Unverified Commit 533b8f88 authored by Richard Henderson's avatar Richard Henderson Committed by Palmer Dabbelt
Browse files

RISC-V: Mark mstatus.fs dirty 

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.

Signed-off-by: default avatarMichael Clark <mjc@sifive.com>
Reviewed-by: default avatarMichael Clark <mjc@sifive.com>
Signed-off-by: default avatarAlistair Francis <alistair.francis@wdc.com>

Co-authored-by: default avatarRichard Henderson <richard.henderson@linaro.org>
Co-authored-by: default avatarMichael Clark <mjc@sifive.com>
Signed-off-by: default avatarPalmer Dabbelt <palmer@sifive.com>
parent 83a71719

target/riscv/csr.c

+0 −12
Original line number Diff line number Diff line
@@ -317,18 +317,6 @@ 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);

target/riscv/translate.c

+39 −1
Original line number Diff line number Diff line
@@ -651,6 +651,31 @@ 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)

{
@@ -679,6 +704,8 @@ 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,
@@ -944,6 +971,7 @@ 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;
@@ -1006,6 +1034,7 @@ 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:
@@ -1035,6 +1064,7 @@ 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:
@@ -1085,6 +1115,7 @@ 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:
@@ -1177,6 +1208,7 @@ 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:
@@ -1206,6 +1238,7 @@ 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:
@@ -1254,6 +1287,7 @@ static void gen_fp_arith(DisasContext *ctx, uint32_t opc, int rd, 
        default:

            goto do_illegal;

        }

        fp_output = false;

        break;



#if defined(TARGET_RISCV64)
@@ -1271,7 +1305,11 @@ 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);

    }

}