[v2,08/15] target/m68k: Fix address argument for EXCP_TRACE

Commit Message

Richard Henderson Dec. 2, 2021, 8:48 p.m. UTC

According to the M68040 Users Manual, section 8.4.3,
Six word stack frame (format 2), Trace (and others) is
supposed to record the next insn in PC and the address
of the trapping instruction in ADDRESS.

Create gen_raise_exception_format2 to record the trapping
pc in env->mmu.ar.  Update m68k_interrupt_all to pass the
value to do_stack_frame.  Update cpu_loop to handle EXCP_TRACE.

Signed-off-by: Richard Henderson <[e-mail]>
---
 linux-user/m68k/cpu_loop.c |  3 +++
 target/m68k/op_helper.c    |  2 +-
 target/m68k/translate.c    | 27 ++++++++++++++++++---------
 3 files changed, 22 insertions(+), 10 deletions(-)

Comments

Richard Henderson Dec. 3, 2021, 2:21 p.m. UTC | #1

On 12/2/21 12:48 PM, Richard Henderson wrote:
> +static void gen_raise_exception_format2(DisasContext *s, int nr)
> +{
> +    /*
> +     * Pass the address of the insn to the exception handler,
> +     * for recording in the Format $2 (6-word) stack frame.
> +     * Re-use mmu.ar for the purpose, since that's only valid
> +     * after tlb_fill.
> +     */
> +    tcg_gen_st_i32(tcg_constant_i32(s->base.pc_next), cpu_env,
> +                   offsetof(CPUM68KState, mmu.ar));
> +    gen_raise_exception(nr);
> +    s->base.is_jmp = DISAS_NORETURN;
> +}

Hmph, I think this only really works from within m68k_tr_translate_insn. But most of the 
uses are from within m68k_rt_tb_stop, where we have already advanced pc_next to the next 
instruction.

I'm not sure how to test this...


r~

Patch

diff --git a/linux-user/m68k/cpu_loop.c b/linux-user/m68k/cpu_loop.c
index 267df05372..8e2b79550d 100644
--- a/linux-user/m68k/cpu_loop.c
+++ b/linux-user/m68k/cpu_loop.c
@@ -54,6 +54,9 @@  void cpu_loop(CPUM68KState *env)
         case EXCP_DIV0:
             force_sig_fault(TARGET_SIGFPE, TARGET_FPE_INTDIV, env->mmu.ar);
             break;
+        case EXCP_TRACE:
+            force_sig_fault(TARGET_SIGTRAP, TARGET_TRAP_TRACE, env->mmu.ar);
+            break;
         case EXCP_TRAP0:
             {
                 abi_long ret;
diff --git a/target/m68k/op_helper.c b/target/m68k/op_helper.c
index a6e4f5719f..c9ea28bf68 100644
--- a/target/m68k/op_helper.c
+++ b/target/m68k/op_helper.c
@@ -396,13 +396,13 @@  static void m68k_interrupt_all(CPUM68KState *env, int is_hw)
 
     case EXCP_ILLEGAL:
     case EXCP_TRAPCC:
-    case EXCP_TRACE:
         /* FIXME: addr is not only env->pc */
         do_stack_frame(env, &sp, 2, oldsr, env->pc, env->pc);
         break;
 
     case EXCP_CHK:
     case EXCP_DIV0:
+    case EXCP_TRACE:
         do_stack_frame(env, &sp, 2, oldsr, env->mmu.ar, env->pc);
         break;
 
diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index ae9f5a5222..fc2b6a3085 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -298,6 +298,20 @@  static void gen_raise_exception(int nr)
     tcg_temp_free_i32(tmp);
 }
 
+static void gen_raise_exception_format2(DisasContext *s, int nr)
+{
+    /*
+     * Pass the address of the insn to the exception handler,
+     * for recording in the Format $2 (6-word) stack frame.
+     * Re-use mmu.ar for the purpose, since that's only valid
+     * after tlb_fill.
+     */
+    tcg_gen_st_i32(tcg_constant_i32(s->base.pc_next), cpu_env,
+                   offsetof(CPUM68KState, mmu.ar));
+    gen_raise_exception(nr);
+    s->base.is_jmp = DISAS_NORETURN;
+}
+
 static void gen_exception(DisasContext *s, uint32_t dest, int nr)
 {
     update_cc_op(s);
@@ -1499,7 +1513,7 @@  static void gen_jmp_tb(DisasContext *s, int n, uint32_t dest)
     if (unlikely(s->ss_active)) {
         update_cc_op(s);
         tcg_gen_movi_i32(QREG_PC, dest);
-        gen_raise_exception(EXCP_TRACE);
+        gen_raise_exception_format2(s, EXCP_TRACE);
     } else if (translator_use_goto_tb(&s->base, dest)) {
         tcg_gen_goto_tb(n);
         tcg_gen_movi_i32(QREG_PC, dest);
@@ -6225,17 +6239,12 @@  static void m68k_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
         break;
     case DISAS_TOO_MANY:
         update_cc_op(dc);
-        if (dc->ss_active) {
-            tcg_gen_movi_i32(QREG_PC, dc->pc);
-            gen_raise_exception(EXCP_TRACE);
-        } else {
-            gen_jmp_tb(dc, 0, dc->pc);
-        }
+        gen_jmp_tb(dc, 0, dc->pc);
         break;
     case DISAS_JUMP:
         /* We updated CC_OP and PC in gen_jmp/gen_jmp_im.  */
         if (dc->ss_active) {
-            gen_raise_exception(EXCP_TRACE);
+            gen_raise_exception_format2(dc, EXCP_TRACE);
         } else {
             tcg_gen_lookup_and_goto_ptr();
         }
@@ -6246,7 +6255,7 @@  static void m68k_tr_tb_stop(DisasContextBase *dcbase, CPUState *cpu)
          * other state that may require returning to the main loop.
          */
         if (dc->ss_active) {
-            gen_raise_exception(EXCP_TRACE);
+            gen_raise_exception_format2(dc, EXCP_TRACE);
         } else {
             tcg_gen_exit_tb(NULL, 0);
         }