lib: add Dhrystone benchmark test

When working on SoC bring-up, (a full) userspace may not be available,
making it hard to benchmark the CPU performance of the system under
development.  Still, one may want to have a rough idea of the (relative)
performance of one or more CPU cores, especially when working on e.g.  the
clock driver that controls the CPU core clock(s).

Hence make the classical Dhrystone 2.1 benchmark available as a Linux
kernel test module, based on[1].

When built-in, this benchmark can be run without any userspace present.

Parallel runs (run on multiple CPU cores) are supported, just kick the
"run" file multiple times.

Note that the actual figures depend on the configuration options that
control compiler optimization (e.g.  CONFIG_CC_OPTIMIZE_FOR_SIZE vs. 
CONFIG_CC_OPTIMIZE_FOR_PERFORMANCE), and on the compiler options used when
building the kernel in general.  Hence numbers may differ from those
obtained by running similar benchmarks in userspace.

[1] https://github.com/qris/dhrystone-deb.git

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lkml.kernel.org/r/4d07ad990740a5f1e426ce4566fb514f60ec9bdd.1670509558.git.geert+renesas@glider.be
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
[geert+renesas@glider.be: fix uninitialized use of ret]
 Link: https://lkml.kernel.org/r/alpine.DEB.2.22.394.2212190857310.137329@ramsan.of.borg
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 283 insertions, 0 deletions

diff --git a/lib/dhry_1.c b/lib/dhry_1.c
new file mode 100644
index 000000000000..83247106824c
--- /dev/null
+++ b/lib/dhry_1.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+/*
+ ****************************************************************************
+ *
+ *                   "DHRYSTONE" Benchmark Program
+ *                   -----------------------------
+ *
+ *  Version:    C, Version 2.1
+ *
+ *  File:       dhry_1.c (part 2 of 3)
+ *
+ *  Date:       May 25, 1988
+ *
+ *  Author:     Reinhold P. Weicker
+ *
+ ****************************************************************************
+ */
+
+#include "dhry.h"
+
+#include <linux/ktime.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+/* Global Variables: */
+
+int Int_Glob;
+char Ch_1_Glob;
+
+static Rec_Pointer Ptr_Glob, Next_Ptr_Glob;
+static Boolean Bool_Glob;
+static char Ch_2_Glob;
+static int Arr_1_Glob[50];
+static int Arr_2_Glob[50][50];
+
+static void Proc_3(Rec_Pointer *Ptr_Ref_Par)
+/******************/
+/* executed once */
+/* Ptr_Ref_Par becomes Ptr_Glob */
+{
+	if (Ptr_Glob) {
+		/* then, executed */
+		*Ptr_Ref_Par = Ptr_Glob->Ptr_Comp;
+	}
+	Proc_7(10, Int_Glob, &Ptr_Glob->variant.var_1.Int_Comp);
+} /* Proc_3 */
+
+
+static void Proc_1(Rec_Pointer Ptr_Val_Par)
+/******************/
+/* executed once */
+{
+	Rec_Pointer Next_Record = Ptr_Val_Par->Ptr_Comp;
+						/* == Ptr_Glob_Next */
+	/* Local variable, initialized with Ptr_Val_Par->Ptr_Comp,    */
+	/* corresponds to "rename" in Ada, "with" in Pascal           */
+
+	*Ptr_Val_Par->Ptr_Comp = *Ptr_Glob;
+	Ptr_Val_Par->variant.var_1.Int_Comp = 5;
+	Next_Record->variant.var_1.Int_Comp =
+		Ptr_Val_Par->variant.var_1.Int_Comp;
+	Next_Record->Ptr_Comp = Ptr_Val_Par->Ptr_Comp;
+	Proc_3(&Next_Record->Ptr_Comp);
+	/* Ptr_Val_Par->Ptr_Comp->Ptr_Comp == Ptr_Glob->Ptr_Comp */
+	if (Next_Record->Discr == Ident_1) {
+		/* then, executed */
+		Next_Record->variant.var_1.Int_Comp = 6;
+		Proc_6(Ptr_Val_Par->variant.var_1.Enum_Comp,
+		       &Next_Record->variant.var_1.Enum_Comp);
+		Next_Record->Ptr_Comp = Ptr_Glob->Ptr_Comp;
+		Proc_7(Next_Record->variant.var_1.Int_Comp, 10,
+		       &Next_Record->variant.var_1.Int_Comp);
+	} else {
+		/* not executed */
+		*Ptr_Val_Par = *Ptr_Val_Par->Ptr_Comp;
+	}
+} /* Proc_1 */
+
+
+static void Proc_2(One_Fifty *Int_Par_Ref)
+/******************/
+/* executed once */
+/* *Int_Par_Ref == 1, becomes 4 */
+{
+	One_Fifty  Int_Loc;
+	Enumeration   Enum_Loc;
+
+	Int_Loc = *Int_Par_Ref + 10;
+	do {
+		/* executed once */
+		if (Ch_1_Glob == 'A') {
+			/* then, executed */
+			Int_Loc -= 1;
+			*Int_Par_Ref = Int_Loc - Int_Glob;
+			Enum_Loc = Ident_1;
+		} /* if */
+	} while (Enum_Loc != Ident_1); /* true */
+} /* Proc_2 */
+
+
+static void Proc_4(void)
+/*******/
+/* executed once */
+{
+	Boolean Bool_Loc;
+
+	Bool_Loc = Ch_1_Glob == 'A';
+	Bool_Glob = Bool_Loc | Bool_Glob;
+	Ch_2_Glob = 'B';
+} /* Proc_4 */
+
+
+static void Proc_5(void)
+/*******/
+/* executed once */
+{
+	Ch_1_Glob = 'A';
+	Bool_Glob = false;
+} /* Proc_5 */
+
+
+int dhry(int n)
+/*****/
+
+  /* main program, corresponds to procedures        */
+  /* Main and Proc_0 in the Ada version             */
+{
+	One_Fifty Int_1_Loc;
+	One_Fifty Int_2_Loc;
+	One_Fifty Int_3_Loc;
+	char Ch_Index;
+	Enumeration Enum_Loc;
+	Str_30 Str_1_Loc;
+	Str_30 Str_2_Loc;
+	int Run_Index;
+	int Number_Of_Runs;
+	ktime_t Begin_Time, End_Time;
+	u32 User_Time;
+
+	/* Initializations */
+
+	Next_Ptr_Glob = (Rec_Pointer)kzalloc(sizeof(Rec_Type), GFP_KERNEL);
+	Ptr_Glob = (Rec_Pointer)kzalloc(sizeof(Rec_Type), GFP_KERNEL);
+
+	Ptr_Glob->Ptr_Comp = Next_Ptr_Glob;
+	Ptr_Glob->Discr = Ident_1;
+	Ptr_Glob->variant.var_1.Enum_Comp = Ident_3;
+	Ptr_Glob->variant.var_1.Int_Comp = 40;
+	strcpy(Ptr_Glob->variant.var_1.Str_Comp,
+	       "DHRYSTONE PROGRAM, SOME STRING");
+	strcpy(Str_1_Loc, "DHRYSTONE PROGRAM, 1'ST STRING");
+
+	Arr_2_Glob[8][7] = 10;
+	/* Was missing in published program. Without this statement,    */
+	/* Arr_2_Glob[8][7] would have an undefined value.             */
+	/* Warning: With 16-Bit processors and Number_Of_Runs > 32000,  */
+	/* overflow may occur for this array element.                   */
+
+	pr_debug("Dhrystone Benchmark, Version 2.1 (Language: C)\n");
+
+	Number_Of_Runs = n;
+
+	pr_debug("Execution starts, %d runs through Dhrystone\n",
+		 Number_Of_Runs);
+
+	/***************/
+	/* Start timer */
+	/***************/
+
+	Begin_Time = ktime_get();
+
+	for (Run_Index = 1; Run_Index <= Number_Of_Runs; ++Run_Index) {
+		Proc_5();
+		Proc_4();
+		/* Ch_1_Glob == 'A', Ch_2_Glob == 'B', Bool_Glob == true */
+		Int_1_Loc = 2;
+		Int_2_Loc = 3;
+		strcpy(Str_2_Loc, "DHRYSTONE PROGRAM, 2'ND STRING");
+		Enum_Loc = Ident_2;
+		Bool_Glob = !Func_2(Str_1_Loc, Str_2_Loc);
+		/* Bool_Glob == 1 */
+		while (Int_1_Loc < Int_2_Loc) {
+			/* loop body executed once */
+			Int_3_Loc = 5 * Int_1_Loc - Int_2_Loc;
+			/* Int_3_Loc == 7 */
+			Proc_7(Int_1_Loc, Int_2_Loc, &Int_3_Loc);
+			/* Int_3_Loc == 7 */
+			Int_1_Loc += 1;
+		} /* while */
+		/* Int_1_Loc == 3, Int_2_Loc == 3, Int_3_Loc == 7 */
+		Proc_8(Arr_1_Glob, Arr_2_Glob, Int_1_Loc, Int_3_Loc);
+		/* Int_Glob == 5 */
+		Proc_1(Ptr_Glob);
+		for (Ch_Index = 'A'; Ch_Index <= Ch_2_Glob; ++Ch_Index) {
+			/* loop body executed twice */
+			if (Enum_Loc == Func_1(Ch_Index, 'C')) {
+				/* then, not executed */
+				Proc_6(Ident_1, &Enum_Loc);
+				strcpy(Str_2_Loc, "DHRYSTONE PROGRAM, 3'RD STRING");
+				Int_2_Loc = Run_Index;
+				Int_Glob = Run_Index;
+			}
+		}
+		/* Int_1_Loc == 3, Int_2_Loc == 3, Int_3_Loc == 7 */
+		Int_2_Loc = Int_2_Loc * Int_1_Loc;
+		Int_1_Loc = Int_2_Loc / Int_3_Loc;
+		Int_2_Loc = 7 * (Int_2_Loc - Int_3_Loc) - Int_1_Loc;
+		/* Int_1_Loc == 1, Int_2_Loc == 13, Int_3_Loc == 7 */
+		Proc_2(&Int_1_Loc);
+		/* Int_1_Loc == 5 */
+
+	} /* loop "for Run_Index" */
+
+	/**************/
+	/* Stop timer */
+	/**************/
+
+	End_Time = ktime_get();
+
+#define dhry_assert_int_eq(val, expected)				\
+	if (val != expected)						\
+		pr_err("%s: %d (FAIL, expected %d)\n", #val, val,	\
+		       expected);					\
+	else								\
+		pr_debug("%s: %d (OK)\n", #val, val)
+
+#define dhry_assert_char_eq(val, expected)				\
+	if (val != expected)						\
+		pr_err("%s: %c (FAIL, expected %c)\n", #val, val,	\
+		       expected);					\
+	else								\
+		pr_debug("%s: %c (OK)\n", #val, val)
+
+#define dhry_assert_string_eq(val, expected)				\
+	if (strcmp(val, expected))					\
+		pr_err("%s: %s (FAIL, expected %s)\n", #val, val,	\
+		       expected);					\
+	else								\
+		pr_debug("%s: %s (OK)\n", #val, val)
+
+	pr_debug("Execution ends\n");
+	pr_debug("Final values of the variables used in the benchmark:\n");
+	dhry_assert_int_eq(Int_Glob, 5);
+	dhry_assert_int_eq(Bool_Glob, 1);
+	dhry_assert_char_eq(Ch_1_Glob, 'A');
+	dhry_assert_char_eq(Ch_2_Glob, 'B');
+	dhry_assert_int_eq(Arr_1_Glob[8], 7);
+	dhry_assert_int_eq(Arr_2_Glob[8][7], Number_Of_Runs + 10);
+	pr_debug("Ptr_Comp: %px\n", Ptr_Glob->Ptr_Comp);
+	dhry_assert_int_eq(Ptr_Glob->Discr, 0);
+	dhry_assert_int_eq(Ptr_Glob->variant.var_1.Enum_Comp, 2);
+	dhry_assert_int_eq(Ptr_Glob->variant.var_1.Int_Comp, 17);
+	dhry_assert_string_eq(Ptr_Glob->variant.var_1.Str_Comp,
+			      "DHRYSTONE PROGRAM, SOME STRING");
+	if (Next_Ptr_Glob->Ptr_Comp != Ptr_Glob->Ptr_Comp)
+		pr_err("Next_Ptr_Glob->Ptr_Comp: %px (expected %px)\n",
+		       Next_Ptr_Glob->Ptr_Comp, Ptr_Glob->Ptr_Comp);
+	else
+		pr_debug("Next_Ptr_Glob->Ptr_Comp: %px\n",
+			 Next_Ptr_Glob->Ptr_Comp);
+	dhry_assert_int_eq(Next_Ptr_Glob->Discr, 0);
+	dhry_assert_int_eq(Next_Ptr_Glob->variant.var_1.Enum_Comp, 1);
+	dhry_assert_int_eq(Next_Ptr_Glob->variant.var_1.Int_Comp, 18);
+	dhry_assert_string_eq(Next_Ptr_Glob->variant.var_1.Str_Comp,
+			      "DHRYSTONE PROGRAM, SOME STRING");
+	dhry_assert_int_eq(Int_1_Loc, 5);
+	dhry_assert_int_eq(Int_2_Loc, 13);
+	dhry_assert_int_eq(Int_3_Loc, 7);
+	dhry_assert_int_eq(Enum_Loc, 1);
+	dhry_assert_string_eq(Str_1_Loc, "DHRYSTONE PROGRAM, 1'ST STRING");
+	dhry_assert_string_eq(Str_2_Loc, "DHRYSTONE PROGRAM, 2'ND STRING");
+
+	User_Time = ktime_to_ms(ktime_sub(End_Time, Begin_Time));
+
+	kfree(Ptr_Glob);
+	kfree(Next_Ptr_Glob);
+
+	/* Measurements should last at least 2 seconds */
+	if (User_Time < 2 * MSEC_PER_SEC)
+		return -EAGAIN;
+
+	return div_u64(mul_u32_u32(MSEC_PER_SEC, Number_Of_Runs), User_Time);
+}