1 /*- 2 * Copyright (c) 2013-2021 Dmitry Chagin <dchagin@FreeBSD.org> 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer 9 * in this position and unchanged. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 26 #include <sys/cdefs.h> 27 __FBSDID("$FreeBSD$"); 28 29 #if defined(__i386__) || (defined(__amd64__) && defined(COMPAT_LINUX32)) 30 #define __ELF_WORD_SIZE 32 31 #else 32 #define __ELF_WORD_SIZE 64 33 #endif 34 35 #include <sys/param.h> 36 #include <sys/systm.h> 37 #include <sys/elf.h> 38 #include <sys/imgact.h> 39 #include <sys/kernel.h> 40 #include <sys/proc.h> 41 #include <sys/rwlock.h> 42 #include <sys/queue.h> 43 #include <sys/sysent.h> 44 45 #include <vm/vm_param.h> 46 #include <vm/pmap.h> 47 #include <vm/vm_extern.h> 48 #include <vm/vm_map.h> 49 #include <vm/vm_object.h> 50 #include <vm/vm_page.h> 51 #include <vm/vm_pager.h> 52 53 #include <compat/linux/linux_vdso.h> 54 55 SLIST_HEAD(, linux_vdso_sym) __elfN(linux_vdso_syms) = 56 SLIST_HEAD_INITIALIZER(__elfN(linux_vdso_syms)); 57 58 void 59 __elfN(linux_vdso_sym_init)(struct linux_vdso_sym *s) 60 { 61 62 SLIST_INSERT_HEAD(&__elfN(linux_vdso_syms), s, sym); 63 } 64 65 vm_object_t 66 __elfN(linux_shared_page_init)(char **mapping, vm_size_t size) 67 { 68 vm_page_t m; 69 vm_object_t obj; 70 vm_offset_t addr; 71 size_t n, pages; 72 73 pages = size / PAGE_SIZE; 74 75 addr = kva_alloc(size); 76 obj = vm_pager_allocate(OBJT_PHYS, 0, size, 77 VM_PROT_DEFAULT, 0, NULL); 78 VM_OBJECT_WLOCK(obj); 79 for (n = 0; n < pages; n++) { 80 m = vm_page_grab(obj, n, 81 VM_ALLOC_ZERO); 82 vm_page_valid(m); 83 vm_page_xunbusy(m); 84 pmap_qenter(addr + n * PAGE_SIZE, &m, 1); 85 } 86 VM_OBJECT_WUNLOCK(obj); 87 *mapping = (char *)addr; 88 return (obj); 89 } 90 91 void 92 __elfN(linux_shared_page_fini)(vm_object_t obj, void *mapping, 93 vm_size_t size) 94 { 95 vm_offset_t va; 96 97 va = (vm_offset_t)mapping; 98 pmap_qremove(va, size / PAGE_SIZE); 99 kva_free(va, size); 100 vm_object_deallocate(obj); 101 } 102 103 void 104 __elfN(linux_vdso_fixup)(char *base, vm_offset_t offset) 105 { 106 struct linux_vdso_sym *lsym; 107 const Elf_Shdr *shdr; 108 Elf_Ehdr *ehdr; 109 Elf_Sym *dsym, *sym; 110 char *strtab, *symname; 111 int i, symcnt; 112 113 ehdr = (Elf_Ehdr *)base; 114 115 MPASS(IS_ELF(*ehdr)); 116 MPASS(ehdr->e_ident[EI_CLASS] == ELF_TARG_CLASS); 117 MPASS(ehdr->e_ident[EI_DATA] == ELF_TARG_DATA); 118 MPASS(ehdr->e_ident[EI_VERSION] == EV_CURRENT); 119 MPASS(ehdr->e_shentsize == sizeof(Elf_Shdr)); 120 MPASS(ehdr->e_shoff != 0); 121 MPASS(ehdr->e_type == ET_DYN); 122 123 shdr = (const Elf_Shdr *)(base + ehdr->e_shoff); 124 125 dsym = NULL; 126 for (i = 0; i < ehdr->e_shnum; i++) { 127 if (shdr[i].sh_size == 0) 128 continue; 129 if (shdr[i].sh_type == SHT_DYNSYM) { 130 dsym = (Elf_Sym *)(base + shdr[i].sh_offset); 131 strtab = base + shdr[shdr[i].sh_link].sh_offset; 132 symcnt = shdr[i].sh_size / sizeof(*dsym); 133 break; 134 } 135 } 136 MPASS(dsym != NULL); 137 138 ehdr->e_ident[EI_OSABI] = ELFOSABI_LINUX; 139 140 /* 141 * VDSO is readonly mapped to the process VA and 142 * can't be relocated by rtld. 143 */ 144 SLIST_FOREACH(lsym, &__elfN(linux_vdso_syms), sym) { 145 for (i = 0, sym = dsym; i < symcnt; i++, sym++) { 146 symname = strtab + sym->st_name; 147 if (strncmp(lsym->symname, symname, lsym->size) == 0) { 148 sym->st_value += offset; 149 *lsym->ptr = sym->st_value; 150 break; 151 152 } 153 } 154 } 155 } 156 157 int 158 linux_map_vdso(struct proc *p, vm_object_t obj, vm_offset_t base, 159 vm_offset_t size, struct image_params *imgp) 160 { 161 struct vmspace *vmspace; 162 vm_map_t map; 163 int error; 164 165 MPASS((imgp->sysent->sv_flags & SV_ABI_MASK) == SV_ABI_LINUX); 166 MPASS(obj != NULL); 167 168 vmspace = p->p_vmspace; 169 map = &vmspace->vm_map; 170 171 vm_object_reference(obj); 172 error = vm_map_fixed(map, obj, 0, base, size, 173 VM_PROT_READ | VM_PROT_EXECUTE, 174 VM_PROT_READ | VM_PROT_EXECUTE, 175 MAP_INHERIT_SHARE | MAP_ACC_NO_CHARGE); 176 if (error != KERN_SUCCESS) { 177 vm_object_deallocate(obj); 178 return (vm_mmap_to_errno(error)); 179 } 180 return (0); 181 } 182