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target/riscv: Prevent lost illegal instruction exceptions 

When decode_insn16() fails, we fall back to decode_RV32_64C() for
further compressed instruction decoding. However, prior to this change,
we did not raise an illegal instruction exception, if decode_RV32_64C()
fails to decode the instruction. This means that we skipped illegal
compressed instructions instead of raising an illegal instruction
exception.

Instead of patching decode_RV32_64C(), we can just remove it,
as it is dead code since f330433b36 anyway.

Signed-off-by: Georg Kotheimer <georg.kotheimer@kernkonzept.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20210322121609.3097928-1-georg.kotheimer@kernkonzept.com
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
This commit is contained in:
Georg Kotheimer 2021-03-22 13:16:09 +01:00 committed by Alistair Francis
parent d4e28f0eb8
commit 9a27f69bd6
1 changed files with 1 additions and 178 deletions
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179
target/riscv/translate.c
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@ -67,20 +67,6 @@ typedef struct DisasContext {
CPUState *cs;
} DisasContext;
#ifdef TARGET_RISCV64
/* convert riscv funct3 to qemu memop for load/store */
static const int tcg_memop_lookup[8] = {
[0 ... 7] = -1,
[0] = MO_SB,
[1] = MO_TESW,
[2] = MO_TESL,
[3] = MO_TEQ,
[4] = MO_UB,
[5] = MO_TEUW,
[6] = MO_TEUL,
};
#endif
#ifdef TARGET_RISCV64
#define CASE_OP_32_64(X) case X: case glue(X, W)
#else
@ -374,48 +360,6 @@ static void gen_jal(DisasContext *ctx, int rd, target_ulong imm)
ctx->base.is_jmp = DISAS_NORETURN;
}
#ifdef TARGET_RISCV64
static void gen_load_c(DisasContext *ctx, uint32_t opc, int rd, int rs1,
target_long imm)
{
TCGv t0 = tcg_temp_new();
TCGv t1 = tcg_temp_new();
gen_get_gpr(t0, rs1);
tcg_gen_addi_tl(t0, t0, imm);
int memop = tcg_memop_lookup[(opc >> 12) & 0x7];
if (memop < 0) {
gen_exception_illegal(ctx);
return;
}
tcg_gen_qemu_ld_tl(t1, t0, ctx->mem_idx, memop);
gen_set_gpr(rd, t1);
tcg_temp_free(t0);
tcg_temp_free(t1);
}
static void gen_store_c(DisasContext *ctx, uint32_t opc, int rs1, int rs2,
target_long imm)
{
TCGv t0 = tcg_temp_new();
TCGv dat = tcg_temp_new();
gen_get_gpr(t0, rs1);
tcg_gen_addi_tl(t0, t0, imm);
gen_get_gpr(dat, rs2);
int memop = tcg_memop_lookup[(opc >> 12) & 0x7];
if (memop < 0) {
gen_exception_illegal(ctx);
return;
}
tcg_gen_qemu_st_tl(dat, t0, ctx->mem_idx, memop);
tcg_temp_free(t0);
tcg_temp_free(dat);
}
#endif
#ifndef CONFIG_USER_ONLY
/* The states of mstatus_fs are:
* 0 = disabled, 1 = initial, 2 = clean, 3 = dirty
@ -447,83 +391,6 @@ static void mark_fs_dirty(DisasContext *ctx)
static inline void mark_fs_dirty(DisasContext *ctx) { }
#endif
#if !defined(TARGET_RISCV64)
static void gen_fp_load(DisasContext *ctx, uint32_t opc, int rd,
int rs1, target_long imm)
{
TCGv t0;
if (ctx->mstatus_fs == 0) {
gen_exception_illegal(ctx);
return;
}
t0 = tcg_temp_new();
gen_get_gpr(t0, rs1);
tcg_gen_addi_tl(t0, t0, imm);
switch (opc) {
case OPC_RISC_FLW:
if (!has_ext(ctx, RVF)) {
goto do_illegal;
}
tcg_gen_qemu_ld_i64(cpu_fpr[rd], t0, ctx->mem_idx, MO_TEUL);
/* RISC-V requires NaN-boxing of narrower width floating point values */
tcg_gen_ori_i64(cpu_fpr[rd], cpu_fpr[rd], 0xffffffff00000000ULL);
break;
case OPC_RISC_FLD:
if (!has_ext(ctx, RVD)) {
goto do_illegal;
}
tcg_gen_qemu_ld_i64(cpu_fpr[rd], t0, ctx->mem_idx, MO_TEQ);
break;
do_illegal:
default:
gen_exception_illegal(ctx);
break;
}
tcg_temp_free(t0);
mark_fs_dirty(ctx);
}
static void gen_fp_store(DisasContext *ctx, uint32_t opc, int rs1,
int rs2, target_long imm)
{
TCGv t0;
if (ctx->mstatus_fs == 0) {
gen_exception_illegal(ctx);
return;
}
t0 = tcg_temp_new();
gen_get_gpr(t0, rs1);
tcg_gen_addi_tl(t0, t0, imm);
switch (opc) {
case OPC_RISC_FSW:
if (!has_ext(ctx, RVF)) {
goto do_illegal;
}
tcg_gen_qemu_st_i64(cpu_fpr[rs2], t0, ctx->mem_idx, MO_TEUL);
break;
case OPC_RISC_FSD:
if (!has_ext(ctx, RVD)) {
goto do_illegal;
}
tcg_gen_qemu_st_i64(cpu_fpr[rs2], t0, ctx->mem_idx, MO_TEQ);
break;
do_illegal:
default:
gen_exception_illegal(ctx);
break;
}
tcg_temp_free(t0);
}
#endif
static void gen_set_rm(DisasContext *ctx, int rm)
{
TCGv_i32 t0;
@ -537,49 +404,6 @@ static void gen_set_rm(DisasContext *ctx, int rm)
tcg_temp_free_i32(t0);
}
static void decode_RV32_64C0(DisasContext *ctx, uint16_t opcode)
{
uint8_t funct3 = extract16(opcode, 13, 3);
uint8_t rd_rs2 = GET_C_RS2S(opcode);
uint8_t rs1s = GET_C_RS1S(opcode);
switch (funct3) {
case 3:
#if defined(TARGET_RISCV64)
/* C.LD(RV64/128) -> ld rd', offset[7:3](rs1')*/
gen_load_c(ctx, OPC_RISC_LD, rd_rs2, rs1s,
GET_C_LD_IMM(opcode));
#else
/* C.FLW (RV32) -> flw rd', offset[6:2](rs1')*/
gen_fp_load(ctx, OPC_RISC_FLW, rd_rs2, rs1s,
GET_C_LW_IMM(opcode));
#endif
break;
case 7:
#if defined(TARGET_RISCV64)
/* C.SD (RV64/128) -> sd rs2', offset[7:3](rs1')*/
gen_store_c(ctx, OPC_RISC_SD, rs1s, rd_rs2,
GET_C_LD_IMM(opcode));
#else
/* C.FSW (RV32) -> fsw rs2', offset[6:2](rs1')*/
gen_fp_store(ctx, OPC_RISC_FSW, rs1s, rd_rs2,
GET_C_LW_IMM(opcode));
#endif
break;
}
}
static void decode_RV32_64C(DisasContext *ctx, uint16_t opcode)
{
uint8_t op = extract16(opcode, 0, 2);
switch (op) {
case 0:
decode_RV32_64C0(ctx, opcode);
break;
}
}
static int ex_plus_1(DisasContext *ctx, int nf)
{
return nf + 1;
@ -779,8 +603,7 @@ static void decode_opc(CPURISCVState *env, DisasContext *ctx, uint16_t opcode)
} else {
ctx->pc_succ_insn = ctx->base.pc_next + 2;
if (!decode_insn16(ctx, opcode)) {
/* fall back to old decoder */
decode_RV32_64C(ctx, opcode);
gen_exception_illegal(ctx);
}
}
} else {