449 lines
14 KiB
C
449 lines
14 KiB
C
/* Machine-dependent ELF dynamic relocation inline functions. PowerPC version.
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Copyright (C) 1995-2022 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef dl_machine_h
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#define dl_machine_h
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#define ELF_MACHINE_NAME "powerpc"
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#include <assert.h>
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#include <dl-tls.h>
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#include <dl-irel.h>
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#include <hwcapinfo.h>
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#include <dl-static-tls.h>
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#include <dl-machine-rel.h>
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/* Translate a processor specific dynamic tag to the index
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in l_info array. */
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#define DT_PPC(x) (DT_PPC_##x - DT_LOPROC + DT_NUM)
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/* Return nonzero iff ELF header is compatible with the running host. */
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static inline int
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elf_machine_matches_host (const Elf32_Ehdr *ehdr)
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{
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return ehdr->e_machine == EM_PPC;
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}
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/* Return the value of the GOT pointer. */
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static inline Elf32_Addr * __attribute__ ((const))
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ppc_got (void)
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{
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Elf32_Addr *got;
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asm ("bcl 20,31,1f\n"
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"1: mflr %0\n"
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" addis %0,%0,_GLOBAL_OFFSET_TABLE_-1b@ha\n"
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" addi %0,%0,_GLOBAL_OFFSET_TABLE_-1b@l\n"
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: "=b" (got) : : "lr");
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return got;
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}
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/* Return the link-time address of _DYNAMIC, stored as
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the first value in the GOT. */
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static inline Elf32_Addr __attribute__ ((const))
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elf_machine_dynamic (void)
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{
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return *ppc_got ();
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}
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/* Return the run-time load address of the shared object. */
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static inline Elf32_Addr __attribute__ ((const))
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elf_machine_load_address (void)
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{
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Elf32_Addr *branchaddr;
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Elf32_Addr runtime_dynamic;
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/* This is much harder than you'd expect. Possibly I'm missing something.
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The 'obvious' way:
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Apparently, "bcl 20,31,$+4" is what should be used to load LR
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with the address of the next instruction.
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I think this is so that machines that do bl/blr pairing don't
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get confused.
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asm ("bcl 20,31,0f ;"
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"0: mflr 0 ;"
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"lis %0,0b@ha;"
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"addi %0,%0,0b@l;"
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"subf %0,%0,0"
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: "=b" (addr) : : "r0", "lr");
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doesn't work, because the linker doesn't have to (and in fact doesn't)
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update the @ha and @l references; the loader (which runs after this
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code) will do that.
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Instead, we use the following trick:
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The linker puts the _link-time_ address of _DYNAMIC at the first
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word in the GOT. We could branch to that address, if we wanted,
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by using an @local reloc; the linker works this out, so it's safe
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to use now. We can't, of course, actually branch there, because
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we'd cause an illegal instruction exception; so we need to compute
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the address ourselves. That gives us the following code: */
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/* Get address of the 'b _DYNAMIC@local'... */
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asm ("bcl 20,31,0f;"
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"b _DYNAMIC@local;"
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"0:"
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: "=l" (branchaddr));
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/* So now work out the difference between where the branch actually points,
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and the offset of that location in memory from the start of the file. */
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runtime_dynamic = ((Elf32_Addr) branchaddr
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+ ((Elf32_Sword) (*branchaddr << 6 & 0xffffff00) >> 6));
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return runtime_dynamic - elf_machine_dynamic ();
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}
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/* The PLT uses Elf32_Rela relocs. */
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#define elf_machine_relplt elf_machine_rela
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/* Mask identifying addresses reserved for the user program,
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where the dynamic linker should not map anything. */
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#define ELF_MACHINE_USER_ADDRESS_MASK 0xf0000000UL
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/* The actual _start code is in dl-start.S. Use a really
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ugly bit of assembler to let dl-start.o see _dl_start. */
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#define RTLD_START asm (".globl _dl_start");
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/* Decide where a relocatable object should be loaded. */
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extern ElfW(Addr)
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__elf_preferred_address(struct link_map *loader, size_t maplength,
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ElfW(Addr) mapstartpref);
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#define ELF_PREFERRED_ADDRESS(loader, maplength, mapstartpref) \
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__elf_preferred_address (loader, maplength, mapstartpref)
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/* ELF_RTYPE_CLASS_PLT iff TYPE describes relocation of a PLT entry, so
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PLT entries should not be allowed to define the value.
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ELF_RTYPE_CLASS_COPY iff TYPE should not be allowed to resolve to one
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of the main executable's symbols, as for a COPY reloc. */
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/* We never want to use a PLT entry as the destination of a
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reloc, when what is being relocated is a branch. This is
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partly for efficiency, but mostly so we avoid loops. */
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#define elf_machine_type_class(type) \
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((((type) == R_PPC_JMP_SLOT \
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|| (type) == R_PPC_REL24 \
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|| ((type) >= R_PPC_DTPMOD32 /* contiguous TLS */ \
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&& (type) <= R_PPC_DTPREL32) \
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|| (type) == R_PPC_ADDR24) * ELF_RTYPE_CLASS_PLT) \
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/* A reloc type used for ld.so cmdline arg lookups to reject PLT entries. */
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#define ELF_MACHINE_JMP_SLOT R_PPC_JMP_SLOT
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/* We define an initialization function to initialize HWCAP/HWCAP2 and
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platform data so it can be copied into the TCB later. This is called
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very early in _dl_sysdep_start for dynamically linked binaries. */
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#ifdef SHARED
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# define DL_PLATFORM_INIT dl_platform_init ()
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static inline void __attribute__ ((unused))
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dl_platform_init (void)
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{
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__tcb_parse_hwcap_and_convert_at_platform ();
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}
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#endif
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/* Set up the loaded object described by MAP so its unrelocated PLT
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entries will jump to the on-demand fixup code in dl-runtime.c.
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Also install a small trampoline to be used by entries that have
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been relocated to an address too far away for a single branch. */
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extern int __elf_machine_runtime_setup (struct link_map *map,
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int lazy, int profile);
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static inline int
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elf_machine_runtime_setup (struct link_map *map, struct r_scope_elem *scope[],
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int lazy, int profile)
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{
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if (map->l_info[DT_JMPREL] == 0)
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return lazy;
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if (map->l_info[DT_PPC(GOT)] == 0)
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/* Handle old style PLT. */
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return __elf_machine_runtime_setup (map, lazy, profile);
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/* New style non-exec PLT consisting of an array of addresses. */
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map->l_info[DT_PPC(GOT)]->d_un.d_ptr += map->l_addr;
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if (lazy)
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{
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Elf32_Addr *plt, *got, glink;
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Elf32_Word num_plt_entries;
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void (*dlrr) (void);
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extern void _dl_runtime_resolve (void);
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extern void _dl_prof_resolve (void);
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if (__glibc_likely (!profile))
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dlrr = _dl_runtime_resolve;
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else
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{
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if (GLRO(dl_profile) != NULL
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&&_dl_name_match_p (GLRO(dl_profile), map))
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GL(dl_profile_map) = map;
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dlrr = _dl_prof_resolve;
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}
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got = (Elf32_Addr *) map->l_info[DT_PPC(GOT)]->d_un.d_ptr;
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glink = got[1];
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got[1] = (Elf32_Addr) dlrr;
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got[2] = (Elf32_Addr) map;
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/* Relocate everything in .plt by the load address offset. */
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plt = (Elf32_Addr *) D_PTR (map, l_info[DT_PLTGOT]);
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num_plt_entries = (map->l_info[DT_PLTRELSZ]->d_un.d_val
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/ sizeof (Elf32_Rela));
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/* If a library is prelinked but we have to relocate anyway,
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we have to be able to undo the prelinking of .plt section.
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The prelinker saved us at got[1] address of .glink
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section's start. */
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if (glink)
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{
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glink += map->l_addr;
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while (num_plt_entries-- != 0)
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*plt++ = glink, glink += 4;
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}
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else
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while (num_plt_entries-- != 0)
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*plt++ += map->l_addr;
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}
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return lazy;
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}
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/* Change the PLT entry whose reloc is 'reloc' to call the actual routine. */
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extern Elf32_Addr __elf_machine_fixup_plt (struct link_map *map,
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Elf32_Addr *reloc_addr,
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Elf32_Addr finaladdr);
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static inline Elf32_Addr
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elf_machine_fixup_plt (struct link_map *map, lookup_t t,
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const ElfW(Sym) *refsym, const ElfW(Sym) *sym,
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const Elf32_Rela *reloc,
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Elf32_Addr *reloc_addr, Elf64_Addr finaladdr)
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{
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if (map->l_info[DT_PPC(GOT)] == 0)
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/* Handle old style PLT. */
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return __elf_machine_fixup_plt (map, reloc_addr, finaladdr);
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*reloc_addr = finaladdr;
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return finaladdr;
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}
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/* Return the final value of a plt relocation. */
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static inline Elf32_Addr
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elf_machine_plt_value (struct link_map *map, const Elf32_Rela *reloc,
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Elf32_Addr value)
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{
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return value + reloc->r_addend;
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}
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/* Names of the architecture-specific auditing callback functions. */
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#define ARCH_LA_PLTENTER ppc32_gnu_pltenter
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#define ARCH_LA_PLTEXIT ppc32_gnu_pltexit
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#endif /* dl_machine_h */
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#ifdef RESOLVE_MAP
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/* Do the actual processing of a reloc, once its target address
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has been determined. */
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extern void __process_machine_rela (struct link_map *map,
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const Elf32_Rela *reloc,
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struct link_map *sym_map,
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const Elf32_Sym *sym,
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const Elf32_Sym *refsym,
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Elf32_Addr *const reloc_addr,
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Elf32_Addr finaladdr,
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int rinfo, bool skip_ifunc)
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attribute_hidden;
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/* Call _dl_signal_error when a resolved value overflows a relocated area. */
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extern void _dl_reloc_overflow (struct link_map *map,
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const char *name,
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Elf32_Addr *const reloc_addr,
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const Elf32_Sym *refsym) attribute_hidden;
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/* Perform the relocation specified by RELOC and SYM (which is fully resolved).
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LOADADDR is the load address of the object; INFO is an array indexed
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by DT_* of the .dynamic section info. */
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static inline void __attribute__ ((always_inline))
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elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
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const Elf32_Rela *reloc, const Elf32_Sym *sym,
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const struct r_found_version *version,
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void *const reloc_addr_arg, int skip_ifunc)
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{
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Elf32_Addr *const reloc_addr = reloc_addr_arg;
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const Elf32_Sym *const refsym = sym;
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Elf32_Addr value;
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const int r_type = ELF32_R_TYPE (reloc->r_info);
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struct link_map *sym_map = NULL;
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if (r_type == R_PPC_RELATIVE)
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{
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*reloc_addr = map->l_addr + reloc->r_addend;
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return;
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}
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if (__glibc_unlikely (r_type == R_PPC_NONE))
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return;
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/* binutils on ppc32 includes st_value in r_addend for relocations
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against local symbols. */
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if (__builtin_expect (ELF32_ST_BIND (sym->st_info) == STB_LOCAL, 0)
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&& sym->st_shndx != SHN_UNDEF)
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{
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sym_map = map;
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value = map->l_addr;
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}
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else
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{
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sym_map = RESOLVE_MAP (map, scope, &sym, version, r_type);
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value = SYMBOL_ADDRESS (sym_map, sym, true);
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}
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value += reloc->r_addend;
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if (sym != NULL
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&& __builtin_expect (ELFW(ST_TYPE) (sym->st_info) == STT_GNU_IFUNC, 0)
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&& __builtin_expect (sym->st_shndx != SHN_UNDEF, 1)
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&& __builtin_expect (!skip_ifunc, 1))
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value = elf_ifunc_invoke (value);
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/* A small amount of code is duplicated here for speed. In libc,
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more than 90% of the relocs are R_PPC_RELATIVE; in the X11 shared
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libraries, 60% are R_PPC_RELATIVE, 24% are R_PPC_GLOB_DAT or
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R_PPC_ADDR32, and 16% are R_PPC_JMP_SLOT (which this routine
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wouldn't usually handle). As an bonus, doing this here allows
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the switch statement in __process_machine_rela to work. */
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switch (r_type)
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{
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case R_PPC_GLOB_DAT:
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case R_PPC_ADDR32:
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*reloc_addr = value;
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break;
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#ifdef RTLD_BOOTSTRAP
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# define NOT_BOOTSTRAP 0
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#else
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# define NOT_BOOTSTRAP 1
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#endif
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case R_PPC_DTPMOD32:
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if (map->l_info[DT_PPC(OPT)]
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&& (map->l_info[DT_PPC(OPT)]->d_un.d_val & PPC_OPT_TLS))
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{
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if (!NOT_BOOTSTRAP)
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{
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reloc_addr[0] = 0;
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reloc_addr[1] = (sym_map->l_tls_offset - TLS_TP_OFFSET
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+ TLS_DTV_OFFSET);
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break;
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}
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else if (sym_map != NULL)
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{
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#ifndef SHARED
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CHECK_STATIC_TLS (map, sym_map);
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#else
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if (TRY_STATIC_TLS (map, sym_map))
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#endif
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{
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reloc_addr[0] = 0;
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/* Set up for local dynamic. */
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reloc_addr[1] = (sym_map->l_tls_offset - TLS_TP_OFFSET
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+ TLS_DTV_OFFSET);
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break;
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}
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}
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}
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if (!NOT_BOOTSTRAP)
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/* During startup the dynamic linker is always index 1. */
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*reloc_addr = 1;
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else if (sym_map != NULL)
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/* Get the information from the link map returned by the
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RESOLVE_MAP function. */
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*reloc_addr = sym_map->l_tls_modid;
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break;
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case R_PPC_DTPREL32:
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if (map->l_info[DT_PPC(OPT)]
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&& (map->l_info[DT_PPC(OPT)]->d_un.d_val & PPC_OPT_TLS))
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{
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if (!NOT_BOOTSTRAP)
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{
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*reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
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break;
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}
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else if (sym_map != NULL)
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{
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/* This reloc is always preceded by R_PPC_DTPMOD32. */
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#ifndef SHARED
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assert (HAVE_STATIC_TLS (map, sym_map));
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#else
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if (HAVE_STATIC_TLS (map, sym_map))
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#endif
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{
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*reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
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break;
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}
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}
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}
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/* During relocation all TLS symbols are defined and used.
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Therefore the offset is already correct. */
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if (NOT_BOOTSTRAP && sym_map != NULL)
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*reloc_addr = TLS_DTPREL_VALUE (sym, reloc);
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break;
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case R_PPC_TPREL32:
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if (!NOT_BOOTSTRAP || sym_map != NULL)
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{
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if (NOT_BOOTSTRAP)
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CHECK_STATIC_TLS (map, sym_map);
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*reloc_addr = TLS_TPREL_VALUE (sym_map, sym, reloc);
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}
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break;
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case R_PPC_JMP_SLOT:
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if (map->l_info[DT_PPC(GOT)] != 0)
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{
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*reloc_addr = value;
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break;
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}
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/* FALLTHROUGH */
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default:
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__process_machine_rela (map, reloc, sym_map, sym, refsym,
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reloc_addr, value, r_type, skip_ifunc);
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}
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}
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static inline void __attribute__ ((always_inline))
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elf_machine_rela_relative (Elf32_Addr l_addr, const Elf32_Rela *reloc,
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void *const reloc_addr_arg)
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{
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Elf32_Addr *const reloc_addr = reloc_addr_arg;
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*reloc_addr = l_addr + reloc->r_addend;
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}
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static inline void __attribute__ ((always_inline))
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elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
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Elf32_Addr l_addr, const Elf32_Rela *reloc,
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int skip_ifunc)
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{
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/* elf_machine_runtime_setup handles this. */
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}
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#endif /* RESOLVE_MAP */
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