Process irelocs for statically linked binaries from crt1 on x86.

This makes statically linked binaries with ifuncs operational.

Reported and tested by:	mjg
Reviewed by:	emaste, markj
Sponsored by:	The FreeBSD Foundation
Approved by:	re (rgrimes)
Differential revision:	https://reviews.freebsd.org/D17363

3 files changed, 72 insertions, 4 deletions

diff --git a/lib/csu/amd64/Makefile b/lib/csu/amd64/Makefile
index a6a2d5ec658d..493ad93173b0 100644
--- a/lib/csu/amd64/Makefile
+++ b/lib/csu/amd64/Makefile
@@ -5,9 +5,9 @@
 SRCS=		crt1.c crti.S crtn.S
 OBJS=		${SRCS:N*.h:R:S/$/.o/g}
 OBJS+=		Scrt1.o gcrt1.o
-CFLAGS+=	-I${.CURDIR:H}/common \
+CFLAGS+=	-I${.CURDIR} -I${.CURDIR:H}/common \
 		-I${SRCTOP}/lib/libc/include
-CFLAGS+=	-fno-omit-frame-pointer
+CFLAGS+=	-fno-omit-frame-pointer -DCRT_IRELOC_RELA
 
 FILES=		${OBJS}
 FILESMODE=	${LIBMODE}
diff --git a/lib/csu/amd64/crt1.c b/lib/csu/amd64/crt1.c
index a6001b2d5851..7b9b442a4c0a 100644
--- a/lib/csu/amd64/crt1.c
+++ b/lib/csu/amd64/crt1.c
@@ -59,10 +59,12 @@ _start(char **ap, void (*cleanup)(void))
 	env = ap + 2 + argc;
 	handle_argv(argc, argv, env);
 
-	if (&_DYNAMIC != NULL)
+	if (&_DYNAMIC != NULL) {
 		atexit(cleanup);
-	else
+	} else {
+		process_irelocs();
 		_init_tls();
+	}
 
 #ifdef GCRT
 	atexit(_mcleanup);
diff --git a/lib/csu/amd64/reloc.c b/lib/csu/amd64/reloc.c
new file mode 100644
index 000000000000..cc4a7e73caba
--- /dev/null
+++ b/lib/csu/amd64/reloc.c
@@ -0,0 +1,66 @@
+/*-
+ * Copyright (c) 2018 The FreeBSD Foundation
+ *
+ * This software was developed by Konstantin Belousov <kib@FreeBSD.org>
+ * 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 <machine/specialreg.h>
+#include <machine/cpufunc.h>
+
+static void
+crt1_handle_rela(const Elf_Rela *r)
+{
+	Elf_Addr *ptr, *where, target;
+	u_int p[4];
+	uint32_t cpu_feature, cpu_feature2;
+	uint32_t cpu_stdext_feature, cpu_stdext_feature2;
+
+	do_cpuid(1, p);
+	cpu_feature = p[3];
+	cpu_feature2 = p[2];
+	do_cpuid(0, p);
+	if (p[0] >= 7) {
+		cpuid_count(7, 0, p);
+		cpu_stdext_feature = p[1];
+		cpu_stdext_feature2 = p[2];
+	} else {
+		cpu_stdext_feature = 0;
+		cpu_stdext_feature2 = 0;
+	}
+
+	switch (ELF_R_TYPE(r->r_info)) {
+	case R_X86_64_IRELATIVE:
+		ptr = (Elf_Addr *)r->r_addend;
+		where = (Elf_Addr *)r->r_offset;
+		target = ((Elf_Addr (*)(uint32_t, uint32_t, uint32_t,
+		    uint32_t))ptr)(cpu_feature, cpu_feature2,
+		    cpu_stdext_feature, cpu_stdext_feature2);
+		*where = target;
+		break;
+	}
+}