--- /dev/null
+/*
+ * S390 Basic Architecture
+ *
+ * Copyright (c) 2019 Jason J. Herne <jjherne@us.ibm.com>
+ *
+ * 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.
+ */
+
+#ifndef S390_ARCH_H
+#define S390_ARCH_H
+
+typedef struct PSW {
+ uint64_t mask;
+ uint64_t addr;
+} __attribute__ ((aligned(8))) PSW;
+_Static_assert(sizeof(struct PSW) == 16, "PSW size incorrect");
+
+/* Older PSW format used by LPSW instruction */
+typedef struct PSWLegacy {
+ uint32_t mask;
+ uint32_t addr;
+} __attribute__ ((aligned(8))) PSWLegacy;
+_Static_assert(sizeof(struct PSWLegacy) == 8, "PSWLegacy size incorrect");
+
+/* s390 psw bit masks */
+#define PSW_MASK_IOINT 0x0200000000000000ULL
+#define PSW_MASK_WAIT 0x0002000000000000ULL
+#define PSW_MASK_EAMODE 0x0000000100000000ULL
+#define PSW_MASK_BAMODE 0x0000000080000000ULL
+#define PSW_MASK_ZMODE (PSW_MASK_EAMODE | PSW_MASK_BAMODE)
+
+/* Low core mapping */
+typedef struct LowCore {
+ /* prefix area: defined by architecture */
+ PSWLegacy ipl_psw; /* 0x000 */
+ uint32_t ccw1[2]; /* 0x008 */
+ uint32_t ccw2[2]; /* 0x010 */
+ uint8_t pad1[0x80 - 0x18]; /* 0x018 */
+ uint32_t ext_params; /* 0x080 */
+ uint16_t cpu_addr; /* 0x084 */
+ uint16_t ext_int_code; /* 0x086 */
+ uint16_t svc_ilen; /* 0x088 */
+ uint16_t svc_code; /* 0x08a */
+ uint16_t pgm_ilen; /* 0x08c */
+ uint16_t pgm_code; /* 0x08e */
+ uint32_t data_exc_code; /* 0x090 */
+ uint16_t mon_class_num; /* 0x094 */
+ uint16_t per_perc_atmid; /* 0x096 */
+ uint64_t per_address; /* 0x098 */
+ uint8_t exc_access_id; /* 0x0a0 */
+ uint8_t per_access_id; /* 0x0a1 */
+ uint8_t op_access_id; /* 0x0a2 */
+ uint8_t ar_access_id; /* 0x0a3 */
+ uint8_t pad2[0xA8 - 0xA4]; /* 0x0a4 */
+ uint64_t trans_exc_code; /* 0x0a8 */
+ uint64_t monitor_code; /* 0x0b0 */
+ uint16_t subchannel_id; /* 0x0b8 */
+ uint16_t subchannel_nr; /* 0x0ba */
+ uint32_t io_int_parm; /* 0x0bc */
+ uint32_t io_int_word; /* 0x0c0 */
+ uint8_t pad3[0xc8 - 0xc4]; /* 0x0c4 */
+ uint32_t stfl_fac_list; /* 0x0c8 */
+ uint8_t pad4[0xe8 - 0xcc]; /* 0x0cc */
+ uint64_t mcic; /* 0x0e8 */
+ uint8_t pad5[0xf4 - 0xf0]; /* 0x0f0 */
+ uint32_t external_damage_code; /* 0x0f4 */
+ uint64_t failing_storage_address; /* 0x0f8 */
+ uint8_t pad6[0x110 - 0x100]; /* 0x100 */
+ uint64_t per_breaking_event_addr; /* 0x110 */
+ uint8_t pad7[0x120 - 0x118]; /* 0x118 */
+ PSW restart_old_psw; /* 0x120 */
+ PSW external_old_psw; /* 0x130 */
+ PSW svc_old_psw; /* 0x140 */
+ PSW program_old_psw; /* 0x150 */
+ PSW mcck_old_psw; /* 0x160 */
+ PSW io_old_psw; /* 0x170 */
+ uint8_t pad8[0x1a0 - 0x180]; /* 0x180 */
+ PSW restart_new_psw; /* 0x1a0 */
+ PSW external_new_psw; /* 0x1b0 */
+ PSW svc_new_psw; /* 0x1c0 */
+ PSW program_new_psw; /* 0x1d0 */
+ PSW mcck_new_psw; /* 0x1e0 */
+ PSW io_new_psw; /* 0x1f0 */
+} __attribute__((packed, aligned(8192))) LowCore;
+
+extern LowCore const *lowcore;
+
+#endif