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[Qemu-devel] [PATCH] Target-arm: Add the THUMB_DSP feature


From: Aurelio C. Remonda
Subject: [Qemu-devel] [PATCH] Target-arm: Add the THUMB_DSP feature
Date: Mon, 1 Jun 2015 11:30:23 -0300

I created an ARM_FEATURE_THUMB_DSP to be added to any non-M 
thumb2-compatible CPU that uses DSP instructions.
There are 85 DSP instructions (all of them thumb2). On disas_thumb2_insn
the DSP feature is tested before the instruction is generated; if it's not
enabled then its an illegal op.

Signed-off-by: Aurelio C. Remonda <address@hidden>
---
 target-arm/cpu.h       |   1 +
 target-arm/translate.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 107 insertions(+), 4 deletions(-)

diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 21b5b8e..2e03d8e 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -890,6 +890,7 @@ enum arm_features {
     ARM_FEATURE_V8_SHA1, /* implements SHA1 part of v8 Crypto Extensions */
     ARM_FEATURE_V8_SHA256, /* implements SHA256 part of v8 Crypto Extensions */
     ARM_FEATURE_V8_PMULL, /* implements PMULL part of v8 Crypto Extensions */
+    ARM_FEATURE_THUMB_DSP, /* DSP insns supported in the Thumb encodings */
 };
 
 static inline int arm_feature(CPUARMState *env, int feature)
diff --git a/target-arm/translate.c b/target-arm/translate.c
index 39692d7..2d14a2c 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -9444,6 +9444,10 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
 
         op = (insn >> 21) & 0xf;
         if (op == 6) {
+            if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                /* pkhtb, pkfbt are DSP instructions  */
+                goto illegal_op;
+            }
             /* Halfword pack.  */
             tmp = load_reg(s, rn);
             tmp2 = load_reg(s, rm);
@@ -9518,13 +9522,35 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
             switch (op) {
             case 0: gen_sxth(tmp);   break;
             case 1: gen_uxth(tmp);   break;
-            case 2: gen_sxtb16(tmp); break;
-            case 3: gen_uxtb16(tmp); break;
+            case 2:
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* sxtab16, sxtb16 are DSP instructions  */
+                    tcg_temp_free_i32(tmp);
+                    goto illegal_op;
+                }
+                gen_sxtb16(tmp);
+                break;
+            case 3:
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* uxtb16, uxtab16 are DSP instructions */
+                    tcg_temp_free_i32(tmp);
+                    goto illegal_op;
+                }
+                gen_uxtb16(tmp);
+                break;
             case 4: gen_sxtb(tmp);   break;
             case 5: gen_uxtb(tmp);   break;
             default: goto illegal_op;
             }
             if (rn != 15) {
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* sxtab, sxtah, uxtab, uxtah are DSP instructions.
+                     * sxtb, sxth, uxtb, uxth are not DSP according to
+                     * ARMv7-M Architecture Reference Manual
+                     */
+                    tcg_temp_free_i32(tmp);
+                    goto illegal_op;
+                }
                 tmp2 = load_reg(s, rn);
                 if ((op >> 1) == 1) {
                     gen_add16(tmp, tmp2);
@@ -9537,6 +9563,12 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
             break;
         case 2: /* SIMD add/subtract.  */
             op = (insn >> 20) & 7;
+            if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                /* add16, sub16, asx, sax, add8, sub8 (with q, s, sh, u, uh,
+                 * and uq variants) and usad8, usada8
+                 */
+                goto illegal_op;
+            }
             shift = (insn >> 4) & 7;
             if ((op & 3) == 3 || (shift & 3) == 3)
                 goto illegal_op;
@@ -9550,6 +9582,10 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
             op = ((insn >> 17) & 0x38) | ((insn >> 4) & 7);
             if (op < 4) {
                 /* Saturating add/subtract.  */
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* qsub, qadd, qdadd, qdsub are DSP instructions. */
+                    goto illegal_op;
+                }
                 tmp = load_reg(s, rn);
                 tmp2 = load_reg(s, rm);
                 if (op & 1)
@@ -9575,6 +9611,11 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                     gen_revsh(tmp);
                     break;
                 case 0x10: /* sel */
+                    if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* sel is a DSP instruction. */
+                    tcg_temp_free_i32(tmp);
+                    goto illegal_op;
+                    }
                     tmp2 = load_reg(s, rm);
                     tmp3 = tcg_temp_new_i32();
                     tcg_gen_ld_i32(tmp3, cpu_env, offsetof(CPUARMState, GE));
@@ -9640,6 +9681,14 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                 }
                 break;
             case 1: /* 16 x 16 -> 32 */
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* smlabb, smlabt, smlatb, smlatt, smulbb, smulbt, smultt
+                     * and smultb are DSP instructions
+                     */
+                    tcg_temp_free_i32(tmp);
+                    tcg_temp_free_i32(tmp2);
+                    goto illegal_op;
+                }
                 gen_mulxy(tmp, tmp2, op & 2, op & 1);
                 tcg_temp_free_i32(tmp2);
                 if (rs != 15) {
@@ -9650,6 +9699,12 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                 break;
             case 2: /* Dual multiply add.  */
             case 4: /* Dual multiply subtract.  */
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* smlad, smladx, smlsd, smusd are DSP instructions */
+                    tcg_temp_free_i32(tmp);
+                    tcg_temp_free_i32(tmp2);
+                    goto illegal_op;
+                }
                 if (op)
                     gen_swap_half(tmp2);
                 gen_smul_dual(tmp, tmp2);
@@ -9672,6 +9727,12 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                   }
                 break;
             case 3: /* 32 * 16 -> 32msb */
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* smlawb, smlawt, smulwt, smulwb are DSP instructions */
+                    tcg_temp_free_i32(tmp);
+                    tcg_temp_free_i32(tmp2);
+                    goto illegal_op;
+                }
                 if (op)
                     tcg_gen_sari_i32(tmp2, tmp2, 16);
                 else
@@ -9689,6 +9750,14 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                   }
                 break;
             case 5: case 6: /* 32 * 32 -> 32msb (SMMUL, SMMLA, SMMLS) */
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* smmla, smmls, smmul, smuad, smmlar,
+                     * smmlsr, smmulr are DSP instructions
+                     */
+                    tcg_temp_free_i32(tmp);
+                    tcg_temp_free_i32(tmp2);
+                    goto illegal_op;
+                }
                 tmp64 = gen_muls_i64_i32(tmp, tmp2);
                 if (rs != 15) {
                     tmp = load_reg(s, rs);
@@ -9735,6 +9804,12 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                 store_reg(s, rd, tmp);
             } else if ((op & 0xe) == 0xc) {
                 /* Dual multiply accumulate long.  */
+                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                    /* smlald, smlsld are DSP instructions */
+                    tcg_temp_free_i32(tmp);
+                    tcg_temp_free_i32(tmp2);
+                    goto illegal_op;
+                }
                 if (op & 1)
                     gen_swap_half(tmp2);
                 gen_smul_dual(tmp, tmp2);
@@ -9758,6 +9833,14 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                 } else {
                     if (op & 8) {
                         /* smlalxy */
+                        if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                            /* smlalbb, smlalbt, smlaltb, smlaltt
+                             * are DSP instructions
+                             */
+                            tcg_temp_free_i32(tmp2);
+                            tcg_temp_free_i32(tmp);
+                            goto illegal_op;
+                        }
                         gen_mulxy(tmp, tmp2, op & 2, op & 1);
                         tcg_temp_free_i32(tmp2);
                         tmp64 = tcg_temp_new_i64();
@@ -9770,6 +9853,11 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                 }
                 if (op & 4) {
                     /* umaal */
+                    if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) {
+                        /* ummal is a DSP instruction */
+                        tcg_temp_free_i64(tmp64);
+                        goto illegal_op;
+                    }
                     gen_addq_lo(s, tmp64, rs);
                     gen_addq_lo(s, tmp64, rd);
                 } else if (op & 0x40) {
@@ -10034,14 +10122,28 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
                         tmp2 = tcg_const_i32(imm);
                         if (op & 4) {
                             /* Unsigned.  */
-                            if ((op & 1) && shift == 0)
+                            if ((op & 1) && shift == 0){
+                                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) 
{
+                                    /* usat16 is a DSP instruction */
+                                    tcg_temp_free_i32(tmp);
+                                    tcg_temp_free_i32(tmp2);
+                                    goto illegal_op;
+                                }
                                 gen_helper_usat16(tmp, cpu_env, tmp, tmp2);
+                            }
                             else
                                 gen_helper_usat(tmp, cpu_env, tmp, tmp2);
                         } else {
                             /* Signed.  */
-                            if ((op & 1) && shift == 0)
+                            if ((op & 1) && shift == 0){
+                                if (!arm_dc_feature(s, ARM_FEATURE_THUMB_DSP)) 
{
+                                    /* ssat16 is a DSP instruction */
+                                    tcg_temp_free_i32(tmp);
+                                    tcg_temp_free_i32(tmp2);
+                                    goto illegal_op;
+                                }
                                 gen_helper_ssat16(tmp, cpu_env, tmp, tmp2);
+                            }
                             else
                                 gen_helper_ssat(tmp, cpu_env, tmp, tmp2);
                         }
1.9.1




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