s390/disassembler: generate opcode tables from text file

The current way of adding new instructions to the opcode tables is
painful and error prone. Therefore add, similar to binutils, a text
file which contains all opcodes and the corresponding mnemonics and
instruction formats.

A small gen_opcode_table tool then generates a header file with the
required enums and opcode table initializers at the prepare step of
the kernel build.

This way only a simple text file has to be maintained, which can be
rather easily extended.

Unlike before where there were plenty of opcode tables and a large
switch statement to find the correct opcode table, there is now only
one opcode table left which contains all instructions. A second opcode
offset table now contains offsets within the opcode table to find
instructions which have the same opcode prefix. In order to save space
all 1-byte opcode instructions are grouped together at the end of the
opcode table. This is also quite similar to like it was before.

In addition also move and change code and definitions within the
disassembler. As a side effect this reduces the size required for the
code and opcode tables by ~1.5k.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>

1 files changed, 336 insertions, 0 deletions

diff --git a/arch/s390/tools/gen_opcode_table.c b/arch/s390/tools/gen_opcode_table.c
new file mode 100644
index 000000000000..01d4c5a4bfe9
--- /dev/null
+++ b/arch/s390/tools/gen_opcode_table.c
@@ -0,0 +1,336 @@
+/*
+ * Generate opcode table initializers for the in-kernel disassembler.
+ *
+ *    Copyright IBM Corp. 2017
+ *
+ */
+
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <stdio.h>
+
+#define STRING_SIZE_MAX 20
+
+struct insn_type {
+	unsigned char byte;
+	unsigned char mask;
+	char **format;
+};
+
+struct insn {
+	struct insn_type *type;
+	char opcode[STRING_SIZE_MAX];
+	char name[STRING_SIZE_MAX];
+	char upper[STRING_SIZE_MAX];
+	char format[STRING_SIZE_MAX];
+	unsigned int name_len;
+};
+
+struct insn_group {
+	struct insn_type *type;
+	int offset;
+	int count;
+	char opcode[2];
+};
+
+struct insn_format {
+	char *format;
+	int type;
+};
+
+struct gen_opcode {
+	struct insn *insn;
+	int nr;
+	struct insn_group *group;
+	int nr_groups;
+};
+
+/*
+ * Table of instruction format types. Each opcode is defined with at
+ * least one byte (two nibbles), three nibbles, or two bytes (four
+ * nibbles).
+ * The byte member of each instruction format type entry defines
+ * within which byte of an instruction the third (and fourth) nibble
+ * of an opcode can be found. The mask member is the and-mask that
+ * needs to be applied on this byte in order to get the third (and
+ * fourth) nibble of the opcode.
+ * The format array defines all instruction formats (as defined in the
+ * Principles of Operation) which have the same position of the opcode
+ * nibbles.
+ * A special case are instruction formats with 1-byte opcodes. In this
+ * case the byte member always is zero, so that the mask is applied on
+ * the (only) byte that contains the opcode.
+ */
+static struct insn_type insn_type_table[] = {
+	{
+		.byte = 0,
+		.mask = 0xff,
+		.format = (char *[]) {
+			"MII",
+			"RR",
+			"RS",
+			"RSI",
+			"RX",
+			"SI",
+			"SMI",
+			"SS",
+			NULL,
+		},
+	},
+	{
+		.byte = 1,
+		.mask = 0x0f,
+		.format = (char *[]) {
+			"RI",
+			"RIL",
+			"SSF",
+			NULL,
+		},
+	},
+	{
+		.byte = 1,
+		.mask = 0xff,
+		.format = (char *[]) {
+			"E",
+			"IE",
+			"RRE",
+			"RRF",
+			"RRR",
+			"S",
+			"SIL",
+			"SSE",
+			NULL,
+		},
+	},
+	{
+		.byte = 5,
+		.mask = 0xff,
+		.format = (char *[]) {
+			"RIE",
+			"RIS",
+			"RRS",
+			"RSE",
+			"RSL",
+			"RSY",
+			"RXE",
+			"RXF",
+			"RXY",
+			"SIY",
+			"VRI",
+			"VRR",
+			"VRS",
+			"VRV",
+			"VRX",
+			"VSI",
+			NULL,
+		},
+	},
+};
+
+static struct insn_type *insn_format_to_type(char *format)
+{
+	char tmp[STRING_SIZE_MAX];
+	char *base_format, **ptr;
+	int i;
+
+	strcpy(tmp, format);
+	base_format = tmp;
+	base_format = strsep(&base_format, "_");
+	for (i = 0; i < sizeof(insn_type_table) / sizeof(insn_type_table[0]); i++) {
+		ptr = insn_type_table[i].format;
+		while (*ptr) {
+			if (!strcmp(base_format, *ptr))
+				return &insn_type_table[i];
+			ptr++;
+		}
+	}
+	exit(EXIT_FAILURE);
+}
+
+static void read_instructions(struct gen_opcode *desc)
+{
+	struct insn insn;
+	int rc, i;
+
+	while (1) {
+		rc = scanf("%s %s %s", insn.opcode, insn.name, insn.format);
+		if (rc == EOF)
+			break;
+		if (rc != 3)
+			exit(EXIT_FAILURE);
+		insn.type = insn_format_to_type(insn.format);
+		insn.name_len = strlen(insn.name);
+		for (i = 0; i <= insn.name_len; i++)
+			insn.upper[i] = toupper((unsigned char)insn.name[i]);
+		desc->nr++;
+		desc->insn = realloc(desc->insn, desc->nr * sizeof(*desc->insn));
+		if (!desc->insn)
+			exit(EXIT_FAILURE);
+		desc->insn[desc->nr - 1] = insn;
+	}
+}
+
+static int cmpformat(const void *a, const void *b)
+{
+	return strcmp(((struct insn *)a)->format, ((struct insn *)b)->format);
+}
+
+static void print_formats(struct gen_opcode *desc)
+{
+	char *format;
+	int i, count;
+
+	qsort(desc->insn, desc->nr, sizeof(*desc->insn), cmpformat);
+	format = "";
+	count = 0;
+	printf("enum {\n");
+	for (i = 0; i < desc->nr; i++) {
+		if (!strcmp(format, desc->insn[i].format))
+			continue;
+		count++;
+		format = desc->insn[i].format;
+		printf("\tINSTR_%s,\n", format);
+	}
+	printf("}; /* %d */\n\n", count);
+}
+
+static int cmp_long_insn(const void *a, const void *b)
+{
+	return strcmp(((struct insn *)a)->name, ((struct insn *)b)->name);
+}
+
+static void print_long_insn(struct gen_opcode *desc)
+{
+	struct insn *insn;
+	int i, count;
+
+	qsort(desc->insn, desc->nr, sizeof(*desc->insn), cmp_long_insn);
+	count = 0;
+	printf("enum {\n");
+	for (i = 0; i < desc->nr; i++) {
+		insn = &desc->insn[i];
+		if (insn->name_len < 6)
+			continue;
+		printf("\tLONG_INSN_%s,\n", insn->upper);
+		count++;
+	}
+	printf("}; /* %d */\n\n", count);
+
+	printf("#define LONG_INSN_INITIALIZER { \\\n");
+	for (i = 0; i < desc->nr; i++) {
+		insn = &desc->insn[i];
+		if (insn->name_len < 6)
+			continue;
+		printf("\t[LONG_INSN_%s] = \"%s\", \\\n", insn->upper, insn->name);
+	}
+	printf("}\n\n");
+}
+
+static void print_opcode(struct insn *insn, int nr)
+{
+	char *opcode;
+
+	opcode = insn->opcode;
+	if (insn->type->byte != 0)
+		opcode += 2;
+	printf("\t[%4d] = { .opfrag = 0x%s, .format = INSTR_%s, ", nr, opcode, insn->format);
+	if (insn->name_len < 6)
+		printf(".name = \"%s\" ", insn->name);
+	else
+		printf(".offset = LONG_INSN_%s ", insn->upper);
+	printf("}, \\\n");
+}
+
+static void add_to_group(struct gen_opcode *desc, struct insn *insn, int offset)
+{
+	struct insn_group *group;
+
+	group = desc->group ? &desc->group[desc->nr_groups - 1] : NULL;
+	if (group && (!strncmp(group->opcode, insn->opcode, 2) || group->type->byte == 0)) {
+		group->count++;
+		return;
+	}
+	desc->nr_groups++;
+	desc->group = realloc(desc->group, desc->nr_groups * sizeof(*desc->group));
+	if (!desc->group)
+		exit(EXIT_FAILURE);
+	group = &desc->group[desc->nr_groups - 1];
+	strncpy(group->opcode, insn->opcode, 2);
+	group->type = insn->type;
+	group->offset = offset;
+	group->count = 1;
+}
+
+static int cmpopcode(const void *a, const void *b)
+{
+	return strcmp(((struct insn *)a)->opcode, ((struct insn *)b)->opcode);
+}
+
+static void print_opcode_table(struct gen_opcode *desc)
+{
+	char opcode[2] = "";
+	struct insn *insn;
+	int i, offset;
+
+	qsort(desc->insn, desc->nr, sizeof(*desc->insn), cmpopcode);
+	printf("#define OPCODE_TABLE_INITIALIZER { \\\n");
+	offset = 0;
+	for (i = 0; i < desc->nr; i++) {
+		insn = &desc->insn[i];
+		if (insn->type->byte == 0)
+			continue;
+		add_to_group(desc, insn, offset);
+		if (strncmp(opcode, insn->opcode, 2)) {
+			strncpy(opcode, insn->opcode, 2);
+			printf("\t/* %.2s */ \\\n", opcode);
+		}
+		print_opcode(insn, offset);
+		offset++;
+	}
+	printf("\t/* 1-byte opcode instructions */ \\\n");
+	for (i = 0; i < desc->nr; i++) {
+		insn = &desc->insn[i];
+		if (insn->type->byte != 0)
+			continue;
+		add_to_group(desc, insn, offset);
+		print_opcode(insn, offset);
+		offset++;
+	}
+	printf("}\n\n");
+}
+
+static void print_opcode_table_offsets(struct gen_opcode *desc)
+{
+	struct insn_group *group;
+	int i;
+
+	printf("#define OPCODE_OFFSET_INITIALIZER { \\\n");
+	for (i = 0; i < desc->nr_groups; i++) {
+		group = &desc->group[i];
+		printf("\t{ .opcode = 0x%.2s, .mask = 0x%02x, .byte = %d, .offset = %d, .count = %d }, \\\n",
+		       group->opcode, group->type->mask, group->type->byte, group->offset, group->count);
+	}
+	printf("}\n\n");
+}
+
+int main(int argc, char **argv)
+{
+	struct gen_opcode _desc = { 0 };
+	struct gen_opcode *desc = &_desc;
+
+	read_instructions(desc);
+	printf("#ifndef __S390_GENERATED_DIS_H__\n");
+	printf("#define __S390_GENERATED_DIS_H__\n");
+	printf("/*\n");
+	printf(" * DO NOT MODIFY.\n");
+	printf(" *\n");
+	printf(" * This file was generated by %s\n", __FILE__);
+	printf(" */\n\n");
+	print_formats(desc);
+	print_long_insn(desc);
+	print_opcode_table(desc);
+	print_opcode_table_offsets(desc);
+	printf("#endif\n");
+	exit(EXIT_SUCCESS);
+}