[PATCH 1/1] cmd/exception: test RISC-V 16 bit aligned instruction

[Heinrich Schuchardt]

A 16 bit aligned instruction should generated an exception if the C
extension is not available.

Provide an 'extension ialign16' command for testing exception handling.

For testing build qemu-riscv64_defconfig with CONFIG_RISCV_ISA_C=n
and run with

    qemu-system-riscv64 -M virt -bios u-boot -nographic -cpu rv64,c=false

    => exception ialign16
    Unhandled exception: Instruction address misaligned
    EPC: 0000000087719138 RA: 0000000087719218 TVAL: 000000008771913e
    EPC: 0000000080020138 RA: 0000000080020218 reloc adjusted

    Code: 0113 0101 8067 0000 0113 ff01 3423 0011 (006f 0060)

Signed-off-by: Heinrich Schuchardt <heinrich.schucha...@canonical.com>
---
 cmd/riscv/exception.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/cmd/riscv/exception.c b/cmd/riscv/exception.c
index db8d8af048..f38f454a0b 100644
--- a/cmd/riscv/exception.c
+++ b/cmd/riscv/exception.c
@@ -24,6 +24,19 @@ static int do_ebreak(struct cmd_tbl *cmdtp, int flag, int 
argc,
        return CMD_RET_FAILURE;
 }
 
+static int do_ialign16(struct cmd_tbl *cmdtp, int flag, int argc,
+                      char *const argv[])
+{
+       asm volatile (
+               /* jump skipping 2 bytes */
+               ".long 0x0060006f\n"
+               ".long 0x006f0000\n"
+               ".long 0x00000060\n"
+       );
+       printf("The system supports 16 bit aligned instructions.\n");
+       return CMD_RET_SUCCESS;
+}
+
 static int do_unaligned(struct cmd_tbl *cmdtp, int flag, int argc,
                        char *const argv[])
 {
@@ -48,6 +61,8 @@ static struct cmd_tbl cmd_sub[] = {
                         "", ""),
        U_BOOT_CMD_MKENT(ebreak, CONFIG_SYS_MAXARGS, 1, do_ebreak,
                         "", ""),
+       U_BOOT_CMD_MKENT(ialign16, CONFIG_SYS_MAXARGS, 1, do_ialign16,
+                        "", ""),
        U_BOOT_CMD_MKENT(unaligned, CONFIG_SYS_MAXARGS, 1, do_unaligned,
                         "", ""),
        U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
@@ -59,6 +74,7 @@ static char exception_help_text[] =
        "  The following exceptions are available:\n"
        "  compressed - compressed instruction\n"
        "  ebreak     - breakpoint\n"
+       "  ialign16   - 16 bit aligned instruction\n"
        "  undefined  - illegal instruction\n"
        "  unaligned  - load address misaligned\n"
        ;
-- 
2.40.1