Fix preemption and SMP problems in the FP emulator code.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

5 files changed, 122 insertions, 119 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 15fed02..b3ecd02 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -551,6 +551,14 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 
 		preempt_disable();
 
+#ifdef CONFIG_PREEMPT
+		if (!is_fpu_owner()) {
+			/* We might lose fpu before disabling preempt... */
+			own_fpu();
+			BUG_ON(!used_math());
+			restore_fp(current);
+		}
+#endif
 		/*
 	 	 * Unimplemented operation exception.  If we've got the full
 		 * software emulator on-board, let's use it...
@@ -562,11 +570,18 @@ asmlinkage void do_fpe(struct pt_regs *regs, unsigned long fcr31)
 		 * a bit extreme for what should be an infrequent event.
 		 */
 		save_fp(current);
+		/* Ensure 'resume' not overwrite saved fp context again. */
+		lose_fpu();
+
+		preempt_enable();
 
 		/* Run the emulator */
 		sig = fpu_emulator_cop1Handler (0, regs,
 			&current->thread.fpu.soft);
 
+		preempt_disable();
+
+		own_fpu();	/* Using the FPU again.  */
 		/*
 		 * We can't allow the emulated instruction to leave any of
 		 * the cause bit set in $fcr31.
@@ -712,6 +727,8 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 			set_used_math();
 		}
 
+		preempt_enable();
+
 		if (!cpu_has_fpu) {
 			int sig = fpu_emulator_cop1Handler(0, regs,
 						&current->thread.fpu.soft);
@@ -719,8 +736,6 @@ asmlinkage void do_cpu(struct pt_regs *regs)
 				force_sig(sig, current);
 		}
 
-		preempt_enable();
-
 		return;
 
 	case 2:
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index c70f25f..6fed6ce 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -79,7 +79,17 @@ struct mips_fpu_emulator_private fpuemuprivate;
 
 /* Convert Mips rounding mode (0..3) to IEEE library modes. */
 static const unsigned char ieee_rm[4] = {
-	IEEE754_RN, IEEE754_RZ, IEEE754_RU, IEEE754_RD
+	[FPU_CSR_RN] = IEEE754_RN,
+	[FPU_CSR_RZ] = IEEE754_RZ,
+	[FPU_CSR_RU] = IEEE754_RU,
+	[FPU_CSR_RD] = IEEE754_RD,
+};
+/* Convert IEEE library modes to Mips rounding mode (0..3). */
+static const unsigned char mips_rm[4] = {
+	[IEEE754_RN] = FPU_CSR_RN,
+	[IEEE754_RZ] = FPU_CSR_RZ,
+	[IEEE754_RD] = FPU_CSR_RD,
+	[IEEE754_RU] = FPU_CSR_RU,
 };
 
 #if __mips >= 4
@@ -368,6 +378,7 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_soft_struct *ctx)
 			}
 			if (MIPSInst_RD(ir) == FPCREG_CSR) {
 				value = ctx->fcr31;
+				value = (value & ~0x3) | mips_rm[value & 0x3];
 #ifdef CSRTRACE
 				printk("%p gpr[%d]<-csr=%08x\n",
 					(void *) (xcp->cp0_epc),
@@ -400,11 +411,10 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_soft_struct *ctx)
 					(void *) (xcp->cp0_epc),
 					MIPSInst_RT(ir), value);
 #endif
-				ctx->fcr31 = value;
-				/* copy new rounding mode and
-				   flush bit to ieee library state! */
-				ieee754_csr.nod = (ctx->fcr31 & 0x1000000) != 0;
-				ieee754_csr.rm = ieee_rm[value & 0x3];
+				value &= (FPU_CSR_FLUSH | FPU_CSR_ALL_E | FPU_CSR_ALL_S | 0x03);
+				ctx->fcr31 &= ~(FPU_CSR_FLUSH | FPU_CSR_ALL_E | FPU_CSR_ALL_S | 0x03);
+				/* convert to ieee library modes */
+				ctx->fcr31 |= (value & ~0x3) | ieee_rm[value & 0x3];
 			}
 			if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
 				return SIGFPE;
@@ -570,7 +580,7 @@ static const unsigned char cmptab[8] = {
 static ieee754##p fpemu_##p##_##name (ieee754##p r, ieee754##p s, \
     ieee754##p t) \
 { \
-	struct ieee754_csr ieee754_csr_save; \
+	struct _ieee754_csr ieee754_csr_save; \
 	s = f1 (s, t); \
 	ieee754_csr_save = ieee754_csr; \
 	s = f2 (s, r); \
@@ -699,8 +709,6 @@ static int fpux_emu(struct pt_regs *xcp, struct mips_fpu_soft_struct *ctx,
 				rcsr |= FPU_CSR_INV_X | FPU_CSR_INV_S;
 
 			ctx->fcr31 = (ctx->fcr31 & ~FPU_CSR_ALL_X) | rcsr;
-			if (ieee754_csr.nod)
-				ctx->fcr31 |= 0x1000000;
 			if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
 				/*printk ("SIGFPE: fpu csr = %08x\n",
 				   ctx->fcr31); */
@@ -1297,12 +1305,17 @@ int fpu_emulator_cop1Handler(int xcptno, struct pt_regs *xcp,
 		if (insn == 0)
 			xcp->cp0_epc += 4;	/* skip nops */
 		else {
-			/* Update ieee754_csr. Only relevant if we have a
-			   h/w FPU */
-			ieee754_csr.nod = (ctx->fcr31 & 0x1000000) != 0;
-			ieee754_csr.rm = ieee_rm[ctx->fcr31 & 0x3];
-			ieee754_csr.cx = (ctx->fcr31 >> 12) & 0x1f;
+			/*
+			 * The 'ieee754_csr' is an alias of
+			 * ctx->fcr31.  No need to copy ctx->fcr31 to
+			 * ieee754_csr.  But ieee754_csr.rm is ieee
+			 * library modes. (not mips rounding mode)
+			 */
+			/* convert to ieee library modes */
+			ieee754_csr.rm = ieee_rm[ieee754_csr.rm];
 			sig = cop1Emulate(xcp, ctx);
+			/* revert to mips rounding mode */
+			ieee754_csr.rm = mips_rm[ieee754_csr.rm];
 		}
 
 		if (cpu_has_fpu)
diff --git a/arch/mips/math-emu/dp_sqrt.c b/arch/mips/math-emu/dp_sqrt.c
index c35e871..032328c 100644
--- a/arch/mips/math-emu/dp_sqrt.c
+++ b/arch/mips/math-emu/dp_sqrt.c
@@ -37,7 +37,7 @@ static const unsigned table[] = {
 
 ieee754dp ieee754dp_sqrt(ieee754dp x)
 {
-	struct ieee754_csr oldcsr;
+	struct _ieee754_csr oldcsr;
 	ieee754dp y, z, t;
 	unsigned scalx, yh;
 	COMPXDP;
diff --git a/arch/mips/math-emu/ieee754.c b/arch/mips/math-emu/ieee754.c
index f0a364a..97a752f 100644
--- a/arch/mips/math-emu/ieee754.c
+++ b/arch/mips/math-emu/ieee754.c
@@ -50,10 +50,6 @@ const char *const ieee754_cname[] = {
 	"SNaN",
 };
 
-/* the control status register
-*/
-struct ieee754_csr ieee754_csr;
-
 /* special constants
 */
 
diff --git a/arch/mips/math-emu/ieee754.h b/arch/mips/math-emu/ieee754.h
index b8772f4..5689b0c 100644
--- a/arch/mips/math-emu/ieee754.h
+++ b/arch/mips/math-emu/ieee754.h
@@ -1,13 +1,8 @@
-/* single and double precision fp ops
- * missing extended precision.
-*/
 /*
  * MIPS floating point support
  * Copyright (C) 1994-2000 Algorithmics Ltd.
  * http://www.algor.co.uk
  *
- * ########################################################################
- *
  *  This program is free software; you can distribute it and/or modify it
  *  under the terms of the GNU General Public License (Version 2) as
  *  published by the Free Software Foundation.
@@ -21,20 +16,16 @@
  *  with this program; if not, write to the Free Software Foundation, Inc.,
  *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
  *
- * ########################################################################
- */
-
-/**************************************************************************
  *  Nov 7, 2000
  *  Modification to allow integration with Linux kernel
  *
  *  Kevin D. Kissell, kevink@mips.com and Carsten Langgard, carstenl@mips.com
  *  Copyright (C) 2000 MIPS Technologies, Inc. All rights reserved.
- *************************************************************************/
+ */
 
-#ifdef __KERNEL__
-/* Going from Algorithmics to Linux native environment, add this */
+#include <asm/byteorder.h>
 #include <linux/types.h>
+#include <linux/sched.h>
 
 /*
  * Not very pretty, but the Linux kernel's normal va_list definition
@@ -44,18 +35,7 @@
 #include <stdarg.h>
 #endif
 
-#else
-
-/* Note that __KERNEL__ is taken to mean Linux kernel */
-
-#if #system(OpenBSD)
-#include <machine/types.h>
-#endif
-#include <machine/endian.h>
-
-#endif				/* __KERNEL__ */
-
-#if (defined(BYTE_ORDER) && BYTE_ORDER == LITTLE_ENDIAN) || defined(__MIPSEL__)
+#ifdef __LITTLE_ENDIAN
 struct ieee754dp_konst {
 	unsigned mantlo:32;
 	unsigned manthi:20;
@@ -86,13 +66,14 @@ typedef union _ieee754sp {
 } ieee754sp;
 #endif
 
-#if (defined(BYTE_ORDER) && BYTE_ORDER == BIG_ENDIAN) || defined(__MIPSEB__)
+#ifdef __BIG_ENDIAN
 struct ieee754dp_konst {
 	unsigned sign:1;
 	unsigned bexp:11;
 	unsigned manthi:20;
 	unsigned mantlo:32;
 };
+
 typedef union _ieee754dp {
 	struct ieee754dp_konst oparts;
 	struct {
@@ -251,93 +232,109 @@ extern const char *const ieee754_cname[];
 
 /* "normal" comparisons
 */
-static __inline int ieee754sp_eq(ieee754sp x, ieee754sp y)
+static inline int ieee754sp_eq(ieee754sp x, ieee754sp y)
 {
 	return ieee754sp_cmp(x, y, IEEE754_CEQ, 0);
 }
 
-static __inline int ieee754sp_ne(ieee754sp x, ieee754sp y)
+static inline int ieee754sp_ne(ieee754sp x, ieee754sp y)
 {
 	return ieee754sp_cmp(x, y,
 			     IEEE754_CLT | IEEE754_CGT | IEEE754_CUN, 0);
 }
 
-static __inline int ieee754sp_lt(ieee754sp x, ieee754sp y)
+static inline int ieee754sp_lt(ieee754sp x, ieee754sp y)
 {
 	return ieee754sp_cmp(x, y, IEEE754_CLT, 0);
 }
 
-static __inline int ieee754sp_le(ieee754sp x, ieee754sp y)
+static inline int ieee754sp_le(ieee754sp x, ieee754sp y)
 {
 	return ieee754sp_cmp(x, y, IEEE754_CLT | IEEE754_CEQ, 0);
 }
 
-static __inline int ieee754sp_gt(ieee754sp x, ieee754sp y)
+static inline int ieee754sp_gt(ieee754sp x, ieee754sp y)
 {
 	return ieee754sp_cmp(x, y, IEEE754_CGT, 0);
 }
 
 
-static __inline int ieee754sp_ge(ieee754sp x, ieee754sp y)
+static inline int ieee754sp_ge(ieee754sp x, ieee754sp y)
 {
 	return ieee754sp_cmp(x, y, IEEE754_CGT | IEEE754_CEQ, 0);
 }
 
-static __inline int ieee754dp_eq(ieee754dp x, ieee754dp y)
+static inline int ieee754dp_eq(ieee754dp x, ieee754dp y)
 {
 	return ieee754dp_cmp(x, y, IEEE754_CEQ, 0);
 }
 
-static __inline int ieee754dp_ne(ieee754dp x, ieee754dp y)
+static inline int ieee754dp_ne(ieee754dp x, ieee754dp y)
 {
 	return ieee754dp_cmp(x, y,
 			     IEEE754_CLT | IEEE754_CGT | IEEE754_CUN, 0);
 }
 
-static __inline int ieee754dp_lt(ieee754dp x, ieee754dp y)
+static inline int ieee754dp_lt(ieee754dp x, ieee754dp y)
 {
 	return ieee754dp_cmp(x, y, IEEE754_CLT, 0);
 }
 
-static __inline int ieee754dp_le(ieee754dp x, ieee754dp y)
+static inline int ieee754dp_le(ieee754dp x, ieee754dp y)
 {
 	return ieee754dp_cmp(x, y, IEEE754_CLT | IEEE754_CEQ, 0);
 }
 
-static __inline int ieee754dp_gt(ieee754dp x, ieee754dp y)
+static inline int ieee754dp_gt(ieee754dp x, ieee754dp y)
 {
 	return ieee754dp_cmp(x, y, IEEE754_CGT, 0);
 }
 
-static __inline int ieee754dp_ge(ieee754dp x, ieee754dp y)
+static inline int ieee754dp_ge(ieee754dp x, ieee754dp y)
 {
 	return ieee754dp_cmp(x, y, IEEE754_CGT | IEEE754_CEQ, 0);
 }
 
 
-/* like strtod
-*/
+/*
+ * Like strtod
+ */
 ieee754dp ieee754dp_fstr(const char *s, char **endp);
 char *ieee754dp_tstr(ieee754dp x, int prec, int fmt, int af);
 
 
-/* the control status register
-*/
-struct ieee754_csr {
-	unsigned pad:13;
+/*
+ * The control status register
+ */
+struct _ieee754_csr {
+#ifdef __BIG_ENDIAN
+	unsigned pad0:7;
 	unsigned nod:1;		/* set 1 for no denormalised numbers */
-	unsigned cx:5;		/* exceptions this operation */
+	unsigned c:1;		/* condition */
+	unsigned pad1:5;
+	unsigned cx:6;		/* exceptions this operation */
 	unsigned mx:5;		/* exception enable  mask */
 	unsigned sx:5;		/* exceptions total */
 	unsigned rm:2;		/* current rounding mode */
+#endif
+#ifdef __LITTLE_ENDIAN
+	unsigned rm:2;		/* current rounding mode */
+	unsigned sx:5;		/* exceptions total */
+	unsigned mx:5;		/* exception enable  mask */
+	unsigned cx:6;		/* exceptions this operation */
+	unsigned pad1:5;
+	unsigned c:1;		/* condition */
+	unsigned nod:1;		/* set 1 for no denormalised numbers */
+	unsigned pad0:7;
+#endif
 };
-extern struct ieee754_csr ieee754_csr;
+#define ieee754_csr (*(struct _ieee754_csr *)(&current->thread.fpu.soft.fcr31))
 
-static __inline unsigned ieee754_getrm(void)
+static inline unsigned ieee754_getrm(void)
 {
 	return (ieee754_csr.rm);
 }
-static __inline unsigned ieee754_setrm(unsigned rm)
+static inline unsigned ieee754_setrm(unsigned rm)
 {
 	return (ieee754_csr.rm = rm);
 }
@@ -345,14 +342,14 @@ static __inline unsigned ieee754_setrm(unsigned rm)
 /*
  * get current exceptions
  */
-static __inline unsigned ieee754_getcx(void)
+static inline unsigned ieee754_getcx(void)
 {
 	return (ieee754_csr.cx);
 }
 
 /* test for current exception condition
  */
-static __inline int ieee754_cxtest(unsigned n)
+static inline int ieee754_cxtest(unsigned n)
 {
 	return (ieee754_csr.cx & n);
 }
@@ -360,21 +357,21 @@ static __inline int ieee754_cxtest(unsigned n)
 /*
  * get sticky exceptions
  */
-static __inline unsigned ieee754_getsx(void)
+static inline unsigned ieee754_getsx(void)
 {
 	return (ieee754_csr.sx);
 }
 
 /* clear sticky conditions
 */
-static __inline unsigned ieee754_clrsx(void)
+static inline unsigned ieee754_clrsx(void)
 {
 	return (ieee754_csr.sx = 0);
 }
 
 /* test for sticky exception condition
  */
-static __inline int ieee754_sxtest(unsigned n)
+static inline int ieee754_sxtest(unsigned n)
 {
 	return (ieee754_csr.sx & n);
 }
@@ -406,52 +403,34 @@ extern const struct ieee754sp_konst __ieee754sp_spcvals[];
 #define ieee754dp_spcvals ((const ieee754dp *)__ieee754dp_spcvals)
 #define ieee754sp_spcvals ((const ieee754sp *)__ieee754sp_spcvals)
 
-/* return infinity with given sign
-*/
-#define ieee754dp_inf(sn)	\
-  (ieee754dp_spcvals[IEEE754_SPCVAL_PINFINITY+(sn)])
-#define ieee754dp_zero(sn) \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
-#define ieee754dp_one(sn) \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
-#define ieee754dp_ten(sn) \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
-#define ieee754dp_indef() \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_INDEF])
-#define ieee754dp_max(sn) \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
-#define ieee754dp_min(sn) \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
-#define ieee754dp_mind(sn) \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
-#define ieee754dp_1e31() \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_P1E31])
-#define ieee754dp_1e63() \
-  (ieee754dp_spcvals[IEEE754_SPCVAL_P1E63])
-
-#define ieee754sp_inf(sn) \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_PINFINITY+(sn)])
-#define ieee754sp_zero(sn) \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
-#define ieee754sp_one(sn) \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
-#define ieee754sp_ten(sn) \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
-#define ieee754sp_indef() \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_INDEF])
-#define ieee754sp_max(sn) \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
-#define ieee754sp_min(sn) \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
-#define ieee754sp_mind(sn) \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
-#define ieee754sp_1e31() \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_P1E31])
-#define ieee754sp_1e63() \
-  (ieee754sp_spcvals[IEEE754_SPCVAL_P1E63])
-
-/* indefinite integer value
-*/
+/*
+ * Return infinity with given sign
+ */
+#define ieee754dp_inf(sn)     (ieee754dp_spcvals[IEEE754_SPCVAL_PINFINITY+(sn)])
+#define ieee754dp_zero(sn)	(ieee754dp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
+#define ieee754dp_one(sn)	(ieee754dp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
+#define ieee754dp_ten(sn)	(ieee754dp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
+#define ieee754dp_indef()	(ieee754dp_spcvals[IEEE754_SPCVAL_INDEF])
+#define ieee754dp_max(sn)	(ieee754dp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
+#define ieee754dp_min(sn)	(ieee754dp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
+#define ieee754dp_mind(sn)	(ieee754dp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
+#define ieee754dp_1e31()	(ieee754dp_spcvals[IEEE754_SPCVAL_P1E31])
+#define ieee754dp_1e63()	(ieee754dp_spcvals[IEEE754_SPCVAL_P1E63])
+
+#define ieee754sp_inf(sn)     (ieee754sp_spcvals[IEEE754_SPCVAL_PINFINITY+(sn)])
+#define ieee754sp_zero(sn)	(ieee754sp_spcvals[IEEE754_SPCVAL_PZERO+(sn)])
+#define ieee754sp_one(sn)	(ieee754sp_spcvals[IEEE754_SPCVAL_PONE+(sn)])
+#define ieee754sp_ten(sn)	(ieee754sp_spcvals[IEEE754_SPCVAL_PTEN+(sn)])
+#define ieee754sp_indef()	(ieee754sp_spcvals[IEEE754_SPCVAL_INDEF])
+#define ieee754sp_max(sn)	(ieee754sp_spcvals[IEEE754_SPCVAL_PMAX+(sn)])
+#define ieee754sp_min(sn)	(ieee754sp_spcvals[IEEE754_SPCVAL_PMIN+(sn)])
+#define ieee754sp_mind(sn)	(ieee754sp_spcvals[IEEE754_SPCVAL_PMIND+(sn)])
+#define ieee754sp_1e31()	(ieee754sp_spcvals[IEEE754_SPCVAL_P1E31])
+#define ieee754sp_1e63()	(ieee754sp_spcvals[IEEE754_SPCVAL_P1E63])
+
+/*
+ * Indefinite integer value
+ */
 #define ieee754si_indef()	INT_MAX
 #ifdef LONG_LONG_MAX
 #define ieee754di_indef()	LONG_LONG_MAX