From: Richard Henderson <richard.hender...@linaro.org> Modifed from Richard Henderson's patch [1] to integrate with the new control and status register implementation.
[1] https://lists.nongnu.org/archive/html/qemu-devel/2018-03/msg07034.html Note: the f* CSRs already mark mstatus.FS dirty using env->mstatus |= mstatus.FS so the bug in the first spin of this patch has been fixed in a prior commit. Cc: Sagar Karandikar <sag...@eecs.berkeley.edu> Cc: Bastian Koppelmann <kbast...@mail.uni-paderborn.de> Cc: Palmer Dabbelt <pal...@sifive.com> Cc: Alistair Francis <alistair.fran...@wdc.com> Cc: Richard Henderson <richard.hender...@linaro.org> Signed-off-by: Michael Clark <m...@sifive.com> Co-authored-by: Richard Henderson <richard.hender...@linaro.org> Co-authored-by: Michael Clark <m...@sifive.com> --- target/riscv/csr.c | 12 ------------ target/riscv/translate.c | 40 +++++++++++++++++++++++++++++++++++++++- 2 files changed, 39 insertions(+), 13 deletions(-) diff --git a/target/riscv/csr.c b/target/riscv/csr.c index ecf74a0..e005285 100644 --- a/target/riscv/csr.c +++ b/target/riscv/csr.c @@ -325,18 +325,6 @@ static int write_mstatus(CPURISCVState *env, int csrno, target_ulong val) mstatus = (mstatus & ~mask) | (val & mask); - /* Note: this is a workaround for an issue where mstatus.FS - does not report dirty after floating point operations - that modify floating point state. This workaround is - technically compliant with the RISC-V Privileged - specification as it is legal to return only off, or dirty. - at the expense of extra floating point save/restore. */ - - /* FP is always dirty or off */ - if (mstatus & MSTATUS_FS) { - mstatus |= MSTATUS_FS; - } - int dirty = ((mstatus & MSTATUS_FS) == MSTATUS_FS) | ((mstatus & MSTATUS_XS) == MSTATUS_XS); mstatus = set_field(mstatus, MSTATUS_SD, dirty); diff --git a/target/riscv/translate.c b/target/riscv/translate.c index 4180c42..442c8cd 100644 --- a/target/riscv/translate.c +++ b/target/riscv/translate.c @@ -659,6 +659,31 @@ static void gen_store(DisasContext *ctx, uint32_t opc, int rs1, int rs2, tcg_temp_free(dat); } +#ifndef CONFIG_USER_ONLY +/* The states of mstatus_fs are: + * 0 = disabled, 1 = initial, 2 = clean, 3 = dirty + * We will have already diagnosed disabled state, + * and need to turn initial/clean into dirty. + */ +static void mark_fs_dirty(DisasContext *ctx) +{ + TCGv tmp; + if (ctx->mstatus_fs == MSTATUS_FS) { + return; + } + /* Remember the state change for the rest of the TB. */ + ctx->mstatus_fs = MSTATUS_FS; + + tmp = tcg_temp_new(); + tcg_gen_ld_tl(tmp, cpu_env, offsetof(CPURISCVState, mstatus)); + tcg_gen_ori_tl(tmp, tmp, MSTATUS_FS); + tcg_gen_st_tl(tmp, cpu_env, offsetof(CPURISCVState, mstatus)); + tcg_temp_free(tmp); +} +#else +static inline void mark_fs_dirty(DisasContext *ctx) { } +#endif + static void gen_fp_load(DisasContext *ctx, uint32_t opc, int rd, int rs1, target_long imm) { @@ -687,6 +712,8 @@ static void gen_fp_load(DisasContext *ctx, uint32_t opc, int rd, break; } tcg_temp_free(t0); + + mark_fs_dirty(ctx); } static void gen_fp_store(DisasContext *ctx, uint32_t opc, int rs1, @@ -984,6 +1011,7 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, int rs1, int rs2, int rm) { TCGv t0 = NULL; + bool fp_output = true; if (ctx->mstatus_fs == 0) { goto do_illegal; @@ -1046,6 +1074,7 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, } gen_set_gpr(rd, t0); tcg_temp_free(t0); + fp_output = false; break; case OPC_RISC_FCVT_W_S: @@ -1075,6 +1104,7 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, } gen_set_gpr(rd, t0); tcg_temp_free(t0); + fp_output = false; break; case OPC_RISC_FCVT_S_W: @@ -1125,6 +1155,7 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, } gen_set_gpr(rd, t0); tcg_temp_free(t0); + fp_output = false; break; case OPC_RISC_FMV_S_X: @@ -1217,6 +1248,7 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, } gen_set_gpr(rd, t0); tcg_temp_free(t0); + fp_output = false; break; case OPC_RISC_FCVT_W_D: @@ -1246,6 +1278,7 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, } gen_set_gpr(rd, t0); tcg_temp_free(t0); + fp_output = false; break; case OPC_RISC_FCVT_D_W: @@ -1293,6 +1326,7 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, default: goto do_illegal; } + fp_output = false; break; case OPC_RISC_FMV_D_X: @@ -1309,7 +1343,11 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, tcg_temp_free(t0); } gen_exception_illegal(ctx); - break; + return; + } + + if (fp_output) { + mark_fs_dirty(ctx); } } -- 2.7.0
