* [PATCH] target/riscv: fix RV128 lq encoding
@ 2022-01-18 15:12 Christoph Muellner
2022-01-18 16:07 ` Christoph Müllner
0 siblings, 1 reply; 2+ messages in thread
From: Christoph Muellner @ 2022-01-18 15:12 UTC (permalink / raw)
To: Palmer Dabbelt, Alistair Francis, Bin Meng, qemu-riscv,
qemu-devel, Philipp Tomsich
Cc: Christoph Muellner
If LQ has func3==010 and is located in the MISC-MEM opcodes,
then it conflicts with the CBO opcode space.
However, since LQ is specified as: "LQ is added to the MISC-MEM major
opcode", we have an implementation bug, because 'major opcode'
refers to func3, which must be 111.
This results in the following instruction encodings:
lq ........ ........ .111.... .0001111
cbo_clean 00000000 0001.... .0100000 00001111
cbo_flush 00000000 0010.... .0100000 00001111
cbo_inval 00000000 0000.... .0100000 00001111
cbo_zero 00000000 0100.... .0100000 00001111
^^^-func3
^^^^^^^-opcode
Signed-off-by: Christoph Muellner <cmuellner@linux.com>
---
target/riscv/insn32.decode | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
index 5bbedc254c..d3f798ca10 100644
--- a/target/riscv/insn32.decode
+++ b/target/riscv/insn32.decode
@@ -168,7 +168,7 @@ sraw 0100000 ..... ..... 101 ..... 0111011 @r
# *** RV128I Base Instruction Set (in addition to RV64I) ***
ldu ............ ..... 111 ..... 0000011 @i
-lq ............ ..... 010 ..... 0001111 @i
+lq ............ ..... 111 ..... 0001111 @i
sq ............ ..... 100 ..... 0100011 @s
addid ............ ..... 000 ..... 1011011 @i
sllid 000000 ...... ..... 001 ..... 1011011 @sh6
--
2.34.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] target/riscv: fix RV128 lq encoding
2022-01-18 15:12 [PATCH] target/riscv: fix RV128 lq encoding Christoph Muellner
@ 2022-01-18 16:07 ` Christoph Müllner
0 siblings, 0 replies; 2+ messages in thread
From: Christoph Müllner @ 2022-01-18 16:07 UTC (permalink / raw)
To: Palmer Dabbelt, Alistair Francis, Bin Meng, qemu-riscv,
qemu-devel, Philipp Tomsich
Resend from the correct email address to get accepted by Mailman.
On Tue, Jan 18, 2022 at 4:12 PM Christoph Muellner <cmuellner@linux.com> wrote:
>
> If LQ has func3==010 and is located in the MISC-MEM opcodes,
> then it conflicts with the CBO opcode space.
> However, since LQ is specified as: "LQ is added to the MISC-MEM major
> opcode", we have an implementation bug, because 'major opcode'
> refers to func3, which must be 111.
>
> This results in the following instruction encodings:
>
> lq ........ ........ .111.... .0001111
> cbo_clean 00000000 0001.... .0100000 00001111
> cbo_flush 00000000 0010.... .0100000 00001111
> cbo_inval 00000000 0000.... .0100000 00001111
> cbo_zero 00000000 0100.... .0100000 00001111
> ^^^-func3
> ^^^^^^^-opcode
>
> Signed-off-by: Christoph Muellner <cmuellner@linux.com>
> ---
> target/riscv/insn32.decode | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
> index 5bbedc254c..d3f798ca10 100644
> --- a/target/riscv/insn32.decode
> +++ b/target/riscv/insn32.decode
> @@ -168,7 +168,7 @@ sraw 0100000 ..... ..... 101 ..... 0111011 @r
>
> # *** RV128I Base Instruction Set (in addition to RV64I) ***
> ldu ............ ..... 111 ..... 0000011 @i
> -lq ............ ..... 010 ..... 0001111 @i
> +lq ............ ..... 111 ..... 0001111 @i
> sq ............ ..... 100 ..... 0100011 @s
> addid ............ ..... 000 ..... 1011011 @i
> sllid 000000 ...... ..... 001 ..... 1011011 @sh6
> --
> 2.34.1
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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