arm64: gdb(4) machine-dependent bits

Everything required for remote kernel debugging over a serial
connection. For FDT-based systems, a debug port can be specified by
setting hw.fdt.dbgport to the desired device tree node in loader.conf.
For example, hw.fdt.dbgport="uart1", or
hw.fdt.dbgport="serial@ff1a0000".

Looks good:	emaste
Tested by:	rwatson
MFC after:	2 weeks
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D27727

1 files changed, 81 insertions, 0 deletions

diff --git a/sys/arm64/include/gdb_machdep.h b/sys/arm64/include/gdb_machdep.h
new file mode 100644
index 000000000000..755c5d1657c0
--- /dev/null
+++ b/sys/arm64/include/gdb_machdep.h
@@ -0,0 +1,81 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2020 The FreeBSD Foundation
+ *
+ * This software was developed by Mitchell Horne under sponsorship from
+ * the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#ifndef _MACHINE_GDB_MACHDEP_H_
+#define	_MACHINE_GDB_MACHDEP_H_
+
+#define	GDB_BUFSZ	4096
+#define	GDB_NREGS	68
+#define	GDB_REG_X0	0
+#define	GDB_REG_X29	29
+#define	GDB_REG_LR	30
+#define	GDB_REG_SP	31
+#define	GDB_REG_PC	32
+#define	GDB_REG_CSPR	33
+#define	GDB_REG_V0	34
+#define	GDB_REG_V31	65
+#define	GDB_REG_FPSR	66
+#define	GDB_REG_FPCR	67
+_Static_assert(GDB_BUFSZ >= (GDB_NREGS * 16), "buffer fits 'g' regs");
+
+static __inline size_t
+gdb_cpu_regsz(int regnum)
+{
+	if (regnum == GDB_REG_CSPR || regnum == GDB_REG_FPSR ||
+	    regnum == GDB_REG_FPCR)
+		return (4);
+	else if (regnum >= GDB_REG_V0 && regnum <= GDB_REG_V31)
+		return (16);
+
+	return (8);
+}
+
+static __inline int
+gdb_cpu_query(void)
+{
+	return (0);
+}
+
+static __inline void *
+gdb_begin_write(void)
+{
+	return (NULL);
+}
+
+static __inline void
+gdb_end_write(void *arg __unused)
+{
+}
+
+void *gdb_cpu_getreg(int, size_t *);
+void gdb_cpu_setreg(int, void *);
+int gdb_cpu_signal(int, int);
+
+#endif /* !_MACHINE_GDB_MACHDEP_H_ */