[PowerPC] Fix SPE floating point environment manipulation

Fix multiple problems in the powerpcspe floating point code.

* Endianness handling of the SPEFSCR in fenv.h was completely broken.
* Ensure SPEFSCR synchronization requirements are being met.

The __r.__d -> __r transformations were written by jhibbits.

Reviewed by:	jhibbits
Differential Revision:	https://reviews.freebsd.org/D22526

lib/libc/powerpcspe/gen/fpsetmask.c

@@ -47,7 +47,7 @@ fpsetmask(fp_except_t mask)
 	__asm__ __volatile("mfspr %0, %1" : "=r"(fpscr) : "K"(SPR_SPEFSCR));
 	old = (fp_rnd_t)((fpscr >> 2) & 0x1f);
 	fpscr = (fpscr & 0xffffff83) | (mask << 2);
-	__asm__ __volatile("mtspr %1,%0" :: "r"(fpscr), "K"(SPR_SPEFSCR));
+	__asm__ __volatile("mtspr %1,%0;isync" :: "r"(fpscr), "K"(SPR_SPEFSCR));
 	return (old);
 }
 #endif

lib/libc/powerpcspe/gen/fpsetround.c

@@ -47,7 +47,7 @@ fpsetround(fp_rnd_t rnd_dir)
 	__asm__ __volatile("mfspr %0, %1" : "=r"(fpscr) : "K"(SPR_SPEFSCR) );
 	old = (fp_rnd_t)(fpscr & 0x3);
 	fpscr = (fpscr & 0xfffffffc) | rnd_dir;
-	__asm__ __volatile("mtspr %1, %0" :: "r"(fpscr), "K"(SPR_SPEFSCR));
+	__asm__ __volatile("mtspr %1, %0;isync" :: "r"(fpscr), "K"(SPR_SPEFSCR));
 	return (old);
 }
 #endif

lib/msun/powerpc/fenv.h

@@ -32,6 +32,7 @@
 #define	_FENV_H_
 
 #include <sys/_types.h>
+#include <machine/endian.h>
 
 #ifndef	__fenv_static
 #define	__fenv_static	static
@@ -90,11 +91,15 @@ extern const fenv_t	__fe_dfl_env;
 
 #ifndef _SOFT_FLOAT
 #ifdef __SPE__
-#define	__mffs(__env)	__asm __volatile("mfspr %0, 512" : "=r" (*(__env)))
-#define	__mtfsf(__env)	__asm __volatile("mtspr 512,%0" : : "r" (__env))
+#define	__mffs(__env) \
+	__asm __volatile("mfspr %0, 512" : "=r" ((__env)->__bits.__reg))
+#define	__mtfsf(__env) \
+	__asm __volatile("mtspr 512,%0;isync" :: "r" ((__env).__bits.__reg))
 #else
-#define	__mffs(__env)	__asm __volatile("mffs %0" : "=f" (*(__env)))
-#define	__mtfsf(__env)	__asm __volatile("mtfsf 255,%0" : : "f" (__env))
+#define	__mffs(__env) \
+	__asm __volatile("mffs %0" : "=f" ((__env)->__d))
+#define	__mtfsf(__env) \
+	__asm __volatile("mtfsf 255,%0" :: "f" ((__env).__d))
 #endif
 #else
 #define	__mffs(__env)
@@ -121,9 +126,9 @@ feclearexcept(int __excepts)
 
 	if (__excepts & FE_INVALID)
 		__excepts |= FE_ALL_INVALID;
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	__r.__bits.__reg &= ~__excepts;
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return (0);
 }
 
@@ -132,7 +137,7 @@ fegetexceptflag(fexcept_t *__flagp, int __excepts)
 {
 	union __fpscr __r;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	*__flagp = __r.__bits.__reg & __excepts;
 	return (0);
 }
@@ -144,10 +149,10 @@ fesetexceptflag(const fexcept_t *__flagp, int __excepts)
 
 	if (__excepts & FE_INVALID)
 		__excepts |= FE_ALL_EXCEPT;
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	__r.__bits.__reg &= ~__excepts;
 	__r.__bits.__reg |= *__flagp & __excepts;
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return (0);
 }
 
@@ -158,9 +163,9 @@ feraiseexcept(int __excepts)
 
 	if (__excepts & FE_INVALID)
 		__excepts |= FE_VXSOFT;
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	__r.__bits.__reg |= __excepts;
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return (0);
 }
 
@@ -169,7 +174,7 @@ fetestexcept(int __excepts)
 {
 	union __fpscr __r;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	return (__r.__bits.__reg & __excepts);
 }
 
@@ -178,7 +183,7 @@ fegetround(void)
 {
 	union __fpscr __r;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	return (__r.__bits.__reg & _ROUND_MASK);
 }
 
@@ -189,10 +194,10 @@ fesetround(int __round)
 
 	if (__round & ~_ROUND_MASK)
 		return (-1);
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	__r.__bits.__reg &= ~_ROUND_MASK;
 	__r.__bits.__reg |= __round;
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return (0);
 }
 
@@ -201,7 +206,7 @@ fegetenv(fenv_t *__envp)
 {
 	union __fpscr __r;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	*__envp = __r.__bits.__reg;
 	return (0);
 }
@@ -211,10 +216,10 @@ feholdexcept(fenv_t *__envp)
 {
 	union __fpscr __r;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	*__envp = __r.__d;
 	__r.__bits.__reg &= ~(FE_ALL_EXCEPT | _ENABLE_MASK);
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return (0);
 }
 
@@ -224,7 +229,7 @@ fesetenv(const fenv_t *__envp)
 	union __fpscr __r;
 
 	__r.__bits.__reg = *__envp;
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return (0);
 }
 
@@ -233,10 +238,10 @@ feupdateenv(const fenv_t *__envp)
 {
 	union __fpscr __r;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	__r.__bits.__reg &= FE_ALL_EXCEPT;
 	__r.__bits.__reg |= *__envp;
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return (0);
 }
 
@@ -250,10 +255,10 @@ feenableexcept(int __mask)
 	union __fpscr __r;
 	fenv_t __oldmask;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	__oldmask = __r.__bits.__reg;
 	__r.__bits.__reg |= (__mask & FE_ALL_EXCEPT) >> _FPUSW_SHIFT;
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return ((__oldmask & _ENABLE_MASK) << _FPUSW_SHIFT);
 }
 
@@ -263,10 +268,10 @@ fedisableexcept(int __mask)
 	union __fpscr __r;
 	fenv_t __oldmask;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	__oldmask = __r.__bits.__reg;
 	__r.__bits.__reg &= ~((__mask & FE_ALL_EXCEPT) >> _FPUSW_SHIFT);
-	__mtfsf(__r.__d);
+	__mtfsf(__r);
 	return ((__oldmask & _ENABLE_MASK) << _FPUSW_SHIFT);
 }
 
@@ -275,7 +280,7 @@ fegetexcept(void)
 {
 	union __fpscr __r;
 
-	__mffs(&__r.__d);
+	__mffs(&__r);
 	return ((__r.__bits.__reg & _ENABLE_MASK) << _FPUSW_SHIFT);
 }
 

sys/powerpc/booke/spe.c

@@ -134,7 +134,7 @@ enable_vec(struct thread *td)
 
 	/* Restore SPEFSCR and ACC.  Use %r0 as the scratch for ACC. */
 	mtspr(SPR_SPEFSCR, pcb->pcb_vec.vscr);
-	__asm __volatile("evldd 0, 0(%0); evmra 0,0\n"
+	__asm __volatile("isync;evldd 0, 0(%0); evmra 0,0\n"
 	    :: "b"(&pcb->pcb_vec.spare[0]));
 
 	/*