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SubjectRe: [PATCH v3 2/2] scripts/decodecode: Add support for RISC-V
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Hi Björn,

On 1/19/23 08:47, Björn Töpel wrote:
> From: Björn Töpel <bjorn@rivosinc.com>
>
> RISC-V has some GNU disassembly quirks, e.g. it requires '-D' to
> properly disassemble .2byte directives similar to Arm [1]. Further,
> GNU objdump groups RISC-V instruction by 2 or 4 byte chunks, instead
> doing byte-for-byte.
>
> Add the required switches, and translate from short/word to bytes when
> ARCH is "riscv".
>
> An example how to invoke decodecode for RISC-V:
> $ echo 'Code: bf45 f793 1007 f7d9 50ef 37af d541 b7d9 7097 00c8 (80e7)
> 6140' | AFLAGS="-march=rv64imac_zicbom_zihintpause" \
> ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- ./scripts/decodecode
> Code: bf45 f793 1007 f7d9 50ef 37af d541 b7d9 7097 00c8 (80e7) 6140
> All code
> ========
> 0: bf45 c.j 0xffffffffffffffb0
> 2: 1007f793 andi a5,a5,256
> 6: f7d9 c.bnez a5,0xffffffffffffff94
> 8: 37af50ef jal ra,0xf5382
> c: d541 c.beqz a0,0xffffffffffffff94
> e: b7d9 c.j 0xffffffffffffffd4
> 10: 00c87097 auipc ra,0xc87
> 14:* 614080e7 jalr ra,1556(ra) # 0xc87624 <-- trapping instruction
>
> Code starting with the faulting instruction
> ===========================================
> 0: 614080e7 jalr ra,1556(ra)
>
> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=10263
>
> Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
> ---
> scripts/decodecode | 12 +++++++++++-
> 1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/scripts/decodecode b/scripts/decodecode
> index b28fd2686561..8fe71c292381 100755
> --- a/scripts/decodecode
> +++ b/scripts/decodecode
> @@ -93,6 +93,11 @@ disas() {
> ${CROSS_COMPILE}strip $t.o
> fi
>
> + if [ "$ARCH" = "riscv" ]; then
> + OBJDUMPFLAGS="-M no-aliases --section=.text -D"
> + ${CROSS_COMPILE}strip $t.o
> + fi
> +
> if [ $pc_sub -ne 0 ]; then
> if [ $PC ]; then
> adj_vma=$(( $PC - $pc_sub ))
> @@ -126,8 +131,13 @@ get_substr_opcode_bytes_num()
> do
> substr+="$opc"
>
> + opcode="$substr"
> + if [ "$ARCH" = "riscv" ]; then
> + opcode=$(echo $opcode | tr ' ' '\n' | tac | tr -d '\n')
> + fi
> +
> # return if opcode bytes do not match @opline anymore
> - if ! echo $opline | grep -q "$substr";
> + if ! echo $opline | grep -q "$opcode";
> then
> break
> fi


Tested-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Thanks, that's very useful!

Alex

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