On Tue, Aug 27, 2024 at 1:33 AM Deepak Gupta <debug@rivosinc.com> wrote:
>
> Shadow stack instructions can be decoded as zimop / zcmop or shadow stack
> instructions depending on whether shadow stack are enabled at current
> privilege. This requires a TB flag so that correct TB generation and correct
> TB lookup happens. `DisasContext` gets a field indicating whether bcfi is
> enabled or not.
>
> 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>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Alistair
> ---
> target/riscv/cpu.h | 2 ++
> target/riscv/cpu_helper.c | 4 ++++
> target/riscv/translate.c | 4 ++++
> 3 files changed, 10 insertions(+)
>
> diff --git a/target/riscv/cpu.h b/target/riscv/cpu.h
> index 5a57099d59..dcc3bc9d93 100644
> --- a/target/riscv/cpu.h
> +++ b/target/riscv/cpu.h
> @@ -613,6 +613,8 @@ FIELD(TB_FLAGS, AXL, 26, 2)
> /* zicfilp needs a TB flag to track indirect branches */
> FIELD(TB_FLAGS, FCFI_ENABLED, 28, 1)
> FIELD(TB_FLAGS, FCFI_LP_EXPECTED, 29, 1)
> +/* zicfiss needs a TB flag so that correct TB is located based on tb flags */
> +FIELD(TB_FLAGS, BCFI_ENABLED, 30, 1)
>
> #ifdef TARGET_RISCV32
> #define riscv_cpu_mxl(env) ((void)(env), MXL_RV32)
> diff --git a/target/riscv/cpu_helper.c b/target/riscv/cpu_helper.c
> index c9165b1d86..ca6d8f1f39 100644
> --- a/target/riscv/cpu_helper.c
> +++ b/target/riscv/cpu_helper.c
> @@ -168,6 +168,10 @@ void cpu_get_tb_cpu_state(CPURISCVState *env, vaddr *pc,
> flags = FIELD_DP32(flags, TB_FLAGS, FCFI_ENABLED, 1);
> }
>
> + if (cpu_get_bcfien(env)) {
> + flags = FIELD_DP32(flags, TB_FLAGS, BCFI_ENABLED, 1);
> + }
> +
> #ifdef CONFIG_USER_ONLY
> fs = EXT_STATUS_DIRTY;
> vs = EXT_STATUS_DIRTY;
> diff --git a/target/riscv/translate.c b/target/riscv/translate.c
> index b5c0511b4b..b1d251e893 100644
> --- a/target/riscv/translate.c
> +++ b/target/riscv/translate.c
> @@ -119,6 +119,8 @@ typedef struct DisasContext {
> /* zicfilp extension. fcfi_enabled, lp expected or not */
> bool fcfi_enabled;
> bool fcfi_lp_expected;
> + /* zicfiss extension, if shadow stack was enabled during TB gen */
> + bool bcfi_enabled;
> } DisasContext;
>
> static inline bool has_ext(DisasContext *ctx, uint32_t ext)
> @@ -1241,6 +1243,8 @@ static void riscv_tr_init_disas_context(DisasContextBase *dcbase, CPUState *cs)
> ctx->pm_base_enabled = FIELD_EX32(tb_flags, TB_FLAGS, PM_BASE_ENABLED);
> ctx->ztso = cpu->cfg.ext_ztso;
> ctx->itrigger = FIELD_EX32(tb_flags, TB_FLAGS, ITRIGGER);
> + ctx->bcfi_enabled = cpu_get_bcfien(env) &&
> + FIELD_EX32(tb_flags, TB_FLAGS, BCFI_ENABLED);
> ctx->fcfi_lp_expected = FIELD_EX32(tb_flags, TB_FLAGS, FCFI_LP_EXPECTED);
> ctx->fcfi_enabled = FIELD_EX32(tb_flags, TB_FLAGS, FCFI_ENABLED);
> ctx->zero = tcg_constant_tl(0);
> --
> 2.44.0
>
>