MIPS: math-emu: Add mfhc1 & mthc1 support.

This patch adds support for the mfhc1 & mthc1 instructions to the FPU
emulator. These instructions were introduced in release 2 of the MIPS32
& MIPS64 architectures and allow access to the most significant 32 bits
of a 64-bit FP register.

[ralf@linux-mips.org: Fix ifdef hell added by original patch.]

Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Signed-off-by: Steven J. Hill <Steven.Hill@imgtec.com>
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6112/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

2 files changed, 27 insertions, 2 deletions

diff --git a/arch/mips/include/uapi/asm/inst.h b/arch/mips/include/uapi/asm/inst.h
index e5a676e3d3c0..0ee96563e6f0 100644
--- a/arch/mips/include/uapi/asm/inst.h
+++ b/arch/mips/include/uapi/asm/inst.h
@@ -98,8 +98,9 @@ enum rt_op {
  */
 enum cop_op {
         mfc_op        = 0x00, dmfc_op       = 0x01,
-        cfc_op        = 0x02, mtc_op        = 0x04,
-        dmtc_op       = 0x05, ctc_op        = 0x06,
+        cfc_op        = 0x02, mfhc_op       = 0x03,
+        mtc_op        = 0x04, dmtc_op       = 0x05,
+        ctc_op        = 0x06, mthc_op       = 0x07,
         bc_op         = 0x08, cop_op        = 0x10,
         copm_op       = 0x18
 };
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index efe008846ed0..aaf7c92f4629 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -878,6 +878,10 @@ static inline int cop1_64bit(struct pt_regs *xcp)
                         ctx->fpr[x & ~1] >> 32 << 32 | (u32)(si) : \
                         ctx->fpr[x & ~1] << 32 >> 32 | (u64)(si) << 32)
 
+#define SIFROMHREG(si, x)       ((si) = (int)(ctx->fpr[x] >> 32))
+#define SITOHREG(si, x)         (ctx->fpr[x] = \
+                                ctx->fpr[x] << 32 >> 32 | (u64)(si) << 32)
+
 #define DIFROMREG(di, x) ((di) = ctx->fpr[x & ~(cop1_64bit(xcp) == 0)])
 #define DITOREG(di, x)  (ctx->fpr[x & ~(cop1_64bit(xcp) == 0)] = (di))
 
@@ -1055,6 +1059,25 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
                         break;
 #endif
 
+                case mfhc_op:
+                        if (!cpu_has_mips_r2)
+                                goto sigill;
+
+                        /* copregister rd -> gpr[rt] */
+                        if (MIPSInst_RT(ir) != 0) {
+                                SIFROMHREG(xcp->regs[MIPSInst_RT(ir)],
+                                        MIPSInst_RD(ir));
+                        }
+                        break;
+
+                case mthc_op:
+                        if (!cpu_has_mips_r2)
+                                goto sigill;
+
+                        /* copregister rd <- gpr[rt] */
+                        SITOHREG(xcp->regs[MIPSInst_RT(ir)], MIPSInst_RD(ir));
+                        break;
+
                 case mfc_op:
                         /* copregister rd -> gpr[rt] */
                         if (MIPSInst_RT(ir) != 0) {
@@ -1263,6 +1286,7 @@ static int cop1Emulate(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
 #endif
 
         default:
+sigill:
                 return SIGILL;
         }