RISC-V Debug Specification: https://github.com/riscv/riscv-debug-spec/releases/tag/1.0 Add DRET decode/translate and a helper to leave Debug Mode and return to dpc. Executing DRET outside Debug Mode raises illegal instruction. Signed-off-by: Chao Liu <chao.liu.zevorn@gmail.com> --- target/riscv/helper.h | 1 + target/riscv/insn32.decode | 1 + target/riscv/insn_trans/trans_privileged.c.inc | 18 ++++++++++++++++++ target/riscv/op_helper.c | 16 ++++++++++++++++ 4 files changed, 36 insertions(+) diff --git a/target/riscv/helper.h b/target/riscv/helper.h index b785456ee0..6140b6340d 100644 --- a/target/riscv/helper.h +++ b/target/riscv/helper.h @@ -131,6 +131,7 @@ DEF_HELPER_6(csrrw_i128, tl, env, int, tl, tl, tl, tl) #ifndef CONFIG_USER_ONLY DEF_HELPER_1(sret, tl, env) DEF_HELPER_1(mret, tl, env) +DEF_HELPER_1(dret, tl, env) DEF_HELPER_1(mnret, tl, env) DEF_HELPER_1(ctr_clear, void, env) DEF_HELPER_1(wfi, void, env) diff --git a/target/riscv/insn32.decode b/target/riscv/insn32.decode index 6e35c4b1e6..4db842d5d9 100644 --- a/target/riscv/insn32.decode +++ b/target/riscv/insn32.decode @@ -118,6 +118,7 @@ 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 +dret 0111101 10010 00000 000 00000 1110011 wfi 0001000 00101 00000 000 00000 1110011 sfence_vma 0001001 ..... ..... 000 00000 1110011 @sfence_vma diff --git a/target/riscv/insn_trans/trans_privileged.c.inc b/target/riscv/insn_trans/trans_privileged.c.inc index 8a62b4cfcd..f8641b1977 100644 --- a/target/riscv/insn_trans/trans_privileged.c.inc +++ b/target/riscv/insn_trans/trans_privileged.c.inc @@ -125,6 +125,24 @@ static bool trans_mret(DisasContext *ctx, arg_mret *a) #endif } +static bool trans_dret(DisasContext *ctx, arg_dret *a) +{ +#ifndef CONFIG_USER_ONLY + if (!ctx->cfg_ptr->ext_sdext) { + return false; + } + decode_save_opc(ctx, 0); + translator_io_start(&ctx->base); + gen_update_pc(ctx, 0); + gen_helper_dret(cpu_pc, tcg_env); + exit_tb(ctx); /* no chaining */ + ctx->base.is_jmp = DISAS_NORETURN; + return true; +#else + return false; +#endif +} + static bool trans_mnret(DisasContext *ctx, arg_mnret *a) { #ifndef CONFIG_USER_ONLY diff --git a/target/riscv/op_helper.c b/target/riscv/op_helper.c index 6ccc127c30..99736bbebb 100644 --- a/target/riscv/op_helper.c +++ b/target/riscv/op_helper.c @@ -454,6 +454,22 @@ target_ulong helper_mret(CPURISCVState *env) return retpc; } +target_ulong helper_dret(CPURISCVState *env) +{ + uintptr_t ra = GETPC(); +#ifdef CONFIG_USER_ONLY + riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, ra); + return 0; +#else + if (!riscv_cpu_cfg(env)->ext_sdext || !env->debug_mode) { + riscv_raise_exception(env, RISCV_EXCP_ILLEGAL_INST, ra); + } + target_ulong retpc = env->dpc & get_xepc_mask(env); + riscv_cpu_leave_debug_mode(env); + return retpc; +#endif +} + target_ulong helper_mnret(CPURISCVState *env) { target_ulong retpc = env->mnepc; -- 2.52.0