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ELF linker can produce objects with native ABI

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* module/system/vm/elf.scm: Define more ABI types and ELF object types.
  Export the ABI, object type, and machine type values.

* module/system/vm/linker.scm (<linker-reloc>, process-reloc): Allow
  rel32/1 relocs.
  (add-elf-objects, allocate-elf, link-elf): Allow the user to set an
  ABI, type, and machine-type.
This commit is contained in:
Andy Wingo 2014-02-16 12:18:44 +01:00
parent a104380d53
commit c90c81898e
2 changed files with 48 additions and 10 deletions
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29
module/system/vm/elf.scm
View file

@ -47,6 +47,16 @@
elf-entry elf-phoff elf-shoff elf-flags elf-ehsize
elf-phentsize elf-phnum elf-shentsize elf-shnum elf-shstrndx
ELFOSABI_NONE ELFOSABI_HPUX ELFOSABI_NETBSD ELFOSABI_GNU
ELFOSABI_SOLARIS ELFOSABI_AIX ELFOSABI_IRIX ELFOSABI_FREEBSD
ELFOSABI_TRU64 ELFOSABI_MODESTO ELFOSABI_OPENBSD
ELFOSABI_ARM_AEABI ELFOSABI_ARM ELFOSABI_STANDALONE
ET_NONE ET_REL ET_EXEC ET_DYN ET_CORE
EM_NONE EM_SPARC EM_386 EM_MIPS EM_PPC EM_PPC64 EM_ARM EM_SH
EM_SPARCV9 EM_IA_64 EM_X86_64
elf-header-len elf-header-shoff-offset
write-elf-header
@ -169,9 +179,26 @@
(define EV_CURRENT 1) ; Current version
(define ELFOSABI_NONE 0) ; UNIX System V ABI */
(define ELFOSABI_HPUX 1) ; HP-UX
(define ELFOSABI_NETBSD 2) ; NetBSD.
(define ELFOSABI_GNU 3) ; Object uses GNU ELF extensions.
(define ELFOSABI_SOLARIS 6) ; Sun Solaris.
(define ELFOSABI_AIX 7) ; IBM AIX.
(define ELFOSABI_IRIX 8) ; SGI Irix.
(define ELFOSABI_FREEBSD 9) ; FreeBSD.
(define ELFOSABI_TRU64 10) ; Compaq TRU64 UNIX.
(define ELFOSABI_MODESTO 11) ; Novell Modesto.
(define ELFOSABI_OPENBSD 12) ; OpenBSD.
(define ELFOSABI_ARM_AEABI 64) ; ARM EABI
(define ELFOSABI_ARM 97) ; ARM
(define ELFOSABI_STANDALONE 255) ; Standalone (embedded) application
(define ET_DYN 3) ; Shared object file
(define ET_NONE 0) ; No file type
(define ET_REL 1) ; Relocatable file
(define ET_EXEC 2) ; Executable file
(define ET_DYN 3) ; Shared object file
(define ET_CORE 4) ; Core file
;;
;; Machine types

29
module/system/vm/linker.scm
View file

@ -1,6 +1,6 @@
;;; Guile ELF linker
;; Copyright (C) 2011, 2012, 2013 Free Software Foundation, Inc.
;; Copyright (C) 2011, 2012, 2013, 2014 Free Software Foundation, Inc.
;;;; This library is free software; you can redistribute it and/or
;;;; modify it under the terms of the GNU Lesser General Public
@ -108,13 +108,13 @@
;; to the address.
;;
;; Two types. Abs32/1 and Abs64/1 are absolute offsets in bytes.
;; Rel32/4 is a relative signed offset in 32-bit units. Either can have
;; an arbitrary addend as well.
;; Rel32/1 and Rel32/1 are relative signed offsets, in 8-bit or 32-bit
;; units, respectively. Either can have an arbitrary addend as well.
;;
(define-record-type <linker-reloc>
(make-linker-reloc type loc addend symbol)
linker-reloc?
(type linker-reloc-type) ;; rel32/4, abs32/1, abs64/1
(type linker-reloc-type) ;; rel32/1, rel32/4, abs32/1, abs64/1
(loc linker-reloc-loc)
(addend linker-reloc-addend)
(symbol linker-reloc-symbol))
@ -402,6 +402,11 @@ symbol, as present in @var{symtab}."
(bytevector-s32-set! bv offset
(+ (/ diff 4) (linker-reloc-addend reloc))
endianness)))
((rel32/1)
(let ((diff (- target offset)))
(bytevector-s32-set! bv offset
(+ diff (linker-reloc-addend reloc))
endianness)))
((abs32/1)
(bytevector-u32-set! bv offset target endianness))
((abs64/1)
@ -447,7 +452,7 @@ section index."
(elf-section-index section))))
objects))
(define (add-elf-objects objects endianness word-size)
(define (add-elf-objects objects endianness word-size abi type machine-type)
"Given the list of linker objects supplied by the user, add linker
objects corresponding to parts of the ELF file: the null object, the ELF
header, and the section table.
@ -485,6 +490,7 @@ list of objects, augmented with objects for the special ELF sections."
;;
(define (make-header phnum index shoff-label)
(let* ((header (make-elf #:byte-order endianness #:word-size word-size
#:abi abi #:type type #:machine-type machine-type
#:phoff phoff #:phnum phnum #:phentsize phentsize
#:shoff 0 #:shnum shnum #:shentsize shentsize
#:shstrndx (or (find-shstrndx objects) SHN_UNDEF)))
@ -574,7 +580,8 @@ list of objects, augmented with objects for the special ELF sections."
(values write-segment-header! objects)))
(define (allocate-elf objects page-aligned? endianness word-size)
(define (allocate-elf objects page-aligned? endianness word-size
abi type machine-type)
"Lay out @var{objects} into an ELF image, computing the size of the
file, the positions of the objects, and the global symbol table.
@ -588,7 +595,7 @@ sections default to 8-byte alignment.
Returns three values: the total image size, a list of objects with
relocated headers, and the global symbol table."
(receive (write-segment-header! objects)
(add-elf-objects objects endianness word-size)
(add-elf-objects objects endianness word-size abi type machine-type)
(let lp ((seglists (collate-objects-into-segments objects))
(objects '())
(phidx 0)
@ -646,7 +653,10 @@ section.)"
(define* (link-elf objects #:key
(page-aligned? #t)
(endianness (target-endianness))
(word-size (target-word-size)))
(word-size (target-word-size))
(abi ELFOSABI_STANDALONE)
(type ET_DYN)
(machine-type EM_NONE))
"Create an ELF image from the linker objects, @var{objects}.
If @var{page-aligned?} is true, read-only and writable data are
@ -659,7 +669,8 @@ alignment.
Returns a bytevector."
(check-section-numbers objects)
(receive (size objects symtab)
(allocate-elf objects page-aligned? endianness word-size)
(allocate-elf objects page-aligned? endianness word-size
abi type machine-type)
(let ((bv (make-bytevector size 0)))
(for-each
(lambda (object)