x86, perf: Add a build-time sanity test to the x86 decoder

Add a sanity test of x86 insn decoder against a stream
of randomly generated input, at build time.

This test is also able to reproduce any bug that might
trigger by allowing the passing of random-seed and
iteration-number to the test, or by passing input
which has invalid byte code.

Changes in V2:
 - Code cleanup.
 - Show how to reproduce the error by insn_sanity test.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: acme@redhat.com
Cc: ming.m.lin@intel.com
Cc: robert.richter@amd.com
Cc: ravitillo@lbl.gov
Cc: yrl.pp-manager.tt@hitachi.com
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20111020140109.20938.92572.stgit@localhost.localdomain
Signed-off-by: Ingo Molnar <mingo@elte.hu>

2 files changed, 284 insertions, 1 deletions

diff --git a/arch/x86/tools/Makefile b/arch/x86/tools/Makefile
index f82082677337..3255c3df67f4 100644
--- a/arch/x86/tools/Makefile
+++ b/arch/x86/tools/Makefile
@@ -18,14 +18,22 @@ chkobjdump = $(srctree)/arch/x86/tools/chkobjdump.awk
 quiet_cmd_posttest = TEST    $@
       cmd_posttest = ($(OBJDUMP) -v | $(AWK) -f $(chkobjdump)) || $(OBJDUMP) -d -j .text $(objtree)/vmlinux | $(AWK) -f $(distill_awk) | $(obj)/test_get_len $(posttest_64bit) $(posttest_verbose)
 
-posttest: $(obj)/test_get_len vmlinux
+quiet_cmd_sanitytest = TEST    $@
+      cmd_sanitytest = $(obj)/insn_sanity $(posttest_64bit) -m 1000000
+
+posttest: $(obj)/test_get_len vmlinux $(obj)/insn_sanity
         $(call cmd,posttest)
+        $(call cmd,sanitytest)
 
 hostprogs-y     := test_get_len
+hostprogs-y     := insn_sanity
 
 # -I needed for generated C source and C source which in the kernel tree.
 HOSTCFLAGS_test_get_len.o := -Wall -I$(objtree)/arch/x86/lib/ -I$(srctree)/arch/x86/include/ -I$(srctree)/arch/x86/lib/ -I$(srctree)/include/
 
+HOSTCFLAGS_insn_sanity.o := -Wall -I$(objtree)/arch/x86/lib/ -I$(srctree)/arch/x86/include/ -I$(srctree)/arch/x86/lib/ -I$(srctree)/include/
+
 # Dependencies are also needed.
 $(obj)/test_get_len.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
 
+$(obj)/insn_sanity.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
diff --git a/arch/x86/tools/insn_sanity.c b/arch/x86/tools/insn_sanity.c
new file mode 100644
index 000000000000..334d9de7d0ca
--- /dev/null
+++ b/arch/x86/tools/insn_sanity.c
@@ -0,0 +1,275 @@
+/*
+ * x86 decoder sanity test - based on test_get_insn.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2009
+ * Copyright (C) Hitachi, Ltd., 2011
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#define unlikely(cond) (cond)
+#define ARRAY_SIZE(a)   (sizeof(a)/sizeof(a[0]))
+
+#include <asm/insn.h>
+#include <inat.c>
+#include <insn.c>
+
+/*
+ * Test of instruction analysis against tampering.
+ * Feed random binary to instruction decoder and ensure not to
+ * access out-of-instruction-buffer.
+ */
+
+#define DEFAULT_MAX_ITER        10000
+#define INSN_NOP 0x90
+
+static const char       *prog;          /* Program name */
+static int              verbose;        /* Verbosity */
+static int              x86_64;         /* x86-64 bit mode flag */
+static unsigned int     seed;           /* Random seed */
+static unsigned long    iter_start;     /* Start of iteration number */
+static unsigned long    iter_end = DEFAULT_MAX_ITER;    /* End of iteration number */
+static FILE             *input_file;    /* Input file name */
+
+static void usage(const char *err)
+{
+        if (err)
+                fprintf(stderr, "Error: %s\n\n", err);
+        fprintf(stderr, "Usage: %s [-y|-n|-v] [-s seed[,no]] [-m max] [-i input]\n", prog);
+        fprintf(stderr, "\t-y   64bit mode\n");
+        fprintf(stderr, "\t-n   32bit mode\n");
+        fprintf(stderr, "\t-v   Verbose mode\n");
+        fprintf(stderr, "\t-s   Give a random seed (and iteration number)\n");
+        fprintf(stderr, "\t-m   Give a maximum iteration number\n");
+        fprintf(stderr, "\t-i   Give an input file with decoded binary\n");
+        exit(1);
+}
+
+static void dump_field(FILE *fp, const char *name, const char *indent,
+                       struct insn_field *field)
+{
+        fprintf(fp, "%s.%s = {\n", indent, name);
+        fprintf(fp, "%s\t.value = %d, bytes[] = {%x, %x, %x, %x},\n",
+                indent, field->value, field->bytes[0], field->bytes[1],
+                field->bytes[2], field->bytes[3]);
+        fprintf(fp, "%s\t.got = %d, .nbytes = %d},\n", indent,
+                field->got, field->nbytes);
+}
+
+static void dump_insn(FILE *fp, struct insn *insn)
+{
+        fprintf(fp, "Instruction = {\n");
+        dump_field(fp, "prefixes", "\t",        &insn->prefixes);
+        dump_field(fp, "rex_prefix", "\t",      &insn->rex_prefix);
+        dump_field(fp, "vex_prefix", "\t",      &insn->vex_prefix);
+        dump_field(fp, "opcode", "\t",          &insn->opcode);
+        dump_field(fp, "modrm", "\t",           &insn->modrm);
+        dump_field(fp, "sib", "\t",             &insn->sib);
+        dump_field(fp, "displacement", "\t",    &insn->displacement);
+        dump_field(fp, "immediate1", "\t",      &insn->immediate1);
+        dump_field(fp, "immediate2", "\t",      &insn->immediate2);
+        fprintf(fp, "\t.attr = %x, .opnd_bytes = %d, .addr_bytes = %d,\n",
+                insn->attr, insn->opnd_bytes, insn->addr_bytes);
+        fprintf(fp, "\t.length = %d, .x86_64 = %d, .kaddr = %p}\n",
+                insn->length, insn->x86_64, insn->kaddr);
+}
+
+static void dump_stream(FILE *fp, const char *msg, unsigned long nr_iter,
+                        unsigned char *insn_buf, struct insn *insn)
+{
+        int i;
+
+        fprintf(fp, "%s:\n", msg);
+
+        dump_insn(stderr, insn);
+
+        fprintf(fp, "You can reproduce this with below command(s);\n");
+
+        /* Input a decoded instruction sequence directly */
+        fprintf(fp, " $ echo ");
+        for (i = 0; i < MAX_INSN_SIZE; i++)
+                fprintf(fp, " %02x", insn_buf[i]);
+        fprintf(fp, " | %s -i -\n", prog);
+
+        if (!input_file) {
+                fprintf(fp, "Or \n");
+                /* Give a seed and iteration number */
+                fprintf(fp, " $ %s -s 0x%x,%lu\n", prog, seed, nr_iter);
+        }
+}
+
+static void init_random_seed(void)
+{
+        int fd;
+
+        fd = open("/dev/urandom", O_RDONLY);
+        if (fd < 0)
+                goto fail;
+
+        if (read(fd, &seed, sizeof(seed)) != sizeof(seed))
+                goto fail;
+
+        close(fd);
+        return;
+fail:
+        usage("Failed to open /dev/urandom");
+}
+
+/* Read given instruction sequence from the input file */
+static int read_next_insn(unsigned char *insn_buf)
+{
+        char buf[256]  = "", *tmp;
+        int i;
+
+        tmp = fgets(buf, ARRAY_SIZE(buf), input_file);
+        if (tmp == NULL || feof(input_file))
+                return 0;
+
+        for (i = 0; i < MAX_INSN_SIZE; i++) {
+                insn_buf[i] = (unsigned char)strtoul(tmp, &tmp, 16);
+                if (*tmp != ' ')
+                        break;
+        }
+
+        return i;
+}
+
+static int generate_insn(unsigned char *insn_buf)
+{
+        int i;
+
+        if (input_file)
+                return read_next_insn(insn_buf);
+
+        /* Fills buffer with random binary up to MAX_INSN_SIZE */
+        for (i = 0; i < MAX_INSN_SIZE - 1; i += 2)
+                *(unsigned short *)(&insn_buf[i]) = random() & 0xffff;
+
+        while (i < MAX_INSN_SIZE)
+                insn_buf[i++] = random() & 0xff;
+
+        return i;
+}
+
+static void parse_args(int argc, char **argv)
+{
+        int c;
+        char *tmp = NULL;
+        int set_seed = 0;
+
+        prog = argv[0];
+        while ((c = getopt(argc, argv, "ynvs:m:i:")) != -1) {
+                switch (c) {
+                case 'y':
+                        x86_64 = 1;
+                        break;
+                case 'n':
+                        x86_64 = 0;
+                        break;
+                case 'v':
+                        verbose = 1;
+                        break;
+                case 'i':
+                        if (strcmp("-", optarg) == 0)
+                                input_file = stdin;
+                        else
+                                input_file = fopen(optarg, "r");
+                        if (!input_file)
+                                usage("Failed to open input file");
+                        break;
+                case 's':
+                        seed = (unsigned int)strtoul(optarg, &tmp, 0);
+                        if (*tmp == ',') {
+                                optarg = tmp + 1;
+                                iter_start = strtoul(optarg, &tmp, 0);
+                        }
+                        if (*tmp != '\0' || tmp == optarg)
+                                usage("Failed to parse seed");
+                        set_seed = 1;
+                        break;
+                case 'm':
+                        iter_end = strtoul(optarg, &tmp, 0);
+                        if (*tmp != '\0' || tmp == optarg)
+                                usage("Failed to parse max_iter");
+                        break;
+                default:
+                        usage(NULL);
+                }
+        }
+
+        /* Check errors */
+        if (iter_end < iter_start)
+                usage("Max iteration number must be bigger than iter-num");
+
+        if (set_seed && input_file)
+                usage("Don't use input file (-i) with random seed (-s)");
+
+        /* Initialize random seed */
+        if (!input_file) {
+                if (!set_seed)  /* No seed is given */
+                        init_random_seed();
+                srand(seed);
+        }
+}
+
+int main(int argc, char **argv)
+{
+        struct insn insn;
+        int insns = 0;
+        int errors = 0;
+        unsigned long i;
+        unsigned char insn_buf[MAX_INSN_SIZE * 2];
+
+        parse_args(argc, argv);
+
+        /* Prepare stop bytes with NOPs */
+        memset(insn_buf + MAX_INSN_SIZE, INSN_NOP, MAX_INSN_SIZE);
+
+        for (i = 0; i < iter_end; i++) {
+                if (generate_insn(insn_buf) <= 0)
+                        break;
+
+                if (i < iter_start)     /* Skip to given iteration number */
+                        continue;
+
+                /* Decode an instruction */
+                insn_init(&insn, insn_buf, x86_64);
+                insn_get_length(&insn);
+
+                if (verbose && !insn_complete(&insn))
+                        dump_stream(stdout, "Info: Found an undecodable input", i, insn_buf, &insn);
+
+                if (insn.next_byte <= insn.kaddr ||
+                    insn.kaddr + MAX_INSN_SIZE < insn.next_byte) {
+                        /* Access out-of-range memory */
+                        dump_stream(stdout, "Error: Found an access violation", i, insn_buf, &insn);
+                        errors++;
+                }
+                insns++;
+        }
+
+        fprintf(stdout, "%s: decoded and checked %d %s instructions with %d errors (seed:0x%x)\n", (errors) ? "Failure" : "Success", insns, (input_file) ? "given" : "random", errors, seed);
+
+        return errors ? 1 : 0;
+}