As the Meltdown workaround for i386 changes the f00f Pentium bug

workaround, the new code should be tested.  Fortunately I have such  
a beast at home.  This regression test halts my Intel Pentium/MMX
CPU unless the fix_f00f() function has been called.

2 files changed, 111 insertions, 0 deletions

diff --git a/regress/sys/arch/i386/f00f/Makefile b/regress/sys/arch/i386/f00f/Makefile
new file mode 100644
index 00000000000..fa7aec4b01a
--- /dev/null
+++ b/regress/sys/arch/i386/f00f/Makefile
@@ -0,0 +1,5 @@
+#	$OpenBSD: Makefile,v 1.1.1.1 2018/05/21 23:19:32 bluhm Exp $
+
+PROG=	f00f
+
+.include <bsd.regress.mk>
diff --git a/regress/sys/arch/i386/f00f/f00f.c b/regress/sys/arch/i386/f00f/f00f.c
new file mode 100644
index 00000000000..6f027c6947f
--- /dev/null
+++ b/regress/sys/arch/i386/f00f/f00f.c
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2018 Alexander Bluhm <bluhm@genua.de>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* Test the Pentium f00f bug workaround by executing 0xF0,0x0F,0xC7,0xC8. */
+
+#include <err.h>
+#include <signal.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+void
+handler(int sig, siginfo_t *sip, void *ctx)
+{
+	printf("signo %d, code %d, errno %d\n",
+	    sip->si_signo, sip->si_code, sip->si_errno);
+	if (sig != SIGILL)
+		errx(1, "expected SIGILL: %d", sig);
+	printf("addr %p, trapno %d\n", sip->si_addr, sip->si_trapno);
+	printf("instruction %.2x %.2x %.2x %.2x\n",
+	    ((uint8_t *)sip->si_addr)[0],
+	    ((uint8_t *)sip->si_addr)[1],
+	    ((uint8_t *)sip->si_addr)[2],
+	    ((uint8_t *)sip->si_addr)[3]);
+	if (*((uint32_t *)sip->si_addr) != 0xc8c70ff0)
+		errx(1, "expected instrcution f0 0f c7 c8");
+
+	exit(0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct sigaction sa;
+	uint64_t mem;
+	uint32_t eax, ebx, ecx, edx;
+
+	mem = 0x0123456789abcdefLL;
+	eax = 0x11111111;
+	ebx = 0x22222222;
+	ecx = 0x33333333;
+	edx = 0x44444444;
+
+	/* First check that the cmpxchg8b instruction works as expected. */
+	printf("mem %.16llx, edx:eax %.8x%8x, ecx:ebx %.8x%.8x\n",
+	    mem, edx, eax, ecx, ebx);
+	printf("cmpxchg8b mem, mem != edx:eax\n");
+	asm volatile (
+		"lock	cmpxchg8b %0"
+		: "+m" (mem), "+a" (eax), "+b" (ebx), "+c" (ecx), "+d" (edx));
+	printf("mem %.16llx, edx:eax %.8x%8x, ecx:ebx %.8x%.8x\n",
+	    mem, edx, eax, ecx, ebx);
+
+	if (mem != 0x0123456789abcdefLL)
+		errx(1, "expected mem 0x0123456789abcdef");
+	if (edx != 0x01234567 || eax != 0x89abcdef)
+		errx(1, "expected edx:eax 0x0123456789abcdef");
+	if (ecx != 0x33333333 || ebx != 0x22222222)
+		errx(1, "expected ecx:ebx 0x3333333322222222");
+
+	printf("cmpxchg8b mem, mem == edx:eax\n");
+	asm volatile (
+		"lock cmpxchg8b %0"
+		: "+m" (mem), "+a" (eax), "+b" (ebx), "+c" (ecx), "+d" (edx));
+	printf("mem %.16llx, edx:eax %.8x%8x, ecx:ebx %.8x%.8x\n",
+	    mem, edx, eax, ecx, ebx);
+
+	if (mem != 0x3333333322222222LL)
+		errx(1, "expected mem 0x3333333322222222");
+	if (edx != 0x01234567 || eax != 0x89abcdef)
+		errx(1, "expected edx:eax 0x0123456789abcdef");
+	if (ecx != 0x33333333 || ebx != 0x22222222)
+		errx(1, "expected ecx:ebx 0x3333333322222222");
+
+	/* An illegal instruction must be signalled to user land. */
+	memset(&sa, 0 ,sizeof(sa));
+	sa.sa_sigaction = handler;
+	sa.sa_flags = SA_SIGINFO;
+	if (sigaction(SIGILL, &sa, NULL) == -1)
+		err(2, "sigaction");
+
+	/* Execute the cmpxchg8b instruction with invalid addressing mode. */
+	printf("cmpxchg8b eax\n");
+	asm volatile (
+		".byte 0xF0,0x0F,0xC7,0xC8"
+		: : : "%eax", "%ebx", "%ecx", "%edx");
+	printf("mem %.16llx, edx:eax %.8x%8x, ecx:ebx %.8x%.8x\n",
+	    mem, edx, eax, ecx, ebx);
+
+	/* Not reached, the processor hangs or the signal handler exits. */
+	errx(1, "expected signal");
+}