[PATCH] ARM: 2837/2: Re: ARM: Make NWFPE preempt safe

Patch from Richard Purdie

NWFPE used global variables which meant it wasn't safe for use with
preemptive kernels. This patch removes them and communicates the
information between functions in a preempt safe manner. Generation
of some exceptions was broken and this has also been corrected.
Tests with glibc's maths test suite show no change in the results
before/after this patch.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 19 insertions, 9 deletions

diff --git a/arch/arm/nwfpe/fpa11_cprt.c b/arch/arm/nwfpe/fpa11_cprt.c
index db01fbc9721..adf8d300054 100644
--- a/arch/arm/nwfpe/fpa11_cprt.c
+++ b/arch/arm/nwfpe/fpa11_cprt.c
@@ -33,8 +33,6 @@ extern flag floatx80_is_nan(floatx80);
 extern flag float64_is_nan(float64);
 extern flag float32_is_nan(float32);
 
-void SetRoundingMode(const unsigned int opcode);
-
 unsigned int PerformFLT(const unsigned int opcode);
 unsigned int PerformFIX(const unsigned int opcode);
 
@@ -77,14 +75,17 @@ unsigned int EmulateCPRT(const unsigned int opcode)
 unsigned int PerformFLT(const unsigned int opcode)
 {
 	FPA11 *fpa11 = GET_FPA11();
-	SetRoundingMode(opcode);
-	SetRoundingPrecision(opcode);
+	struct roundingData roundData;
+
+	roundData.mode = SetRoundingMode(opcode);
+	roundData.precision = SetRoundingPrecision(opcode);
+	roundData.exception = 0;
 
 	switch (opcode & MASK_ROUNDING_PRECISION) {
 	case ROUND_SINGLE:
 		{
 			fpa11->fType[getFn(opcode)] = typeSingle;
-			fpa11->fpreg[getFn(opcode)].fSingle = int32_to_float32(readRegister(getRd(opcode)));
+			fpa11->fpreg[getFn(opcode)].fSingle = int32_to_float32(&roundData, readRegister(getRd(opcode)));
 		}
 		break;
 
@@ -108,6 +109,9 @@ unsigned int PerformFLT(const unsigned int opcode)
 		return 0;
 	}
 
+	if (roundData.exception)
+		float_raise(roundData.exception);
+
 	return 1;
 }
 
@@ -115,26 +119,29 @@ unsigned int PerformFIX(const unsigned int opcode)
 {
 	FPA11 *fpa11 = GET_FPA11();
 	unsigned int Fn = getFm(opcode);
+	struct roundingData roundData;
 
-	SetRoundingMode(opcode);
+	roundData.mode = SetRoundingMode(opcode);
+	roundData.precision = SetRoundingPrecision(opcode);
+	roundData.exception = 0;
 
 	switch (fpa11->fType[Fn]) {
 	case typeSingle:
 		{
-			writeRegister(getRd(opcode), float32_to_int32(fpa11->fpreg[Fn].fSingle));
+			writeRegister(getRd(opcode), float32_to_int32(&roundData, fpa11->fpreg[Fn].fSingle));
 		}
 		break;
 
 	case typeDouble:
 		{
-			writeRegister(getRd(opcode), float64_to_int32(fpa11->fpreg[Fn].fDouble));
+			writeRegister(getRd(opcode), float64_to_int32(&roundData, fpa11->fpreg[Fn].fDouble));
 		}
 		break;
 
 #ifdef CONFIG_FPE_NWFPE_XP
 	case typeExtended:
 		{
-			writeRegister(getRd(opcode), floatx80_to_int32(fpa11->fpreg[Fn].fExtended));
+			writeRegister(getRd(opcode), floatx80_to_int32(&roundData, fpa11->fpreg[Fn].fExtended));
 		}
 		break;
 #endif
@@ -143,6 +150,9 @@ unsigned int PerformFIX(const unsigned int opcode)
 		return 0;
 	}
 
+	if (roundData.exception)
+		float_raise(roundData.exception);
+
 	return 1;
 }