Re: [PATCH v9 01/17] target/riscv: Add zicfilp extension

[Alistair Francis]

On Tue, Aug 27, 2024 at 1:30 AM Deepak Gupta <debug@rivosinc.com> wrote:
>
> zicfilp [1] riscv cpu extension enables forward control flow integrity.
> If enabled, all indirect calls must land on a landing pad instruction.
>
> This patch sets up space for zicfilp extension in cpuconfig. zicfilp
> is dependend on zicsr.
>
> [1] - https://github.com/riscv/riscv-cfi
>
> 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/cpu.c         | 2 ++
>  target/riscv/cpu_cfg.h     | 1 +
>  target/riscv/tcg/tcg-cpu.c | 5 +++++
>  3 files changed, 8 insertions(+)
>
> diff --git a/target/riscv/cpu.c b/target/riscv/cpu.c
> index 33ef4eb795..5dfb3f39ab 100644
> --- a/target/riscv/cpu.c
> +++ b/target/riscv/cpu.c
> @@ -106,6 +106,7 @@ const RISCVIsaExtData isa_edata_arr[] = {
>      ISA_EXT_DATA_ENTRY(ziccif, PRIV_VERSION_1_11_0, has_priv_1_11),
>      ISA_EXT_DATA_ENTRY(zicclsm, PRIV_VERSION_1_11_0, has_priv_1_11),
>      ISA_EXT_DATA_ENTRY(ziccrse, PRIV_VERSION_1_11_0, has_priv_1_11),
> +    ISA_EXT_DATA_ENTRY(zicfilp, PRIV_VERSION_1_12_0, ext_zicfilp),
>      ISA_EXT_DATA_ENTRY(zicond, PRIV_VERSION_1_12_0, ext_zicond),
>      ISA_EXT_DATA_ENTRY(zicntr, PRIV_VERSION_1_12_0, ext_zicntr),
>      ISA_EXT_DATA_ENTRY(zicsr, PRIV_VERSION_1_10_0, ext_zicsr),
> @@ -1472,6 +1473,7 @@ const RISCVCPUMultiExtConfig riscv_cpu_extensions[] = {
>      /* Defaults for standard extensions */
>      MULTI_EXT_CFG_BOOL("sscofpmf", ext_sscofpmf, false),
>      MULTI_EXT_CFG_BOOL("zifencei", ext_zifencei, true),
> +    MULTI_EXT_CFG_BOOL("zicfilp", ext_zicfilp, false),

This should be added in the very last patch (as its own patch) as it
exposes the feature to users. The idea is to add the feature then
allow users to enable it

Alistair

>      MULTI_EXT_CFG_BOOL("zicsr", ext_zicsr, true),
>      MULTI_EXT_CFG_BOOL("zihintntl", ext_zihintntl, true),
>      MULTI_EXT_CFG_BOOL("zihintpause", ext_zihintpause, true),
> diff --git a/target/riscv/cpu_cfg.h b/target/riscv/cpu_cfg.h
> index 120905a254..88d5defbb5 100644
> --- a/target/riscv/cpu_cfg.h
> +++ b/target/riscv/cpu_cfg.h
> @@ -67,6 +67,7 @@ struct RISCVCPUConfig {
>      bool ext_zicbom;
>      bool ext_zicbop;
>      bool ext_zicboz;
> +    bool ext_zicfilp;
>      bool ext_zicond;
>      bool ext_zihintntl;
>      bool ext_zihintpause;
> diff --git a/target/riscv/tcg/tcg-cpu.c b/target/riscv/tcg/tcg-cpu.c
> index b8814ab753..ed19586c9d 100644
> --- a/target/riscv/tcg/tcg-cpu.c
> +++ b/target/riscv/tcg/tcg-cpu.c
> @@ -623,6 +623,11 @@ void riscv_cpu_validate_set_extensions(RISCVCPU *cpu, 
> Error **errp)
>          cpu->pmu_avail_ctrs = 0;
>      }
>
> +    if (cpu->cfg.ext_zicfilp && !cpu->cfg.ext_zicsr) {
> +        error_setg(errp, "zicfilp extension requires zicsr extension");
> +        return;
> +    }
> +
>      /*
>       * Disable isa extensions based on priv spec after we
>       * validated and set everything we need.
> --
> 2.44.0
>
>