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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 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)
/* Handler for PC-relative relocations, which must be handled in
64-bit words. */
static bfd_reloc_status_type
bpf_elf_insn_disp_reloc (bfd *abfd,
arelent *reloc_entry,
asymbol *symbol,
void *data,
asection *input_section,
bfd *output_bfd,
char **error_message ATTRIBUTE_UNUSED)
{
bfd_signed_vma relocation;
bfd_signed_vma addend;
reloc_howto_type *howto = reloc_entry->howto;
/* This part is from bfd_elf_generic_reloc. */
if (output_bfd != NULL
&& (symbol->flags & BSF_SECTION_SYM) == 0
&& (! reloc_entry->howto->partial_inplace
|| reloc_entry->addend == 0))
{
reloc_entry->address += input_section->output_offset;
return bfd_reloc_ok;
}
/* This works because partial_inplace is FALSE. */
if (output_bfd != NULL)
return bfd_reloc_continue;
if (reloc_entry->address > bfd_get_section_limit (abfd, input_section))
return bfd_reloc_outofrange;
relocation = (symbol->value
+ symbol->section->output_section->vma
+ symbol->section->output_offset);
/* Make it PC relative. */
relocation -= (input_section->output_section->vma
+ input_section->output_offset);
relocation -= reloc_entry->address;
/* Make it 64-bit words. */
relocation = relocation / 8;
/* Get the addend from the instruction and apply it. */
switch (howto->bitsize)
{
default:
abort ();
break;
case 16:
addend = bfd_get_16 (abfd, (bfd_byte *) data + reloc_entry->address + 2);
break;
case 32:
addend = bfd_get_32 (abfd, (bfd_byte *) data + reloc_entry->address + 4);
break;
}
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. */
switch (howto->bitsize)
{
default:
abort ();
break;
case 16:
bfd_put_16 (abfd, relocation, (bfd_byte *) data + reloc_entry->address + 2);
break;
case 32:
bfd_put_32 (abfd, relocation, (bfd_byte *) data + reloc_entry->address + 4);
break;
}
/* Check for overflow. */
if (howto->complain_on_overflow == complain_overflow_signed)
{
bfd_signed_vma reloc_signed_max = (1 << (howto->bitsize - 1)) - 1;
bfd_signed_vma reloc_signed_min = ~reloc_signed_max;
if (relocation > reloc_signed_max || relocation < reloc_signed_min)
return bfd_reloc_overflow;
}
else
abort();
return bfd_reloc_ok;
}
/* 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 */
bpf_elf_insn_disp_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 */
bpf_elf_insn_disp_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 indxed 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;
}
/* 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_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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