[Qemu-devel] [PATCH][SPARC] FPU deferred trap-queue

[Qemu-devel] [PATCH][SPARC] FPU deferred trap-queue

[Aurelien Jarno]

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Hi,

The current emulated SPARC FPU does not support deferred trap-queue. In
such cases the STDFQ instruction should generate an fp_exception trap
with the FTT field to sequence_error instead of the current
illegal_instruction trap.

The attached patch fixes that. It also ensures that the qne bit of the
FSR register is always zero, ie that there is no deferred trap-queue
pending.

Bye,
Aurelien

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net

[-- Attachment #2: sparc-qemu-stdfq.diff --]
[-- Type: text/x-diff, Size: 1517 bytes --]

--- qemu.orig/target-sparc/cpu.h	1 Apr 2007 15:15:36 -0000
+++ qemu/target-sparc/cpu.h	2 Apr 2007 22:56:51 -0000
@@ -127,6 +129,7 @@
 #define FSR_FTT_MASK (FSR_FTT2 | FSR_FTT1 | FSR_FTT0)
 #define FSR_FTT_IEEE_EXCP (1 << 14)
 #define FSR_FTT_UNIMPFPOP (3 << 14)
+#define FSR_FTT_SEQ_ERROR (4 << 14)
 #define FSR_FTT_INVAL_FPR (6 << 14)
 
 #define FSR_FCC1  (1<<11)
@@ -239,7 +242,7 @@ typedef struct CPUSPARCState {
 #else
 #define GET_FSR32(env) (env->fsr)
 #define PUT_FSR32(env, val) do { uint32_t _tmp = val;                   \
-        env->fsr = (_tmp & 0xcfc1ffff) | (env->fsr & 0x000e0000);       \
+        env->fsr = (_tmp & 0xcfc1dfff) | (env->fsr & 0x000e0000);       \
     } while (0)
 #endif
 
--- qemu.orig/target-sparc/translate.c	1 Apr 2007 16:23:36 -0000
+++ qemu/target-sparc/translate.c	2 Apr 2007 22:56:52 -0000
@@ -2603,7 +2605,11 @@ static void disas_sparc_insn(DisasContex
 		    gen_op_ldst(stf);
 		    break;
 		case 0x26: /* stdfq */
-		    goto nfpu_insn;
+		    if (!supervisor(dc))
+			goto priv_insn;
+		    if (gen_trap_ifnofpu(dc))
+			goto jmp_insn;
+		    goto nfq_insn;
 		case 0x27:
                     gen_op_load_fpr_DT0(DFPREG(rd));
 		    gen_op_ldst(stdf);
@@ -2671,6 +2681,11 @@ static void disas_sparc_insn(DisasContex
     gen_op_fpexception_im(FSR_FTT_UNIMPFPOP);
     dc->is_br = 1;
     return;
+ nfq_insn:
+    save_state(dc);
+    gen_op_fpexception_im(FSR_FTT_SEQ_ERROR);
+    dc->is_br = 1;
+    return;
 #ifndef TARGET_SPARC64
  ncp_insn:
     save_state(dc);

[Qemu-devel] Re: [PATCH][SPARC] FPU deferred trap-queue

[Aurelien Jarno]

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On Tue, Apr 03, 2007 at 02:12:14AM +0200, Aurelien Jarno wrote:
> Hi,
> 
> The current emulated SPARC FPU does not support deferred trap-queue. In
> such cases the STDFQ instruction should generate an fp_exception trap
> with the FTT field to sequence_error instead of the current
> illegal_instruction trap.
> 
> The attached patch fixes that. It also ensures that the qne bit of the
> FSR register is always zero, ie that there is no deferred trap-queue
> pending.
> 

I have just remarked that my patch breaks the user mode. Please find
attached a new one to fix this problem.

Bye,
Aurelien

-- 
  .''`.  Aurelien Jarno	            | GPG: 1024D/F1BCDB73
 : :' :  Debian developer           | Electrical Engineer
 `. `'   aurel32@debian.org         | aurelien@aurel32.net
   `-    people.debian.org/~aurel32 | www.aurel32.net

[-- Attachment #2: sparc-qemu-stdfq.diff --]
[-- Type: text/x-diff, Size: 1625 bytes --]

diff -u -d -p -r1.32 cpu.h
--- qemu.orig/target-sparc/cpu.h	1 Apr 2007 15:15:36 -0000	1.32
+++ qemu/target-sparc/cpu.h	5 Apr 2007 17:36:19 -0000
@@ -127,6 +127,7 @@
 #define FSR_FTT_MASK (FSR_FTT2 | FSR_FTT1 | FSR_FTT0)
 #define FSR_FTT_IEEE_EXCP (1 << 14)
 #define FSR_FTT_UNIMPFPOP (3 << 14)
+#define FSR_FTT_SEQ_ERROR (4 << 14)
 #define FSR_FTT_INVAL_FPR (6 << 14)
 
 #define FSR_FCC1  (1<<11)
@@ -239,7 +240,7 @@ typedef struct CPUSPARCState {
 #else
 #define GET_FSR32(env) (env->fsr)
 #define PUT_FSR32(env, val) do { uint32_t _tmp = val;                   \
-        env->fsr = (_tmp & 0xcfc1ffff) | (env->fsr & 0x000e0000);       \
+        env->fsr = (_tmp & 0xcfc1dfff) | (env->fsr & 0x000e0000);       \
     } while (0)
 #endif
 
diff -u -d -p -r1.44 translate.c
--- qemu.orig/target-sparc/translate.c	1 Apr 2007 16:23:36 -0000	1.44
+++ qemu/target-sparc/translate.c	5 Apr 2007 17:36:19 -0000
@@ -2602,8 +2602,14 @@ static void disas_sparc_insn(DisasContex
 		    gen_op_stfsr();
 		    gen_op_ldst(stf);
 		    break;
+#if !defined(CONFIG_USER_ONLY)
 		case 0x26: /* stdfq */
-		    goto nfpu_insn;
+		    if (!supervisor(dc))
+			goto priv_insn;
+		    if (gen_trap_ifnofpu(dc))
+			goto jmp_insn;
+		    goto nfq_insn;
+#endif
 		case 0x27:
                     gen_op_load_fpr_DT0(DFPREG(rd));
 		    gen_op_ldst(stdf);
@@ -2665,6 +2671,11 @@ static void disas_sparc_insn(DisasContex
     gen_op_exception(TT_PRIV_INSN);
     dc->is_br = 1;
     return;
+ nfq_insn:
+    save_state(dc);
+    gen_op_fpexception_im(FSR_FTT_SEQ_ERROR);
+    dc->is_br = 1;
+    return;
 #endif
  nfpu_insn:
     save_state(dc);