[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, 17 insertions, 11 deletions

diff --git a/arch/arm/nwfpe/fpa11_cpdo.c b/arch/arm/nwfpe/fpa11_cpdo.c
index 1bea67437b6f..4a31dfd94068 100644
--- a/arch/arm/nwfpe/fpa11_cpdo.c
+++ b/arch/arm/nwfpe/fpa11_cpdo.c
@@ -24,15 +24,16 @@
 #include "fpa11.h"
 #include "fpopcode.h"
 
-unsigned int SingleCPDO(const unsigned int opcode, FPREG * rFd);
-unsigned int DoubleCPDO(const unsigned int opcode, FPREG * rFd);
-unsigned int ExtendedCPDO(const unsigned int opcode, FPREG * rFd);
+unsigned int SingleCPDO(struct roundingData *roundData, const unsigned int opcode, FPREG * rFd);
+unsigned int DoubleCPDO(struct roundingData *roundData, const unsigned int opcode, FPREG * rFd);
+unsigned int ExtendedCPDO(struct roundingData *roundData, const unsigned int opcode, FPREG * rFd);
 
 unsigned int EmulateCPDO(const unsigned int opcode)
 {
 	FPA11 *fpa11 = GET_FPA11();
 	FPREG *rFd;
 	unsigned int nType, nDest, nRc;
+	struct roundingData roundData;
 
 	/* Get the destination size.  If not valid let Linux perform
 	   an invalid instruction trap. */
@@ -40,7 +41,9 @@ unsigned int EmulateCPDO(const unsigned int opcode)
 	if (typeNone == nDest)
 		return 0;
 
-	SetRoundingMode(opcode);
+	roundData.mode = SetRoundingMode(opcode);
+	roundData.precision = SetRoundingPrecision(opcode);
+	roundData.exception = 0;
 
 	/* Compare the size of the operands in Fn and Fm.
 	   Choose the largest size and perform operations in that size,
@@ -63,14 +66,14 @@ unsigned int EmulateCPDO(const unsigned int opcode)
 
 	switch (nType) {
 	case typeSingle:
-		nRc = SingleCPDO(opcode, rFd);
+		nRc = SingleCPDO(&roundData, opcode, rFd);
 		break;
 	case typeDouble:
-		nRc = DoubleCPDO(opcode, rFd);
+		nRc = DoubleCPDO(&roundData, opcode, rFd);
 		break;
 #ifdef CONFIG_FPE_NWFPE_XP
 	case typeExtended:
-		nRc = ExtendedCPDO(opcode, rFd);
+		nRc = ExtendedCPDO(&roundData, opcode, rFd);
 		break;
 #endif
 	default:
@@ -93,9 +96,9 @@ unsigned int EmulateCPDO(const unsigned int opcode)
 			case typeSingle:
 				{
 					if (typeDouble == nType)
-						rFd->fSingle = float64_to_float32(rFd->fDouble);
+						rFd->fSingle = float64_to_float32(&roundData, rFd->fDouble);
 					else
-						rFd->fSingle = floatx80_to_float32(rFd->fExtended);
+						rFd->fSingle = floatx80_to_float32(&roundData, rFd->fExtended);
 				}
 				break;
 
@@ -104,7 +107,7 @@ unsigned int EmulateCPDO(const unsigned int opcode)
 					if (typeSingle == nType)
 						rFd->fDouble = float32_to_float64(rFd->fSingle);
 					else
-						rFd->fDouble = floatx80_to_float64(rFd->fExtended);
+						rFd->fDouble = floatx80_to_float64(&roundData, rFd->fExtended);
 				}
 				break;
 
@@ -121,12 +124,15 @@ unsigned int EmulateCPDO(const unsigned int opcode)
 #else
 		if (nDest != nType) {
 			if (nDest == typeSingle)
-				rFd->fSingle = float64_to_float32(rFd->fDouble);
+				rFd->fSingle = float64_to_float32(&roundData, rFd->fDouble);
 			else
 				rFd->fDouble = float32_to_float64(rFd->fSingle);
 		}
 #endif
 	}
 
+	if (roundData.exception)
+		float_raise(roundData.exception);
+
 	return nRc;
 }