elf: Avoid nested functions in the loader [BZ #27220]

[thirdparty/glibc.git] / sysdeps / sparc / sparc32 / dl-machine.h

/* Machine-dependent ELF dynamic relocation inline functions.  SPARC version.
   Copyright (C) 1996-2021 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef dl_machine_h
#define dl_machine_h

#define ELF_MACHINE_NAME "sparc"

#include <string.h>
#include <sys/param.h>
#include <ldsodefs.h>
#include <sysdep.h>
#include <tls.h>
#include <dl-plt.h>
#include <elf/dl-hwcaps.h>

/* Return nonzero iff ELF header is compatible with the running host.  */
static inline int
elf_machine_matches_host (const Elf32_Ehdr *ehdr)
{
  if (ehdr->e_machine == EM_SPARC)
    return 1;
  else if (ehdr->e_machine == EM_SPARC32PLUS)
    {
#if HAVE_TUNABLES || defined SHARED
      uint64_t hwcap_mask = GET_HWCAP_MASK();
      return GLRO(dl_hwcap) & hwcap_mask & HWCAP_SPARC_V9;
#else
      return GLRO(dl_hwcap) & HWCAP_SPARC_V9;
#endif
    }
  else
    return 0;
}

/* We have to do this because elf_machine_{dynamic,load_address} can be
   invoked from functions that have no GOT references, and thus the compiler
   has no obligation to load the PIC register.  */
#define LOAD_PIC_REG(PIC_REG)   \
do {    register Elf32_Addr pc __asm("o7"); \
        __asm("sethi %%hi(_GLOBAL_OFFSET_TABLE_-4), %1\n\t" \
              "call 1f\n\t" \
              "add %1, %%lo(_GLOBAL_OFFSET_TABLE_+4), %1\n" \
              "1:\tadd %1, %0, %1" \
              : "=r" (pc), "=r" (PIC_REG)); \
} while (0)

/* Return the link-time address of _DYNAMIC.  Conveniently, this is the
   first element of the GOT.  This must be inlined in a function which
   uses global data.  */
static inline Elf32_Addr
elf_machine_dynamic (void)
{
  register Elf32_Addr *got asm ("%l7");

  LOAD_PIC_REG (got);

  return *got;
}

/* Return the run-time load address of the shared object.  */
static inline Elf32_Addr
elf_machine_load_address (void)
{
  register Elf32_Addr *pc __asm ("%o7"), *got __asm ("%l7");

  __asm ("sethi %%hi(_GLOBAL_OFFSET_TABLE_-4), %1\n\t"
         "call 1f\n\t"
         " add %1, %%lo(_GLOBAL_OFFSET_TABLE_+4), %1\n\t"
         "call _DYNAMIC\n\t"
         "call _GLOBAL_OFFSET_TABLE_\n"
         "1:\tadd %1, %0, %1\n\t" : "=r" (pc), "=r" (got));

  /* got is now l_addr + _GLOBAL_OFFSET_TABLE_
     *got is _DYNAMIC
     pc[2]*4 is l_addr + _DYNAMIC - (long)pc - 8
     pc[3]*4 is l_addr + _GLOBAL_OFFSET_TABLE_ - (long)pc - 12  */
  return (Elf32_Addr) got - *got + (pc[2] - pc[3]) * 4 - 4;
}

/* Set up the loaded object described by L so its unrelocated PLT
   entries will jump to the on-demand fixup code in dl-runtime.c.  */

static inline int
elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
                           int lazy, int profile)
{
  Elf32_Addr *plt;
  extern void _dl_runtime_resolve (Elf32_Word);
  extern void _dl_runtime_profile (Elf32_Word);

  if (l->l_info[DT_JMPREL] && lazy)
    {
      Elf32_Addr rfunc;

      /* The entries for functions in the PLT have not yet been filled in.
         Their initial contents will arrange when called to set the high 22
         bits of %g1 with an offset into the .rela.plt section and jump to
         the beginning of the PLT.  */
      plt = (Elf32_Addr *) D_PTR (l, l_info[DT_PLTGOT]);
      if (__builtin_expect(profile, 0))
        {
          rfunc = (Elf32_Addr) &_dl_runtime_profile;

          if (GLRO(dl_profile) != NULL
              && _dl_name_match_p (GLRO(dl_profile), l))
            GL(dl_profile_map) = l;
        }
      else
        {
          rfunc = (Elf32_Addr) &_dl_runtime_resolve;
        }

      /* The beginning of the PLT does:

                sethi %hi(_dl_runtime_{resolve,profile}), %g2
         pltpc: jmpl %g2 + %lo(_dl_runtime_{resolve,profile}), %g2
                 nop
                .word MAP

         The PC value (pltpc) saved in %g2 by the jmpl points near the
         location where we store the link_map pointer for this object.  */

      plt[0] = 0x05000000 | ((rfunc >> 10) & 0x003fffff);
      plt[1] = 0x85c0a000 | (rfunc & 0x3ff);
      plt[2] = OPCODE_NOP;      /* Fill call delay slot.  */
      plt[3] = (Elf32_Addr) l;
      if (__builtin_expect (l->l_info[VALIDX(DT_GNU_PRELINKED)] != NULL, 0)
          || __builtin_expect (l->l_info [VALIDX (DT_GNU_LIBLISTSZ)] != NULL, 0))
        {
          /* Need to reinitialize .plt to undo prelinking.  */
          Elf32_Rela *rela = (Elf32_Rela *) D_PTR (l, l_info[DT_JMPREL]);
          Elf32_Rela *relaend
            = (Elf32_Rela *) ((char *) rela
                              + l->l_info[DT_PLTRELSZ]->d_un.d_val);
#if !defined RTLD_BOOTSTRAP && !defined __sparc_v9__
          /* Note that we don't mask the hwcap here, as the flush is
             essential to functionality on those cpu's that implement it.
             For sparcv9 we can assume flush is present.  */
          const int do_flush = GLRO(dl_hwcap) & HWCAP_SPARC_FLUSH;
#else
          const int do_flush = 1;
#endif

          /* prelink must ensure there are no R_SPARC_NONE relocs left
             in .rela.plt.  */
          while (rela < relaend)
            {
              *(unsigned int *) (rela->r_offset + l->l_addr)
                = OPCODE_SETHI_G1 | (rela->r_offset + l->l_addr
                                     - (Elf32_Addr) plt);
              *(unsigned int *) (rela->r_offset + l->l_addr + 4)
                = OPCODE_BA | ((((Elf32_Addr) plt
                                 - rela->r_offset - l->l_addr - 4) >> 2)
                               & 0x3fffff);
              if (do_flush)
                {
                  __asm __volatile ("flush %0" : : "r" (rela->r_offset
                                                        + l->l_addr));
                  __asm __volatile ("flush %0+4" : : "r" (rela->r_offset
                                                          + l->l_addr));
                }
              ++rela;
            }
        }
    }

  return lazy;
}

/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
   PLT entries should not be allowed to define the value.
   ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
   of the main executable's symbols, as for a COPY reloc.  */
#define elf_machine_type_class(type) \
  ((((type) == R_SPARC_JMP_SLOT                                               \
     || ((type) >= R_SPARC_TLS_GD_HI22 && (type) <= R_SPARC_TLS_TPOFF64))     \
    * ELF_RTYPE_CLASS_PLT)                                                    \
   | (((type) == R_SPARC_COPY) * ELF_RTYPE_CLASS_COPY))

/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries.  */
#define ELF_MACHINE_JMP_SLOT    R_SPARC_JMP_SLOT

/* The SPARC never uses Elf32_Rel relocations.  */
#define ELF_MACHINE_NO_REL 1
#define ELF_MACHINE_NO_RELA 0

/* Undo the sub %sp, 6*4, %sp; add %sp, 22*4, %o0 below to get at the
   value we want in __libc_stack_end.  */
#define DL_STACK_END(cookie) \
  ((void *) (((long) (cookie)) - (22 - 6) * 4))

/* Initial entry point code for the dynamic linker.
   The C function `_dl_start' is the real entry point;
   its return value is the user program's entry point.  */

#define RTLD_GOT_ADDRESS(pic_reg, reg, symbol)  \
        "sethi  %gdop_hix22(" #symbol "), " #reg "\n\t" \
        "xor    " #reg ", %gdop_lox10(" #symbol "), " #reg "\n\t" \
        "ld     [" #pic_reg " + " #reg "], " #reg ", %gdop(" #symbol ")"

#define RTLD_START __asm__ ("\
        .text\n\
        .globl  _start\n\
        .type   _start, @function\n\
        .align  32\n\
_start:\n\
  /* Allocate space for functions to drop their arguments.  */\n\
        sub     %sp, 6*4, %sp\n\
  /* Pass pointer to argument block to _dl_start.  */\n\
        call    _dl_start\n\
         add    %sp, 22*4, %o0\n\
        /* FALTHRU */\n\
        .globl  _dl_start_user\n\
        .type   _dl_start_user, @function\n\
_dl_start_user:\n\
  /* Load the PIC register.  */\n\
1:      call    2f\n\
         sethi  %hi(_GLOBAL_OFFSET_TABLE_-(1b-.)), %l7\n\
2:      or      %l7, %lo(_GLOBAL_OFFSET_TABLE_-(1b-.)), %l7\n\
        add     %l7, %o7, %l7\n\
  /* Save the user entry point address in %l0 */\n\
        mov     %o0, %l0\n\
  /* See if we were run as a command with the executable file name as an\n\
     extra leading argument.  If so, adjust the contents of the stack.  */\n\
        " RTLD_GOT_ADDRESS(%l7, %g2, _dl_skip_args) "\n\
        ld      [%g2], %i0\n\
        tst     %i0\n\
        beq     3f\n\
         ld     [%sp+22*4], %i5         /* load argc */\n\
        /* Find out how far to shift.  */\n\
        " RTLD_GOT_ADDRESS(%l7, %l3, _dl_argv) "\n\
        sub     %i5, %i0, %i5\n\
        ld      [%l3], %l4\n\
        sll     %i0, 2, %i2\n\
        st      %i5, [%sp+22*4]\n\
        sub     %l4, %i2, %l4\n\
        add     %sp, 23*4, %i1\n\
        add     %i1, %i2, %i2\n\
        st      %l4, [%l3]\n\
        /* Copy down argv */\n\
21:     ld      [%i2], %i3\n\
        add     %i2, 4, %i2\n\
        tst     %i3\n\
        st      %i3, [%i1]\n\
        bne     21b\n\
         add    %i1, 4, %i1\n\
        /* Copy down env */\n\
22:     ld      [%i2], %i3\n\
        add     %i2, 4, %i2\n\
        tst     %i3\n\
        st      %i3, [%i1]\n\
        bne     22b\n\
         add    %i1, 4, %i1\n\
        /* Copy down auxiliary table.  */\n\
23:     ld      [%i2], %i3\n\
        ld      [%i2+4], %i4\n\
        add     %i2, 8, %i2\n\
        tst     %i3\n\
        st      %i3, [%i1]\n\
        st      %i4, [%i1+4]\n\
        bne     23b\n\
         add    %i1, 8, %i1\n\
  /* %o0 = _dl_loaded, %o1 = argc, %o2 = argv, %o3 = envp.  */\n\
3:      " RTLD_GOT_ADDRESS(%l7, %o0, _rtld_local) "\n\
        add     %sp, 23*4, %o2\n\
        sll     %i5, 2, %o3\n\
        add     %o3, 4, %o3\n\
        mov     %i5, %o1\n\
        add     %o2, %o3, %o3\n\
        call    _dl_init\n\
         ld     [%o0], %o0\n\
  /* Pass our finalizer function to the user in %g1.  */\n\
        " RTLD_GOT_ADDRESS(%l7, %g1, _dl_fini) "\n\
  /* Jump to the user's entry point and deallocate the extra stack we got.  */\n\
        jmp     %l0\n\
         add    %sp, 6*4, %sp\n\
        .size   _dl_start_user, . - _dl_start_user\n\
        .previous");

static inline Elf32_Addr
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
                       const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
                       const Elf32_Rela *reloc,
                       Elf32_Addr *reloc_addr, Elf32_Addr value)
{
#ifdef __sparc_v9__
  /* Sparc v9 can assume flush is always present.  */
  const int do_flush = 1;
#else
  /* Note that we don't mask the hwcap here, as the flush is essential to
     functionality on those cpu's that implement it.  */
  const int do_flush = GLRO(dl_hwcap) & HWCAP_SPARC_FLUSH;
#endif
  return sparc_fixup_plt (reloc, reloc_addr, value, 1, do_flush);
}

/* Return the final value of a plt relocation.  */
static inline Elf32_Addr
elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
                       Elf32_Addr value)
{
  return value + reloc->r_addend;
}

#endif /* dl_machine_h */

#define ARCH_LA_PLTENTER        sparc32_gnu_pltenter
#define ARCH_LA_PLTEXIT         sparc32_gnu_pltexit

#ifdef RESOLVE_MAP

/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
   MAP is the object containing the reloc.  */

static inline void
__attribute__ ((always_inline))
elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
                  const Elf32_Rela *reloc, const Elf32_Sym *sym,
                  const struct r_found_version *version,
                  void *const reloc_addr_arg, int skip_ifunc)
{
  Elf32_Addr *const reloc_addr = reloc_addr_arg;
#if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP
  const Elf32_Sym *const refsym = sym;
#endif
  Elf32_Addr value;
  const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
#if !defined RESOLVE_CONFLICT_FIND_MAP
  struct link_map *sym_map = NULL;
#endif

#if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
  /* This is defined in rtld.c, but nowhere in the static libc.a; make the
     reference weak so static programs can still link.  This declaration
     cannot be done when compiling rtld.c (i.e.  #ifdef RTLD_BOOTSTRAP)
     because rtld.c contains the common defn for _dl_rtld_map, which is
     incompatible with a weak decl in the same file.  */
  weak_extern (_dl_rtld_map);
#endif

  if (__glibc_unlikely (r_type == R_SPARC_NONE))
    return;

  if (__glibc_unlikely (r_type == R_SPARC_SIZE32))
    {
      *reloc_addr = sym->st_size + reloc->r_addend;
      return;
    }

#if !defined RTLD_BOOTSTRAP || !defined HAVE_Z_COMBRELOC
  if (__glibc_unlikely (r_type == R_SPARC_RELATIVE))
    {
# if !defined RTLD_BOOTSTRAP && !defined HAVE_Z_COMBRELOC
      if (map != &_dl_rtld_map) /* Already done in rtld itself. */
# endif
        *reloc_addr += map->l_addr + reloc->r_addend;
      return;
    }
#endif

#ifndef RESOLVE_CONFLICT_FIND_MAP
  if (__builtin_expect (ELF32_ST_BIND (sym->st_info) == STB_LOCAL, 0)
      && sym->st_shndx != SHN_UNDEF)
    {
      sym_map = map;
      value = map->l_addr;
    }
  else
    {
      sym_map = RESOLVE_MAP (map, scope, &sym, version, r_type);
      value = SYMBOL_ADDRESS (sym_map, sym, true);
    }
#else
  value = 0;
#endif

  value += reloc->r_addend;     /* Assume copy relocs have zero addend.  */

  if (sym != NULL
      && __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
      && __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
      && __builtin_expect (!skip_ifunc, 1))
    {
      value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
    }

  switch (r_type)
    {
#if !defined RTLD_BOOTSTRAP && !defined RESOLVE_CONFLICT_FIND_MAP
    case R_SPARC_COPY:
      if (sym == NULL)
        /* This can happen in trace mode if an object could not be
           found.  */
        break;
      if (sym->st_size > refsym->st_size
          || (GLRO(dl_verbose) && sym->st_size < refsym->st_size))
        {
          const char *strtab;

          strtab = (const void *) D_PTR (map, l_info[DT_STRTAB]);
          _dl_error_printf ("\
%s: Symbol `%s' has different size in shared object, consider re-linking\n",
                            RTLD_PROGNAME, strtab + refsym->st_name);
        }
      memcpy (reloc_addr_arg, (void *) value,
              MIN (sym->st_size, refsym->st_size));
      break;
#endif
    case R_SPARC_GLOB_DAT:
    case R_SPARC_32:
      *reloc_addr = value;
      break;
    case R_SPARC_IRELATIVE:
      if (__glibc_likely (!skip_ifunc))
        value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
      *reloc_addr = value;
      break;
    case R_SPARC_JMP_IREL:
      if (__glibc_likely (!skip_ifunc))
        value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
      /* Fall thru */
    case R_SPARC_JMP_SLOT:
      {
#if !defined RTLD_BOOTSTRAP && !defined __sparc_v9__
        /* Note that we don't mask the hwcap here, as the flush is
           essential to functionality on those cpu's that implement
           it.  For sparcv9 we can assume flush is present.  */
        const int do_flush = GLRO(dl_hwcap) & HWCAP_SPARC_FLUSH;
#else
        /* Unfortunately, this is necessary, so that we can ensure
           ld.so will not execute corrupt PLT entry instructions. */
        const int do_flush = 1;
#endif
        /* At this point we don't need to bother with thread safety,
           so we can optimize the first instruction of .plt out.  */
        sparc_fixup_plt (reloc, reloc_addr, value, 0, do_flush);
      }
      break;
#ifndef RESOLVE_CONFLICT_FIND_MAP
    case R_SPARC_TLS_DTPMOD32:
      /* Get the information from the link map returned by the
         resolv function.  */
      if (sym_map != NULL)
        *reloc_addr = sym_map->l_tls_modid;
      break;
    case R_SPARC_TLS_DTPOFF32:
      /* During relocation all TLS symbols are defined and used.
         Therefore the offset is already correct.  */
      *reloc_addr = (sym == NULL ? 0 : sym->st_value) + reloc->r_addend;
      break;
    case R_SPARC_TLS_TPOFF32:
      /* The offset is negative, forward from the thread pointer.  */
      /* We know the offset of object the symbol is contained in.
         It is a negative value which will be added to the
         thread pointer.  */
      if (sym != NULL)
        {
          CHECK_STATIC_TLS (map, sym_map);
          *reloc_addr = sym->st_value - sym_map->l_tls_offset
            + reloc->r_addend;
        }
      break;
# ifndef RTLD_BOOTSTRAP
    case R_SPARC_TLS_LE_HIX22:
    case R_SPARC_TLS_LE_LOX10:
      if (sym != NULL)
        {
          CHECK_STATIC_TLS (map, sym_map);
          value = sym->st_value - sym_map->l_tls_offset
            + reloc->r_addend;
          if (r_type == R_SPARC_TLS_LE_HIX22)
            *reloc_addr = (*reloc_addr & 0xffc00000) | ((~value) >> 10);
          else
            *reloc_addr = (*reloc_addr & 0xffffe000) | (value & 0x3ff)
              | 0x1c00;
        }
      break;
# endif
#endif
#ifndef RTLD_BOOTSTRAP
    case R_SPARC_8:
      *(char *) reloc_addr = value;
      break;
    case R_SPARC_16:
      *(short *) reloc_addr = value;
      break;
    case R_SPARC_DISP8:
      *(char *) reloc_addr = (value - (Elf32_Addr) reloc_addr);
      break;
    case R_SPARC_DISP16:
      *(short *) reloc_addr = (value - (Elf32_Addr) reloc_addr);
      break;
    case R_SPARC_DISP32:
      *reloc_addr = (value - (Elf32_Addr) reloc_addr);
      break;
    case R_SPARC_LO10:
      *reloc_addr = (*reloc_addr & ~0x3ff) | (value & 0x3ff);
      break;
    case R_SPARC_WDISP30:
      *reloc_addr = ((*reloc_addr & 0xc0000000)
                     | ((value - (unsigned int) reloc_addr) >> 2));
      break;
    case R_SPARC_HI22:
      *reloc_addr = (*reloc_addr & 0xffc00000) | (value >> 10);
      break;
    case R_SPARC_UA16:
      ((unsigned char *) reloc_addr_arg) [0] = value >> 8;
      ((unsigned char *) reloc_addr_arg) [1] = value;
      break;
    case R_SPARC_UA32:
      ((unsigned char *) reloc_addr_arg) [0] = value >> 24;
      ((unsigned char *) reloc_addr_arg) [1] = value >> 16;
      ((unsigned char *) reloc_addr_arg) [2] = value >> 8;
      ((unsigned char *) reloc_addr_arg) [3] = value;
      break;
#endif
#if !defined RTLD_BOOTSTRAP || defined _NDEBUG
    default:
      _dl_reloc_bad_type (map, r_type, 0);
      break;
#endif
    }
}

static inline void
__attribute__ ((always_inline))
elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
                           void *const reloc_addr_arg)
{
  Elf32_Addr *const reloc_addr = reloc_addr_arg;
  *reloc_addr += l_addr + reloc->r_addend;
}

static inline void
__attribute__ ((always_inline))
elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
                      Elf32_Addr l_addr, const Elf32_Rela *reloc,
                      int skip_ifunc)
{
  Elf32_Addr *const reloc_addr = (void *) (l_addr + reloc->r_offset);
  const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);

  if (__glibc_likely (r_type == R_SPARC_JMP_SLOT))
    ;
  else if (r_type == R_SPARC_JMP_IREL)
    {
      Elf32_Addr value = map->l_addr + reloc->r_addend;
      if (__glibc_likely (!skip_ifunc))
        value = ((Elf32_Addr (*) (int)) value) (GLRO(dl_hwcap));
      sparc_fixup_plt (reloc, reloc_addr, value, 1, 1);
    }
  else if (r_type == R_SPARC_NONE)
    ;
  else
    _dl_reloc_bad_type (map, r_type, 1);
}

#endif  /* RESOLVE_MAP */