cmd: add exception command

The 'exception' command allows to test exception handling.

This implementation supports ARM, x86, RISC-V and the following exceptions:
* 'breakpoint' - prefetch abort exception (ARM 32bit only)
* 'unaligned'  - data abort exception (ARM only)
* 'undefined'  - undefined instruction exception

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

9 files changed, 171 insertions, 0 deletions

diff --git a/cmd/Kconfig b/cmd/Kconfig
index 2bdbfcb3d0..5d1999ee0b 100644
--- a/cmd/Kconfig
+++ b/cmd/Kconfig
@@ -1433,6 +1433,12 @@ config CMD_EFIDEBUG
 	  particularly for managing boot parameters as  well as examining
 	  various EFI status for debugging.
 
+config CMD_EXCEPTION
+	bool "exception - raise exception"
+	depends on ARM || RISCV || X86
+	help
+	  Enable the 'exception' command which allows to raise an exception.
+
 config CMD_LED
 	bool "led"
 	depends on LED
diff --git a/cmd/Makefile b/cmd/Makefile
index 6b1c6b094e..7864fcf95c 100644
--- a/cmd/Makefile
+++ b/cmd/Makefile
@@ -173,6 +173,8 @@ obj-$(CONFIG_CMD_BLOB) += blob.o
 # Android Verified Boot 2.0
 obj-$(CONFIG_CMD_AVB) += avb.o
 
+obj-$(CONFIG_ARM) += arm/
+obj-$(CONFIG_RISCV) += riscv/
 obj-$(CONFIG_X86) += x86/
 
 obj-$(CONFIG_ARCH_MVEBU) += mvebu/
diff --git a/cmd/arm/Makefile b/cmd/arm/Makefile
new file mode 100644
index 0000000000..94367dcb45
--- /dev/null
+++ b/cmd/arm/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+ifdef CONFIG_ARM64
+obj-$(CONFIG_CMD_EXCEPTION) += exception64.o
+else
+obj-$(CONFIG_CMD_EXCEPTION) += exception.o
+endif
diff --git a/cmd/arm/exception.c b/cmd/arm/exception.c
new file mode 100644
index 0000000000..33bc75976f
--- /dev/null
+++ b/cmd/arm/exception.c
@@ -0,0 +1,61 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * The 'exception' command can be used for testing exception handling.
+ *
+ * Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+
+#include <common.h>
+#include <command.h>
+
+static int do_unaligned(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	/*
+	 * The LDRD instruction requires the data source to be four byte aligned
+	 * even if strict alignment fault checking is disabled in the system
+	 * control register.
+	 */
+	asm volatile (
+		"MOV r5, sp\n"
+		"ADD r5, #1\n"
+		"LDRD r6, r7, [r5]\n");
+	return CMD_RET_FAILURE;
+}
+
+static int do_breakpoint(cmd_tbl_t *cmdtp, int flag, int argc,
+			 char * const argv[])
+{
+	asm volatile ("BKPT #123\n");
+	return CMD_RET_FAILURE;
+}
+
+static int do_undefined(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	/*
+	 * 0xe7f...f.	is undefined in ARM mode
+	 * 0xde..	is undefined in Thumb mode
+	 */
+	asm volatile (".word 0xe7f7defb\n");
+	return CMD_RET_FAILURE;
+}
+
+static cmd_tbl_t cmd_sub[] = {
+	U_BOOT_CMD_MKENT(breakpoint, CONFIG_SYS_MAXARGS, 1, do_breakpoint,
+			 "", ""),
+	U_BOOT_CMD_MKENT(unaligned, CONFIG_SYS_MAXARGS, 1, do_unaligned,
+			 "", ""),
+	U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
+			 "", ""),
+};
+
+static char exception_help_text[] =
+	"<ex>\n"
+	"  The following exceptions are available:\n"
+	"  breakpoint - prefetch abort\n"
+	"  unaligned  - data abort\n"
+	"  undefined  - undefined instruction\n"
+	;
+
+#include <exception.h>
diff --git a/cmd/arm/exception64.c b/cmd/arm/exception64.c
new file mode 100644
index 0000000000..a363818532
--- /dev/null
+++ b/cmd/arm/exception64.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * The 'exception' command can be used for testing exception handling.
+ *
+ * Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+
+#include <common.h>
+#include <command.h>
+
+static int do_undefined(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	/*
+	 * 0xe7f...f.	is undefined in ARM mode
+	 * 0xde..	is undefined in Thumb mode
+	 */
+	asm volatile (".word 0xe7f7defb\n");
+	return CMD_RET_FAILURE;
+}
+
+static cmd_tbl_t cmd_sub[] = {
+	U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
+			 "", ""),
+};
+
+static char exception_help_text[] =
+	"<ex>\n"
+	"  The following exceptions are available:\n"
+	"  undefined  - undefined instruction\n"
+	;
+
+#include <exception.h>
diff --git a/cmd/riscv/Makefile b/cmd/riscv/Makefile
new file mode 100644
index 0000000000..24df023ece
--- /dev/null
+++ b/cmd/riscv/Makefile
@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+obj-$(CONFIG_CMD_EXCEPTION) += exception.o
diff --git a/cmd/riscv/exception.c b/cmd/riscv/exception.c
new file mode 100644
index 0000000000..547fb7d132
--- /dev/null
+++ b/cmd/riscv/exception.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * The 'exception' command can be used for testing exception handling.
+ *
+ * Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+
+#include <common.h>
+#include <command.h>
+
+static int do_undefined(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	asm volatile (".word 0xffffffff\n");
+	return CMD_RET_FAILURE;
+}
+
+static cmd_tbl_t cmd_sub[] = {
+	U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
+			 "", ""),
+};
+
+static char exception_help_text[] =
+	"<ex>\n"
+	"  The following exceptions are available:\n"
+	"  undefined  - undefined instruction\n"
+	;
+
+#include <exception.h>
diff --git a/cmd/x86/Makefile b/cmd/x86/Makefile
index bcc6d06582..707161440d 100644
--- a/cmd/x86/Makefile
+++ b/cmd/x86/Makefile
@@ -1,4 +1,5 @@
 # SPDX-License-Identifier: GPL-2.0+
 
 obj-y += mtrr.o
+obj-$(CONFIG_CMD_EXCEPTION) += exception.o
 obj-$(CONFIG_HAVE_FSP) += fsp.o
diff --git a/cmd/x86/exception.c b/cmd/x86/exception.c
new file mode 100644
index 0000000000..ade1e2ea92
--- /dev/null
+++ b/cmd/x86/exception.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * The 'exception' command can be used for testing exception handling.
+ *
+ * Copyright (c) 2018, Heinrich Schuchardt <xypron.glpk@gmx.de>
+ */
+
+#include <common.h>
+#include <command.h>
+
+static int do_undefined(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	asm volatile (".word 0xffff\n");
+	return CMD_RET_FAILURE;
+}
+
+static cmd_tbl_t cmd_sub[] = {
+	U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
+			 "", ""),
+};
+
+static char exception_help_text[] =
+	"<ex>\n"
+	"  The following exceptions are available:\n"
+	"  undefined  - undefined instruction\n"
+	;
+
+#include <exception.h>