x86/fpu/math-emu, selftests: Add test for FISTTP instructions

$ ./test_FISTTP_32
[RUN] Testing fisttp instructions
[OK] fisttp

Signed-off-by: Denys Vlasenko <[e-mail]>
Cc: Andy Lutomirski <[e-mail]>
Cc: Borislav Petkov <[e-mail]>
Cc: Brian Gerst <[e-mail]>
Cc: H. Peter Anvin <[e-mail]>
Cc: Kees Cook <[e-mail]>
Cc: Linus Torvalds <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Shuah Khan <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Ingo Molnar <[e-mail]>

tools/testing/selftests/x86/Makefile

···
 
 TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs ldt_gdt syscall_nt
 TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault sigreturn \
-			test_FCMOV test_FCOMI
+			test_FCMOV test_FCOMI test_FISTTP
 
 TARGETS_C_32BIT_ALL := $(TARGETS_C_BOTHBITS) $(TARGETS_C_32BIT_ONLY)
 BINARIES_32 := $(TARGETS_C_32BIT_ALL:%=%_32)

tools/testing/selftests/x86/test_FISTTP.c

···
+#undef _GNU_SOURCE
+#define _GNU_SOURCE 1
+#undef __USE_GNU
+#define __USE_GNU 1
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/select.h>
+#include <sys/time.h>
+#include <sys/wait.h>
+#include <fenv.h>
+
+unsigned long long res64 = -1;
+unsigned int res32 = -1;
+unsigned short res16 = -1;
+
+int test(void)
+{
+	int ex;
+
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	asm volatile ("\n"
+	"	fld1""\n"
+	"	fisttp	res16""\n"
+	"	fld1""\n"
+	"	fisttpl	res32""\n"
+	"	fld1""\n"
+	"	fisttpll res64""\n"
+	: : : "memory"
+	);
+	if (res16 != 1 || res32 != 1 || res64 != 1) {
+		printf("[BAD]\tfisttp 1\n");
+		return 1;
+	}
+	ex = fetestexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	if (ex != 0) {
+		printf("[BAD]\tfisttp 1: wrong exception state\n");
+		return 1;
+	}
+
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	asm volatile ("\n"
+	"	fldpi""\n"
+	"	fisttp	res16""\n"
+	"	fldpi""\n"
+	"	fisttpl	res32""\n"
+	"	fldpi""\n"
+	"	fisttpll res64""\n"
+	: : : "memory"
+	);
+	if (res16 != 3 || res32 != 3 || res64 != 3) {
+		printf("[BAD]\tfisttp pi\n");
+		return 1;
+	}
+	ex = fetestexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	if (ex != FE_INEXACT) {
+		printf("[BAD]\tfisttp pi: wrong exception state\n");
+		return 1;
+	}
+
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	asm volatile ("\n"
+	"	fldpi""\n"
+	"	fchs""\n"
+	"	fisttp	res16""\n"
+	"	fldpi""\n"
+	"	fchs""\n"
+	"	fisttpl	res32""\n"
+	"	fldpi""\n"
+	"	fchs""\n"
+	"	fisttpll res64""\n"
+	: : : "memory"
+	);
+	if (res16 != 0xfffd || res32 != 0xfffffffd || res64 != 0xfffffffffffffffdULL) {
+		printf("[BAD]\tfisttp -pi\n");
+		return 1;
+	}
+	ex = fetestexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	if (ex != FE_INEXACT) {
+		printf("[BAD]\tfisttp -pi: wrong exception state\n");
+		return 1;
+	}
+
+	feclearexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	asm volatile ("\n"
+	"	fldln2""\n"
+	"	fisttp	res16""\n"
+	"	fldln2""\n"
+	"	fisttpl	res32""\n"
+	"	fldln2""\n"
+	"	fisttpll res64""\n"
+	: : : "memory"
+	);
+	/* Test truncation to zero (round-to-nearest would give 1 here) */
+	if (res16 != 0 || res32 != 0 || res64 != 0) {
+		printf("[BAD]\tfisttp ln2\n");
+		return 1;
+	}
+	ex = fetestexcept(FE_DIVBYZERO|FE_INEXACT|FE_INVALID|FE_OVERFLOW|FE_UNDERFLOW);
+	if (ex != FE_INEXACT) {
+		printf("[BAD]\tfisttp ln2: wrong exception state\n");
+		return 1;
+	}
+
+	return 0;
+}
+
+void sighandler(int sig)
+{
+	printf("[FAIL]\tGot signal %d, exiting\n", sig);
+	exit(1);
+}
+
+int main(int argc, char **argv, char **envp)
+{
+	int err = 0;
+
+	/* SIGILL triggers on 32-bit kernels w/o fisttp emulation
+	 * when run with "no387 nofxsr". Other signals are caught
+	 * just in case.
+	 */
+	signal(SIGILL, sighandler);
+	signal(SIGFPE, sighandler);
+	signal(SIGSEGV, sighandler);
+
+	printf("[RUN]\tTesting fisttp instructions\n");
+	err |= test();
+	if (!err)
+		printf("[OK]\tfisttp\n");
+	else
+		printf("[FAIL]\tfisttp errors: %d\n", err);
+
+	return err;
+}