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>
diff --git a/cmd/arm/exception.c b/cmd/arm/exception.c
new file mode 100644
index 0000000..33bc759
--- /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>