The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/amd64/amd64/elf_machdep.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright 1996-1998 John D. Polstra.
    5  * All rights reserved.
    6  *
    7  * Redistribution and use in source and binary forms, with or without
    8  * modification, are permitted provided that the following conditions
    9  * are met:
   10  * 1. Redistributions of source code must retain the above copyright
   11  *    notice, this list of conditions and the following disclaimer.
   12  * 2. Redistributions in binary form must reproduce the above copyright
   13  *    notice, this list of conditions and the following disclaimer in the
   14  *    documentation and/or other materials provided with the distribution.
   15  *
   16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   26  */
   27 
   28 #include <sys/cdefs.h>
   29 __FBSDID("$FreeBSD$");
   30 
   31 #include <sys/param.h>
   32 #include <sys/kernel.h>
   33 #include <sys/systm.h>
   34 #include <sys/exec.h>
   35 #include <sys/imgact.h>
   36 #include <sys/linker.h>
   37 #include <sys/proc.h>
   38 #include <sys/reg.h>
   39 #include <sys/sysent.h>
   40 #include <sys/imgact_elf.h>
   41 #include <sys/syscall.h>
   42 #include <sys/signalvar.h>
   43 #include <sys/vnode.h>
   44 
   45 #include <vm/vm.h>
   46 #include <vm/pmap.h>
   47 #include <vm/vm_param.h>
   48 
   49 #include <machine/elf.h>
   50 #include <machine/fpu.h>
   51 #include <machine/md_var.h>
   52 
   53 #include "vdso_offsets.h"
   54 
   55 extern const char _binary_elf_vdso_so_1_start[];
   56 extern const char _binary_elf_vdso_so_1_end[];
   57 extern char _binary_elf_vdso_so_1_size;
   58 
   59 struct sysentvec elf64_freebsd_sysvec_la48 = {
   60         .sv_size        = SYS_MAXSYSCALL,
   61         .sv_table       = sysent,
   62         .sv_fixup       = __elfN(freebsd_fixup),
   63         .sv_sendsig     = sendsig,
   64         .sv_sigcode     = _binary_elf_vdso_so_1_start,
   65         .sv_szsigcode   = (int *)&_binary_elf_vdso_so_1_size,
   66         .sv_sigcodeoff  = VDSO_SIGCODE_OFFSET,
   67         .sv_name        = "FreeBSD ELF64",
   68         .sv_coredump    = __elfN(coredump),
   69         .sv_elf_core_osabi = ELFOSABI_FREEBSD,
   70         .sv_elf_core_abi_vendor = FREEBSD_ABI_VENDOR,
   71         .sv_elf_core_prepare_notes = __elfN(prepare_notes),
   72         .sv_imgact_try  = NULL,
   73         .sv_minsigstksz = MINSIGSTKSZ,
   74         .sv_minuser     = VM_MIN_ADDRESS,
   75         .sv_maxuser     = VM_MAXUSER_ADDRESS_LA48,
   76         .sv_usrstack    = USRSTACK_LA48,
   77         .sv_psstrings   = PS_STRINGS_LA48,
   78         .sv_psstringssz = sizeof(struct ps_strings),
   79         .sv_stackprot   = VM_PROT_ALL,
   80         .sv_copyout_auxargs = __elfN(freebsd_copyout_auxargs),
   81         .sv_copyout_strings     = exec_copyout_strings,
   82         .sv_setregs     = exec_setregs,
   83         .sv_fixlimit    = NULL,
   84         .sv_maxssiz     = NULL,
   85         .sv_flags       = SV_ABI_FREEBSD | SV_ASLR | SV_LP64 | SV_SHP |
   86                             SV_TIMEKEEP | SV_RNG_SEED_VER | SV_DSO_SIG,
   87         .sv_set_syscall_retval = cpu_set_syscall_retval,
   88         .sv_fetch_syscall_args = cpu_fetch_syscall_args,
   89         .sv_syscallnames = syscallnames,
   90         .sv_shared_page_base = SHAREDPAGE_LA48,
   91         .sv_shared_page_len = PAGE_SIZE,
   92         .sv_schedtail   = NULL,
   93         .sv_thread_detach = NULL,
   94         .sv_trap        = NULL,
   95         .sv_onexec_old  = exec_onexec_old,
   96         .sv_onexit      = exit_onexit,
   97         .sv_set_fork_retval = x86_set_fork_retval,
   98         .sv_regset_begin = SET_BEGIN(__elfN(regset)),
   99         .sv_regset_end  = SET_LIMIT(__elfN(regset)),
  100 };
  101 
  102 struct sysentvec elf64_freebsd_sysvec_la57 = {
  103         .sv_size        = SYS_MAXSYSCALL,
  104         .sv_table       = sysent,
  105         .sv_fixup       = __elfN(freebsd_fixup),
  106         .sv_sendsig     = sendsig,
  107         .sv_sigcode     = _binary_elf_vdso_so_1_start,
  108         .sv_szsigcode   = (int *)&_binary_elf_vdso_so_1_size,
  109         .sv_sigcodeoff  = VDSO_SIGCODE_OFFSET,
  110         .sv_name        = "FreeBSD ELF64",
  111         .sv_coredump    = __elfN(coredump),
  112         .sv_elf_core_osabi = ELFOSABI_FREEBSD,
  113         .sv_elf_core_abi_vendor = FREEBSD_ABI_VENDOR,
  114         .sv_elf_core_prepare_notes = __elfN(prepare_notes),
  115         .sv_imgact_try  = NULL,
  116         .sv_minsigstksz = MINSIGSTKSZ,
  117         .sv_minuser     = VM_MIN_ADDRESS,
  118         .sv_maxuser     = VM_MAXUSER_ADDRESS_LA57,
  119         .sv_usrstack    = USRSTACK_LA57,
  120         .sv_psstrings   = PS_STRINGS_LA57,
  121         .sv_psstringssz = sizeof(struct ps_strings),
  122         .sv_stackprot   = VM_PROT_ALL,
  123         .sv_copyout_auxargs = __elfN(freebsd_copyout_auxargs),
  124         .sv_copyout_strings     = exec_copyout_strings,
  125         .sv_setregs     = exec_setregs,
  126         .sv_fixlimit    = NULL,
  127         .sv_maxssiz     = NULL,
  128         .sv_flags       = SV_ABI_FREEBSD | SV_ASLR | SV_LP64 | SV_SHP |
  129                             SV_TIMEKEEP | SV_RNG_SEED_VER | SV_DSO_SIG,
  130         .sv_set_syscall_retval = cpu_set_syscall_retval,
  131         .sv_fetch_syscall_args = cpu_fetch_syscall_args,
  132         .sv_syscallnames = syscallnames,
  133         .sv_shared_page_base = SHAREDPAGE_LA57,
  134         .sv_shared_page_len = PAGE_SIZE,
  135         .sv_schedtail   = NULL,
  136         .sv_thread_detach = NULL,
  137         .sv_trap        = NULL,
  138         .sv_onexec_old  = exec_onexec_old,
  139         .sv_onexit      = exit_onexit,
  140         .sv_set_fork_retval=  x86_set_fork_retval,
  141         .sv_regset_begin = SET_BEGIN(__elfN(regset)),
  142         .sv_regset_end  = SET_LIMIT(__elfN(regset)),
  143 };
  144 
  145 static void
  146 amd64_init_sysvecs(void *arg)
  147 {
  148         amd64_lower_shared_page(&elf64_freebsd_sysvec_la48);
  149         if (la57) {
  150                 exec_sysvec_init(&elf64_freebsd_sysvec_la57);
  151                 exec_sysvec_init_secondary(&elf64_freebsd_sysvec_la57,
  152                     &elf64_freebsd_sysvec_la48);
  153         } else {
  154                 exec_sysvec_init(&elf64_freebsd_sysvec_la48);
  155         }
  156 }
  157 SYSINIT(elf64_sysvec, SI_SUB_EXEC, SI_ORDER_ANY, amd64_init_sysvecs, NULL);
  158 
  159 void
  160 amd64_lower_shared_page(struct sysentvec *sv)
  161 {
  162         if (hw_lower_amd64_sharedpage != 0) {
  163                 sv->sv_maxuser -= PAGE_SIZE;
  164                 sv->sv_shared_page_base -= PAGE_SIZE;
  165                 sv->sv_usrstack -= PAGE_SIZE;
  166                 sv->sv_psstrings -= PAGE_SIZE;
  167         }
  168 }
  169 
  170 static boolean_t
  171 freebsd_brand_info_la57_img_compat(struct image_params *imgp,
  172     int32_t *osrel __unused, uint32_t *fctl0)
  173 {
  174         if ((imgp->proc->p_md.md_flags & P_MD_LA57) != 0)
  175                 return (TRUE);
  176         if (fctl0 == NULL || (*fctl0 & NT_FREEBSD_FCTL_LA48) != 0)
  177                 return (FALSE);
  178         if ((imgp->proc->p_md.md_flags & P_MD_LA48) != 0)
  179                 return (FALSE);
  180         return (TRUE);
  181 }
  182 
  183 static Elf64_Brandinfo freebsd_brand_info_la48 = {
  184         .brand          = ELFOSABI_FREEBSD,
  185         .machine        = EM_X86_64,
  186         .compat_3_brand = "FreeBSD",
  187         .emul_path      = NULL,
  188         .interp_path    = "/libexec/ld-elf.so.1",
  189         .sysvec         = &elf64_freebsd_sysvec_la48,
  190         .interp_newpath = NULL,
  191         .brand_note     = &elf64_freebsd_brandnote,
  192         .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE,
  193 };
  194 
  195 static Elf64_Brandinfo freebsd_brand_info_la57 = {
  196         .brand          = ELFOSABI_FREEBSD,
  197         .machine        = EM_X86_64,
  198         .compat_3_brand = "FreeBSD",
  199         .emul_path      = NULL,
  200         .interp_path    = "/libexec/ld-elf.so.1",
  201         .sysvec         = &elf64_freebsd_sysvec_la57,
  202         .interp_newpath = NULL,
  203         .brand_note     = &elf64_freebsd_brandnote,
  204         .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE,
  205         .header_supported = freebsd_brand_info_la57_img_compat,
  206 };
  207 
  208 static void
  209 sysinit_register_elf64_brand_entries(void *arg __unused)
  210 {
  211         /*
  212          * _57 must go first so it can either claim the image or hand
  213          * it to _48.
  214          */
  215         if (la57)
  216                 elf64_insert_brand_entry(&freebsd_brand_info_la57);
  217         elf64_insert_brand_entry(&freebsd_brand_info_la48);
  218 }
  219 SYSINIT(elf64, SI_SUB_EXEC, SI_ORDER_FIRST,
  220     sysinit_register_elf64_brand_entries, NULL);
  221 
  222 static Elf64_Brandinfo freebsd_brand_oinfo = {
  223         .brand          = ELFOSABI_FREEBSD,
  224         .machine        = EM_X86_64,
  225         .compat_3_brand = "FreeBSD",
  226         .emul_path      = NULL,
  227         .interp_path    = "/usr/libexec/ld-elf.so.1",
  228         .sysvec         = &elf64_freebsd_sysvec_la48,
  229         .interp_newpath = NULL,
  230         .brand_note     = &elf64_freebsd_brandnote,
  231         .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE
  232 };
  233 
  234 SYSINIT(oelf64, SI_SUB_EXEC, SI_ORDER_ANY,
  235     (sysinit_cfunc_t)elf64_insert_brand_entry, &freebsd_brand_oinfo);
  236 
  237 static Elf64_Brandinfo kfreebsd_brand_info = {
  238         .brand          = ELFOSABI_FREEBSD,
  239         .machine        = EM_X86_64,
  240         .compat_3_brand = "FreeBSD",
  241         .emul_path      = NULL,
  242         .interp_path    = "/lib/ld-kfreebsd-x86-64.so.1",
  243         .sysvec         = &elf64_freebsd_sysvec_la48,
  244         .interp_newpath = NULL,
  245         .brand_note     = &elf64_kfreebsd_brandnote,
  246         .flags          = BI_CAN_EXEC_DYN | BI_BRAND_NOTE_MANDATORY
  247 };
  248 
  249 SYSINIT(kelf64, SI_SUB_EXEC, SI_ORDER_ANY,
  250     (sysinit_cfunc_t)elf64_insert_brand_entry, &kfreebsd_brand_info);
  251 
  252 void
  253 elf64_dump_thread(struct thread *td, void *dst, size_t *off)
  254 {
  255         void *buf;
  256         size_t len;
  257 
  258         len = 0;
  259         if (use_xsave) {
  260                 if (dst != NULL) {
  261                         fpugetregs(td);
  262                         len += elf64_populate_note(NT_X86_XSTATE,
  263                             get_pcb_user_save_td(td), dst,
  264                             cpu_max_ext_state_size, &buf);
  265                         *(uint64_t *)((char *)buf + X86_XSTATE_XCR0_OFFSET) =
  266                             xsave_mask;
  267                 } else
  268                         len += elf64_populate_note(NT_X86_XSTATE, NULL, NULL,
  269                             cpu_max_ext_state_size, NULL);
  270         }
  271         *off = len;
  272 }
  273 
  274 bool
  275 elf_is_ifunc_reloc(Elf_Size r_info)
  276 {
  277 
  278         return (ELF_R_TYPE(r_info) == R_X86_64_IRELATIVE);
  279 }
  280 
  281 /* Process one elf relocation with addend. */
  282 static int
  283 elf_reloc_internal(linker_file_t lf, Elf_Addr relocbase, const void *data,
  284     int type, bool late_ifunc, elf_lookup_fn lookup)
  285 {
  286         Elf64_Addr *where, val;
  287         Elf32_Addr *where32, val32;
  288         Elf_Addr addr;
  289         Elf_Addr addend;
  290         Elf_Size rtype, symidx;
  291         const Elf_Rel *rel;
  292         const Elf_Rela *rela;
  293         int error;
  294 
  295         switch (type) {
  296         case ELF_RELOC_REL:
  297                 rel = (const Elf_Rel *)data;
  298                 where = (Elf_Addr *) (relocbase + rel->r_offset);
  299                 rtype = ELF_R_TYPE(rel->r_info);
  300                 symidx = ELF_R_SYM(rel->r_info);
  301                 /* Addend is 32 bit on 32 bit relocs */
  302                 switch (rtype) {
  303                 case R_X86_64_PC32:
  304                 case R_X86_64_32S:
  305                 case R_X86_64_PLT32:
  306                         addend = *(Elf32_Addr *)where;
  307                         break;
  308                 default:
  309                         addend = *where;
  310                         break;
  311                 }
  312                 break;
  313         case ELF_RELOC_RELA:
  314                 rela = (const Elf_Rela *)data;
  315                 where = (Elf_Addr *) (relocbase + rela->r_offset);
  316                 addend = rela->r_addend;
  317                 rtype = ELF_R_TYPE(rela->r_info);
  318                 symidx = ELF_R_SYM(rela->r_info);
  319                 break;
  320         default:
  321                 panic("unknown reloc type %d\n", type);
  322         }
  323 
  324         if (late_ifunc) {
  325                 KASSERT(type == ELF_RELOC_RELA,
  326                     ("Only RELA ifunc relocations are supported"));
  327                 if (rtype != R_X86_64_IRELATIVE)
  328                         return (0);
  329         }
  330 
  331         switch (rtype) {
  332                 case R_X86_64_NONE:     /* none */
  333                         break;
  334 
  335                 case R_X86_64_64:       /* S + A */
  336                         error = lookup(lf, symidx, 1, &addr);
  337                         val = addr + addend;
  338                         if (error != 0)
  339                                 return (-1);
  340                         if (*where != val)
  341                                 *where = val;
  342                         break;
  343 
  344                 case R_X86_64_PC32:     /* S + A - P */
  345                 case R_X86_64_PLT32:    /* L + A - P, L is PLT location for
  346                                            the symbol, which we treat as S */
  347                         error = lookup(lf, symidx, 1, &addr);
  348                         where32 = (Elf32_Addr *)where;
  349                         val32 = (Elf32_Addr)(addr + addend - (Elf_Addr)where);
  350                         if (error != 0)
  351                                 return (-1);
  352                         if (*where32 != val32)
  353                                 *where32 = val32;
  354                         break;
  355 
  356                 case R_X86_64_32S:      /* S + A sign extend */
  357                         error = lookup(lf, symidx, 1, &addr);
  358                         val32 = (Elf32_Addr)(addr + addend);
  359                         where32 = (Elf32_Addr *)where;
  360                         if (error != 0)
  361                                 return (-1);
  362                         if (*where32 != val32)
  363                                 *where32 = val32;
  364                         break;
  365 
  366                 case R_X86_64_COPY:     /* none */
  367                         /*
  368                          * There shouldn't be copy relocations in kernel
  369                          * objects.
  370                          */
  371                         printf("kldload: unexpected R_COPY relocation, "
  372                             "symbol index %ld\n", symidx);
  373                         return (-1);
  374 
  375                 case R_X86_64_GLOB_DAT: /* S */
  376                 case R_X86_64_JMP_SLOT: /* XXX need addend + offset */
  377                         error = lookup(lf, symidx, 1, &addr);
  378                         if (error != 0)
  379                                 return (-1);
  380                         if (*where != addr)
  381                                 *where = addr;
  382                         break;
  383 
  384                 case R_X86_64_RELATIVE: /* B + A */
  385                         addr = elf_relocaddr(lf, relocbase + addend);
  386                         val = addr;
  387                         if (*where != val)
  388                                 *where = val;
  389                         break;
  390 
  391                 case R_X86_64_IRELATIVE:
  392                         addr = relocbase + addend;
  393                         val = ((Elf64_Addr (*)(void))addr)();
  394                         if (*where != val)
  395                                 *where = val;
  396                         break;
  397 
  398                 default:
  399                         printf("kldload: unexpected relocation type %ld, "
  400                             "symbol index %ld\n", rtype, symidx);
  401                         return (-1);
  402         }
  403         return (0);
  404 }
  405 
  406 int
  407 elf_reloc(linker_file_t lf, Elf_Addr relocbase, const void *data, int type,
  408     elf_lookup_fn lookup)
  409 {
  410 
  411         return (elf_reloc_internal(lf, relocbase, data, type, false, lookup));
  412 }
  413 
  414 int
  415 elf_reloc_local(linker_file_t lf, Elf_Addr relocbase, const void *data,
  416     int type, elf_lookup_fn lookup)
  417 {
  418 
  419         return (elf_reloc_internal(lf, relocbase, data, type, false, lookup));
  420 }
  421 
  422 int
  423 elf_reloc_late(linker_file_t lf, Elf_Addr relocbase, const void *data,
  424     int type, elf_lookup_fn lookup)
  425 {
  426 
  427         return (elf_reloc_internal(lf, relocbase, data, type, true, lookup));
  428 }
  429 
  430 int
  431 elf_cpu_load_file(linker_file_t lf __unused)
  432 {
  433 
  434         return (0);
  435 }
  436 
  437 int
  438 elf_cpu_unload_file(linker_file_t lf __unused)
  439 {
  440 
  441         return (0);
  442 }
  443 
  444 int
  445 elf_cpu_parse_dynamic(caddr_t loadbase __unused, Elf_Dyn *dynamic __unused)
  446 {
  447 
  448         return (0);
  449 }

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