Hi Heinrich
> From: Heinrich Schuchardt [mailto:xypron.g...@gmx.de]
> Sent: Tuesday, August 04, 2020 7:10 PM
> To: Rick Jian-Zhi Chen(陳建志)
> Cc: u-boot@lists.denx.de; Heinrich Schuchardt
> Subject: [PATCH 1/1] cmd: exception: unaligned data access on RISC-V
>
> The command 'exception' can be used to test the handling of exceptions.
>
> Currently the exception command only allows to create an illegal instruction
> exception on RISC-V.
>
> Provide a sub-command 'exception unaligned' to cause a misaligned load
> address exception.
>
> Adjust the online help for 'exception undefined'.
>
> Signed-off-by: Heinrich Schuchardt <xypron.g...@gmx.de>
> ---
> cmd/riscv/exception.c | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/cmd/riscv/exception.c b/cmd/riscv/exception.c index
> 3c8dbbec0e..53159531d9 100644
> --- a/cmd/riscv/exception.c
> +++ b/cmd/riscv/exception.c
> @@ -8,6 +8,17 @@
> #include <common.h>
> #include <command.h>
>
> +static int do_unaligned(struct cmd_tbl *cmdtp, int flag, int argc,
> + char *const argv[])
> +{
> + asm volatile (
> + "auipc a1, 0\n"
> + "ori a1, a1, 3\n"
> + "lw a2, (0)(a1)\n"
> + );
> + return CMD_RET_FAILURE;
I suggest that we can modify it as below to print the unaligned
address and data for more debug information.
int ret = 0;
int addr = 0;
asm volatile (
"auipc a1, 0\n"
"ori %0, a1, 3\n"
"lw %1, (0)(a1)\n"
: "=r" (addr), "=r" (ret)
:
: "memory"
);
printf("unaligned addr 0x%x , ret 0x%x\n",addr,ret);
return CMD_RET_SUCCESS;
====================================
So if run in S-Mode, it will work as below:
RISC-V # exception unaligned
unaligned addr 0x3ff92fd7 , ret 0x35e59300
RISC-V #
(gdb) x/4x 0x3ff92fd0
0x3ff92fd0: 0x7ac362ef 0x00000597 0x0035e593 0xc5174190
(gdb)
====================================
If run in M-Mode, it will work as below:
RISC-V # exception unaligned
Unhandled exception: Load address misaligned
EPC: 000000003ff92fdc RA: 000000003ff93032 TVAL: 000000003ff92fd7
EPC: 0000000000009fdc RA: 000000000000a032 reloc adjusted
### ERROR ### Please RESET the board ###
Thanks,
Rick
> +}
> +
> static int do_undefined(struct cmd_tbl *cmdtp, int flag, int argc,
> char *const argv[])
> {
> @@ -16,6 +27,8 @@ static int do_undefined(struct cmd_tbl *cmdtp, int flag,
> int argc, }
>
> static struct cmd_tbl cmd_sub[] = {
> + U_BOOT_CMD_MKENT(unaligned, CONFIG_SYS_MAXARGS, 1, do_unaligned,
> + "", ""),
> U_BOOT_CMD_MKENT(undefined, CONFIG_SYS_MAXARGS, 1, do_undefined,
> "", ""),
> };
> @@ -23,7 +36,8 @@ static struct cmd_tbl cmd_sub[] = { static char
> exception_help_text[] =
> "<ex>\n"
> " The following exceptions are available:\n"
> - " undefined - undefined instruction\n"
> + " undefined - illegal instruction\n"
> + " unaligned - load address misaligned\n"
> ;
>
> #include <exception.h>
> --
> 2.27.0
