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[Qemu-devel] [PATCH] Target-arm: Add the Cortex-M4 CPU


From: Aurelio C. Remonda
Subject: [Qemu-devel] [PATCH] Target-arm: Add the Cortex-M4 CPU
Date: Thu, 28 May 2015 18:09:58 -0300

This patch adds the Cortex-M4 CPU. The M4 is basically the same as the M3,
the main differences being the DSP instructions and an optional FPU.
The DSP instructions are already implemented in Qemu, as the A and R profiles
use them.

I created an ARM_FEATURE_THUMB_DSP to be added to any non-M thumb2-compatible
CPU that uses DSP instructions, and I manually added it to the M4 in its initfn.

The optional FPU in the M4 could be added in the future as a "Cortex-M4F" CPU.
All we'd have to do is add the ARM_FEATURE_VFP4 to the initfn.

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.c       |  22 +++++++++
 target-arm/cpu.h       |   1 +
 target-arm/translate.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++--
 3 files changed, 149 insertions(+), 4 deletions(-)

diff --git a/target-arm/cpu.c b/target-arm/cpu.c
index 3ca3fa8..9be4a06 100644
--- a/target-arm/cpu.c
+++ b/target-arm/cpu.c
@@ -512,6 +512,10 @@ static void arm_cpu_realizefn(DeviceState *dev, Error 
**errp)
     if (arm_feature(env, ARM_FEATURE_CBAR_RO)) {
         set_feature(env, ARM_FEATURE_CBAR);
     }
+    if (arm_feature(env,ARM_FEATURE_THUMB2) &&
+        !arm_feature(env,ARM_FEATURE_M)) {
+        set_feature(env, ARM_FEATURE_THUMB_DSP);
+    }
 
     if (cpu->reset_hivecs) {
             cpu->reset_sctlr |= (1 << 13);
@@ -761,6 +765,22 @@ static void cortex_m3_initfn(Object *obj)
     set_feature(&cpu->env, ARM_FEATURE_M);
     cpu->midr = 0x410fc231;
 }
+static void cortex_m4_initfn(Object *obj)
+{
+    ARMCPU *cpu = ARM_CPU(obj);
+    set_feature(&cpu->env, ARM_FEATURE_V7);
+    set_feature(&cpu->env, ARM_FEATURE_M);
+    set_feature(&cpu->env, ARM_FEATURE_THUMB_DSP);
+    cpu->midr = 0x410fc240;
+    /* Main id register CPUID bit assignments
+     * Bits    NAME        Function
+     * [31:24] IMPLEMENTER Indicates implementor: 0x41 = ARM
+     * [23:20] VARIANT     Indicates processor revision: 0x0 = Revision 0
+     * [19:16] (Constant)  Reads as 0xF
+     * [15:4]  PARTNO      Indicates part number: 0xC24 = Cortex-M4
+     * [3:0]   REVISION    Indicates patch release: 0x0 = Patch 0.
+     */
+}
 
 static void arm_v7m_class_init(ObjectClass *oc, void *data)
 {
@@ -1164,6 +1184,8 @@ static const ARMCPUInfo arm_cpus[] = {
     { .name = "arm11mpcore", .initfn = arm11mpcore_initfn },
     { .name = "cortex-m3",   .initfn = cortex_m3_initfn,
                              .class_init = arm_v7m_class_init },
+    { .name = "cortex-m4",   .initfn = cortex_m4_initfn,
+                             .class_init = arm_v7m_class_init },
     { .name = "cortex-a8",   .initfn = cortex_a8_initfn },
     { .name = "cortex-a9",   .initfn = cortex_a9_initfn },
     { .name = "cortex-a15",  .initfn = cortex_a15_initfn },
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index d4a5899..fa5c3bc 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -886,6 +886,7 @@ 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 9116529..c9d2e4f 100644
--- a/target-arm/translate.c
+++ b/target-arm/translate.c
@@ -9428,6 +9428,10 @@ 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);
@@ -9502,13 +9506,37 @@ 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;
             }
+            /*-sxtab->-sxtab16->*/
             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
+                     */
+                    /* need to free this so there's no TCG temporary leak */
+                    tcg_temp_free_i32(tmp);
+                    goto illegal_op;
+                }
                 tmp2 = load_reg(s, rn);
                 if ((op >> 1) == 1) {
                     gen_add16(tmp, tmp2);
@@ -9521,6 +9549,12 @@ 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;
@@ -9532,8 +9566,13 @@ static int disas_thumb2_insn(CPUARMState *env, 
DisasContext *s, uint16_t insn_hw
             break;
         case 3: /* Other data processing.  */
             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)
@@ -9559,6 +9598,12 @@ 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. */
+                    /* need to free this so there's no TCG temporary leak */
+                    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));
@@ -9624,6 +9669,15 @@ 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
+                     */
+                     /* need to free this so there's no TCG temporary leak */
+                    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) {
@@ -9634,6 +9688,14 @@ 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 */
+
+                    /* need to free this so there's no TCG temporary leak */
+                    tcg_temp_free_i32(tmp);
+                    tcg_temp_free_i32(tmp2);
+                    goto illegal_op;
+                }
                 if (op)
                     gen_swap_half(tmp2);
                 gen_smul_dual(tmp, tmp2);
@@ -9656,6 +9718,13 @@ 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 */
+                    /* need to free this so there's no TCG temporary leak */
+                    tcg_temp_free_i32(tmp);
+                    tcg_temp_free_i32(tmp2);
+                    goto illegal_op;
+                }
                 if (op)
                     tcg_gen_sari_i32(tmp2, tmp2, 16);
                 else
@@ -9673,6 +9742,15 @@ 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
+                     */
+                     /* need to free this so there's no TCG temporary leak */
+                    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);
@@ -9719,6 +9797,13 @@ 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 */
+                    /* need to free this so there's no TCG temporary leak */
+                    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);
@@ -9742,6 +9827,17 @@ 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
+                             */
+                            /* need to free this so there's no TCG
+                             * temporary leak
+                             */
+                            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();
@@ -9754,6 +9850,12 @@ 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 */
+                        /* need to free this so there's no TCG temporary leak 
*/
+                        tcg_temp_free_i64(tmp64);
+                        goto illegal_op;
+                    }
                     gen_addq_lo(s, tmp64, rs);
                     gen_addq_lo(s, tmp64, rd);
                 } else if (op & 0x40) {
@@ -10018,14 +10120,34 @@ 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 */
+                                    /* need to free this so there's no TCG
+                                     * temporary leak
+                                     */
+                                    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 */
+                                    /* need to free this so there's no TCG
+                                     * temporary leak
+                                     */
+                                    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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