MIPS: math-emu: Add IEEE754 exception statistics to debugfs

Sometimes it's useful to let the user, while doing performance research,
know what in the IEEE754 exceptions has caused many times of FP emulation
when running a specific application. This patch adds 5 more files to
/sys/kernel/debug/mips/fpuemustats/, whose filenames begin with "ieee754".
These stats are in addition to the existing cp1ops, cp1xops, errors, loads
and stores, which may not be useful in understanding the reasons of ieee754
exceptions.

[ralf@linux-mips.org: Fixed reject due to other changes to the kernel
FP assist software.]
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Steven.Hill@imgtec.com
Cc: james.hogan@imgtec.com
Patchwork: http://patchwork.linux-mips.org/patch/7044/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/fpu_emulator.h

@@ -39,6 +39,11 @@ struct mips_fpu_emulator_stats {
 	local_t cp1ops;
 	local_t cp1xops;
 	local_t errors;
+	local_t ieee754_inexact;
+	local_t ieee754_underflow;
+	local_t ieee754_overflow;
+	local_t ieee754_zerodiv;
+	local_t ieee754_invalidop;
 };
 
 DECLARE_PER_CPU(struct mips_fpu_emulator_stats, fpuemustats);

arch/mips/math-emu/cp1emu.c

@@ -1234,14 +1234,22 @@ static int fpux_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
 			SPTOREG(fd, MIPSInst_FD(ir));
 
 		      copcsr:
-			if (ieee754_cxtest(IEEE754_INEXACT))
+			if (ieee754_cxtest(IEEE754_INEXACT)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_inexact);
 				rcsr |= FPU_CSR_INE_X | FPU_CSR_INE_S;
-			if (ieee754_cxtest(IEEE754_UNDERFLOW))
+			}
+			if (ieee754_cxtest(IEEE754_UNDERFLOW)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_underflow);
 				rcsr |= FPU_CSR_UDF_X | FPU_CSR_UDF_S;
-			if (ieee754_cxtest(IEEE754_OVERFLOW))
+			}
+			if (ieee754_cxtest(IEEE754_OVERFLOW)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_overflow);
 				rcsr |= FPU_CSR_OVF_X | FPU_CSR_OVF_S;
-			if (ieee754_cxtest(IEEE754_INVALID_OPERATION))
+			}
+			if (ieee754_cxtest(IEEE754_INVALID_OPERATION)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_invalidop);
 				rcsr |= FPU_CSR_INV_X | FPU_CSR_INV_S;
+			}
 
 			ctx->fcr31 = (ctx->fcr31 & ~FPU_CSR_ALL_X) | rcsr;
 			if ((ctx->fcr31 >> 5) & ctx->fcr31 & FPU_CSR_ALL_E) {
@@ -1468,16 +1476,26 @@ static int fpu_emu(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
 			rv.s = (*handler.u) (fs);
 			goto copcsr;
 copcsr:
-			if (ieee754_cxtest(IEEE754_INEXACT))
+			if (ieee754_cxtest(IEEE754_INEXACT)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_inexact);
 				rcsr |= FPU_CSR_INE_X | FPU_CSR_INE_S;
-			if (ieee754_cxtest(IEEE754_UNDERFLOW))
+			}
+			if (ieee754_cxtest(IEEE754_UNDERFLOW)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_underflow);
 				rcsr |= FPU_CSR_UDF_X | FPU_CSR_UDF_S;
-			if (ieee754_cxtest(IEEE754_OVERFLOW))
+			}
+			if (ieee754_cxtest(IEEE754_OVERFLOW)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_overflow);
 				rcsr |= FPU_CSR_OVF_X | FPU_CSR_OVF_S;
-			if (ieee754_cxtest(IEEE754_ZERO_DIVIDE))
+			}
+			if (ieee754_cxtest(IEEE754_ZERO_DIVIDE)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_zerodiv);
 				rcsr |= FPU_CSR_DIV_X | FPU_CSR_DIV_S;
-			if (ieee754_cxtest(IEEE754_INVALID_OPERATION))
+			}
+			if (ieee754_cxtest(IEEE754_INVALID_OPERATION)) {
+				MIPS_FPU_EMU_INC_STATS(ieee754_invalidop);
 				rcsr |= FPU_CSR_INV_X | FPU_CSR_INV_S;
+			}
 			break;
 
 			/* unary conv ops */

arch/mips/math-emu/me-debugfs.c

@@ -56,6 +56,11 @@ do {									\
 	FPU_STAT_CREATE(cp1ops);
 	FPU_STAT_CREATE(cp1xops);
 	FPU_STAT_CREATE(errors);
+	FPU_STAT_CREATE(ieee754_inexact);
+	FPU_STAT_CREATE(ieee754_underflow);
+	FPU_STAT_CREATE(ieee754_overflow);
+	FPU_STAT_CREATE(ieee754_zerodiv);
+	FPU_STAT_CREATE(ieee754_invalidop);
 
 	return 0;
 }