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-rw-r--r--payloads/libpayload/arch/arm/Makefile.inc2
-rw-r--r--payloads/libpayload/arch/arm/gdb.c114
2 files changed, 116 insertions, 0 deletions
diff --git a/payloads/libpayload/arch/arm/Makefile.inc b/payloads/libpayload/arch/arm/Makefile.inc
index 41bf7348c4..6c8667adc6 100644
--- a/payloads/libpayload/arch/arm/Makefile.inc
+++ b/payloads/libpayload/arch/arm/Makefile.inc
@@ -42,6 +42,8 @@ libc-y += selfboot.c
# Will fall back to default_memXXX() in libc/memory.c if GPL not allowed.
libc-$(CONFIG_LP_GPL) += memcpy.S memset.S memmove.S
+libgdb-y += gdb.c
+
libcbfs-$(CONFIG_LP_CBFS) += dummy_media.c
# Add other classes here when you put assembly files into them!
diff --git a/payloads/libpayload/arch/arm/gdb.c b/payloads/libpayload/arch/arm/gdb.c
new file mode 100644
index 0000000000..faf9eb48f2
--- /dev/null
+++ b/payloads/libpayload/arch/arm/gdb.c
@@ -0,0 +1,114 @@
+/*
+ * 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
+{
+ u32 r[16];
+ struct fp_reg
+ {
+ u8 byte[12];
+ } __attribute__((packed)) f[8];
+ u32 fps;
+ u32 cpsr;
+} __attribute__((packed));
+
+static const u8 type_to_signal[] = {
+ [EXC_UNDEF] = GDB_SIGILL,
+ [EXC_SWI] = GDB_SIGTRAP,
+ [EXC_PABORT] = GDB_SIGSEGV,
+ [EXC_DABORT] = GDB_SIGSEGV,
+};
+
+/* Scratch value to write reentrant exception states to. We never read it. */
+static struct exception_state sentinel_exception_state;
+
+static int gdb_exception_hook(u32 type)
+{
+ /*
+ * If we were not resumed we are in deep trouble here. GDB probably told
+ * us to do something stupid and caused a reentrant exception. All we
+ * can do is just blindly send an error code and keep going. Eventually
+ * GDB will tell us to resume and we return right back to the original
+ * exception state ("jumping over" all the nested ones).
+ */
+ if (gdb_state.connected && !gdb_state.resumed) {
+ static const char error_code[] = "E22"; /* EINVAL? */
+ static const struct gdb_message tmp_reply = {
+ .buf = (u8 *)error_code,
+ .used = sizeof(error_code),
+ .size = sizeof(error_code),
+ };
+ gdb_send_reply(&tmp_reply);
+ gdb_command_loop(gdb_state.signal); /* preserve old signal */
+ } else {
+ if (type >= ARRAY_SIZE(type_to_signal) || !type_to_signal[type])
+ return 0;
+ exception_state_ptr = &sentinel_exception_state;
+ gdb_command_loop(type_to_signal[type]);
+ }
+
+ exception_state_ptr = &exception_state;
+ return 1;
+}
+
+void gdb_arch_init(void)
+{
+ exception_install_hook(&gdb_exception_hook);
+}
+
+void gdb_arch_enter(void)
+{
+ u32 *sp;
+
+ asm volatile ("mov %0, %%sp" : "=r"(sp) );
+
+ /* Avoid reentrant exceptions, just call the hook if in one already. */
+ if (sp >= exception_stack && sp <= exception_stack_end)
+ gdb_exception_hook(EXC_SWI);
+ else
+ asm volatile ("svc #0");
+}
+
+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)
+{
+ gdb_message_encode_bytes(message, exception_state.regs,
+ sizeof(exception_state.regs));
+ gdb_message_encode_zero_bytes(message,
+ offsetof(struct gdb_regs, cpsr) - offsetof(struct gdb_regs, f));
+ gdb_message_encode_bytes(message, &exception_state.cpsr,
+ sizeof(exception_state.cpsr));
+}
+
+void gdb_arch_decode_regs(int offset, struct gdb_message *message)
+{
+ const int cpsr_hex_offset = offsetof(struct gdb_regs, cpsr) * 2;
+ gdb_message_decode_bytes(message, offset,
+ exception_state.regs, sizeof(exception_state.regs));
+ gdb_message_decode_bytes(message, offset + cpsr_hex_offset,
+ &exception_state.cpsr, sizeof(exception_state.cpsr));
+}