svn commit: r338478 - in head: contrib/elftoolchain/elfcopy contrib/elftoolchain/libelf sys/sys
John Baldwin
jhb at FreeBSD.org
Wed Sep 5 20:51:56 UTC 2018
Author: jhb
Date: Wed Sep 5 20:51:53 2018
New Revision: 338478
URL: https://svnweb.freebsd.org/changeset/base/338478
Log:
Fix objcopy for little-endian MIPS64 objects.
MIPS64 does not store the 'r_info' field of a relocation table entry as
a 64-bit value consisting of a 32-bit symbol index in the high 32 bits
and a 32-bit type in the low 32 bits as on other architectures. Instead,
the 64-bit 'r_info' field is really a 32-bit symbol index followed by four
individual byte type fields. For big-endian MIPS64, treating this as a
64-bit integer happens to be compatible with the layout expected by other
architectures (symbol index in upper 32-bits of resulting "native" 64-bit
integer). However, for little-endian MIPS64 the parsed 64-bit integer
contains the symbol index in the low 32 bits and the 4 individual byte
type fields in the upper 32-bits (but as if the upper 32-bits were
byte-swapped).
To cope, add two helper routines in gelf_getrel.c to translate between the
correct native 'r_info' value and the value obtained after the normal
byte-swap translation. Use these routines in gelf_getrel(), gelf_getrela(),
gelf_update_rel(), and gelf_update_rela(). This fixes 'readelf -r' on
little-endian MIPS64 objects which was previously decoding incorrect
relocations as well as 'objcopy: invalid symbox index' warnings from
objcopy when extracting debug symbols from kernel modules.
Even with this fixed, objcopy was still crashing when trying to extract
debug symbols from little-endian MIPS64 modules. The workaround in
gelf_*rel*() depends on the current ELF object having a valid ELF header
so that the 'e_machine' field can be compared against EM_MIPS. objcopy
was parsing the relocation entries to possibly rewrite the 'r_info' fields
in the update_relocs() function before writing the initial ELF header to
the destination object file. Move the initial write of the ELF header
earlier before copy_contents() so that update_relocs() uses the correct
symbol index values.
Note that this change should really go upstream. The binutils readelf
source has a similar hack for MIPS64EL though I implemented this version
from scratch using the MIPS64 ABI PDF as a reference.
Discussed with: jkoshy
Reviewed by: emaste, imp
Approved by: re (gjb, kib)
MFC after: 1 month
Differential Revision: https://reviews.freebsd.org/D15734
Added:
head/contrib/elftoolchain/libelf/gelf_mips64el.c (contents, props changed)
Modified:
head/contrib/elftoolchain/elfcopy/main.c
head/contrib/elftoolchain/libelf/Makefile
head/contrib/elftoolchain/libelf/_libelf.h
head/contrib/elftoolchain/libelf/gelf_rel.c
head/contrib/elftoolchain/libelf/gelf_rela.c
head/sys/sys/param.h
Modified: head/contrib/elftoolchain/elfcopy/main.c
==============================================================================
--- head/contrib/elftoolchain/elfcopy/main.c Wed Sep 5 20:47:51 2018 (r338477)
+++ head/contrib/elftoolchain/elfcopy/main.c Wed Sep 5 20:51:53 2018 (r338478)
@@ -372,6 +372,14 @@ create_elf(struct elfcopy *ecp)
create_symtab(ecp);
/*
+ * Write the underlying ehdr. Note that it should be called
+ * before elf_setshstrndx() since it will overwrite e->e_shstrndx.
+ */
+ if (gelf_update_ehdr(ecp->eout, &oeh) == 0)
+ errx(EXIT_FAILURE, "gelf_update_ehdr() failed: %s",
+ elf_errmsg(-1));
+
+ /*
* First processing of output sections: at this stage we copy the
* content of each section from input to output object. Section
* content will be modified and printed (mcs) if need. Also content of
@@ -379,14 +387,6 @@ create_elf(struct elfcopy *ecp)
* to symbol table changes.
*/
copy_content(ecp);
-
- /*
- * Write the underlying ehdr. Note that it should be called
- * before elf_setshstrndx() since it will overwrite e->e_shstrndx.
- */
- if (gelf_update_ehdr(ecp->eout, &oeh) == 0)
- errx(EXIT_FAILURE, "gelf_update_ehdr() failed: %s",
- elf_errmsg(-1));
/* Generate section name string table (.shstrtab). */
set_shstrtab(ecp);
Modified: head/contrib/elftoolchain/libelf/Makefile
==============================================================================
--- head/contrib/elftoolchain/libelf/Makefile Wed Sep 5 20:47:51 2018 (r338477)
+++ head/contrib/elftoolchain/libelf/Makefile Wed Sep 5 20:51:53 2018 (r338478)
@@ -35,6 +35,7 @@ SRCS= elf.c \
gelf_ehdr.c \
gelf_getclass.c \
gelf_fsize.c \
+ gelf_mips64el.c \
gelf_move.c \
gelf_phdr.c \
gelf_rel.c \
Modified: head/contrib/elftoolchain/libelf/_libelf.h
==============================================================================
--- head/contrib/elftoolchain/libelf/_libelf.h Wed Sep 5 20:47:51 2018 (r338477)
+++ head/contrib/elftoolchain/libelf/_libelf.h Wed Sep 5 20:51:53 2018 (r338478)
@@ -216,12 +216,15 @@ int (*_libelf_get_translator(Elf_Type _t, int _directi
void *_libelf_getphdr(Elf *_e, int _elfclass);
void *_libelf_getshdr(Elf_Scn *_scn, int _elfclass);
void _libelf_init_elf(Elf *_e, Elf_Kind _kind);
+int _libelf_is_mips64el(Elf *e);
int _libelf_load_section_headers(Elf *e, void *ehdr);
unsigned int _libelf_malign(Elf_Type _t, int _elfclass);
Elf *_libelf_memory(unsigned char *_image, size_t _sz, int _reporterror);
size_t _libelf_msize(Elf_Type _t, int _elfclass, unsigned int _version);
void *_libelf_newphdr(Elf *_e, int _elfclass, size_t _count);
Elf *_libelf_open_object(int _fd, Elf_Cmd _c, int _reporterror);
+Elf64_Xword _libelf_mips64el_r_info_tof(Elf64_Xword r_info);
+Elf64_Xword _libelf_mips64el_r_info_tom(Elf64_Xword r_info);
struct _Libelf_Data *_libelf_release_data(struct _Libelf_Data *_d);
Elf *_libelf_release_elf(Elf *_e);
Elf_Scn *_libelf_release_scn(Elf_Scn *_s);
Added: head/contrib/elftoolchain/libelf/gelf_mips64el.c
==============================================================================
--- /dev/null 00:00:00 1970 (empty, because file is newly added)
+++ head/contrib/elftoolchain/libelf/gelf_mips64el.c Wed Sep 5 20:51:53 2018 (r338478)
@@ -0,0 +1,81 @@
+/*-
+ * Copyright (c) 2018 John Baldwin
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <gelf.h>
+
+#include "_libelf.h"
+
+ELFTC_VCSID("$Id$");
+
+int
+_libelf_is_mips64el(Elf *e)
+{
+
+ return (e->e_kind == ELF_K_ELF && e->e_byteorder == ELFDATA2LSB &&
+ e->e_u.e_elf.e_ehdr.e_ehdr64->e_machine == EM_MIPS);
+}
+
+/*
+ * For MIPS64, the r_info field is actually stored as a 32-bit symbol
+ * index (r_sym) followed by four single-byte fields (r_ssym, r_type3,
+ * r_type2, and r_type). The byte-swap for the little-endian case
+ * jumbles this incorrectly so compensate.
+ */
+Elf64_Xword
+_libelf_mips64el_r_info_tof(Elf64_Xword r_info)
+{
+ Elf64_Xword new_info;
+ uint8_t ssym, type3, type2, type;
+
+ ssym = r_info >> 24;
+ type3 = r_info >> 16;
+ type2 = r_info >> 8;
+ type = r_info;
+ new_info = r_info >> 32;
+ new_info |= (Elf64_Xword)ssym << 32;
+ new_info |= (Elf64_Xword)type3 << 40;
+ new_info |= (Elf64_Xword)type2 << 48;
+ new_info |= (Elf64_Xword)type << 56;
+ return (new_info);
+}
+
+Elf64_Xword
+_libelf_mips64el_r_info_tom(Elf64_Xword r_info)
+{
+ Elf64_Xword new_info;
+ uint8_t ssym, type3, type2, type;
+
+ ssym = r_info >> 32;
+ type3 = r_info >> 40;
+ type2 = r_info >> 48;
+ type = r_info >> 56;
+ new_info = (r_info & 0xffffffff) << 32;
+ new_info |= (Elf64_Xword)ssym << 24;
+ new_info |= (Elf64_Xword)type3 << 16;
+ new_info |= (Elf64_Xword)type2 << 8;
+ new_info |= (Elf64_Xword)type;
+ return (new_info);
+}
Modified: head/contrib/elftoolchain/libelf/gelf_rel.c
==============================================================================
--- head/contrib/elftoolchain/libelf/gelf_rel.c Wed Sep 5 20:47:51 2018 (r338477)
+++ head/contrib/elftoolchain/libelf/gelf_rel.c Wed Sep 5 20:51:53 2018 (r338478)
@@ -90,6 +90,9 @@ gelf_getrel(Elf_Data *ed, int ndx, GElf_Rel *dst)
rel64 = (Elf64_Rel *) d->d_data.d_buf + ndx;
*dst = *rel64;
+
+ if (_libelf_is_mips64el(e))
+ dst->r_info = _libelf_mips64el_r_info_tom(rel64->r_info);
}
return (dst);
@@ -156,6 +159,9 @@ gelf_update_rel(Elf_Data *ed, int ndx, GElf_Rel *dr)
rel64 = (Elf64_Rel *) d->d_data.d_buf + ndx;
*rel64 = *dr;
+
+ if (_libelf_is_mips64el(e))
+ rel64->r_info = _libelf_mips64el_r_info_tof(dr->r_info);
}
return (1);
Modified: head/contrib/elftoolchain/libelf/gelf_rela.c
==============================================================================
--- head/contrib/elftoolchain/libelf/gelf_rela.c Wed Sep 5 20:47:51 2018 (r338477)
+++ head/contrib/elftoolchain/libelf/gelf_rela.c Wed Sep 5 20:51:53 2018 (r338478)
@@ -91,6 +91,10 @@ gelf_getrela(Elf_Data *ed, int ndx, GElf_Rela *dst)
rela64 = (Elf64_Rela *) d->d_data.d_buf + ndx;
*dst = *rela64;
+
+ if (_libelf_is_mips64el(e))
+ dst->r_info =
+ _libelf_mips64el_r_info_tom(rela64->r_info);
}
return (dst);
@@ -159,6 +163,9 @@ gelf_update_rela(Elf_Data *ed, int ndx, GElf_Rela *dr)
rela64 = (Elf64_Rela *) d->d_data.d_buf + ndx;
*rela64 = *dr;
+
+ if (_libelf_is_mips64el(e))
+ rela64->r_info = _libelf_mips64el_r_info_tof(dr->r_info);
}
return (1);
Modified: head/sys/sys/param.h
==============================================================================
--- head/sys/sys/param.h Wed Sep 5 20:47:51 2018 (r338477)
+++ head/sys/sys/param.h Wed Sep 5 20:51:53 2018 (r338478)
@@ -60,7 +60,7 @@
* in the range 5 to 9.
*/
#undef __FreeBSD_version
-#define __FreeBSD_version 1200083 /* Master, propagated to newvers */
+#define __FreeBSD_version 1200084 /* Master, propagated to newvers */
/*
* __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,
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