3.16.55-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Maciej W. Rozycki" <ma...@linux-mips.org>

commit f1f3b7ebac08161761c352fd070cfa07b7b94c54 upstream.

Define IEEE 754-2008 feature control bits: FIR.HAS2008, FCSR.ABS2008 and
FCSR.NAN2008, and update the `_ieee754_csr' structure accordingly.

For completeness define FIR.UFRP too.

Signed-off-by: Maciej W. Rozycki <ma...@linux-mips.org>
Cc: linux-m...@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9709/
Signed-off-by: Ralf Baechle <r...@linux-mips.org>
[bwh: Backported to 3.16: In cop1Emulate(), keep converting the rounding mode]
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -136,10 +136,13 @@
 #define FPU_CSR_COND7  0x80000000      /* $fcc7 */
 
 /*
- * Bits 18 - 20 of the FPU Status Register will be read as 0,
+ * Bits 22:20 of the FPU Status Register will be read as 0,
  * and should be written as zero.
  */
-#define FPU_CSR_RSVD   0x001c0000
+#define FPU_CSR_RSVD   (_ULCAST_(7) << 20)
+
+#define FPU_CSR_ABS2008        (_ULCAST_(1) << 19)
+#define FPU_CSR_NAN2008        (_ULCAST_(1) << 18)
 
 /*
  * X the exception cause indicator
@@ -687,6 +690,8 @@
 #define MIPS_FPIR_W            (_ULCAST_(1) << 20)
 #define MIPS_FPIR_L            (_ULCAST_(1) << 21)
 #define MIPS_FPIR_F64          (_ULCAST_(1) << 22)
+#define MIPS_FPIR_HAS2008      (_ULCAST_(1) << 23)
+#define MIPS_FPIR_UFRP         (_ULCAST_(1) << 28)
 
 /*
  * Bits in the MIPS32 Memory Segmentation registers.
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -929,10 +929,12 @@ emul:
                                         MIPSInst_RT(ir), value);
 
                                /*
-                                * Don't write reserved bits,
+                                * Don't write unsupported bits,
                                 * and convert to ieee library modes
                                 */
-                               ctx->fcr31 = (value & ~(FPU_CSR_RSVD | 
FPU_CSR_RM)) |
+                               ctx->fcr31 = (value &
+                                             ~(FPU_CSR_RSVD | FPU_CSR_ABS2008 |
+                                               FPU_CSR_NAN2008 | FPU_CSR_RM)) |
                                             modeindex(value);
                        }
                        if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
--- a/arch/mips/math-emu/ieee754.h
+++ b/arch/mips/math-emu/ieee754.h
@@ -195,15 +195,17 @@ static inline int ieee754dp_ge(union iee
  * The control status register
  */
 struct _ieee754_csr {
-       __BITFIELD_FIELD(unsigned pad0:7,
-       __BITFIELD_FIELD(unsigned nod:1,        /* set 1 for no denormalised 
numbers */
-       __BITFIELD_FIELD(unsigned c:1,          /* condition */
-       __BITFIELD_FIELD(unsigned pad1:5,
+       __BITFIELD_FIELD(unsigned fcc:7,        /* condition[7:1] */
+       __BITFIELD_FIELD(unsigned nod:1,        /* set 1 for no denormals */
+       __BITFIELD_FIELD(unsigned c:1,          /* condition[0] */
+       __BITFIELD_FIELD(unsigned pad0:3,
+       __BITFIELD_FIELD(unsigned abs2008:1,    /* IEEE 754-2008 ABS/NEG.fmt */
+       __BITFIELD_FIELD(unsigned nan2008:1,    /* IEEE 754-2008 NaN mode */
        __BITFIELD_FIELD(unsigned cx:6,         /* exceptions this operation */
        __BITFIELD_FIELD(unsigned mx:5,         /* exception enable  mask */
        __BITFIELD_FIELD(unsigned sx:5,         /* exceptions total */
        __BITFIELD_FIELD(unsigned rm:2,         /* current rounding mode */
-       ;))))))))
+       ;))))))))))
 };
 #define ieee754_csr (*(struct _ieee754_csr *)(&current->thread.fpu.fcr31))
 

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