bfd: add support for eBPF

This patch adds support to BFD for elf64-bpf, in both little-endian
and big-endian variants.

bfd/ChangeLog:

2019-05-23  Jose E. Marchesi  <jose.marchesi@oracle.com>

	* configure.ac: Add bpf_elf64_le_vec and bpf_elf64_be_vec.
	* configure: Regenerated.
	* Makefile.am (ALL_MACHINES): Add cpu-bpf.lo.
	(ALL_MACHINES_CFILES): Add cpu-bpf.c.
	(BFD64_BACKENDS): Add elf64-bpf.lo.
	(BFD64_BACKENDS_CFILES): Add elf64-bpf.c.
	* Makefile.in (SOURCE_HFILES): Regenerate.
	* config.bfd (targ_cpu): Handle bpf-*-* targets.
	* cpu-bpf.c: New file.
	* elf64-bpf.c: Likewise.
	* targets.c (_bfd_target_vector): Add bpf_elf64_be_vec and
	bpf_elf64_le_vec.
	* archures.c: Define architecture bfd_arch_bpf and machine
	bfd_arch_bpf.
	* reloc.c: Define BFD relocations used by the BPF target.
	* bfd-in2.h: Regenerated.
	* libbfd.h: Likewise.

1 files changed, 463 insertions, 0 deletions

diff --git a/bfd/elf64-bpf.c b/bfd/elf64-bpf.c
new file mode 100644
index 0000000..3bfa25b
--- /dev/null
+++ b/bfd/elf64-bpf.c
@@ -0,0 +1,463 @@
+/* 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"