[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, 14 insertions, 8 deletions

diff --git a/arch/arm/nwfpe/fpa11_cpdt.c b/arch/arm/nwfpe/fpa11_cpdt.c
index 95fb63fa9d1..b0db5cbcc3b 100644
--- a/arch/arm/nwfpe/fpa11_cpdt.c
+++ b/arch/arm/nwfpe/fpa11_cpdt.c
@@ -96,7 +96,7 @@ static inline void loadMultiple(const unsigned int Fn, const unsigned int __user
 	}
 }
 
-static inline void storeSingle(const unsigned int Fn, unsigned int __user *pMem)
+static inline void storeSingle(struct roundingData *roundData, const unsigned int Fn, unsigned int __user *pMem)
 {
 	FPA11 *fpa11 = GET_FPA11();
 	union {
@@ -106,12 +106,12 @@ static inline void storeSingle(const unsigned int Fn, unsigned int __user *pMem)
 
 	switch (fpa11->fType[Fn]) {
 	case typeDouble:
-		val.f = float64_to_float32(fpa11->fpreg[Fn].fDouble);
+		val.f = float64_to_float32(roundData, fpa11->fpreg[Fn].fDouble);
 		break;
 
 #ifdef CONFIG_FPE_NWFPE_XP
 	case typeExtended:
-		val.f = floatx80_to_float32(fpa11->fpreg[Fn].fExtended);
+		val.f = floatx80_to_float32(roundData, fpa11->fpreg[Fn].fExtended);
 		break;
 #endif
 
@@ -122,7 +122,7 @@ static inline void storeSingle(const unsigned int Fn, unsigned int __user *pMem)
 	put_user(val.i[0], pMem);
 }
 
-static inline void storeDouble(const unsigned int Fn, unsigned int __user *pMem)
+static inline void storeDouble(struct roundingData *roundData, const unsigned int Fn, unsigned int __user *pMem)
 {
 	FPA11 *fpa11 = GET_FPA11();
 	union {
@@ -137,7 +137,7 @@ static inline void storeDouble(const unsigned int Fn, unsigned int __user *pMem)
 
 #ifdef CONFIG_FPE_NWFPE_XP
 	case typeExtended:
-		val.f = floatx80_to_float64(fpa11->fpreg[Fn].fExtended);
+		val.f = floatx80_to_float64(roundData, fpa11->fpreg[Fn].fExtended);
 		break;
 #endif
 
@@ -259,8 +259,11 @@ unsigned int PerformSTF(const unsigned int opcode)
 {
 	unsigned int __user *pBase, *pAddress, *pFinal;
 	unsigned int nRc = 1, write_back = WRITE_BACK(opcode);
+	struct roundingData roundData;
 
-	SetRoundingMode(ROUND_TO_NEAREST);
+	roundData.mode = SetRoundingMode(opcode);
+	roundData.precision = SetRoundingPrecision(opcode);
+	roundData.exception = 0;
 
 	pBase = (unsigned int __user *) readRegister(getRn(opcode));
 	if (REG_PC == getRn(opcode)) {
@@ -281,10 +284,10 @@ unsigned int PerformSTF(const unsigned int opcode)
 
 	switch (opcode & MASK_TRANSFER_LENGTH) {
 	case TRANSFER_SINGLE:
-		storeSingle(getFd(opcode), pAddress);
+		storeSingle(&roundData, getFd(opcode), pAddress);
 		break;
 	case TRANSFER_DOUBLE:
-		storeDouble(getFd(opcode), pAddress);
+		storeDouble(&roundData, getFd(opcode), pAddress);
 		break;
 #ifdef CONFIG_FPE_NWFPE_XP
 	case TRANSFER_EXTENDED:
@@ -295,6 +298,9 @@ unsigned int PerformSTF(const unsigned int opcode)
 		nRc = 0;
 	}
 
+	if (roundData.exception)
+		float_raise(roundData.exception);
+
 	if (write_back)
 		writeRegister(getRn(opcode), (unsigned long) pFinal);
 	return nRc;