /*
+     * HACK ALERT.
+     * We use the load normal reset to keep r15 unchanged. jump_to_IPL_2
+     * can then use r15 as its stack pointer.
+     */
+    asm volatile("lghi 1,1\n\t"
+                 "diag 1,1,0x308\n\t"
+                 : : : "1", "memory");
+    panic("\n! IPL returns !\n");
+}
+
+void jump_to_low_kernel(void)
+{
+    /*
+     * If it looks like a Linux binary, i.e. there is the "S390EP" magic from
+     * arch/s390/kernel/head.S here, then let's jump to the well-known Linux
+     * kernel start address (when jumping to the PSW-at-zero address instead,
+     * the kernel startup code fails when we booted from a network device).
+     */
+    if (!memcmp((char *)0x10008, "S390EP", 6)) {
+        jump_to_IPL_code(KERN_IMAGE_START);
+    }
+
+    /* Trying to get PSW at zero address */
+    if (*((uint64_t *)0) & IPL_PSW_MASK) {
+        jump_to_IPL_code((*((uint64_t *)0)) & 0x7fffffff);
+    }
+
+    /* No other option left, so use the Linux kernel start address */
+    jump_to_IPL_code(KERN_IMAGE_START);
+}