[v3] riscv support for control flow integrity extensions

[PATCH v3 13/20] target/riscv: compressed encodings for sspush and sspopchk

Posted by Deepak Gupta 3 months, 2 weeks ago

sspush/sspopchk have compressed encodings carved out of zcmops.
compressed sspush is designated as c.mop.1 while compressed sspopchk
is designated as c.mop.5.

Note that c.sspush x1 exists while c.sspush x5 doesn't. Similarly
c.sspopchk x5 exists while c.sspopchk x1 doesn't.

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
Co-developed-by: Jim Shu <jim.shu@sifive.com>
Co-developed-by: Andy Chiu <andy.chiu@sifive.com>
---
 target/riscv/insn16.decode | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/target/riscv/insn16.decode b/target/riscv/insn16.decode
index 3953bcf82d..d9fb74fef6 100644
--- a/target/riscv/insn16.decode
+++ b/target/riscv/insn16.decode
@@ -69,10 +69,12 @@
 # Formats 16:
 @cr        ....  ..... .....  .. &r      rs2=%rs2_5       rs1=%rd     %rd
 @ci        ... . ..... .....  .. &i      imm=%imm_ci      rs1=%rd     %rd
+@c_sspop   ... . ..... .....  .. &i      imm=0      rs1=5     rd=0
 @cl_q      ... . .....  ..... .. &i      imm=%uimm_cl_q   rs1=%rs1_3  rd=%rs2_3
 @cl_d      ... ... ... .. ... .. &i      imm=%uimm_cl_d   rs1=%rs1_3  rd=%rs2_3
 @cl_w      ... ... ... .. ... .. &i      imm=%uimm_cl_w   rs1=%rs1_3  rd=%rs2_3
 @cs_2      ... ... ... .. ... .. &r      rs2=%rs2_3       rs1=%rs1_3  rd=%rs1_3
+@c_sspush  ... ... ... .. ... .. &s      imm=0 rs1=0 rs2=1
 @cs_q      ... ... ... .. ... .. &s      imm=%uimm_cl_q   rs1=%rs1_3  rs2=%rs2_3
 @cs_d      ... ... ... .. ... .. &s      imm=%uimm_cl_d   rs1=%rs1_3  rs2=%rs2_3
 @cs_w      ... ... ... .. ... .. &s      imm=%uimm_cl_w   rs1=%rs1_3  rs2=%rs2_3
@@ -140,6 +142,8 @@ sw                110  ... ... .. ... 00 @cs_w
 addi              000 .  .....  ..... 01 @ci
 addi              010 .  .....  ..... 01 @c_li
 {
+  sspush          011 0  00001  00000 01 @c_sspush # c.sspush x1 carving out of zcmops
+  sspopchk        011 0  00101  00000 01 @c_sspop # c.sspopchk x5 carving out of zcmops
   c_mop_n         011 0 0 n:3 1 00000 01
   illegal         011 0  -----  00000 01 # c.addi16sp and c.lui, RES nzimm=0
   addi            011 .  00010  ..... 01 @c_addi16sp
-- 
2.44.0

Re: [PATCH v3 13/20] target/riscv: compressed encodings for sspush and sspopchk

Posted by Richard Henderson 3 months, 2 weeks ago

On 8/7/24 10:06, Deepak Gupta wrote:
> sspush/sspopchk have compressed encodings carved out of zcmops.
> compressed sspush is designated as c.mop.1 while compressed sspopchk
> is designated as c.mop.5.
> 
> Note that c.sspush x1 exists while c.sspush x5 doesn't. Similarly
> c.sspopchk x5 exists while c.sspopchk x1 doesn't.
> 
> Signed-off-by: Deepak Gupta <debug@rivosinc.com>
> Co-developed-by: Jim Shu <jim.shu@sifive.com>
> Co-developed-by: Andy Chiu <andy.chiu@sifive.com>
> ---
>   target/riscv/insn16.decode | 4 ++++
>   1 file changed, 4 insertions(+)
> 
> diff --git a/target/riscv/insn16.decode b/target/riscv/insn16.decode
> index 3953bcf82d..d9fb74fef6 100644
> --- a/target/riscv/insn16.decode
> +++ b/target/riscv/insn16.decode
> @@ -69,10 +69,12 @@
>   # Formats 16:
>   @cr        ....  ..... .....  .. &r      rs2=%rs2_5       rs1=%rd     %rd
>   @ci        ... . ..... .....  .. &i      imm=%imm_ci      rs1=%rd     %rd
> +@c_sspop   ... . ..... .....  .. &i      imm=0      rs1=5     rd=0
>   @cl_q      ... . .....  ..... .. &i      imm=%uimm_cl_q   rs1=%rs1_3  rd=%rs2_3
>   @cl_d      ... ... ... .. ... .. &i      imm=%uimm_cl_d   rs1=%rs1_3  rd=%rs2_3
>   @cl_w      ... ... ... .. ... .. &i      imm=%uimm_cl_w   rs1=%rs1_3  rd=%rs2_3
>   @cs_2      ... ... ... .. ... .. &r      rs2=%rs2_3       rs1=%rs1_3  rd=%rs1_3
> +@c_sspush  ... ... ... .. ... .. &s      imm=0 rs1=0 rs2=1
>   @cs_q      ... ... ... .. ... .. &s      imm=%uimm_cl_q   rs1=%rs1_3  rs2=%rs2_3
>   @cs_d      ... ... ... .. ... .. &s      imm=%uimm_cl_d   rs1=%rs1_3  rs2=%rs2_3
>   @cs_w      ... ... ... .. ... .. &s      imm=%uimm_cl_w   rs1=%rs1_3  rs2=%rs2_3
> @@ -140,6 +142,8 @@ sw                110  ... ... .. ... 00 @cs_w
>   addi              000 .  .....  ..... 01 @ci
>   addi              010 .  .....  ..... 01 @c_li
>   {
> +  sspush          011 0  00001  00000 01 @c_sspush # c.sspush x1 carving out of zcmops
> +  sspopchk        011 0  00101  00000 01 @c_sspop # c.sspopchk x5 carving out of zcmops

Again, drop the single-use formats.


r~