path: root/sysdeps/sparc/sparc32/dl-machine.h

/* Machine-dependent ELF dynamic relocation inline functions.  SPARC version.
   Copyright (C) 1996-2023 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)
    {
#if defined SHARED
      uint64_t hwcap_mask = TUNABLE_GET (glibc, cpu, hwcap_mask, uint64_t,
					 NULL);
      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;
    }

  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 "], &quo