1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2013-2021 Dmitry Chagin <dchagin@FreeBSD.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32)) 29 #define __ELF_WORD_SIZE 32 30 #else 31 #define __ELF_WORD_SIZE 64 32 #endif 33 34 #include <sys/param.h> 35 #include <sys/elf.h> 36 #include <sys/imgact.h> 37 #include <sys/lock.h> 38 #include <sys/proc.h> 39 #include <sys/rwlock.h> 40 #include <sys/sysent.h> 41 42 #include <vm/pmap.h> 43 #include <vm/vm_extern.h> 44 #include <vm/vm_map.h> 45 #include <vm/vm_object.h> 46 #include <vm/vm_page.h> 47 #include <vm/vm_pager.h> 48 #include <vm/vm_param.h> 49 50 #include <compat/linux/linux_vdso.h> 51 52 SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) = 53 SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms)); 54 55 void 56 __elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s) 57 { 58 59 SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym); 60 } 61 62 vm_object_t 63 __elfN(linux_shared_page_init)(char **mapping, vm_size_t size) 64 { 65 vm_page_t m; 66 vm_object_t obj; 67 vm_offset_t addr; 68 size_t n, pages; 69 70 pages = size / PAGE_SIZE; 71 72 addr = kva_alloc(size); 73 obj = vm_pager_allocate(OBJT_PHYS, 0, size, 74 VM_PROT_DEFAULT, 0, NULL); 75 VM_OBJECT_WLOCK(obj); 76 for (n = 0; n < pages; n++) { 77 m = vm_page_grab(obj, n, 78 VM_ALLOC_ZERO); 79 vm_page_valid(m); 80 vm_page_xunbusy(m); 81 pmap_qenter(addr + n * PAGE_SIZE, &m, 1); 82 } 83 VM_OBJECT_WUNLOCK(obj); 84 *mapping = (char *)addr; 85 return (obj); 86 } 87 88 void 89 __elfN(linux_shared_page_fini)(vm_object_t obj, void *mapping, 90 vm_size_t size) 91 { 92 vm_offset_t va; 93 94 va = (vm_offset_t)mapping; 95 pmap_qremove(va, size / PAGE_SIZE); 96 kva_free(va, size); 97 vm_object_deallocate(obj); 98 } 99 100 void 101 __elfN(linux_vdso_fixup)(char *base, vm_offset_t offset) 102 { 103 struct linux_vdso_sym *lsym; 104 const Elf_Shdr *shdr; 105 Elf_Ehdr *ehdr; 106 Elf_Sym *dsym, *sym; 107 char *strtab, *symname; 108 int i, symcnt; 109 110 ehdr = (Elf_Ehdr *)base; 111 112 MPASS(IS_ELF(*ehdr)); 113 MPASS(ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS); 114 MPASS(ehdr->e_ident[EI_DATA] == ELF_TARG_DATA); 115 MPASS(ehdr->e_ident[EI_VERSION] == EV_CURRENT); 116 MPASS(ehdr->e_shentsize == sizeof(Elf_Shdr)); 117 MPASS(ehdr->e_shoff != 0); 118 MPASS(ehdr->e_type == ET_DYN); 119 120 shdr = (const Elf_Shdr *)(base + ehdr->e_shoff); 121 122 dsym = NULL; 123 for (i = 0; i < ehdr->e_shnum; i++) { 124 if (shdr[i].sh_size == 0) 125 continue; 126 if (shdr[i].sh_type == SHT_DYNSYM) { 127 dsym = (Elf_Sym *)(base + shdr[i].sh_offset); 128 strtab = base + shdr[shdr[i].sh_link].sh_offset; 129 symcnt = shdr[i].sh_size / sizeof(*dsym); 130 break; 131 } 132 } 133 MPASS(dsym != NULL); 134 135 ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX; 136 137 /* 138 * VDSO is readonly mapped to the process VA and 139 * can't be relocated by rtld. 140 */ 141 SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym) { 142 for (i = 0, sym = dsym; i < symcnt; i++, sym++) { 143 symname = strtab + sym->st_name; 144 if (strncmp(lsym->symname, symname, lsym->size) == 0) { 145 sym->st_value += offset; 146 *lsym->ptr = sym->st_value; 147 break; 148 149 } 150 } 151 } 152 } 153 154 int 155 linux_map_vdso(struct proc *p, vm_object_t obj, vm_offset_t base, 156 vm_offset_t size, struct image_params *imgp) 157 { 158 struct vmspace *vmspace; 159 vm_map_t map; 160 int error; 161 162 MPASS((imgp->sysent->sv_flags & SV_ABI_MASK) == SV_ABI_LINUX); 163 MPASS(obj != NULL); 164 165 vmspace = p->p_vmspace; 166 map = &vmspace->vm_map; 167 168 vm_object_reference(obj); 169 error = vm_map_fixed(map, obj, 0, base, size, 170 VM_PROT_READ | VM_PROT_EXECUTE, 171 VM_PROT_READ | VM_PROT_EXECUTE, 172 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 173 if (error != KERN_SUCCESS) { 174 vm_object_deallocate(obj); 175 return (vm_mmap_to_errno(error)); 176 } 177 return (0); 178 } 179