13b4b4df98
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
89 lines
2.8 KiB
C
89 lines
2.8 KiB
C
/*-
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* Copyright (c) 2016 Nuxi, https://nuxi.nl/
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/types.h>
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#include <sys/lock.h>
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#include <sys/sysent.h>
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#include <sys/rwlock.h>
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <vm/vm_extern.h>
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#include <vm/vm_object.h>
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#include <vm/vm_page.h>
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#include <vm/vm_pager.h>
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#include <compat/cloudabi/cloudabi_util.h>
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void
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cloudabi_vdso_init(struct sysentvec *sv, char *begin, char *end)
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{
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vm_page_t m;
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vm_object_t obj;
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vm_offset_t addr;
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size_t i, pages, pages_length, vdso_length;
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/* Determine the number of pages needed to store the vDSO. */
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vdso_length = end - begin;
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pages = howmany(vdso_length, PAGE_SIZE);
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pages_length = pages * PAGE_SIZE;
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/* Allocate a VM object and fill it with the vDSO. */
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obj = vm_pager_allocate(OBJT_PHYS, 0, pages_length,
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VM_PROT_DEFAULT, 0, NULL);
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addr = kva_alloc(PAGE_SIZE);
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for (i = 0; i < pages; ++i) {
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VM_OBJECT_WLOCK(obj);
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m = vm_page_grab(obj, i, VM_ALLOC_NOBUSY | VM_ALLOC_ZERO);
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m->valid = VM_PAGE_BITS_ALL;
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VM_OBJECT_WUNLOCK(obj);
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pmap_qenter(addr, &m, 1);
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memcpy((void *)addr, begin + i * PAGE_SIZE,
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MIN(vdso_length - i * PAGE_SIZE, PAGE_SIZE));
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pmap_qremove(addr, 1);
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}
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kva_free(addr, PAGE_SIZE);
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/*
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* Place the vDSO at the top of the address space. The user
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* stack can start right below it.
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*/
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sv->sv_shared_page_base = sv->sv_maxuser - pages_length;
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sv->sv_shared_page_len = pages_length;
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sv->sv_shared_page_obj = obj;
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sv->sv_usrstack = sv->sv_shared_page_base;
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}
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void
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cloudabi_vdso_destroy(struct sysentvec *sv)
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{
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vm_object_deallocate(sv->sv_shared_page_obj);
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}
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