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binutils-gdb/bfd/elf64-bpf.c

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/* Linux bpf specific support for 64-bit ELF
Copyright (C) 2019-2020 Free Software Foundation, Inc.
Contributed by Oracle Inc.
This file is part of BFD, the Binary File Descriptor library.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
MA 02110-1301, USA. */
#include "sysdep.h"
#include "bfd.h"
#include "libbfd.h"
#include "elf-bfd.h"
#include "elf/bpf.h"
#include "libiberty.h"
/* In case we're on a 32-bit machine, construct a 64-bit "-1" value. */
#define MINUS_ONE (~ (bfd_vma) 0)
#define BASEADDR(SEC) ((SEC)->output_section->vma + (SEC)->output_offset)
/* Relocation tables. */
static reloc_howto_type bpf_elf_howto_table [] =
{
/* This reloc does nothing. */
HOWTO (R_BPF_NONE, /* type */
0, /* rightshift */
3, /* size (0 = byte, 1 = short, 2 = long) */
0, /* bitsize */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_dont, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_NONE", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0, /* dst_mask */
FALSE), /* pcrel_offset */
/* 64-immediate in LDDW instruction. */
HOWTO (R_BPF_INSN_64, /* type */
0, /* rightshift */
4, /* size (0 = byte, 1 = short, 2 = long) */
64, /* bitsize */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_INSN_64", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
MINUS_ONE, /* dst_mask */
TRUE), /* pcrel_offset */
/* 32-immediate in LDDW instruction. */
HOWTO (R_BPF_INSN_32, /* type */
0, /* rightshift */
2, /* size (0 = byte, 1 = short, 2 = long) */
32, /* bitsize */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_INSN_32", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0xffffffff, /* dst_mask */
TRUE), /* pcrel_offset */
/* 16-bit offsets in instructions. */
HOWTO (R_BPF_INSN_16, /* type */
0, /* rightshift */
1, /* size (0 = byte, 1 = short, 2 = long) */
16, /* bitsize */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_INSN_16", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0x0000ffff, /* dst_mask */
TRUE), /* pcrel_offset */
/* 16-bit PC-relative address in jump instructions. */
HOWTO (R_BPF_INSN_DISP16, /* type */
0, /* rightshift */
1, /* size (0 = byte, 1 = short, 2 = long) */
16, /* bitsize */
TRUE, /* pc_relative */
32, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_INSN_DISP16", /* name */
FALSE, /* partial_inplace */
0xffff, /* src_mask */
0xffff, /* dst_mask */
TRUE), /* pcrel_offset */
HOWTO (R_BPF_DATA_8_PCREL,
0, /* rightshift */
0, /* size (0 = byte, 1 = short, 2 = long) */
8, /* bitsize */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_8_PCREL", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0xff, /* dst_mask */
TRUE), /* pcrel_offset */
HOWTO (R_BPF_DATA_16_PCREL,
0, /* rightshift */
1, /* size (0 = byte, 1 = short, 2 = long) */
16, /* bitsize */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_16_PCREL", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0xffff, /* dst_mask */
TRUE), /* pcrel_offset */
HOWTO (R_BPF_DATA_32_PCREL,
0, /* rightshift */
2, /* size (0 = byte, 1 = short, 2 = long) */
32, /* bitsize */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_32_PCREL", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0xffffffff, /* dst_mask */
TRUE), /* pcrel_offset */
HOWTO (R_BPF_DATA_8,
0, /* rightshift */
0, /* size (0 = byte, 1 = short, 2 = long) */
8, /* bitsize */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_unsigned, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_DATA_8", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0xff, /* dst_mask */
FALSE), /* pcrel_offset */
HOWTO (R_BPF_DATA_16,
0, /* rightshift */
1, /* size (0 = byte, 1 = short, 2 = long) */
16, /* bitsize */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_unsigned, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_DATA_16", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0xffff, /* dst_mask */
FALSE), /* pcrel_offset */
/* 32-bit PC-relative address in call instructions. */
HOWTO (R_BPF_INSN_DISP32, /* type */
0, /* rightshift */
2, /* size (0 = byte, 1 = short, 2 = long) */
32, /* bitsize */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_INSN_DISP32", /* name */
FALSE, /* partial_inplace */
0xffffffff, /* src_mask */
0xffffffff, /* dst_mask */
TRUE), /* pcrel_offset */
/* 32-bit data. */
HOWTO (R_BPF_DATA_32, /* type */
0, /* rightshift */
2, /* size (0 = byte, 1 = short, 2 = long) */
32, /* bitsize */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_bitfield, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_DATA_32", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
0xffffffff, /* dst_mask */
TRUE), /* pcrel_offset */
/* 64-bit data. */
HOWTO (R_BPF_DATA_64, /* type */
0, /* rightshift */
4, /* size (0 = byte, 1 = short, 2 = long) */
64, /* bitsize */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_bitfield, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_DATA_64", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
MINUS_ONE, /* dst_mask */
TRUE), /* pcrel_offset */
HOWTO (R_BPF_DATA_64_PCREL,
0, /* rightshift */
4, /* size (0 = byte, 1 = short, 2 = long) */
64, /* bitsize */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
bfd_elf_generic_reloc, /* special_function */
"R_BPF_64_PCREL", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
MINUS_ONE, /* dst_mask */
TRUE), /* pcrel_offset */
};
#undef AHOW
/* Map BFD reloc types to bpf ELF reloc types. */
static reloc_howto_type *
bpf_reloc_type_lookup (bfd * abfd ATTRIBUTE_UNUSED,
bfd_reloc_code_real_type code)
{
/* Note that the bpf_elf_howto_table is indexed by the R_ constants.
Thus, the order that the howto records appear in the table *must*
match the order of the relocation types defined in
include/elf/bpf.h. */
switch (code)
{
case BFD_RELOC_NONE:
return &bpf_elf_howto_table[ (int) R_BPF_NONE];
case BFD_RELOC_8_PCREL:
return &bpf_elf_howto_table[ (int) R_BPF_DATA_8_PCREL];
case BFD_RELOC_16_PCREL:
return &bpf_elf_howto_table[ (int) R_BPF_DATA_16_PCREL];
case BFD_RELOC_32_PCREL:
return &bpf_elf_howto_table[ (int) R_BPF_DATA_32_PCREL];
case BFD_RELOC_64_PCREL:
return &bpf_elf_howto_table[ (int) R_BPF_DATA_64_PCREL];
case BFD_RELOC_8:
return &bpf_elf_howto_table[ (int) R_BPF_DATA_8];
case BFD_RELOC_16:
return &bpf_elf_howto_table[ (int) R_BPF_DATA_16];
case BFD_RELOC_32:
return &bpf_elf_howto_table[ (int) R_BPF_DATA_32];
case BFD_RELOC_64:
return &bpf_elf_howto_table[ (int) R_BPF_DATA_64];
case BFD_RELOC_BPF_64:
return &bpf_elf_howto_table[ (int) R_BPF_INSN_64];
case BFD_RELOC_BPF_32:
return &bpf_elf_howto_table[ (int) R_BPF_INSN_32];
case BFD_RELOC_BPF_16:
return &bpf_elf_howto_table[ (int) R_BPF_INSN_16];
case BFD_RELOC_BPF_DISP16:
return &bpf_elf_howto_table[ (int) R_BPF_INSN_DISP16];
case BFD_RELOC_BPF_DISP32:
return &bpf_elf_howto_table[ (int) R_BPF_INSN_DISP32];
default:
/* Pacify gcc -Wall. */
return NULL;
}
return NULL;
}
/* Map BFD reloc names to bpf ELF reloc names. */
static reloc_howto_type *
bpf_reloc_name_lookup (bfd *abfd ATTRIBUTE_UNUSED, const char *r_name)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE (bpf_elf_howto_table); i++)
if (bpf_elf_howto_table[i].name != NULL
&& strcasecmp (bpf_elf_howto_table[i].name, r_name) == 0)
return &bpf_elf_howto_table[i];
return NULL;
}
/* Set the howto pointer for a bpf reloc. */
static bfd_boolean
bpf_info_to_howto (bfd *abfd, arelent *bfd_reloc,
Elf_Internal_Rela *elf_reloc)
{
unsigned int r_type;
r_type = ELF64_R_TYPE (elf_reloc->r_info);
if (r_type >= (unsigned int) R_BPF_max)
{
/* xgettext:c-format */
_bfd_error_handler (_("%pB: unsupported relocation type %#x"),
abfd, r_type);
bfd_set_error (bfd_error_bad_value);
return FALSE;
}
bfd_reloc->howto = &bpf_elf_howto_table [r_type];
return TRUE;
}
/* Relocate an eBPF ELF section.
The RELOCATE_SECTION function is called by the new ELF backend linker
to handle the relocations for a section.
The relocs are always passed as Rela structures; if the section
actually uses Rel structures, the r_addend field will always be
zero.
This function is responsible for adjusting the section contents as
necessary, and (if using Rela relocs and generating a relocatable
output file) adjusting the reloc addend as necessary.
This function does not have to worry about setting the reloc
address or the reloc symbol index.
LOCAL_SYMS is a pointer to the swapped in local symbols.
LOCAL_SECTIONS is an array giving the section in the input file
corresponding to the st_shndx field of each local symbol.
The global hash table entry for the global symbols can be found
via elf_sym_hashes (input_bfd).
When generating relocatable output, this function must handle
STB_LOCAL/STT_SECTION symbols specially. The output symbol is
going to be the section symbol corresponding to the output
section, which means that the addend must be adjusted
accordingly. */
#define sec_addr(sec) ((sec)->output_section->vma + (sec)->output_offset)
static bfd_boolean
bpf_elf_relocate_section (bfd *output_bfd ATTRIBUTE_UNUSED,
struct bfd_link_info *info,
bfd *input_bfd,
asection *input_section,
bfd_byte *contents,
Elf_Internal_Rela *relocs,
Elf_Internal_Sym *local_syms,
asection **local_sections)
{
Elf_Internal_Shdr *symtab_hdr;
struct elf_link_hash_entry **sym_hashes;
Elf_Internal_Rela *rel;
Elf_Internal_Rela *relend;
symtab_hdr = & elf_tdata (input_bfd)->symtab_hdr;
sym_hashes = elf_sym_hashes (input_bfd);
relend = relocs + input_section->reloc_count;
for (rel = relocs; rel < relend; rel ++)
{
reloc_howto_type * howto;
unsigned long r_symndx;
Elf_Internal_Sym * sym;
asection * sec;
struct elf_link_hash_entry * h;
bfd_vma relocation;
bfd_reloc_status_type r;
const char * name = NULL;
int r_type ATTRIBUTE_UNUSED;
r_type = ELF64_R_TYPE (rel->r_info);
r_symndx = ELF64_R_SYM (rel->r_info);
howto = bpf_elf_howto_table + ELF64_R_TYPE (rel->r_info);
h = NULL;
sym = NULL;
sec = NULL;
if (r_symndx < symtab_hdr->sh_info)
{
sym = local_syms + r_symndx;
sec = local_sections [r_symndx];
relocation = BASEADDR (sec) + sym->st_value;
name = bfd_elf_string_from_elf_section
(input_bfd, symtab_hdr->sh_link, sym->st_name);
name = name == NULL ? bfd_section_name (sec) : name;
}
else
{
bfd_boolean warned ATTRIBUTE_UNUSED;
bfd_boolean unresolved_reloc ATTRIBUTE_UNUSED;
bfd_boolean ignored ATTRIBUTE_UNUSED;
RELOC_FOR_GLOBAL_SYMBOL (info, input_bfd, input_section, rel,
r_symndx, symtab_hdr, sym_hashes,
h, sec, relocation,
unresolved_reloc, warned, ignored);
name = h->root.root.string;
}
if (sec != NULL && discarded_section (sec))
RELOC_AGAINST_DISCARDED_SECTION (info, input_bfd, input_section,
rel, 1, relend, howto, 0, contents);
if (bfd_link_relocatable (info))
continue;
switch (howto->type)
{
case R_BPF_INSN_DISP16:
case R_BPF_INSN_DISP32:
{
bfd_signed_vma addend;
/* Make the relocation PC-relative, and change its unit to
64-bit words. */
relocation -= sec_addr (input_section) + rel->r_offset;
/* Make it 64-bit words. */
relocation = relocation / 8;
/* Get the addend from the instruction and apply it. */
addend = bfd_get (howto->bitsize, input_bfd,
contents + rel->r_offset
+ (howto->bitsize == 16 ? 2 : 4));
if ((addend & (((~howto->src_mask) >> 1) & howto->src_mask)) != 0)
addend -= (((~howto->src_mask) >> 1) & howto->src_mask) << 1;
relocation += addend;
/* Write out the relocated value. */
bfd_put (howto->bitsize, input_bfd, relocation,
contents + rel->r_offset
+ (howto->bitsize == 16 ? 2 : 4));
r = bfd_reloc_ok;
break;
}
default:
r = _bfd_final_link_relocate (howto, input_bfd, input_section,
contents, rel->r_offset, relocation,
rel->r_addend);
}
if (r != bfd_reloc_ok)
{
const char * msg = NULL;
switch (r)
{
case bfd_reloc_overflow:
(*info->callbacks->reloc_overflow)
(info, (h ? &h->root : NULL), name, howto->name,
(bfd_vma) 0, input_bfd, input_section, rel->r_offset);
break;
case bfd_reloc_undefined:
(*info->callbacks->undefined_symbol)
(info, name, input_bfd, input_section, rel->r_offset, TRUE);
break;
case bfd_reloc_outofrange:
msg = _("internal error: out of range error");
break;
case bfd_reloc_notsupported:
if (sym != NULL) /* Only if it's not an unresolved symbol. */
msg = _("internal error: relocation not supported");
break;
case bfd_reloc_dangerous:
msg = _("internal error: dangerous relocation");
break;
default:
msg = _("internal error: unknown error");
break;
}
if (msg)
(*info->callbacks->warning) (info, msg, name, input_bfd,
input_section, rel->r_offset);
}
}
return TRUE;
}
/* Merge backend specific data from an object file to the output
object file when linking. */
static bfd_boolean
elf64_bpf_merge_private_bfd_data (bfd *ibfd, struct bfd_link_info *info)
{
/* Check if we have the same endianness. */
if (! _bfd_generic_verify_endian_match (ibfd, info))
return FALSE;
return TRUE;
}
/* The macros below configure the architecture. */
#define TARGET_LITTLE_SYM bpf_elf64_le_vec
#define TARGET_LITTLE_NAME "elf64-bpfle"
#define TARGET_BIG_SYM bpf_elf64_be_vec
#define TARGET_BIG_NAME "elf64-bpfbe"
#define ELF_ARCH bfd_arch_bpf
#define ELF_MACHINE_CODE EM_BPF
#define ELF_MAXPAGESIZE 0x100000
#define elf_info_to_howto_rel bpf_info_to_howto
#define elf_info_to_howto bpf_info_to_howto
#define elf_backend_may_use_rel_p 1
#define elf_backend_may_use_rela_p 0
#define elf_backend_default_use_rela_p 0
#define elf_backend_relocate_section bpf_elf_relocate_section
#define elf_backend_can_gc_sections 0
#define elf_symbol_leading_char '_'
#define bfd_elf64_bfd_reloc_type_lookup bpf_reloc_type_lookup
#define bfd_elf64_bfd_reloc_name_lookup bpf_reloc_name_lookup
#define bfd_elf64_bfd_merge_private_bfd_data elf64_bpf_merge_private_bfd_data
#include "elf64-target.h"
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