Re: [Qemu-devel] [PATCH v2 4/4] target-mips: add user-mode FR switch support for MIPS32r5

[Eric Johnson]

Reviewed-by: Eric Johnson <address@hidden>
________________________________________
From: address@hidden address@hidden on behalf of Petar Jovanovic address@hidden
Sent: Friday, January 24, 2014 8:18 AM
To: address@hidden
Cc: Petar Jovanovic; address@hidden
Subject: [Qemu-devel] [PATCH v2 4/4] target-mips: add user-mode FR switch       
support for MIPS32r5

From: Petar Jovanovic <address@hidden>

Description of UFR feature:

Required in MIPS32r5 if floating point is implemented and user-mode FR
switching is supported. The UFR register allows user-mode to clear StatusFR
by executing a CTC1 to UFR with GPR[0] as input, and read StatusFR by
executing a CFC1 to UFR.

helper_ctc1 has been extended with an additional parameter rt to check
requirements for UFR feature.
Definition of mips32r5-generic has been modified to include support for UFR.

Signed-off-by: Petar Jovanovic <address@hidden>
---
 target-mips/helper.h         |    2 +-
 target-mips/op_helper.c      |   41 ++++++++++++++++++++++++++++++++++++++---
 target-mips/translate.c      |   14 ++++++++++++--
 target-mips/translate_init.c |    9 +++++----
 4 files changed, 56 insertions(+), 10 deletions(-)

diff --git a/target-mips/helper.h b/target-mips/helper.h
index b82f8e8..8c7921a 100644
--- a/target-mips/helper.h
+++ b/target-mips/helper.h
@@ -179,7 +179,7 @@ DEF_HELPER_2(yield, tl, env, tl)

 /* CP1 functions */
 DEF_HELPER_2(cfc1, tl, env, i32)
-DEF_HELPER_3(ctc1, void, env, tl, i32)
+DEF_HELPER_4(ctc1, void, env, tl, i32, i32)

 DEF_HELPER_2(float_cvtd_s, i64, env, i32)
 DEF_HELPER_2(float_cvtd_w, i64, env, i32)
diff --git a/target-mips/op_helper.c b/target-mips/op_helper.c
index eaf4d26..2ef6633 100644
--- a/target-mips/op_helper.c
+++ b/target-mips/op_helper.c
@@ -2199,12 +2199,23 @@ static inline void restore_flush_mode(CPUMIPSState *env)

 target_ulong helper_cfc1(CPUMIPSState *env, uint32_t reg)
 {
-    target_ulong arg1;
+    target_ulong arg1 = 0;

     switch (reg) {
     case 0:
         arg1 = (int32_t)env->active_fpu.fcr0;
         break;
+    case 1:
+        /* UFR Support - Read Status FR */
+        if (env->active_fpu.fcr0 & (1 << FCR0_UFRP)) {
+            if (env->CP0_Config5 & (1 << CP0C5_UFR)) {
+                arg1 = (int32_t)
+                       ((env->CP0_Status & (1  << CP0St_FR)) >> CP0St_FR);
+            } else {
+                helper_raise_exception(env, EXCP_RI);
+            }
+        }
+        break;
     case 25:
         arg1 = ((env->active_fpu.fcr31 >> 24) & 0xfe) | 
((env->active_fpu.fcr31 >> 23) & 0x1);
         break;
@@ -2222,9 +2233,33 @@ target_ulong helper_cfc1(CPUMIPSState *env, uint32_t reg)
     return arg1;
 }

-void helper_ctc1(CPUMIPSState *env, target_ulong arg1, uint32_t reg)
+void helper_ctc1(CPUMIPSState *env, target_ulong arg1, uint32_t fs, uint32_t 
rt)
 {
-    switch(reg) {
+    switch (fs) {
+    case 1:
+        /* UFR Alias - Reset Status FR */
+        if (!((env->active_fpu.fcr0 & (1 << FCR0_UFRP)) && (rt == 0))) {
+            return;
+        }
+        if (env->CP0_Config5 & (1 << CP0C5_UFR)) {
+            env->CP0_Status &= ~(1 << CP0St_FR);
+            compute_hflags(env);
+        } else {
+            helper_raise_exception(env, EXCP_RI);
+        }
+        break;
+    case 4:
+        /* UNFR Alias - Set Status FR */
+        if (!((env->active_fpu.fcr0 & (1 << FCR0_UFRP)) && (rt == 0))) {
+            return;
+        }
+        if (env->CP0_Config5 & (1 << CP0C5_UFR)) {
+            env->CP0_Status |= (1 << CP0St_FR);
+            compute_hflags(env);
+        } else {
+            helper_raise_exception(env, EXCP_RI);
+        }
+        break;
     case 25:
         if (arg1 & 0xffffff00)
             return;
diff --git a/target-mips/translate.c b/target-mips/translate.c
index 02a90cb..083f6ab 100644
--- a/target-mips/translate.c
+++ b/target-mips/translate.c
@@ -6818,7 +6818,12 @@ static void gen_mttr(CPUMIPSState *env, DisasContext 
*ctx, int rd, int rt,
         break;
     case 3:
         /* XXX: For now we support only a single FPU context. */
-        gen_helper_0e1i(ctc1, t0, rd);
+        {
+            TCGv_i32 fs_tmp = tcg_const_i32(rd);
+
+            gen_helper_0e2i(ctc1, t0, fs_tmp, rt);
+            tcg_temp_free_i32(fs_tmp);
+        }
         break;
     /* COP2: Not implemented. */
     case 4:
@@ -7254,7 +7259,12 @@ static void gen_cp1 (DisasContext *ctx, uint32_t opc, 
int rt, int fs)
         break;
     case OPC_CTC1:
         gen_load_gpr(t0, rt);
-        gen_helper_0e1i(ctc1, t0, fs);
+        {
+            TCGv_i32 fs_tmp = tcg_const_i32(fs);
+
+            gen_helper_0e2i(ctc1, t0, fs_tmp, rt);
+            tcg_temp_free_i32(fs_tmp);
+        }
         opn = "ctc1";
         break;
 #if defined(TARGET_MIPS64)
diff --git a/target-mips/translate_init.c b/target-mips/translate_init.c
index 3d4dc88..29d39e2 100644
--- a/target-mips/translate_init.c
+++ b/target-mips/translate_init.c
@@ -358,18 +358,19 @@ static const mips_def_t mips_defs[] =
         .CP0_Config3 = MIPS_CONFIG3 | (1 << CP0C3_M),
         .CP0_Config4 = MIPS_CONFIG4 | (1 << CP0C4_M),
         .CP0_Config4_rw_bitmask = 0,
-        .CP0_Config5 = MIPS_CONFIG5,
+        .CP0_Config5 = MIPS_CONFIG5 | (1 << CP0C5_UFR),
         .CP0_Config5_rw_bitmask = (0 << CP0C5_M) | (1 << CP0C5_K) |
                                   (1 << CP0C5_CV) | (0 << CP0C5_EVA) |
-                                  (1 << CP0C5_MSAEn) | (0 << CP0C5_UFR) |
+                                  (1 << CP0C5_MSAEn) | (1 << CP0C5_UFR) |
                                   (0 << CP0C5_NFExists),
         .CP0_LLAddr_rw_bitmask = 0,
         .CP0_LLAddr_shift = 4,
         .SYNCI_Step = 32,
         .CCRes = 2,
         .CP0_Status_rw_bitmask = 0x3778FF1F,
-        .CP1_fcr0 = (1 << FCR0_F64) | (1 << FCR0_L) | (1 << FCR0_W) |
-                    (1 << FCR0_D) | (1 << FCR0_S) | (0x93 << FCR0_PRID),
+        .CP1_fcr0 = (1 << FCR0_UFRP) | (1 << FCR0_F64) | (1 << FCR0_L) |
+                    (1 << FCR0_W) | (1 << FCR0_D) | (1 << FCR0_S) |
+                    (0x93 << FCR0_PRID),
         .SEGBITS = 32,
         .PABITS = 32,
         .insn_flags = CPU_MIPS32R5 | ASE_MIPS16 | ASE_DSP | ASE_DSPR2,
--
1.7.9.5