Rajnesh Kanwal 於 2024/5/30 上午 12:09 寫道:
> CTR extension adds a new instruction sctrclr to quickly
> clear the recorded entries buffer.
>
> Signed-off-by: Rajnesh Kanwal <rkanwal@rivosinc.com>
> ---
> target/riscv/cpu.h | 1 +
> target/riscv/cpu_helper.c | 7 +++++++
> target/riscv/insn32.decode | 1 +
> target/riscv/insn_trans/trans_privileged.c.inc | 10 ++++++++++
> target/riscv/op_helper.c | 5 +++++
> 5 files changed, 24 insertions(+)
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index a294a5372a..fade71aa09 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -572,6 +572,7 @@ void riscv_cpu_set_mode(CPURISCVState *env, target_ulong newpriv, bool virt_en);
> void riscv_ctr_freeze(CPURISCVState *env, uint64_t freeze_mask);
> void riscv_ctr_add_entry(CPURISCVState *env, target_long src, target_long dst,
> uint64_t type, target_ulong prev_priv, bool prev_virt);
> +void riscv_ctr_clear(CPURISCVState *env);
>
> void riscv_translate_init(void);
> G_NORETURN void riscv_raise_exception(CPURISCVState *env,
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index e064a7306e..45502f50a7 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -704,6 +704,13 @@ void riscv_ctr_freeze(CPURISCVState *env, uint64_t freeze_mask)
> }
> }
>
> +void riscv_ctr_clear(CPURISCVState *env)
> +{
> + memset(env->ctr_src, 0x0, sizeof(env->ctr_src));
> + memset(env->ctr_dst, 0x0, sizeof(env->ctr_dst));
> + memset(env->ctr_data, 0x0, sizeof(env->ctr_data));
> +}
> +
> static uint64_t riscv_ctr_priv_to_mask(target_ulong priv, bool virt)
> {
> switch (priv) {
> diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode
> index 9cb1a1b4ec..d3d38c7c68 100644
> --- a/target/riscv/insn32.decode
> +++ b/target/riscv/insn32.decode
> @@ -107,6 +107,7 @@
> # *** Privileged Instructions ***
> ecall 000000000000 00000 000 00000 1110011
> ebreak 000000000001 00000 000 00000 1110011
> +sctrclr 000100000100 00000 000 00000 1110011
> uret 0000000 00010 00000 000 00000 1110011
> sret 0001000 00010 00000 000 00000 1110011
> mret 0011000 00010 00000 000 00000 1110011
> diff --git a/target/riscv/insn_trans/trans_privileged.c.inc b/target/riscv/insn_trans/trans_privileged.c.inc
> index 339d659151..dd9da8651f 100644
> --- a/target/riscv/insn_trans/trans_privileged.c.inc
> +++ b/target/riscv/insn_trans/trans_privileged.c.inc
> @@ -69,6 +69,16 @@ static bool trans_ebreak(DisasContext *ctx, arg_ebreak *a)
> return true;
> }
>
> +static bool trans_sctrclr(DisasContext *ctx, arg_sctrclr *a)
> +{
> +#ifndef CONFIG_USER_ONLY
If both of smctr and ssctr are not enabled, it is an illegal instruction.
> + gen_helper_ctr_clear(tcg_env);
> + return true;
> +#else
> + return false;
> +#endif
> +}
> +
> static bool trans_uret(DisasContext *ctx, arg_uret *a)
> {
> return false;
> diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c
> index c8053d9c2f..89423c04b3 100644
> --- a/target/riscv/op_helper.c
> +++ b/target/riscv/op_helper.c
> @@ -461,6 +461,11 @@ void helper_ctr_branch(CPURISCVState *env, target_ulong src, target_ulong dest,
> }
> }
>
> +void helper_ctr_clear(CPURISCVState *env)
> +{
There should be some checks here.
The spec states:
SCTRCLR raises an illegal-instruction exception in U-mode, and a
virtual-instruction exception in VU-mode, unless CTR state enable access
restrictions apply.
I don't quite understand "unless CTR state enable access restrictions
apply" though.
The next sentence says "See Chapter 5", which states that execution of SCTRCLR raises an illegal instruction exception if mstateen0.CTR=0 and the priv mode is not M-mode, and it raises a virtual instruction exception if mstateen0.CTR=0 && hstateen0.CTR=1 and the priv mode is VS-mode.
> + riscv_ctr_clear(env);
> +}
> +
> void helper_wfi(CPURISCVState *env)
> {
> CPUState *cs = env_cpu(env);