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Install patch for PR ld/16017. This adds support for generating PLT entries
using Thumb2 instructions for those cores which do not support the ARM ISA. * elf32-arm.c (elf32_thumb2_plt0_entry): New array. (elf32_thumb2_plt_entry): New array. (elf32_arm_create_dynamic_sections): Set PLT entry sizes when using thumb2 based PLT. (elf32_arm_populate_plt_entry): Handle generating Thumb2 based PLT entries. (elf32_arm_final_link_relocate): Do not bias jumps to Thumb based PLT entries. (elf32_arm_finish_dynamic_sections): Handle creation of Thumb2 based PLT 0-entry. (elf32_arm_output_plt_map_1): Handle creation of local symbols for Thumb2 based PLT 0-entry. (elf32_arm_output_arch_local_syms): Handle creation of local symbols for Thumb2 based PLT entries.
This commit is contained in:
Nick Clifton
@ -1,3 +1,21 @@
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2014-03-04 Nick Clifton <nickc@redhat.com>
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PR ld/16017
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* elf32-arm.c (elf32_thumb2_plt0_entry): New array.
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(elf32_thumb2_plt_entry): New array.
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(elf32_arm_create_dynamic_sections): Set PLT entry sizes when
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using thumb2 based PLT.
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(elf32_arm_populate_plt_entry): Handle generating Thumb2 based PLT
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entries.
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(elf32_arm_final_link_relocate): Do not bias jumps to Thumb based
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PLT entries.
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(elf32_arm_finish_dynamic_sections): Handle creation of Thumb2
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based PLT 0-entry.
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(elf32_arm_output_plt_map_1): Handle creation of local symbols for
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Thumb2 based PLT 0-entry.
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(elf32_arm_output_arch_local_syms): Handle creation of local
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symbols for Thumb2 based PLT entries.
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2014-02-28 Alan Modra <amodra@gmail.com>
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PR ld/16643
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188
bfd/elf32-arm.c
188
bfd/elf32-arm.c
@ -2125,7 +2125,7 @@ static const bfd_vma elf32_arm_plt_entry [] =
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0x00000000, /* unused */
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};
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#else
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#else /* not FOUR_WORD_PLT */
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/* The first entry in a procedure linkage table looks like
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this. It is set up so that any shared library function that is
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@ -2161,7 +2161,34 @@ static const bfd_vma elf32_arm_plt_entry_long [] =
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static bfd_boolean elf32_arm_use_long_plt_entry = FALSE;
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#endif
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#endif /* not FOUR_WORD_PLT */
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/* The first entry in a procedure linkage table looks like this.
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It is set up so that any shared library function that is called before the
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relocation has been set up calls the dynamic linker first. */
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static const bfd_vma elf32_thumb2_plt0_entry [] =
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{
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/* NOTE: As this is a mixture of 16-bit and 32-bit instructions,
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an instruction maybe encoded to one or two array elements. */
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0xf8dfb500, /* push {lr} */
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0x44fee008, /* ldr.w lr, [pc, #8] */
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/* add lr, pc */
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0xff08f85e, /* ldr.w pc, [lr, #8]! */
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0x00000000, /* &GOT[0] - . */
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};
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/* Subsequent entries in a procedure linkage table for thumb only target
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look like this. */
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static const bfd_vma elf32_thumb2_plt_entry [] =
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{
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/* NOTE: As this is a mixture of 16-bit and 32-bit instructions,
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an instruction maybe encoded to one or two array elements. */
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0x0c00f240, /* movw ip, #0xNNNN */
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0x0c00f2c0, /* movt ip, #0xNNNN */
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0xf8dc44fc, /* add ip, pc */
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0xbf00f000 /* ldr.w pc, [ip] */
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/* nop */
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};
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/* The format of the first entry in the procedure linkage table
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for a VxWorks executable. */
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@ -3329,6 +3356,37 @@ create_ifunc_sections (struct bfd_link_info *info)
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return TRUE;
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}
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/* Determine if we're dealing with a Thumb only architecture. */
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static bfd_boolean
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using_thumb_only (struct elf32_arm_link_hash_table *globals)
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{
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int arch = bfd_elf_get_obj_attr_int (globals->obfd, OBJ_ATTR_PROC,
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Tag_CPU_arch);
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int profile;
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if (arch == TAG_CPU_ARCH_V6_M || arch == TAG_CPU_ARCH_V6S_M)
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return TRUE;
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if (arch != TAG_CPU_ARCH_V7 && arch != TAG_CPU_ARCH_V7E_M)
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return FALSE;
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profile = bfd_elf_get_obj_attr_int (globals->obfd, OBJ_ATTR_PROC,
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Tag_CPU_arch_profile);
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return profile == 'M';
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}
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/* Determine if we're dealing with a Thumb-2 object. */
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static bfd_boolean
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using_thumb2 (struct elf32_arm_link_hash_table *globals)
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{
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int arch = bfd_elf_get_obj_attr_int (globals->obfd, OBJ_ATTR_PROC,
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Tag_CPU_arch);
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return arch == TAG_CPU_ARCH_V6T2 || arch >= TAG_CPU_ARCH_V7;
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}
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/* Create .plt, .rel(a).plt, .got, .got.plt, .rel(a).got, .dynbss, and
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.rel(a).bss sections in DYNOBJ, and set up shortcuts to them in our
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hash table. */
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@ -3372,6 +3430,22 @@ elf32_arm_create_dynamic_sections (bfd *dynobj, struct bfd_link_info *info)
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= 4 * ARRAY_SIZE (elf32_arm_vxworks_exec_plt_entry);
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}
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}
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else
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{
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/* PR ld/16017
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Test for thumb only architectures. Note - we cannot just call
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using_thumb_only() as the attributes in the output bfd have not been
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initialised at this point, so instead we use the input bfd. */
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bfd * saved_obfd = htab->obfd;
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htab->obfd = dynobj;
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if (using_thumb_only (htab))
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{
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htab->plt_header_size = 4 * ARRAY_SIZE (elf32_thumb2_plt0_entry);
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htab->plt_entry_size = 4 * ARRAY_SIZE (elf32_thumb2_plt_entry);
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}
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htab->obfd = saved_obfd;
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}
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if (!htab->root.splt
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|| !htab->root.srelplt
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@ -3503,37 +3577,6 @@ elf32_arm_hash_table_free (struct bfd_link_hash_table *hash)
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_bfd_elf_link_hash_table_free (hash);
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}
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/* Determine if we're dealing with a Thumb only architecture. */
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static bfd_boolean
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using_thumb_only (struct elf32_arm_link_hash_table *globals)
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{
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int arch = bfd_elf_get_obj_attr_int (globals->obfd, OBJ_ATTR_PROC,
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Tag_CPU_arch);
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int profile;
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if (arch == TAG_CPU_ARCH_V6_M || arch == TAG_CPU_ARCH_V6S_M)
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return TRUE;
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if (arch != TAG_CPU_ARCH_V7 && arch != TAG_CPU_ARCH_V7E_M)
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return FALSE;
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profile = bfd_elf_get_obj_attr_int (globals->obfd, OBJ_ATTR_PROC,
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Tag_CPU_arch_profile);
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return profile == 'M';
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}
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/* Determine if we're dealing with a Thumb-2 object. */
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static bfd_boolean
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using_thumb2 (struct elf32_arm_link_hash_table *globals)
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{
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int arch = bfd_elf_get_obj_attr_int (globals->obfd, OBJ_ATTR_PROC,
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Tag_CPU_arch);
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return arch == TAG_CPU_ARCH_V6T2 || arch >= TAG_CPU_ARCH_V7;
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}
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/* Determine what kind of NOPs are available. */
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static bfd_boolean
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@ -7710,13 +7753,43 @@ elf32_arm_populate_plt_entry (bfd *output_bfd, struct bfd_link_info *info,
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}
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else if (using_thumb_only (htab))
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{
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/* PR ld/16017: Do not generate ARM instructions for
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the PLT if compiling for a thumb-only target.
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/* PR ld/16017: Generate thumb only PLT entries. */
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if (!using_thumb2 (htab))
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{
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/* FIXME: We ought to be able to generate thumb-1 PLT
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instructions... */
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_bfd_error_handler (_("%B: Warning: thumb-1 mode PLT generation not currently supported"),
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output_bfd);
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return FALSE;
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}
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FIXME: We ought to be able to generate thumb PLT instructions... */
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_bfd_error_handler (_("%B: Warning: thumb mode PLT generation not currently supported"),
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output_bfd);
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return FALSE;
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/* Calculate the displacement between the PLT slot and the entry in
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the GOT. The 12-byte offset accounts for the value produced by
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adding to pc in the 3rd instruction of the PLT stub. */
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got_displacement = got_address - (plt_address + 12);
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/* As we are using 32 bit instructions we have to use 'put_arm_insn'
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instead of 'put_thumb_insn'. */
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put_arm_insn (htab, output_bfd,
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elf32_thumb2_plt_entry[0]
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| ((got_displacement & 0x000000ff) << 16)
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| ((got_displacement & 0x00000700) << 20)
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| ((got_displacement & 0x00000800) >> 1)
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| ((got_displacement & 0x0000f000) >> 12),
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ptr + 0);
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put_arm_insn (htab, output_bfd,
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elf32_thumb2_plt_entry[1]
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| ((got_displacement & 0x00ff0000) )
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| ((got_displacement & 0x07000000) << 4)
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| ((got_displacement & 0x08000000) >> 17)
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| ((got_displacement & 0xf0000000) >> 28),
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ptr + 4);
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put_arm_insn (htab, output_bfd,
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elf32_thumb2_plt_entry[2],
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ptr + 8);
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put_arm_insn (htab, output_bfd,
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elf32_thumb2_plt_entry[3],
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ptr + 12);
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}
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else
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{
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@ -8961,7 +9034,9 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto,
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+ splt->output_offset
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+ plt_offset);
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if (globals->use_blx && r_type == R_ARM_THM_CALL)
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if (globals->use_blx
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&& r_type == R_ARM_THM_CALL
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&& ! using_thumb_only (globals))
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{
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/* If the Thumb BLX instruction is available, convert
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the BL to a BLX instruction to call the ARM-mode
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@ -8971,8 +9046,9 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto,
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}
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else
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{
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/* Target the Thumb stub before the ARM PLT entry. */
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value -= PLT_THUMB_STUB_SIZE;
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if (! using_thumb_only (globals))
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/* Target the Thumb stub before the ARM PLT entry. */
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value -= PLT_THUMB_STUB_SIZE;
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branch_type = ST_BRANCH_TO_THUMB;
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}
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*unresolved_reloc_p = FALSE;
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@ -14427,6 +14503,20 @@ elf32_arm_finish_dynamic_sections (bfd * output_bfd, struct bfd_link_info * info
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else if (htab->nacl_p)
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arm_nacl_put_plt0 (htab, output_bfd, splt,
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got_address + 8 - (plt_address + 16));
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else if (using_thumb_only (htab))
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{
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got_displacement = got_address - (plt_address + 12);
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plt0_entry = elf32_thumb2_plt0_entry;
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put_arm_insn (htab, output_bfd, plt0_entry[0],
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splt->contents + 0);
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put_arm_insn (htab, output_bfd, plt0_entry[1],
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splt->contents + 4);
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put_arm_insn (htab, output_bfd, plt0_entry[2],
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splt->contents + 8);
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bfd_put_32 (output_bfd, got_displacement, splt->contents + 12);
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}
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else
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{
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got_displacement = got_address - (plt_address + 16);
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@ -14765,6 +14855,11 @@ elf32_arm_output_plt_map_1 (output_arch_syminfo *osi,
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if (!elf32_arm_output_map_sym (osi, ARM_MAP_ARM, addr))
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return FALSE;
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}
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else if (using_thumb_only (htab))
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{
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if (!elf32_arm_output_map_sym (osi, ARM_MAP_THUMB, addr))
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return FALSE;
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}
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else
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{
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bfd_boolean thumb_stub_p;
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@ -15096,6 +15191,15 @@ elf32_arm_output_arch_local_syms (bfd *output_bfd,
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if (!elf32_arm_output_map_sym (&osi, ARM_MAP_ARM, 0))
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return FALSE;
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}
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else if (using_thumb_only (htab))
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{
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if (!elf32_arm_output_map_sym (&osi, ARM_MAP_THUMB, 0))
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return FALSE;
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if (!elf32_arm_output_map_sym (&osi, ARM_MAP_DATA, 12))
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return FALSE;
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if (!elf32_arm_output_map_sym (&osi, ARM_MAP_THUMB, 16))
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return FALSE;
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}
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else if (!htab->symbian_p)
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{
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if (!elf32_arm_output_map_sym (&osi, ARM_MAP_ARM, 0))
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