Provide the CloudABI vDSO to its executables.

CloudABI executables already provide support for passing in vDSOs. This
functionality is used by the emulator for OS X to inject system call
handlers. On FreeBSD, we could use it to optimize calls to
gettimeofday(), etc.

Though I don't have any plans to optimize any system calls right now,
let's go ahead and already pass in a vDSO. This will allow us to
simplify the executables, as the traditional "syscall" shims can be
removed entirely. It also means that we gain more flexibility with
regards to adding and removing system calls.

Reviewed by:	kib
Differential Revision:	https://reviews.freebsd.org/D7438

sys/amd64/cloudabi64/cloudabi64_sysvec.c

@@ -196,7 +196,6 @@ static struct sysentvec cloudabi64_elf_sysvec = {
 	.sv_pagesize		= PAGE_SIZE,
 	.sv_minuser		= VM_MIN_ADDRESS,
 	.sv_maxuser		= VM_MAXUSER_ADDRESS,
-	.sv_usrstack		= USRSTACK,
 	.sv_stackprot		= VM_PROT_READ | VM_PROT_WRITE,
 	.sv_copyout_strings	= cloudabi64_copyout_strings,
 	.sv_setregs		= cloudabi64_proc_setregs,

sys/arm64/cloudabi64/cloudabi64_sysvec.c

@@ -165,7 +165,6 @@ static struct sysentvec cloudabi64_elf_sysvec = {
 	.sv_pagesize		= PAGE_SIZE,
 	.sv_minuser		= VM_MIN_ADDRESS,
 	.sv_maxuser		= VM_MAXUSER_ADDRESS,
-	.sv_usrstack		= USRSTACK,
 	.sv_stackprot		= VM_PROT_READ | VM_PROT_WRITE,
 	.sv_copyout_strings	= cloudabi64_copyout_strings,
 	.sv_setregs		= cloudabi64_proc_setregs,

sys/compat/cloudabi/cloudabi_util.h

@@ -33,6 +33,7 @@
 #include <contrib/cloudabi/cloudabi_types_common.h>
 
 struct file;
+struct sysentvec;
 struct thread;
 struct timespec;
 
@@ -76,4 +77,8 @@ int cloudabi_futex_lock_wrlock(struct thread *, cloudabi_lock_t *,
     cloudabi_scope_t, cloudabi_clockid_t, cloudabi_timestamp_t,
     cloudabi_timestamp_t);
 
+/* vDSO setup and teardown. */
+void cloudabi_vdso_init(struct sysentvec *, char *, char *);
+void cloudabi_vdso_destroy(struct sysentvec *);
+
 #endif

sys/compat/cloudabi/cloudabi_vdso.c

@@ -0,0 +1,88 @@
+/*-
+ * Copyright (c) 2016 Nuxi, https://nuxi.nl/
+ *
+ * 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/types.h>
+#include <sys/lock.h>
+#include <sys/sysent.h>
+#include <sys/rwlock.h>
+
+#include <vm/vm.h>
+#include <vm/pmap.h>
+#include <vm/vm_extern.h>
+#include <vm/vm_object.h>
+#include <vm/vm_page.h>
+#include <vm/vm_pager.h>
+
+#include <compat/cloudabi/cloudabi_util.h>
+
+void
+cloudabi_vdso_init(struct sysentvec *sv, char *begin, char *end)
+{
+	vm_page_t m;
+	vm_object_t obj;
+	vm_offset_t addr;
+	size_t i, pages, pages_length, vdso_length;
+
+	/* Determine the number of pages needed to store the vDSO. */
+	vdso_length = end - begin;
+	pages = howmany(vdso_length, PAGE_SIZE);
+	pages_length = pages * PAGE_SIZE;
+
+	/* Allocate a VM object and fill it with the vDSO. */
+	obj = vm_pager_allocate(OBJT_PHYS, 0, pages_length,
+	    VM_PROT_DEFAULT, 0, NULL);
+	addr = kva_alloc(PAGE_SIZE);
+	for (i = 0; i < pages; ++i) {
+		VM_OBJECT_WLOCK(obj);
+		m = vm_page_grab(obj, i, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO);
+		m->valid = VM_PAGE_BITS_ALL;
+		VM_OBJECT_WUNLOCK(obj);
+
+		pmap_qenter(addr, &m, 1);
+		memcpy((void *)addr, begin + i * PAGE_SIZE,
+		    MIN(vdso_length - i * PAGE_SIZE, PAGE_SIZE));
+		pmap_qremove(addr, 1);
+	}
+	kva_free(addr, PAGE_SIZE);
+
+	/*
+	 * Place the vDSO at the top of the address space. The user
+	 * stack can start right below it.
+	 */
+	sv->sv_shared_page_base = sv->sv_maxuser - pages_length;
+	sv->sv_shared_page_len = pages_length;
+	sv->sv_shared_page_obj = obj;
+	sv->sv_usrstack = sv->sv_shared_page_base;
+}
+
+void
+cloudabi_vdso_destroy(struct sysentvec *sv)
+{
+
+	vm_object_deallocate(sv->sv_shared_page_obj);
+}

sys/compat/cloudabi64/cloudabi64_module.c

@@ -38,8 +38,13 @@ __FBSDID("$FreeBSD$");
 
 #include <contrib/cloudabi/cloudabi64_types.h>
 
+#include <compat/cloudabi/cloudabi_util.h>
+
 #include <compat/cloudabi64/cloudabi64_util.h>
 
+extern char _binary_cloudabi64_vdso_o_start[];
+extern char _binary_cloudabi64_vdso_o_end[];
+
 register_t *
 cloudabi64_copyout_strings(struct image_params *imgp)
 {
@@ -107,6 +112,8 @@ cloudabi64_fixup(register_t **stack_base, struct image_params *imgp)
 		PTR(CLOUDABI_AT_PHDR, args->phdr),
 		VAL(CLOUDABI_AT_PHNUM, args->phnum),
 		VAL(CLOUDABI_AT_TID, td->td_tid),
+		PTR(CLOUDABI_AT_SYSINFO_EHDR,
+		    imgp->proc->p_sysent->sv_shared_page_base),
 #undef VAL
 #undef PTR
 		{ .a_type = CLOUDABI_AT_NULL },
@@ -127,6 +134,9 @@ cloudabi64_modevent(module_t mod, int type, void *data)
 
 	switch (type) {
 	case MOD_LOAD:
+		cloudabi_vdso_init(cloudabi64_brand.sysvec,
+		    _binary_cloudabi64_vdso_o_start,
+		    _binary_cloudabi64_vdso_o_end);
 		if (elf64_insert_brand_entry(&cloudabi64_brand) < 0) {
 			printf("Failed to add CloudABI ELF brand handler\n");
 			return (EINVAL);
@@ -139,6 +149,7 @@ cloudabi64_modevent(module_t mod, int type, void *data)
 			printf("Failed to remove CloudABI ELF brand handler\n");
 			return (EINVAL);
 		}
+		cloudabi_vdso_destroy(cloudabi64_brand.sysvec);
 		return (0);
 	default:
 		return (EOPNOTSUPP);

sys/compat/cloudabi64/cloudabi64_vdso.lds.s

@@ -0,0 +1,51 @@
+/*
+ * Linker script for 64-bit vDSO for CloudABI.
+ * Based on sys/amd64/linux/linux_vdso.lds.s
+ *
+ * $FreeBSD$
+ */
+
+SECTIONS
+{
+	. = . + SIZEOF_HEADERS;
+
+	.hash		: { *(.hash) }			:text
+	.gnu.hash	: { *(.gnu.hash) }
+	.dynsym		: { *(.dynsym) }
+	.dynstr		: { *(.dynstr) }
+	.gnu.version	: { *(.gnu.version) }
+	.gnu.version_d	: { *(.gnu.version_d) }
+	.gnu.version_r	: { *(.gnu.version_r) }
+
+	.note		: { *(.note.*) }		:text	:note
+
+	.eh_frame_hdr	: { *(.eh_frame_hdr) }		:text	:eh_frame_hdr
+	.eh_frame	: { KEEP (*(.eh_frame)) }	:text
+
+	.dynamic	: { *(.dynamic) }		:text	:dynamic
+
+	.rodata		: { *(.rodata*) }		:text
+	.data		: {
+	      *(.data*)
+	      *(.sdata*)
+	      *(.got.plt) *(.got)
+	      *(.gnu.linkonce.d.*)
+	      *(.bss*)
+	      *(.dynbss*)
+	      *(.gnu.linkonce.b.*)
+	}
+
+	.altinstructions	: { *(.altinstructions) }
+	.altinstr_replacement	: { *(.altinstr_replacement) }
+
+	. = ALIGN(0x100);
+	.text		: { *(.test .text*) }			:text	=0x90909090
+}
+
+PHDRS
+{
+	text		PT_LOAD		FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
+	dynamic		PT_DYNAMIC	FLAGS(4);		/* PF_R */
+	note		PT_NOTE		FLAGS(4);		/* PF_R */
+	eh_frame_hdr	PT_GNU_EH_FRAME;
+}

sys/conf/files

@@ -284,6 +284,7 @@ compat/cloudabi/cloudabi_proc.c		optional compat_cloudabi64
 compat/cloudabi/cloudabi_random.c	optional compat_cloudabi64
 compat/cloudabi/cloudabi_sock.c		optional compat_cloudabi64
 compat/cloudabi/cloudabi_thread.c	optional compat_cloudabi64
+compat/cloudabi/cloudabi_vdso.c		optional compat_cloudabi64
 compat/cloudabi64/cloudabi64_fd.c	optional compat_cloudabi64
 compat/cloudabi64/cloudabi64_module.c	optional compat_cloudabi64
 compat/cloudabi64/cloudabi64_poll.c	optional compat_cloudabi64

sys/conf/files.amd64

@@ -8,6 +8,18 @@
 # dependency lines other than the first are silently ignored.
 #
 #
+cloudabi64_vdso.o		optional	compat_cloudabi64	\
+	dependency	"$S/contrib/cloudabi/cloudabi_vdso_x86_64.c"	\
+	compile-with	"${CC} -shared -nostdinc -nostdlib -Wl,-T$S/compat/cloudabi64/cloudabi64_vdso.lds.s -D_KERNEL -I. -I$S -I$S/contrib/cloudabi -O2 -fomit-frame-pointer $S/contrib/cloudabi/cloudabi_vdso_x86_64.c -o ${.TARGET}" \
+	no-obj no-implicit-rule						\
+	clean		"cloudabi64_vdso.o"
+#
+cloudabi64_vdso_blob.o		optional	compat_cloudabi64	\
+	dependency 	"cloudabi64_vdso.o"				\
+	compile-with	"${OBJCOPY} --input-target binary --output-target elf64-x86-64-freebsd --binary-architecture i386 cloudabi64_vdso.o ${.TARGET}" \
+	no-implicit-rule						\
+	clean		"cloudabi64_vdso_blob.o"
+#
 linux32_genassym.o		optional	compat_linux32		\
 	dependency 	"$S/amd64/linux32/linux32_genassym.c"		\
 	compile-with	"${CC} ${CFLAGS:N-fno-common} -c ${.IMPSRC}"	\

sys/conf/files.arm64

@@ -1,4 +1,16 @@
 # $FreeBSD$
+cloudabi64_vdso.o		optional	compat_cloudabi64	\
+	dependency	"$S/contrib/cloudabi/cloudabi_vdso_aarch64.c"	\
+	compile-with	"${CC} -shared -nostdinc -nostdlib -Wl,-T$S/compat/cloudabi64/cloudabi64_vdso.lds.s -D_KERNEL -I. -I$S -I$S/contrib/cloudabi -O2 -fomit-frame-pointer $S/contrib/cloudabi/cloudabi_vdso_aarch64.c -o ${.TARGET}" \
+	no-obj no-implicit-rule						\
+	clean		"cloudabi64_vdso.o"
+#
+cloudabi64_vdso_blob.o		optional	compat_cloudabi64	\
+	dependency 	"cloudabi64_vdso.o"			\
+	compile-with	"${OBJCOPY} --input-target binary --output-target elf64-littleaarch64 --binary-architecture aarch64 cloudabi64_vdso.o ${.TARGET}" \
+	no-implicit-rule						\
+	clean		"cloudabi64_vdso_blob.o"
+#
 arm/arm/generic_timer.c		standard
 arm/arm/gic.c			standard
 arm/arm/gic_fdt.c		optional	fdt

sys/modules/cloudabi/Makefile

@@ -5,6 +5,6 @@
 KMOD=	cloudabi
 SRCS=	cloudabi_clock.c cloudabi_errno.c cloudabi_fd.c cloudabi_file.c \
 	cloudabi_futex.c cloudabi_mem.c cloudabi_proc.c cloudabi_random.c \
-	cloudabi_sock.c cloudabi_thread.c vnode_if.h
+	cloudabi_sock.c cloudabi_thread.c cloudabi_vdso.c vnode_if.h
 
 .include <bsd.kmod.mk>

sys/modules/cloudabi64/Makefile

@@ -1,11 +1,39 @@
 # $FreeBSD$
 
-.PATH: ${.CURDIR}/../../compat/cloudabi64
-.PATH: ${.CURDIR}/../../${MACHINE}/cloudabi64
+SYSDIR?=${.CURDIR}/../..
+
+.PATH: ${SYSDIR}/compat/cloudabi64
+.PATH: ${SYSDIR}/${MACHINE}/cloudabi64
 
 KMOD=	cloudabi64
 SRCS=	cloudabi64_fd.c cloudabi64_module.c cloudabi64_poll.c \
 	cloudabi64_sock.c cloudabi64_syscalls.c cloudabi64_sysent.c \
 	cloudabi64_sysvec.c cloudabi64_thread.c
 
+OBJS=	cloudabi64_vdso_blob.o
+CLEANFILES=cloudabi64_vdso.o
+
+.if ${MACHINE_CPUARCH} == "aarch64"
+VDSO_SRCS=${SYSDIR}/contrib/cloudabi/cloudabi_vdso_aarch64.c
+OUTPUT_TARGET=elf64-littleaarch64
+BINARY_ARCHITECTURE=aarch64
+.elif ${MACHINE_CPUARCH} == "amd64"
+VDSO_SRCS=${SYSDIR}/contrib/cloudabi/cloudabi_vdso_x86_64.c
+OUTPUT_TARGET=elf64-x86-64-freebsd
+BINARY_ARCHITECTURE=i386
+.endif
+
+cloudabi64_vdso.o: ${VDSO_SRCS}
+	${CC} -shared -nostdinc -nostdlib \
+	    -Wl,-T${SYSDIR}/compat/cloudabi64/cloudabi64_vdso.lds.s \
+	    -D_KERNEL -I. -I${SYSDIR} -I${SYSDIR}/contrib/cloudabi \
+	    -O2 -fomit-frame-pointer \
+	    ${VDSO_SRCS} -o ${.TARGET}
+
+cloudabi64_vdso_blob.o: cloudabi64_vdso.o
+	${OBJCOPY} --input-target binary \
+	    --output-target ${OUTPUT_TARGET} \
+	    --binary-architecture ${BINARY_ARCHITECTURE} \
+	    cloudabi64_vdso.o ${.TARGET}
+
 .include <bsd.kmod.mk>