glibc/sysdeps/sparc/sparc32/dl-machine.h

/* Machine-dependent ELF dynamic relocation inline functions.  SPARC version.
   Copyright (C) 1996-2024 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>
#include <dl-static-tls.h>
#include <dl-machine-rel.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)
    {
      return GLRO(dl_hwcap) & HWCAP_SPARC_V9;
    }
  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]);
#ifdef SHARED
      if (__glibc_unlikely (profile))
	{
	  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
#endif
	{
	  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;
    }

  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

/* 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\
	ld	[%sp+22*4], %i5		/* load argc */\n\
  /* %o0 = _dl_loaded, %o1 = argc, %o2 = argv, %o3 = envp.  */\n\
	" 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
  const Elf32_Sym *const refsym = sym;
#endif
  Elf32_Addr value;
  const unsigned int r_type = ELF32_R_TYPE (reloc->r_info);
  struct link_map *sym_map = NULL;

  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
  if (__glibc_unlikely (r_type == R_SPARC_RELATIVE))
    {
      *reloc_addr += map->l_addr + reloc->r_addend;
      return;
    }
#endif

  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);
    }

  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
    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;
    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
#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 */