Add usermode helpers for for Intel userspace protection keys feature.

Reviewed by:	markj
Tested by:	pho
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
Differential revision:	https://reviews.freebsd.org/D18893

lib/libc/amd64/Symbol.map

@@ -44,6 +44,13 @@ FBSD_1.0 {
 	vfork;
 };
 
+FBSD_1.6 {
+	 x86_pkru_get_perm;
+	 x86_pkru_set_perm;
+	 x86_pkru_protect_range;
+	 x86_pkru_unprotect_range;
+};
+
 /*
  *
  * FreeBSD private ABI

lib/libc/i386/Symbol.map

@@ -46,6 +46,13 @@ FBSD_1.0 {
 	___tls_get_addr;
 };
 
+FBSD_1.6 {
+	 x86_pkru_get_perm;
+	 x86_pkru_set_perm;
+	 x86_pkru_protect_range;
+	 x86_pkru_unprotect_range;
+};
+
 FBSDprivate_1.0 {
 	/* PSEUDO syscalls */
 	_getlogin;

lib/libc/x86/sys/Makefile.inc

@@ -3,7 +3,8 @@
 .PATH:	${LIBC_SRCTOP}/x86/sys
 
 SRCS+= \
-	__vdso_gettc.c
+	__vdso_gettc.c \
+	pkru.c
 
 .if ${MACHINE_CPUARCH} == "amd64" && ${MK_HYPERV} != "no"
 CFLAGS+=	-DWANT_HYPERV

lib/libc/x86/sys/pkru.c

@@ -0,0 +1,138 @@
+/*-
+ * Copyright (c) 2019 The FreeBSD Foundation
+ * All rights reserved.
+ *
+ * Portions of this software were developed by Konstantin Belousov
+ * under sponsorship from the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <machine/cpufunc.h>
+#include <machine/specialreg.h>
+#include <machine/sysarch.h>
+#include <x86/ifunc.h>
+#include <errno.h>
+#include <string.h>
+
+#define	MAX_PKRU_IDX	0xf
+#ifdef __i386__
+#define	X86_SET_PKRU	I386_SET_PKRU
+#define	X86_CLEAR_PKRU	I386_CLEAR_PKRU
+#else
+#define	X86_SET_PKRU	AMD64_SET_PKRU
+#define	X86_CLEAR_PKRU	AMD64_CLEAR_PKRU
+#endif
+
+static int
+x86_pkru_get_perm_unsup(u_int keyidx, int *access, int *modify)
+{
+
+	errno = EOPNOTSUPP;
+	return (-1);
+}
+
+static int
+x86_pkru_get_perm_hw(u_int keyidx, int *access, int *modify)
+{
+	uint32_t pkru;
+
+	if (keyidx > MAX_PKRU_IDX) {
+		errno = EINVAL;
+		return (-1);
+	}
+	keyidx *= 2;
+	pkru = rdpkru();
+	*access = (pkru & (1 << keyidx)) == 0;
+	*modify = (pkru & (2 << keyidx)) == 0;
+	return (0);
+}
+
+DEFINE_UIFUNC(, int, x86_pkru_get_perm, (u_int, int *, int *), static)
+{
+
+	return ((cpu_stdext_feature2 & CPUID_STDEXT2_OSPKE) == 0 ?
+	    x86_pkru_get_perm_unsup : x86_pkru_get_perm_hw);
+}
+
+static int
+x86_pkru_set_perm_unsup(u_int keyidx, int access, int modify)
+{
+
+	errno = EOPNOTSUPP;
+	return (-1);
+}
+
+static int
+x86_pkru_set_perm_hw(u_int keyidx, int access, int modify)
+{
+	uint32_t pkru;
+
+	if (keyidx > MAX_PKRU_IDX) {
+		errno = EINVAL;
+		return (-1);
+	}
+	keyidx *= 2;
+	pkru = rdpkru();
+	pkru &= ~(3 << keyidx);
+	if (!access)
+		pkru |= 1 << keyidx;
+	if (!modify)
+		pkru |= 2 << keyidx;
+	wrpkru(pkru);
+	return (0);
+}
+
+DEFINE_UIFUNC(, int, x86_pkru_set_perm, (u_int, int, int), static)
+{
+
+	return ((cpu_stdext_feature2 & CPUID_STDEXT2_OSPKE) == 0 ?
+	    x86_pkru_set_perm_unsup : x86_pkru_set_perm_hw);
+}
+
+int
+x86_pkru_protect_range(void *addr, unsigned long len, u_int keyidx, int flags)
+{
+	struct amd64_set_pkru a64pkru;
+
+	memset(&a64pkru, 0, sizeof(a64pkru));
+	a64pkru.addr = addr;
+	a64pkru.len = len;
+	a64pkru.keyidx = keyidx;
+	a64pkru.flags = flags;
+	return (sysarch(X86_SET_PKRU, &a64pkru));
+}
+
+int
+x86_pkru_unprotect_range(void *addr, unsigned long len)
+{
+	struct amd64_set_pkru a64pkru;
+
+	memset(&a64pkru, 0, sizeof(a64pkru));
+	a64pkru.addr = addr;
+	a64pkru.len = len;
+	return (sysarch(X86_CLEAR_PKRU, &a64pkru));
+}

sys/x86/include/sysarch.h

@@ -142,6 +142,11 @@ int amd64_get_fsbase(void **);
 int amd64_get_gsbase(void **);
 int amd64_set_fsbase(void *);
 int amd64_set_gsbase(void *);
+int x86_pkru_get_perm(unsigned int keyidx, int *access, int *modify);
+int x86_pkru_set_perm(unsigned int keyidx, int access, int modify);
+int x86_pkru_protect_range(void *addr, unsigned long len, unsigned int keyidx,
+    int flag);
+int x86_pkru_unprotect_range(void *addr, unsigned long len);
 int sysarch(int, void *);
 __END_DECLS
 #else