target/mips: reimplement SC instruction emulation and use cmpxchg

Completely rewrite conditional stores handling. Use cmpxchg.

This eliminates need for separate implementations of SC instruction
emulation for user and system emulation.

Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>
Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com>
Signed-off-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Acked-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Emilio G. Cota <cota@braap.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

6 files changed, 44 insertions, 191 deletions

diff --git a/linux-user/mips/cpu_loop.c b/linux-user/mips/cpu_loop.c
index d0f62ec9b6..61dc90d51c 100644
--- a/linux-user/mips/cpu_loop.c
+++ b/linux-user/mips/cpu_loop.c
@@ -392,70 +392,6 @@ static const uint8_t mips_syscall_args[] = {
 #  undef MIPS_SYS
 # endif /* O32 */
 
-static int do_store_exclusive(CPUMIPSState *env)
-{
-    target_ulong addr;
-    target_ulong page_addr;
-    target_ulong val;
-    uint32_t val_wp = 0;
-    uint32_t llnewval_wp = 0;
-    int flags;
-    int segv = 0;
-    int reg;
-    int d;
-    int wp;
-
-    addr = env->lladdr;
-    page_addr = addr & TARGET_PAGE_MASK;
-    start_exclusive();
-    mmap_lock();
-    flags = page_get_flags(page_addr);
-    if ((flags & PAGE_READ) == 0) {
-        segv = 1;
-    } else {
-        reg = env->llreg & 0x1f;
-        d = (env->llreg & 0x20) != 0;
-        wp = (env->llreg & 0x40) != 0;
-        if (!wp) {
-            if (d) {
-                segv = get_user_s64(val, addr);
-            } else {
-                segv = get_user_s32(val, addr);
-            }
-        } else {
-            segv = get_user_s32(val, addr);
-            segv |= get_user_s32(val_wp, addr);
-            llnewval_wp = env->llnewval_wp;
-        }
-        if (!segv) {
-            if (val != env->llval && val_wp == llnewval_wp) {
-                env->active_tc.gpr[reg] = 0;
-            } else {
-                if (!wp) {
-                    if (d) {
-                        segv = put_user_u64(env->llnewval, addr);
-                    } else {
-                        segv = put_user_u32(env->llnewval, addr);
-                    }
-                } else {
-                    segv = put_user_u32(env->llnewval, addr);
-                    segv |= put_user_u32(env->llnewval_wp, addr + 4);
-                }
-                if (!segv) {
-                    env->active_tc.gpr[reg] = 1;
-                }
-            }
-        }
-    }
-    env->lladdr = -1;
-    if (!segv) {
-        env->active_tc.PC += 4;
-    }
-    mmap_unlock();
-    end_exclusive();
-    return segv;
-}
-
 /* Break codes */
 enum {
     BRK_OVERFLOW = 6,
@@ -597,15 +533,6 @@ done_syscall:
             info.si_code = TARGET_TRAP_BRKPT;
             queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
             break;
-        case EXCP_SC:
-            if (do_store_exclusive(env)) {
-                info.si_signo = TARGET_SIGSEGV;
-                info.si_errno = 0;
-                info.si_code = TARGET_SEGV_MAPERR;
-                info._sifields._sigfault._addr = env->active_tc.PC;
-                queue_signal(env, info.si_signo, QEMU_SI_FAULT, &info);
-            }
-            break;
         case EXCP_DSPDIS:
             info.si_signo = TARGET_SIGILL;
             info.si_errno = 0;
diff --git a/target/mips/cpu.h b/target/mips/cpu.h
index f10e016673..eccee375cb 100644
--- a/target/mips/cpu.h
+++ b/target/mips/cpu.h
@@ -876,10 +876,8 @@ struct CPUMIPSState {
  */
     target_ulong lladdr; /* LL virtual address compared against SC */
     target_ulong llval;
-    target_ulong llnewval;
     uint64_t llval_wp;
     uint32_t llnewval_wp;
-    target_ulong llreg;
     uint64_t CP0_LLAddr_rw_bitmask;
     int CP0_LLAddr_shift;
 /*
@@ -1156,8 +1154,6 @@ enum {
 
     EXCP_LAST = EXCP_TLBRI,
 };
-/* Dummy exception for conditional stores.  */
-#define EXCP_SC 0x100
 
 /*
  * This is an internally generated WAKE request line.
diff --git a/target/mips/helper.c b/target/mips/helper.c
index 8988452dbd..944f094566 100644
--- a/target/mips/helper.c
+++ b/target/mips/helper.c
@@ -1463,10 +1463,8 @@ void QEMU_NORETURN do_raise_exception_err(CPUMIPSState *env,
 {
     CPUState *cs = CPU(mips_env_get_cpu(env));
 
-    if (exception < EXCP_SC) {
-        qemu_log_mask(CPU_LOG_INT, "%s: %d %d\n",
-                      __func__, exception, error_code);
-    }
+    qemu_log_mask(CPU_LOG_INT, "%s: %d %d\n",
+                  __func__, exception, error_code);
     cs->exception_index = exception;
     env->error_code = error_code;
 
diff --git a/target/mips/helper.h b/target/mips/helper.h
index 8872c4647b..a6d687e340 100644
--- a/target/mips/helper.h
+++ b/target/mips/helper.h
@@ -13,10 +13,8 @@ DEF_HELPER_4(swr, void, env, tl, tl, int)
 
 #ifndef CONFIG_USER_ONLY
 DEF_HELPER_3(ll, tl, env, tl, int)
-DEF_HELPER_4(sc, tl, env, tl, tl, int)
 #ifdef TARGET_MIPS64
 DEF_HELPER_3(lld, tl, env, tl, int)
-DEF_HELPER_4(scd, tl, env, tl, tl, int)
 #endif
 #endif
 
diff --git a/target/mips/op_helper.c b/target/mips/op_helper.c
index 44f2626f3f..943a7ea579 100644
--- a/target/mips/op_helper.c
+++ b/target/mips/op_helper.c
@@ -380,33 +380,6 @@ HELPER_LD_ATOMIC(ll, lw, 0x3)
 HELPER_LD_ATOMIC(lld, ld, 0x7)
 #endif
 #undef HELPER_LD_ATOMIC
-
-#define HELPER_ST_ATOMIC(name, ld_insn, st_insn, almask)                      \
-target_ulong helper_##name(CPUMIPSState *env, target_ulong arg1,              \
-                           target_ulong arg2, int mem_idx)                    \
-{                                                                             \
-    target_long tmp;                                                          \
-                                                                              \
-    if (arg2 & almask) {                                                      \
-        if (!(env->hflags & MIPS_HFLAG_DM)) {                                 \
-            env->CP0_BadVAddr = arg2;                                         \
-        }                                                                     \
-        do_raise_exception(env, EXCP_AdES, GETPC());                          \
-    }                                                                         \
-    if (arg2 == env->lladdr) {                                                \
-        tmp = do_##ld_insn(env, arg2, mem_idx, GETPC());                      \
-        if (tmp == env->llval) {                                              \
-            do_##st_insn(env, arg2, arg1, mem_idx, GETPC());                  \
-            return 1;                                                         \
-        }                                                                     \
-    }                                                                         \
-    return 0;                                                                 \
-}
-HELPER_ST_ATOMIC(sc, lw, sw, 0x3)
-#ifdef TARGET_MIPS64
-HELPER_ST_ATOMIC(scd, ld, sd, 0x7)
-#endif
-#undef HELPER_ST_ATOMIC
 #endif
 
 #ifdef TARGET_WORDS_BIGENDIAN
diff --git a/target/mips/translate.c b/target/mips/translate.c
index 307d4eaa5e..3b170208c3 100644
--- a/target/mips/translate.c
+++ b/target/mips/translate.c
@@ -2450,6 +2450,7 @@ enum {
 static TCGv cpu_gpr[32], cpu_PC;
 static TCGv cpu_HI[MIPS_DSP_ACC], cpu_LO[MIPS_DSP_ACC];
 static TCGv cpu_dspctrl, btarget, bcond;
+static TCGv cpu_lladdr, cpu_llval;
 static TCGv_i32 hflags;
 static TCGv_i32 fpu_fcr0, fpu_fcr31;
 static TCGv_i64 fpu_f64[32];
@@ -3326,48 +3327,6 @@ OP_LD_ATOMIC(lld,ld64);
 #endif
 #undef OP_LD_ATOMIC
 
-#ifdef CONFIG_USER_ONLY
-#define OP_ST_ATOMIC(insn,fname,ldname,almask)                               \
-static inline void op_st_##insn(TCGv arg1, TCGv arg2, int rt, int mem_idx,   \
-                                DisasContext *ctx)                           \
-{                                                                            \
-    TCGv t0 = tcg_temp_new();                                                \
-    TCGLabel *l1 = gen_new_label();                                          \
-    TCGLabel *l2 = gen_new_label();                                          \
-                                                                             \
-    tcg_gen_andi_tl(t0, arg2, almask);                                       \
-    tcg_gen_brcondi_tl(TCG_COND_EQ, t0, 0, l1);                              \
-    tcg_gen_st_tl(arg2, cpu_env, offsetof(CPUMIPSState, CP0_BadVAddr));          \
-    generate_exception(ctx, EXCP_AdES);                                      \
-    gen_set_label(l1);                                                       \
-    tcg_gen_ld_tl(t0, cpu_env, offsetof(CPUMIPSState, lladdr));                  \
-    tcg_gen_brcond_tl(TCG_COND_NE, arg2, t0, l2);                            \
-    tcg_gen_movi_tl(t0, rt | ((almask << 3) & 0x20));                        \
-    tcg_gen_st_tl(t0, cpu_env, offsetof(CPUMIPSState, llreg));                   \
-    tcg_gen_st_tl(arg1, cpu_env, offsetof(CPUMIPSState, llnewval));              \
-    generate_exception_end(ctx, EXCP_SC);                                    \
-    gen_set_label(l2);                                                       \
-    tcg_gen_movi_tl(t0, 0);                                                  \
-    gen_store_gpr(t0, rt);                                                   \
-    tcg_temp_free(t0);                                                       \
-}
-#else
-#define OP_ST_ATOMIC(insn,fname,ldname,almask)                               \
-static inline void op_st_##insn(TCGv arg1, TCGv arg2, int rt, int mem_idx,   \
-                                DisasContext *ctx)                           \
-{                                                                            \
-    TCGv t0 = tcg_temp_new();                                                \
-    gen_helper_1e2i(insn, t0, arg1, arg2, mem_idx);                          \
-    gen_store_gpr(t0, rt);                                                   \
-    tcg_temp_free(t0);                                                       \
-}
-#endif
-OP_ST_ATOMIC(sc,st32,ld32s,0x3);
-#if defined(TARGET_MIPS64)
-OP_ST_ATOMIC(scd,st64,ld64,0x7);
-#endif
-#undef OP_ST_ATOMIC
-
 static void gen_base_offset_addr (DisasContext *ctx, TCGv addr,
                                   int base, int offset)
 {
@@ -3679,40 +3638,38 @@ static void gen_st (DisasContext *ctx, uint32_t opc, int rt,
 
 
 /* Store conditional */
-static void gen_st_cond (DisasContext *ctx, uint32_t opc, int rt,
-                         int base, int16_t offset)
+static void gen_st_cond(DisasContext *ctx, int rt, int base, int offset,
+                        TCGMemOp tcg_mo, bool eva)
 {
-    TCGv t0, t1;
-    int mem_idx = ctx->mem_idx;
+    TCGv addr, t0, val;
+    TCGLabel *l1 = gen_new_label();
+    TCGLabel *done = gen_new_label();
 
-#ifdef CONFIG_USER_ONLY
-    t0 = tcg_temp_local_new();
-    t1 = tcg_temp_local_new();
-#else
     t0 = tcg_temp_new();
-    t1 = tcg_temp_new();
-#endif
-    gen_base_offset_addr(ctx, t0, base, offset);
-    gen_load_gpr(t1, rt);
-    switch (opc) {
-#if defined(TARGET_MIPS64)
-    case OPC_SCD:
-    case R6_OPC_SCD:
-        op_st_scd(t1, t0, rt, mem_idx, ctx);
-        break;
-#endif
-    case OPC_SCE:
-        mem_idx = MIPS_HFLAG_UM;
-        /* fall through */
-    case OPC_SC:
-    case R6_OPC_SC:
-        op_st_sc(t1, t0, rt, mem_idx, ctx);
-        break;
-    }
-    tcg_temp_free(t1);
+    addr = tcg_temp_new();
+    /* compare the address against that of the preceeding LL */
+    gen_base_offset_addr(ctx, addr, base, offset);
+    tcg_gen_brcond_tl(TCG_COND_EQ, addr, cpu_lladdr, l1);
+    tcg_temp_free(addr);
+    tcg_gen_movi_tl(t0, 0);
+    gen_store_gpr(t0, rt);
+    tcg_gen_br(done);
+
+    gen_set_label(l1);
+    /* generate cmpxchg */
+    val = tcg_temp_new();
+    gen_load_gpr(val, rt);
+    tcg_gen_atomic_cmpxchg_tl(t0, cpu_lladdr, cpu_llval, val,
+                              eva ? MIPS_HFLAG_UM : ctx->mem_idx, tcg_mo);
+    tcg_gen_setcond_tl(TCG_COND_EQ, t0, t0, cpu_llval);
+    gen_store_gpr(t0, rt);
+    tcg_temp_free(val);
+
+    gen_set_label(done);
     tcg_temp_free(t0);
 }
 
+
 static void gen_scwp(DisasContext *ctx, uint32_t base, int16_t offset,
                     uint32_t reg1, uint32_t reg2, bool eva)
 {
@@ -16864,13 +16821,13 @@ static void decode_micromips32_opc(CPUMIPSState *env, DisasContext *ctx)
             gen_st(ctx, mips32_op, rt, rs, offset);
             break;
         case SC:
-            gen_st_cond(ctx, OPC_SC, rt, rs, offset);
+            gen_st_cond(ctx, rt, rs, offset, MO_TESL, false);
             break;
 #if defined(TARGET_MIPS64)
         case SCD:
             check_insn(ctx, ISA_MIPS3);
             check_mips_64(ctx);
-            gen_st_cond(ctx, OPC_SCD, rt, rs, offset);
+            gen_st_cond(ctx, rt, rs, offset, MO_TEQ, false);
             break;
 #endif
         case LD_EVA:
@@ -16951,7 +16908,7 @@ static void decode_micromips32_opc(CPUMIPSState *env, DisasContext *ctx)
                 mips32_op = OPC_SHE;
                 goto do_st_lr;
             case SCE:
-                gen_st_cond(ctx, OPC_SCE, rt, rs, offset);
+                gen_st_cond(ctx, rt, rs, offset, MO_TESL, true);
                 break;
             case SWE:
                 mips32_op = OPC_SWE;
@@ -21558,7 +21515,7 @@ static int decode_nanomips_32_48_opc(CPUMIPSState *env, DisasContext *ctx)
                 case NM_P_SC:
                     switch (ctx->opcode & 0x03) {
                     case NM_SC:
-                        gen_st_cond(ctx, OPC_SC, rt, rs, s);
+                        gen_st_cond(ctx, rt, rs, s, MO_TESL, false);
                         break;
                     case NM_SCWP:
                         check_xnp(ctx);
@@ -21661,7 +21618,7 @@ static int decode_nanomips_32_48_opc(CPUMIPSState *env, DisasContext *ctx)
                         check_xnp(ctx);
                         check_eva(ctx);
                         check_cp0_enabled(ctx);
-                        gen_st_cond(ctx, OPC_SCE, rt, rs, s);
+                        gen_st_cond(ctx, rt, rs, s, MO_TESL, true);
                         break;
                     case NM_SCWPE:
                         check_xnp(ctx);
@@ -26698,7 +26655,7 @@ static void decode_opc_special3_r6(CPUMIPSState *env, DisasContext *ctx)
         }
         break;
     case R6_OPC_SC:
-        gen_st_cond(ctx, op1, rt, rs, imm);
+        gen_st_cond(ctx, rt, rs, imm, MO_TESL, false);
         break;
     case R6_OPC_LL:
         gen_ld(ctx, op1, rt, rs, imm);
@@ -26725,7 +26682,7 @@ static void decode_opc_special3_r6(CPUMIPSState *env, DisasContext *ctx)
         break;
 #if defined(TARGET_MIPS64)
     case R6_OPC_SCD:
-        gen_st_cond(ctx, op1, rt, rs, imm);
+        gen_st_cond(ctx, rt, rs, imm, MO_TEQ, false);
         break;
     case R6_OPC_LLD:
         gen_ld(ctx, op1, rt, rs, imm);
@@ -27580,7 +27537,7 @@ static void decode_opc_special3(CPUMIPSState *env, DisasContext *ctx)
             return;
         case OPC_SCE:
             check_cp0_enabled(ctx);
-            gen_st_cond(ctx, op1, rt, rs, imm);
+            gen_st_cond(ctx, rt, rs, imm, MO_TESL, true);
             return;
         case OPC_CACHEE:
             check_cp0_enabled(ctx);
@@ -29172,8 +29129,8 @@ static void decode_opc(CPUMIPSState *env, DisasContext *ctx)
         if (ctx->insn_flags & INSN_R5900) {
             check_insn_opc_user_only(ctx, INSN_R5900);
         }
-         gen_st_cond(ctx, op, rt, rs, imm);
-         break;
+        gen_st_cond(ctx, rt, rs, imm, MO_TESL, false);
+        break;
     case OPC_CACHE:
         check_insn_opc_removed(ctx, ISA_MIPS32R6);
         check_cp0_enabled(ctx);
@@ -29472,7 +29429,7 @@ static void decode_opc(CPUMIPSState *env, DisasContext *ctx)
             check_insn_opc_user_only(ctx, INSN_R5900);
         }
         check_mips_64(ctx);
-        gen_st_cond(ctx, op, rt, rs, imm);
+        gen_st_cond(ctx, rt, rs, imm, MO_TEQ, false);
         break;
     case OPC_BNVC: /* OPC_BNEZALC, OPC_BNEC, OPC_DADDI */
         if (ctx->insn_flags & ISA_MIPS32R6) {
@@ -29853,6 +29810,10 @@ void mips_tcg_init(void)
     fpu_fcr31 = tcg_global_mem_new_i32(cpu_env,
                                        offsetof(CPUMIPSState, active_fpu.fcr31),
                                        "fcr31");
+    cpu_lladdr = tcg_global_mem_new(cpu_env, offsetof(CPUMIPSState, lladdr),
+                                    "lladdr");
+    cpu_llval = tcg_global_mem_new(cpu_env, offsetof(CPUMIPSState, llval),
+                                   "llval");
 
 #if defined(TARGET_MIPS64)
     cpu_mmr[0] = NULL;