libpayload arm64: Add gdb stub for arm64

Add stub implementation for gdb arm64 support. Currently all functions are kept
empty to enable proper compilation of depthcharge and libpayload. As we get more
clear about context management and stuff, we can add details for gdb as well.

BUG=None
BRANCH=None
TEST=Compiles successfully for rush

Original-Change-Id: I0a8729671ab0764d424c0e3d50af86433d05b1e8
Original-Signed-off-by: Furquan Shaikh <furquan@google.com>
Original-Reviewed-on: https://chromium-review.googlesource.com/204877
Original-Tested-by: Furquan Shaikh <furquan@chromium.org>
Original-Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Original-Commit-Queue: Furquan Shaikh <furquan@chromium.org>
(cherry picked from commit d24e5c26b56a9882b3450b1e4988b56c3d73efd1)
Signed-off-by: Marc Jones <marc.jones@se-eng.com>

Change-Id: I9b7d3d7060dd827ef4a46865e0f9a2b4e063d07d
Reviewed-on: http://review.coreboot.org/8125
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

2 files changed, 71 insertions, 0 deletions

diff --git a/payloads/libpayload/arch/arm64/Makefile.inc b/payloads/libpayload/arch/arm64/Makefile.inc
index 7107d0c799..bb09b8f919 100644
--- a/payloads/libpayload/arch/arm64/Makefile.inc
+++ b/payloads/libpayload/arch/arm64/Makefile.inc
@@ -40,6 +40,8 @@ libc-y += cache.c cpu.S
 libc-y += selfboot.c
 libcbfs-$(CONFIG_LP_CBFS) += dummy_media.c
 
+libgdb-y += gdb.c
+
 # Add other classes here when you put assembly files into them!
  head.o-S-ccopts += $(arm64_asm_flags)
  libc-S-ccopts += $(arm64_asm_flags)
diff --git a/payloads/libpayload/arch/arm64/gdb.c b/payloads/libpayload/arch/arm64/gdb.c
new file mode 100644
index 0000000000..857272f095
--- /dev/null
+++ b/payloads/libpayload/arch/arm64/gdb.c
@@ -0,0 +1,69 @@
+/*
+ * Copyright 2014 Google Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but without any warranty; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <exception.h>
+#include <gdb.h>
+#include <libpayload.h>
+
+struct gdb_regs
+{
+	u64 x[32];
+	struct fp_reg
+	{
+		u64 quad[2];
+	} __attribute__((packed)) f[32];
+	u32 fpcr;
+	u32 fpsr;
+	u32 spsr;
+} __attribute__((packed));
+
+static const u8 type_to_signal[] = {
+	[EXC_INV]    = GDB_SIGILL,
+	[EXC_SYNC]   = GDB_SIGTRAP,
+	[EXC_IRQ]    = GDB_SIGSEGV,
+	[EXC_FIQ]    = GDB_SIGSEGV,
+	[EXC_SERROR] = GDB_SIGSEGV
+};
+
+static int gdb_exception_hook(u32 type)
+{
+	return -1;
+}
+
+void gdb_arch_init(void)
+{
+	exception_install_hook(&gdb_exception_hook);
+}
+
+void gdb_arch_enter(void)
+{
+}
+
+int gdb_arch_set_single_step(int on)
+{
+	/* GDB seems to only need this on x86, ARM works fine without it. */
+	return -1;
+}
+
+void gdb_arch_encode_regs(struct gdb_message *message)
+{
+}
+
+void gdb_arch_decode_regs(int offset, struct gdb_message *message)
+{
+}