/* Linux bpf specific support for 64-bit ELF
- Copyright (C) 2019 Free Software Foundation, Inc.
+ Copyright (C) 2019-2020 Free Software Foundation, Inc.
Contributed by Oracle Inc.
This file is part of BFD, the Binary File Descriptor library.
#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;
-}
+static bfd_reloc_status_type bpf_elf_generic_reloc
+ (bfd *, arelent *, asymbol *, void *, asection *, bfd *, char **);
/* Relocation tables. */
static reloc_howto_type bpf_elf_howto_table [] =
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_dont, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_NONE", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
4, /* size (0 = byte, 1 = short, 2 = long) */
64, /* bitsize */
FALSE, /* pc_relative */
- 0, /* bitpos */
+ 32, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_INSN_64", /* name */
- FALSE, /* partial_inplace */
- 0, /* src_mask */
+ TRUE, /* partial_inplace */
+ MINUS_ONE, /* src_mask */
MINUS_ONE, /* dst_mask */
TRUE), /* pcrel_offset */
- /* 32-immediate in LDDW instruction. */
+ /* 32-immediate in many instructions. */
HOWTO (R_BPF_INSN_32, /* type */
0, /* rightshift */
2, /* size (0 = byte, 1 = short, 2 = long) */
32, /* bitsize */
FALSE, /* pc_relative */
- 0, /* bitpos */
+ 32, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_INSN_32", /* name */
- FALSE, /* partial_inplace */
- 0, /* src_mask */
+ TRUE, /* partial_inplace */
+ 0xffffffff, /* src_mask */
0xffffffff, /* dst_mask */
TRUE), /* pcrel_offset */
1, /* size (0 = byte, 1 = short, 2 = long) */
16, /* bitsize */
FALSE, /* pc_relative */
- 0, /* bitpos */
+ 16, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_INSN_16", /* name */
- FALSE, /* partial_inplace */
- 0, /* src_mask */
+ TRUE, /* partial_inplace */
+ 0x0000ffff, /* src_mask */
0x0000ffff, /* dst_mask */
TRUE), /* pcrel_offset */
1, /* size (0 = byte, 1 = short, 2 = long) */
16, /* bitsize */
TRUE, /* pc_relative */
- 32, /* bitpos */
+ 16, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bpf_elf_insn_disp_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_INSN_DISP16", /* name */
- FALSE, /* partial_inplace */
+ TRUE, /* partial_inplace */
0xffff, /* src_mask */
0xffff, /* dst_mask */
TRUE), /* pcrel_offset */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_8_PCREL", /* name */
- FALSE, /* partial_inplace */
- 0, /* src_mask */
+ TRUE, /* partial_inplace */
+ 0xff, /* src_mask */
0xff, /* dst_mask */
TRUE), /* pcrel_offset */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_16_PCREL", /* name */
FALSE, /* partial_inplace */
- 0, /* src_mask */
+ 0xffff, /* src_mask */
0xffff, /* dst_mask */
TRUE), /* pcrel_offset */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_32_PCREL", /* name */
FALSE, /* partial_inplace */
- 0, /* src_mask */
+ 0xffffffff, /* src_mask */
0xffffffff, /* dst_mask */
TRUE), /* pcrel_offset */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_unsigned, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_DATA_8", /* name */
- FALSE, /* partial_inplace */
- 0, /* src_mask */
+ TRUE, /* partial_inplace */
+ 0xff, /* src_mask */
0xff, /* dst_mask */
FALSE), /* pcrel_offset */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_unsigned, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_DATA_16", /* name */
FALSE, /* partial_inplace */
- 0, /* src_mask */
+ 0xffff, /* src_mask */
0xffff, /* dst_mask */
FALSE), /* pcrel_offset */
2, /* size (0 = byte, 1 = short, 2 = long) */
32, /* bitsize */
TRUE, /* pc_relative */
- 0, /* bitpos */
+ 32, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bpf_elf_insn_disp_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_INSN_DISP32", /* name */
- FALSE, /* partial_inplace */
+ TRUE, /* partial_inplace */
0xffffffff, /* src_mask */
0xffffffff, /* dst_mask */
TRUE), /* pcrel_offset */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_bitfield, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_DATA_32", /* name */
FALSE, /* partial_inplace */
- 0, /* src_mask */
+ 0xffffffff, /* src_mask */
0xffffffff, /* dst_mask */
TRUE), /* pcrel_offset */
FALSE, /* pc_relative */
0, /* bitpos */
complain_overflow_bitfield, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_DATA_64", /* name */
FALSE, /* partial_inplace */
0, /* src_mask */
TRUE, /* pc_relative */
0, /* bitpos */
complain_overflow_signed, /* complain_on_overflow */
- bfd_elf_generic_reloc, /* special_function */
+ bpf_elf_generic_reloc, /* special_function */
"R_BPF_64_PCREL", /* name */
FALSE, /* partial_inplace */
- 0, /* src_mask */
+ MINUS_ONE, /* src_mask */
MINUS_ONE, /* dst_mask */
TRUE), /* pcrel_offset */
};
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
+ /* 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)
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;
+ bfd_signed_vma addend;
+ bfd_byte * where;
+
+ 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;
+ where = contents + rel->r_offset;
+
+ 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:
+ {
+ /* Make the relocation PC-relative, and change its unit to
+ 64-bit words. Note we need *signed* arithmetic
+ here. */
+ relocation = ((bfd_signed_vma) relocation
+ - (sec_addr (input_section) + rel->r_offset));
+ relocation = (bfd_signed_vma) 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;
+ }
+ case R_BPF_DATA_8:
+ case R_BPF_DATA_16:
+ case R_BPF_DATA_32:
+ case R_BPF_DATA_64:
+ {
+ addend = bfd_get (howto->bitsize, input_bfd, where);
+ relocation += addend;
+ bfd_put (howto->bitsize, input_bfd, relocation, where);
+
+ r = bfd_reloc_ok;
+ break;
+ }
+ case R_BPF_INSN_16:
+ {
+
+ addend = bfd_get_16 (input_bfd, where + 2);
+ relocation += addend;
+ bfd_put_16 (input_bfd, relocation, where + 2);
+
+ r = bfd_reloc_ok;
+ break;
+ }
+ case R_BPF_INSN_32:
+ {
+ /* Write relocated value */
+
+ addend = bfd_get_32 (input_bfd, where + 4);
+ relocation += addend;
+ bfd_put_32 (input_bfd, relocation, where + 4);
+
+ r = bfd_reloc_ok;
+ break;
+ }
+ case R_BPF_INSN_64:
+ {
+ /*
+ LDDW instructions are 128 bits long, with a 64-bit immediate.
+ The lower 32 bits of the immediate are in the same position
+ as the imm32 field of other instructions.
+ The upper 32 bits of the immediate are stored at the end of
+ the instruction.
+ */
+
+
+ /* Get the addend. The upper and lower 32 bits are split.
+ 'where' is the beginning of the 16-byte instruction. */
+ addend = bfd_get_32 (input_bfd, where + 4);
+ addend |= (bfd_get_32 (input_bfd, where + 12) << 32);
+
+ relocation += addend;
+
+ bfd_put_32 (input_bfd, (relocation & 0xFFFFFFFF), where + 4);
+ bfd_put_32 (input_bfd, (relocation >> 32), where + 12);
+ r = bfd_reloc_ok;
+ break;
+ }
+ default:
+ r = bfd_reloc_notsupported;
+ }
+
+ if (r == bfd_reloc_ok)
+ r = bfd_check_overflow (howto->complain_on_overflow,
+ howto->bitsize,
+ howto->rightshift,
+ 64, relocation);
+
+ 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. */
return TRUE;
}
+/* A generic howto special function for installing BPF relocations.
+ This function will be called by the assembler (via bfd_install_relocation).
+ At link time, bpf_elf_relocate_section will resolve the final relocations.
+
+ BPF instructions are always big endian, and this approach avoids problems in
+ bfd_install_relocation. */
+
+static bfd_reloc_status_type
+bpf_elf_generic_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_reloc_status_type status;
+ bfd_byte *where;
+
+ /* Sanity check that the address is in range. */
+ if (reloc_entry->address > bfd_get_section_limit (abfd, input_section))
+ return bfd_reloc_outofrange;
+
+ /* Get the symbol value. */
+ if (bfd_is_com_section (symbol->section))
+ relocation = 0;
+ else
+ relocation = symbol->value;
+
+ if (symbol->flags & BSF_SECTION_SYM)
+ /* Relocation against a section symbol: add in the section base address. */
+ relocation += BASEADDR (symbol->section);
+
+ relocation += reloc_entry->addend;
+
+ where = (bfd_byte *) data + reloc_entry->address;
+
+ status = bfd_check_overflow (reloc_entry->howto->complain_on_overflow,
+ reloc_entry->howto->bitsize,
+ reloc_entry->howto->rightshift, 64, relocation);
+
+ if (status != bfd_reloc_ok)
+ return status;
+
+ /* Now finally install the relocation. */
+ if (reloc_entry->howto->type == R_BPF_INSN_64)
+ {
+ /* lddw is a 128-bit (!) instruction that allows loading a 64-bit
+ immediate into a register. the immediate is split in half, with the
+ lower 32 bits in the same position as the imm32 field of other
+ instructions, and the upper 32 bits placed at the very end of the
+ instruction. that is, there are 32 unused bits between them. */
+
+ bfd_put_32 (output_bfd, (relocation & 0xFFFFFFFF), where + 4);
+ bfd_put_32 (output_bfd, (relocation >> 32), where + 12);
+ }
+ else
+ {
+ /* For other kinds of relocations, the relocated value simply goes
+ BITPOS bits from the start of the entry. This is always a multiple
+ of 8, i.e. whole bytes. */
+ bfd_put (reloc_entry->howto->bitsize, output_bfd, relocation,
+ where + reloc_entry->howto->bitpos / 8);
+ }
+
+ reloc_entry->addend = relocation;
+ reloc_entry->address += input_section->output_offset;
+
+ return bfd_reloc_ok;
+}
+
+
/* The macros below configure the architecture. */
#define TARGET_LITTLE_SYM bpf_elf64_le_vec
#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
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