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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: Michael Clark <mjc@sifive.com>
Reviewed-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>

Co-authored-by: Richard Henderson <richard.henderson@linaro.org>
Co-authored-by: Michael Clark <mjc@sifive.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
This commit is contained in:
Richard Henderson 2019-01-14 23:57:59 +00:00 committed by Palmer Dabbelt
parent 83a7171990
commit 533b8f8877
No known key found for this signature in database
GPG Key ID: EF4CA1502CCBAB41
2 changed files with 39 additions and 13 deletions
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12
target/riscv/csr.c
View File

@ -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);

40
target/riscv/translate.c
View File

@ -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);
}
}