target/m68k: Fix pc, c flag, and address argument for EXCP_DIV0

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

While the N, Z and V flags are documented to be undefine on DIV0,
the C flag is documented as always cleared.

Update helper_div* to take the instruction length as an argument
and use raise_exception_format2.  Hoist the reset of the C flag
above the division by zero check.

Update m68k_interrupt_all to pass mmu.ar to do_stack_frame.
Update cpu_loop to pass mmu.ar to siginfo.si_addr, as the
kernel does in trap_c().

Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220602013401.303699-8-richard.henderson@linaro.org>
Signed-off-by: Laurent Vivier <laurent@vivier.eu>

3 files changed, 51 insertions, 42 deletions

diff --git a/target/m68k/helper.h b/target/m68k/helper.h
index 0a6b4146f6..f016c4c1c2 100644
--- a/target/m68k/helper.h
+++ b/target/m68k/helper.h
@@ -1,12 +1,12 @@
 DEF_HELPER_1(bitrev, i32, i32)
 DEF_HELPER_1(ff1, i32, i32)
 DEF_HELPER_FLAGS_2(sats, TCG_CALL_NO_RWG_SE, i32, i32, i32)
-DEF_HELPER_3(divuw, void, env, int, i32)
-DEF_HELPER_3(divsw, void, env, int, s32)
-DEF_HELPER_4(divul, void, env, int, int, i32)
-DEF_HELPER_4(divsl, void, env, int, int, s32)
-DEF_HELPER_4(divull, void, env, int, int, i32)
-DEF_HELPER_4(divsll, void, env, int, int, s32)
+DEF_HELPER_4(divuw, void, env, int, i32, int)
+DEF_HELPER_4(divsw, void, env, int, s32, int)
+DEF_HELPER_5(divul, void, env, int, int, i32, int)
+DEF_HELPER_5(divsl, void, env, int, int, s32, int)
+DEF_HELPER_5(divull, void, env, int, int, i32, int)
+DEF_HELPER_5(divsll, void, env, int, int, s32, int)
 DEF_HELPER_2(set_sr, void, env, i32)
 DEF_HELPER_3(cf_movec_to, void, env, i32, i32)
 DEF_HELPER_3(m68k_movec_to, void, env, i32, i32)
diff --git a/target/m68k/op_helper.c b/target/m68k/op_helper.c
index 750d65576f..729ee0e934 100644
--- a/target/m68k/op_helper.c
+++ b/target/m68k/op_helper.c
@@ -396,7 +396,6 @@ static void m68k_interrupt_all(CPUM68KState *env, int is_hw)
         break;
 
     case EXCP_ILLEGAL:
-    case EXCP_DIV0:
     case EXCP_TRAPCC:
     case EXCP_TRACE:
         /* FIXME: addr is not only env->pc */
@@ -404,6 +403,7 @@ static void m68k_interrupt_all(CPUM68KState *env, int is_hw)
         break;
 
     case EXCP_CHK:
+    case EXCP_DIV0:
         do_stack_frame(env, &sp, 2, oldsr, env->mmu.ar, env->pc);
         break;
 
@@ -574,18 +574,19 @@ raise_exception_format2(CPUM68KState *env, int tt, int ilen, uintptr_t raddr)
     cpu_loop_exit(cs);
 }
 
-void HELPER(divuw)(CPUM68KState *env, int destr, uint32_t den)
+void HELPER(divuw)(CPUM68KState *env, int destr, uint32_t den, int ilen)
 {
     uint32_t num = env->dregs[destr];
     uint32_t quot, rem;
 
+    env->cc_c = 0; /* always cleared, even if div0 */
+
     if (den == 0) {
-        raise_exception_ra(env, EXCP_DIV0, GETPC());
+        raise_exception_format2(env, EXCP_DIV0, ilen, GETPC());
     }
     quot = num / den;
     rem = num % den;
 
-    env->cc_c = 0; /* always cleared, even if overflow */
     if (quot > 0xffff) {
         env->cc_v = -1;
         /*
@@ -601,18 +602,19 @@ void HELPER(divuw)(CPUM68KState *env, int destr, uint32_t den)
     env->cc_v = 0;
 }
 
-void HELPER(divsw)(CPUM68KState *env, int destr, int32_t den)
+void HELPER(divsw)(CPUM68KState *env, int destr, int32_t den, int ilen)
 {
     int32_t num = env->dregs[destr];
     uint32_t quot, rem;
 
+    env->cc_c = 0; /* always cleared, even if overflow/div0 */
+
     if (den == 0) {
-        raise_exception_ra(env, EXCP_DIV0, GETPC());
+        raise_exception_format2(env, EXCP_DIV0, ilen, GETPC());
     }
     quot = num / den;
     rem = num % den;
 
-    env->cc_c = 0; /* always cleared, even if overflow */
     if (quot != (int16_t)quot) {
         env->cc_v = -1;
         /* nothing else is modified */
@@ -629,18 +631,20 @@ void HELPER(divsw)(CPUM68KState *env, int destr, int32_t den)
     env->cc_v = 0;
 }
 
-void HELPER(divul)(CPUM68KState *env, int numr, int regr, uint32_t den)
+void HELPER(divul)(CPUM68KState *env, int numr, int regr,
+                   uint32_t den, int ilen)
 {
     uint32_t num = env->dregs[numr];
     uint32_t quot, rem;
 
+    env->cc_c = 0; /* always cleared, even if div0 */
+
     if (den == 0) {
-        raise_exception_ra(env, EXCP_DIV0, GETPC());
+        raise_exception_format2(env, EXCP_DIV0, ilen, GETPC());
     }
     quot = num / den;
     rem = num % den;
 
-    env->cc_c = 0;
     env->cc_z = quot;
     env->cc_n = quot;
     env->cc_v = 0;
@@ -657,18 +661,20 @@ void HELPER(divul)(CPUM68KState *env, int numr, int regr, uint32_t den)
     }
 }
 
-void HELPER(divsl)(CPUM68KState *env, int numr, int regr, int32_t den)
+void HELPER(divsl)(CPUM68KState *env, int numr, int regr,
+                   int32_t den, int ilen)
 {
     int32_t num = env->dregs[numr];
     int32_t quot, rem;
 
+    env->cc_c = 0; /* always cleared, even if overflow/div0 */
+
     if (den == 0) {
-        raise_exception_ra(env, EXCP_DIV0, GETPC());
+        raise_exception_format2(env, EXCP_DIV0, ilen, GETPC());
     }
     quot = num / den;
     rem = num % den;
 
-    env->cc_c = 0;
     env->cc_z = quot;
     env->cc_n = quot;
     env->cc_v = 0;
@@ -685,19 +691,21 @@ void HELPER(divsl)(CPUM68KState *env, int numr, int regr, int32_t den)
     }
 }
 
-void HELPER(divull)(CPUM68KState *env, int numr, int regr, uint32_t den)
+void HELPER(divull)(CPUM68KState *env, int numr, int regr,
+                    uint32_t den, int ilen)
 {
     uint64_t num = deposit64(env->dregs[numr], 32, 32, env->dregs[regr]);
     uint64_t quot;
     uint32_t rem;
 
+    env->cc_c = 0; /* always cleared, even if overflow/div0 */
+
     if (den == 0) {
-        raise_exception_ra(env, EXCP_DIV0, GETPC());
+        raise_exception_format2(env, EXCP_DIV0, ilen, GETPC());
     }
     quot = num / den;
     rem = num % den;
 
-    env->cc_c = 0; /* always cleared, even if overflow */
     if (quot > 0xffffffffULL) {
         env->cc_v = -1;
         /*
@@ -720,19 +728,21 @@ void HELPER(divull)(CPUM68KState *env, int numr, int regr, uint32_t den)
     env->dregs[numr] = quot;
 }
 
-void HELPER(divsll)(CPUM68KState *env, int numr, int regr, int32_t den)
+void HELPER(divsll)(CPUM68KState *env, int numr, int regr,
+                    int32_t den, int ilen)
 {
     int64_t num = deposit64(env->dregs[numr], 32, 32, env->dregs[regr]);
     int64_t quot;
     int32_t rem;
 
+    env->cc_c = 0; /* always cleared, even if overflow/div0 */
+
     if (den == 0) {
-        raise_exception_ra(env, EXCP_DIV0, GETPC());
+        raise_exception_format2(env, EXCP_DIV0, ilen, GETPC());
     }
     quot = num / den;
     rem = num % den;
 
-    env->cc_c = 0; /* always cleared, even if overflow */
     if (quot != (int32_t)quot) {
         env->cc_v = -1;
         /*
diff --git a/target/m68k/translate.c b/target/m68k/translate.c
index 22e5379d3c..6075f49930 100644
--- a/target/m68k/translate.c
+++ b/target/m68k/translate.c
@@ -1601,6 +1601,7 @@ DISAS_INSN(divw)
     int sign;
     TCGv src;
     TCGv destr;
+    TCGv ilen;
 
     /* divX.w <EA>,Dn    32/16 -> 16r:16q */
 
@@ -1609,20 +1610,20 @@ DISAS_INSN(divw)
     /* dest.l / src.w */
 
     SRC_EA(env, src, OS_WORD, sign, NULL);
-    destr = tcg_const_i32(REG(insn, 9));
+    destr = tcg_constant_i32(REG(insn, 9));
+    ilen = tcg_constant_i32(s->pc - s->base.pc_next);
     if (sign) {
-        gen_helper_divsw(cpu_env, destr, src);
+        gen_helper_divsw(cpu_env, destr, src, ilen);
     } else {
-        gen_helper_divuw(cpu_env, destr, src);
+        gen_helper_divuw(cpu_env, destr, src, ilen);
     }
-    tcg_temp_free(destr);
 
     set_cc_op(s, CC_OP_FLAGS);
 }
 
 DISAS_INSN(divl)
 {
-    TCGv num, reg, den;
+    TCGv num, reg, den, ilen;
     int sign;
     uint16_t ext;
 
@@ -1639,15 +1640,14 @@ DISAS_INSN(divl)
         /* divX.l <EA>, Dr:Dq    64/32 -> 32r:32q */
 
         SRC_EA(env, den, OS_LONG, 0, NULL);
-        num = tcg_const_i32(REG(ext, 12));
-        reg = tcg_const_i32(REG(ext, 0));
+        num = tcg_constant_i32(REG(ext, 12));
+        reg = tcg_constant_i32(REG(ext, 0));
+        ilen = tcg_constant_i32(s->pc - s->base.pc_next);
         if (sign) {
-            gen_helper_divsll(cpu_env, num, reg, den);
+            gen_helper_divsll(cpu_env, num, reg, den, ilen);
         } else {
-            gen_helper_divull(cpu_env, num, reg, den);
+            gen_helper_divull(cpu_env, num, reg, den, ilen);
         }
-        tcg_temp_free(reg);
-        tcg_temp_free(num);
         set_cc_op(s, CC_OP_FLAGS);
         return;
     }
@@ -1656,15 +1656,14 @@ DISAS_INSN(divl)
     /* divXl.l <EA>, Dr:Dq    32/32 -> 32r:32q */
 
     SRC_EA(env, den, OS_LONG, 0, NULL);
-    num = tcg_const_i32(REG(ext, 12));
-    reg = tcg_const_i32(REG(ext, 0));
+    num = tcg_constant_i32(REG(ext, 12));
+    reg = tcg_constant_i32(REG(ext, 0));
+    ilen = tcg_constant_i32(s->pc - s->base.pc_next);
     if (sign) {
-        gen_helper_divsl(cpu_env, num, reg, den);
+        gen_helper_divsl(cpu_env, num, reg, den, ilen);
     } else {
-        gen_helper_divul(cpu_env, num, reg, den);
+        gen_helper_divul(cpu_env, num, reg, den, ilen);
     }
-    tcg_temp_free(reg);
-    tcg_temp_free(num);
 
     set_cc_op(s, CC_OP_FLAGS);
 }