target/mips: Advance pc after semihosting exception

Delay generating the exception until after we know the
insn length, and record that length in env->error_code.

Fixes: 8ec7e3c53d4 ("target/mips: Use an exception for semihosting")
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/1126
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

6 files changed, 16 insertions, 11 deletions

diff --git a/target/mips/tcg/micromips_translate.c.inc b/target/mips/tcg/micromips_translate.c.inc
index 274caf2..b2c696f 100644
--- a/target/mips/tcg/micromips_translate.c.inc
+++ b/target/mips/tcg/micromips_translate.c.inc
@@ -826,7 +826,7 @@ static void gen_pool16c_insn(DisasContext *ctx)
         break;
     case SDBBP16:
         if (is_uhi(extract32(ctx->opcode, 0, 4))) {
-            generate_exception_end(ctx, EXCP_SEMIHOST);
+            ctx->base.is_jmp = DISAS_SEMIHOST;
         } else {
             /*
              * XXX: not clear which exception should be raised
@@ -942,7 +942,7 @@ static void gen_pool16c_r6_insn(DisasContext *ctx)
         case R6_SDBBP16:
             /* SDBBP16 */
             if (is_uhi(extract32(ctx->opcode, 6, 4))) {
-                generate_exception_end(ctx, EXCP_SEMIHOST);
+                ctx->base.is_jmp = DISAS_SEMIHOST;
             } else {
                 if (ctx->hflags & MIPS_HFLAG_SBRI) {
                     generate_exception(ctx, EXCP_RI);
@@ -1311,7 +1311,7 @@ static void gen_pool32axf(CPUMIPSState *env, DisasContext *ctx, int rt, int rs)
             break;
         case SDBBP:
             if (is_uhi(extract32(ctx->opcode, 16, 10))) {
-                generate_exception_end(ctx, EXCP_SEMIHOST);
+                ctx->base.is_jmp = DISAS_SEMIHOST;
             } else {
                 check_insn(ctx, ISA_MIPS_R1);
                 if (ctx->hflags & MIPS_HFLAG_SBRI) {
diff --git a/target/mips/tcg/mips16e_translate.c.inc b/target/mips/tcg/mips16e_translate.c.inc
index 0a3ba25..7568933 100644
--- a/target/mips/tcg/mips16e_translate.c.inc
+++ b/target/mips/tcg/mips16e_translate.c.inc
@@ -952,7 +952,7 @@ static int decode_ase_mips16e(CPUMIPSState *env, DisasContext *ctx)
             break;
         case RR_SDBBP:
             if (is_uhi(extract32(ctx->opcode, 5, 6))) {
-                generate_exception_end(ctx, EXCP_SEMIHOST);
+                ctx->base.is_jmp = DISAS_SEMIHOST;
             } else {
                 /*
                  * XXX: not clear which exception should be raised
diff --git a/target/mips/tcg/nanomips_translate.c.inc b/target/mips/tcg/nanomips_translate.c.inc
index ecb0ebe..b3aff22 100644
--- a/target/mips/tcg/nanomips_translate.c.inc
+++ b/target/mips/tcg/nanomips_translate.c.inc
@@ -3695,7 +3695,7 @@ static int decode_nanomips_32_48_opc(CPUMIPSState *env, DisasContext *ctx)
                 break;
             case NM_SDBBP:
                 if (is_uhi(extract32(ctx->opcode, 0, 19))) {
-                    generate_exception_end(ctx, EXCP_SEMIHOST);
+                    ctx->base.is_jmp = DISAS_SEMIHOST;
                 } else {
                     if (ctx->hflags & MIPS_HFLAG_SBRI) {
                         gen_reserved_instruction(ctx);
@@ -4634,7 +4634,7 @@ static int decode_isa_nanomips(CPUMIPSState *env, DisasContext *ctx)
                 break;
             case NM_SDBBP16:
                 if (is_uhi(extract32(ctx->opcode, 0, 3))) {
-                    generate_exception_end(ctx, EXCP_SEMIHOST);
+                    ctx->base.is_jmp = DISAS_SEMIHOST;
                 } else {
                     if (ctx->hflags & MIPS_HFLAG_SBRI) {
                         gen_reserved_instruction(ctx);
diff --git a/target/mips/tcg/sysemu/tlb_helper.c b/target/mips/tcg/sysemu/tlb_helper.c
index 57ffad2..9d16859 100644
--- a/target/mips/tcg/sysemu/tlb_helper.c
+++ b/target/mips/tcg/sysemu/tlb_helper.c
@@ -1056,6 +1056,7 @@ void mips_cpu_do_interrupt(CPUState *cs)
     case EXCP_SEMIHOST:
         cs->exception_index = EXCP_NONE;
         mips_semihosting(env);
+        env->active_tc.PC += env->error_code;
         return;
     case EXCP_DSS:
         env->CP0_Debug |= 1 << CP0DB_DSS;
diff --git a/target/mips/tcg/translate.c b/target/mips/tcg/translate.c
index 1f6a779..de1511b 100644
--- a/target/mips/tcg/translate.c
+++ b/target/mips/tcg/translate.c
@@ -1213,9 +1213,6 @@ TCGv_i64 fpu_f64[32];
 
 #include "exec/gen-icount.h"
 
-#define DISAS_STOP       DISAS_TARGET_0
-#define DISAS_EXIT       DISAS_TARGET_1
-
 static const char regnames_HI[][4] = {
     "HI0", "HI1", "HI2", "HI3",
 };
@@ -13902,7 +13899,7 @@ static void decode_opc_special_r6(CPUMIPSState *env, DisasContext *ctx)
         break;
     case R6_OPC_SDBBP:
         if (is_uhi(extract32(ctx->opcode, 6, 20))) {
-            generate_exception_end(ctx, EXCP_SEMIHOST);
+            ctx->base.is_jmp = DISAS_SEMIHOST;
         } else {
             if (ctx->hflags & MIPS_HFLAG_SBRI) {
                 gen_reserved_instruction(ctx);
@@ -14314,7 +14311,7 @@ static void decode_opc_special2_legacy(CPUMIPSState *env, DisasContext *ctx)
         break;
     case OPC_SDBBP:
         if (is_uhi(extract32(ctx->opcode, 6, 20))) {
-            generate_exception_end(ctx, EXCP_SEMIHOST);
+            ctx->base.is_jmp = DISAS_SEMIHOST;
         } else {
             /*
              * XXX: not clear which exception should be raised
@@ -16098,6 +16095,9 @@ static void mips_tr_translate_insn(DisasContextBase *dcbase, CPUState *cs)
     if (is_slot) {
         gen_branch(ctx, insn_bytes);
     }
+    if (ctx->base.is_jmp == DISAS_SEMIHOST) {
+        generate_exception_err(ctx, EXCP_SEMIHOST, insn_bytes);
+    }
     ctx->base.pc_next += insn_bytes;
 
     if (ctx->base.is_jmp != DISAS_NEXT) {
diff --git a/target/mips/tcg/translate.h b/target/mips/tcg/translate.h
index 5505322..69f8584 100644
--- a/target/mips/tcg/translate.h
+++ b/target/mips/tcg/translate.h
@@ -51,6 +51,10 @@ typedef struct DisasContext {
     int gi;
 } DisasContext;
 
+#define DISAS_STOP       DISAS_TARGET_0
+#define DISAS_EXIT       DISAS_TARGET_1
+#define DISAS_SEMIHOST   DISAS_TARGET_2
+
 /* MIPS major opcodes */
 #define MASK_OP_MAJOR(op)   (op & (0x3F << 26))