git: d25147c01a20 - stable/13 - riscv: gdb(4) support

From: Mitchell Horne <mhorne_at_FreeBSD.org>
Date: Wed, 19 Jan 2022 18:31:26 UTC
The branch stable/13 has been updated by mhorne:

URL: https://cgit.FreeBSD.org/src/commit/?id=d25147c01a20f4c4ea7194b6f1df94dcc9aad38c

commit d25147c01a20f4c4ea7194b6f1df94dcc9aad38c
Author:     Mitchell Horne <mhorne@FreeBSD.org>
AuthorDate: 2020-09-11 17:02:17 +0000
Commit:     Mitchell Horne <mhorne@FreeBSD.org>
CommitDate: 2022-01-19 18:30:31 +0000

    riscv: gdb(4) support
    
    Add the MD portion required for the gdb stub.
    
    Reviewed by:    jhb (earlier version)
    Discussed with: jrtc27
    MFC after:      1 week
    Differential Revision:  https://reviews.freebsd.org/D33734
    
    (cherry picked from commit d72e944812f8774ab0b78fdff9b0204386dd6151)
---
 sys/conf/files.riscv            |   1 +
 sys/riscv/conf/NOTES            |   3 -
 sys/riscv/include/gdb_machdep.h |  88 ++++++++++++++++++++++++++
 sys/riscv/riscv/gdb_machdep.c   | 135 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 224 insertions(+), 3 deletions(-)

diff --git a/sys/conf/files.riscv b/sys/conf/files.riscv
index 1b03a8840109..37f4f203ab21 100644
--- a/sys/conf/files.riscv
+++ b/sys/conf/files.riscv
@@ -47,6 +47,7 @@ riscv/riscv/dump_machdep.c	standard
 riscv/riscv/elf_machdep.c	standard
 riscv/riscv/exception.S		standard
 riscv/riscv/exec_machdep.c	standard
+riscv/riscv/gdb_machdep.c	optional	gdb
 riscv/riscv/intr_machdep.c	standard
 riscv/riscv/identcpu.c		standard
 riscv/riscv/locore.S		standard	no-obj
diff --git a/sys/riscv/conf/NOTES b/sys/riscv/conf/NOTES
index 7dda89bfe1a8..1e4b8af1840e 100644
--- a/sys/riscv/conf/NOTES
+++ b/sys/riscv/conf/NOTES
@@ -90,9 +90,6 @@ nooptions 	COMPAT_FREEBSD9
 nooptions 	COMPAT_FREEBSD10
 nooptions 	COMPAT_FREEBSD11
 
-# No support for remote GDB
-nooptions 	GDB
-
 # riscv doesn't support inb/outb, so disable chipset probing which needs it
 nooptions 	PPC_PROBE_CHIPSET
 
diff --git a/sys/riscv/include/gdb_machdep.h b/sys/riscv/include/gdb_machdep.h
new file mode 100644
index 000000000000..422f57a5742b
--- /dev/null
+++ b/sys/riscv/include/gdb_machdep.h
@@ -0,0 +1,88 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2021 Mitchell Horne <mhorne@FreeBSD.org>
+ *
+ * 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		33
+#define	GDB_REG_ZERO		0
+#define	GDB_REG_RA		1
+#define	GDB_REG_SP		2
+#define	GDB_REG_GP		3
+#define	GDB_REG_TP		4
+#define	GDB_REG_T0		5
+#define	GDB_REG_FP		8
+#define	GDB_REG_S1		9
+#define	GDB_REG_A0		10
+#define	GDB_REG_S2		18
+#define	GDB_REG_T3		28
+#define	GDB_REG_PC		32
+#define	GDB_REG_CSR_BASE	65
+#define	GDB_REG_SSTATUS		(GDB_REG_CSR_BASE + 0x100)
+#define	GDB_REG_SCAUSE		(GDB_REG_CSR_BASE + 0x142)
+#define	GDB_REG_STVAL		(GDB_REG_CSR_BASE + 0x143)
+_Static_assert(GDB_BUFSZ >= (GDB_NREGS * 8), "buffer fits 'g' regs");
+
+static __inline size_t
+gdb_cpu_regsz(int regnum __unused)
+{
+
+	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)
+{
+
+}
+
+static __inline void
+gdb_cpu_stop_reason(int type __unused, int code __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_ */
diff --git a/sys/riscv/riscv/gdb_machdep.c b/sys/riscv/riscv/gdb_machdep.c
new file mode 100644
index 000000000000..06d4b8ba6e22
--- /dev/null
+++ b/sys/riscv/riscv/gdb_machdep.c
@@ -0,0 +1,135 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2021 Mitchell Horne <mhorne@FreeBSD.org>
+ *
+ * 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.
+ */
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/kdb.h>
+#include <sys/kernel.h>
+#include <sys/proc.h>
+#include <sys/signal.h>
+
+#include <machine/frame.h>
+#include <machine/gdb_machdep.h>
+#include <machine/pcb.h>
+#include <machine/riscvreg.h>
+
+#include <gdb/gdb.h>
+
+void *
+gdb_cpu_getreg(int regnum, size_t *regsz)
+{
+	*regsz = gdb_cpu_regsz(regnum);
+
+	if (kdb_thread == curthread) {
+		switch (regnum) {
+		case GDB_REG_RA:	return (&kdb_frame->tf_ra);
+		case GDB_REG_PC:	return (&kdb_frame->tf_sepc);
+		case GDB_REG_SSTATUS:	return (&kdb_frame->tf_sstatus);
+		case GDB_REG_STVAL:	return (&kdb_frame->tf_stval);
+		case GDB_REG_SCAUSE:	return (&kdb_frame->tf_scause);
+		default:
+			if (regnum >= GDB_REG_A0 && regnum < GDB_REG_S2)
+				return (&kdb_frame->tf_a[regnum - GDB_REG_A0]);
+			if (regnum >= GDB_REG_T0 && regnum < GDB_REG_FP)
+				return (&kdb_frame->tf_t[regnum - GDB_REG_T0]);
+			if (regnum >= GDB_REG_T3 && regnum < GDB_REG_PC)
+				return (&kdb_frame->tf_t[regnum - GDB_REG_T3]);
+			break;
+		}
+	}
+	switch (regnum) {
+	case GDB_REG_PC: /* FALLTHROUGH */
+	case GDB_REG_RA: return (&kdb_thrctx->pcb_ra);
+	case GDB_REG_SP: return (&kdb_thrctx->pcb_sp);
+	case GDB_REG_GP: return (&kdb_thrctx->pcb_gp);
+	case GDB_REG_TP: return (&kdb_thrctx->pcb_tp);
+	case GDB_REG_FP: return (&kdb_thrctx->pcb_s[0]);
+	case GDB_REG_S1: return (&kdb_thrctx->pcb_s[1]);
+	default:
+		if (regnum >= GDB_REG_S2 && regnum < GDB_REG_T3)
+			return (&kdb_thrctx->pcb_s[regnum - GDB_REG_S2]);
+		break;
+	}
+
+	return (NULL);
+}
+
+void
+gdb_cpu_setreg(int regnum, void *val)
+{
+	register_t regval = *(register_t *)val;
+
+	/* For curthread, keep the pcb and trapframe in sync. */
+	if (kdb_thread == curthread) {
+		switch (regnum) {
+		case GDB_REG_PC:	kdb_frame->tf_sepc = regval; break;
+		case GDB_REG_RA:	kdb_frame->tf_ra = regval; break;
+		case GDB_REG_SP:	kdb_frame->tf_sp = regval; break;
+		case GDB_REG_GP:	kdb_frame->tf_gp = regval; break;
+		case GDB_REG_TP:	kdb_frame->tf_tp = regval; break;
+		case GDB_REG_FP:	kdb_frame->tf_s[0] = regval; break;
+		case GDB_REG_S1:	kdb_frame->tf_s[1] = regval; break;
+		case GDB_REG_SSTATUS:	kdb_frame->tf_sstatus = regval; break;
+		case GDB_REG_STVAL:	kdb_frame->tf_stval = regval; break;
+		case GDB_REG_SCAUSE:	kdb_frame->tf_scause = regval; break;
+		default:
+			if (regnum >= GDB_REG_A0 && regnum < GDB_REG_S2)
+				kdb_frame->tf_a[regnum - GDB_REG_A0] = regval;
+			if (regnum >= GDB_REG_S2 && regnum < GDB_REG_T3)
+				kdb_frame->tf_s[regnum - GDB_REG_S2] = regval;
+			if (regnum >= GDB_REG_T0 && regnum < GDB_REG_FP)
+				kdb_frame->tf_t[regnum - GDB_REG_T0] = regval;
+			if (regnum >= GDB_REG_T3 && regnum < GDB_REG_PC)
+				kdb_frame->tf_t[regnum - GDB_REG_T3] = regval;
+			break;
+		}
+	}
+	switch (regnum) {
+	case GDB_REG_PC: /* FALLTHROUGH */
+	case GDB_REG_RA: kdb_thrctx->pcb_ra = regval; break;
+	case GDB_REG_SP: kdb_thrctx->pcb_sp = regval; break;
+	case GDB_REG_GP: kdb_thrctx->pcb_gp = regval; break;
+	case GDB_REG_TP: kdb_thrctx->pcb_tp = regval; break;
+	case GDB_REG_FP: kdb_thrctx->pcb_s[0] = regval; break;
+	case GDB_REG_S1: kdb_thrctx->pcb_s[1] = regval; break;
+	default:
+		if (regnum >= GDB_REG_S2 && regnum < GDB_REG_T3)
+			kdb_thrctx->pcb_s[regnum - GDB_REG_S2] = regval;
+		break;
+	}
+}
+
+int
+gdb_cpu_signal(int type, int code)
+{
+
+	if (type == SCAUSE_BREAKPOINT)
+		return (SIGTRAP);
+
+	return (SIGEMT);
+}