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Separate header PT_LOAD for -z separate-code

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This patch, along with previous patches in the series, supports
putting the ELF file header and program headers in a PT_LOAD without
sections.

Logic governing whether headers a loaded has changed a little:  The
primary reason to include headers is now the presence of
SIZEOF_HEADERS in a linker script.  However, to support scripts that
may have reserved space for headers by hand, we continue to add
headers whenever the first section address is past the end of headers
modulo page size.

include/
	* bfdlink.h (struct bfd_link_info): Add load_phdrs field.
bfd/
	* elf-nacl.c (nacl_modify_segment_map): Cope with header PT_LOAD
	lacking sections.
	* elf.c (_bfd_elf_map_sections_to_segments): Assume file and
	program headers are required when info->load_phdrs.  Reorganize
	code handling program headers.  Generate a mapping without
	sections just for file and program headers when -z separate-code
	would indicate they should be on a different page to the first
	section.
ld/
	* ldexp.c (fold_name <SIZEOF_HEADERS>): Set link_info.load_phdrs.
	* testsuite/ld-elf/loadaddr1.d: Pass -z noseparate-code.
	* testsuite/ld-elf/loadaddr2.d: Likewise.
	* testsuite/ld-i386/vxworks2.sd: Adjust expected output.
	* testsuite/ld-powerpc/vxworks2.sd: Likewise.
	* testsuite/ld-elf/overlay.d: Remove spu xfail.
	* testsuite/ld-spu/ovl.lnk: Don't use SIZEOF_HEADERS.
	* testsuite/ld-tic6x/dsbt-be.ld: Likewise.
	* testsuite/ld-tic6x/dsbt-inrange.ld: Likewise.
	* testsuite/ld-tic6x/dsbt-overflow.ld: Likewise.
	* testsuite/ld-tic6x/dsbt.ld: Likewise.
This commit is contained in:
Alan Modra 2018-10-05 11:40:54 +09:30
parent 7358942661
commit 64029e9368
17 changed files with 151 additions and 93 deletions
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11
bfd/ChangeLog
View File

@ -1,3 +1,14 @@
2018-10-08 Alan Modra <amodra@gmail.com>
* elf-nacl.c (nacl_modify_segment_map): Cope with header PT_LOAD
lacking sections.
* elf.c (_bfd_elf_map_sections_to_segments): Assume file and
program headers are required when info->load_phdrs. Reorganize
code handling program headers. Generate a mapping without
sections just for file and program headers when -z separate-code
would indicate they should be on a different page to the first
section.
2018-10-08 Alan Modra <amodra@gmail.com>
* elf.c (assign_file_positions_for_load_sections): Set p_vaddr

88
bfd/elf-nacl.c
View File

@ -70,8 +70,7 @@ nacl_modify_segment_map (bfd *abfd, struct bfd_link_info *info)
const struct elf_backend_data *const bed = get_elf_backend_data (abfd);
struct elf_segment_map **m = &elf_seg_map (abfd);
struct elf_segment_map **first_load = NULL;
struct elf_segment_map **last_load = NULL;
bfd_boolean moved_headers = FALSE;
struct elf_segment_map **headers = NULL;
int sizeof_headers;
if (info != NULL && info->user_phdrs)
@ -170,56 +169,61 @@ nacl_modify_segment_map (bfd *abfd, struct bfd_link_info *info)
}
/* First, we're just finding the earliest PT_LOAD.
By the normal rules, this will be the lowest-addressed one.
We only have anything interesting to do if it's executable. */
last_load = m;
By the normal rules, this will be the lowest-addressed one. */
if (first_load == NULL)
{
if (!executable)
goto next;
first_load = m;
}
first_load = m;
/* Now that we've noted the first PT_LOAD, we're looking for
the first non-executable PT_LOAD with a nonempty p_filesz. */
else if (!moved_headers
else if (headers == NULL
&& segment_eligible_for_headers (seg, bed->minpagesize,
sizeof_headers))
{
/* This is the one we were looking for!
First, clear the flags on previous segments that
say they include the file header and phdrs. */
struct elf_segment_map *prevseg;
for (prevseg = *first_load;
prevseg != seg;
prevseg = prevseg->next)
if (prevseg->p_type == PT_LOAD)
{
prevseg->includes_filehdr = 0;
prevseg->includes_phdrs = 0;
}
/* This segment will include those headers instead. */
seg->includes_filehdr = 1;
seg->includes_phdrs = 1;
moved_headers = TRUE;
}
headers = m;
}
next:
m = &seg->next;
}
if (first_load != last_load && moved_headers)
if (headers != NULL)
{
/* Now swap the first and last PT_LOAD segments'
positions in segment_map. */
struct elf_segment_map *first = *first_load;
struct elf_segment_map *last = *last_load;
*first_load = first->next;
first->next = last->next;
last->next = first;
struct elf_segment_map **last_load = NULL;
struct elf_segment_map *seg;
m = first_load;
while ((seg = *m) != NULL)
{
if (seg->p_type == PT_LOAD)
{
/* Clear the flags on any previous segment that
included the file header and phdrs. */
seg->includes_filehdr = 0;
seg->includes_phdrs = 0;
/* Also strip out empty segments. */
if (seg->count == 0)
{
if (headers == &seg->next)
headers = m;
*m = seg->next;
continue;
}
last_load = m;
}
m = &seg->next;
}
/* This segment will include those headers instead. */
seg = *headers;
seg->includes_filehdr = 1;
seg->includes_phdrs = 1;
if (last_load != NULL && first_load != last_load && first_load != headers)
{
/* Put the first PT_LOAD header last. */
struct elf_segment_map *first = *first_load;
struct elf_segment_map *last = *last_load;
*first_load = first->next;
first->next = last->next;
last->next = first;
}
}
return TRUE;

99
bfd/elf.c
View File

@ -4597,7 +4597,7 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
unsigned int hdr_index;
bfd_vma maxpagesize;
asection **hdrpp;
bfd_boolean phdr_in_segment = TRUE;
bfd_boolean phdr_in_segment;
bfd_boolean writable;
bfd_boolean executable;
int tls_count = 0;
@ -4606,7 +4606,7 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
asection *dynsec, *eh_frame_hdr;
bfd_size_type amt;
bfd_vma addr_mask, wrap_to = 0;
bfd_boolean linker_created_pt_phdr_segment = FALSE;
bfd_size_type phdr_size;
/* Select the allocated sections, and sort them. */
@ -4638,8 +4638,23 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
qsort (sections, (size_t) count, sizeof (asection *), elf_sort_sections);
/* Build the mapping. */
phdr_size = elf_program_header_size (abfd);
if (phdr_size == (bfd_size_type) -1)
phdr_size = get_program_header_size (abfd, info);
phdr_size += bed->s->sizeof_ehdr;
maxpagesize = bed->maxpagesize;
if (maxpagesize == 0)
maxpagesize = 1;
phdr_in_segment = info != NULL && info->load_phdrs;
if (count != 0
&& (((sections[0]->lma & addr_mask) & (maxpagesize - 1))
>= (phdr_size & (maxpagesize - 1))))
/* For compatibility with old scripts that may not be using
SIZEOF_HEADERS, add headers when it looks like space has
been left for them. */
phdr_in_segment = TRUE;
/* Build the mapping. */
mfirst = NULL;
pm = &mfirst;
@ -4658,7 +4673,7 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
m->p_flags = PF_R;
m->p_flags_valid = 1;
m->includes_phdrs = 1;
linker_created_pt_phdr_segment = TRUE;
phdr_in_segment = TRUE;
*pm = m;
pm = &m->next;
@ -4681,12 +4696,6 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
last_hdr = NULL;
last_size = 0;
hdr_index = 0;
maxpagesize = bed->maxpagesize;
/* PR 17512: file: c8455299.
Avoid divide-by-zero errors later on.
FIXME: Should we abort if the maxpagesize is zero ? */
if (maxpagesize == 0)
maxpagesize = 1;
writable = FALSE;
executable = FALSE;
dynsec = bfd_get_section_by_name (abfd, ".dynamic");
@ -4694,34 +4703,62 @@ _bfd_elf_map_sections_to_segments (bfd *abfd, struct bfd_link_info *info)
&& (dynsec->flags & SEC_LOAD) == 0)
dynsec = NULL;
if ((abfd->flags & D_PAGED) == 0)
phdr_in_segment = FALSE;
/* Deal with -Ttext or something similar such that the first section
is not adjacent to the program headers. This is an
approximation, since at this point we don't know exactly how many
program headers we will need. */
if (count > 0)
if (phdr_in_segment && count > 0)
{
bfd_size_type phdr_size = elf_program_header_size (abfd);
bfd_vma phdr_lma;
bfd_boolean separate_phdr = FALSE;
if (phdr_size == (bfd_size_type) -1)
phdr_size = get_program_header_size (abfd, info);
phdr_size += bed->s->sizeof_ehdr;
if ((abfd->flags & D_PAGED) == 0
|| (sections[0]->lma & addr_mask) < phdr_size
|| ((sections[0]->lma & addr_mask) % maxpagesize
< phdr_size % maxpagesize)
|| (sections[0]->lma & addr_mask & -maxpagesize) < wrap_to)
phdr_lma = (sections[0]->lma - phdr_size) & addr_mask & -maxpagesize;
if (info != NULL
&& info->separate_code
&& (sections[0]->flags & SEC_CODE) != 0)
{
/* PR 20815: The ELF standard says that a PT_PHDR segment, if
present, must be included as part of the memory image of the
program. Ie it must be part of a PT_LOAD segment as well.
If we have had to create our own PT_PHDR segment, but it is
not going to be covered by the first PT_LOAD segment, then
force the inclusion if we can... */
if ((abfd->flags & D_PAGED) != 0
&& linker_created_pt_phdr_segment)
phdr_in_segment = TRUE;
else
phdr_in_segment = FALSE;
/* If data sections should be separate from code and
thus not executable, and the first section is
executable then put the file and program headers in
their own PT_LOAD. */
separate_phdr = TRUE;
if ((((phdr_lma + phdr_size - 1) & addr_mask & -maxpagesize)
== (sections[0]->lma & addr_mask & -maxpagesize)))
{
/* The file and program headers are currently on the
same page as the first section. Put them on the
previous page if we can. */
if (phdr_lma >= maxpagesize)
phdr_lma -= maxpagesize;
else
separate_phdr = FALSE;
}
}
if ((sections[0]->lma & addr_mask) < phdr_lma
|| (sections[0]->lma & addr_mask) < phdr_size)
/* If file and program headers would be placed at the end
of memory then it's probably better to omit them. */
phdr_in_segment = FALSE;
else if (phdr_lma < wrap_to)
/* If a section wraps around to where we'll be placing
file and program headers, then the headers will be
overwritten. */
phdr_in_segment = FALSE;
else if (separate_phdr)
{
m = make_mapping (abfd, sections, 0, 0, phdr_in_segment);
if (m == NULL)
goto error_return;
m->p_paddr = phdr_lma;
m->p_vaddr_offset
= (sections[0]->vma - phdr_size) & addr_mask & -maxpagesize;
m->p_paddr_valid = 1;
*pm = m;
pm = &m->next;
phdr_in_segment = FALSE;
}
}

4
include/ChangeLog
View File

@ -1,3 +1,7 @@
2018-10-08 Alan Modra <amodra@gmail.com>
* bfdlink.h (struct bfd_link_info): Add load_phdrs field.
2018-10-05 Sudakshina Das <sudi.das@arm.com>
* opcode/arm.h (ARM_EXT2_PREDRES): New.

3
include/bfdlink.h
View File

@ -475,6 +475,9 @@ struct bfd_link_info
/* TRUE if the linker script contained an explicit PHDRS command. */
unsigned int user_phdrs: 1;
/* TRUE if program headers ought to be loaded. */
unsigned int load_phdrs: 1;
/* TRUE if we should check relocations after all input files have
been opened. */
unsigned int check_relocs_after_open_input: 1;

14
ld/ChangeLog
View File

@ -1,3 +1,17 @@
2018-10-08 Alan Modra <amodra@gmail.com>
* ldexp.c (fold_name <SIZEOF_HEADERS>): Set link_info.load_phdrs.
* testsuite/ld-elf/loadaddr1.d: Pass -z noseparate-code.
* testsuite/ld-elf/loadaddr2.d: Likewise.
* testsuite/ld-i386/vxworks2.sd: Adjust expected output.
* testsuite/ld-powerpc/vxworks2.sd: Likewise.
* testsuite/ld-elf/overlay.d: Remove spu xfail.
* testsuite/ld-spu/ovl.lnk: Don't use SIZEOF_HEADERS.
* testsuite/ld-tic6x/dsbt-be.ld: Likewise.
* testsuite/ld-tic6x/dsbt-inrange.ld: Likewise.
* testsuite/ld-tic6x/dsbt-overflow.ld: Likewise.
* testsuite/ld-tic6x/dsbt.ld: Likewise.
2018-10-08 Alan Modra <amodra@gmail.com>
* ldlang.c (insert_os_after): Clear ignore_first on assignment to

1
ld/ldexp.c
View File

@ -692,6 +692,7 @@ fold_name (etree_type *tree)
switch (tree->type.node_code)
{
case SIZEOF_HEADERS:
link_info.load_phdrs = 1;
if (expld.phase != lang_first_phase_enum)
{
bfd_vma hdr_size = 0;

2
ld/testsuite/ld-elf/loadaddr1.d
View File

@ -1,5 +1,5 @@
#source: loadaddr.s
#ld: -T loadaddr1.t -T loadaddr.t -z max-page-size=0x200000
#ld: -T loadaddr1.t -T loadaddr.t -z max-page-size=0x200000 -z noseparate-code
#readelf: -l --wide
#target: *-*-linux* *-*-gnu* arm*-*-uclinuxfdpiceabi

2
ld/testsuite/ld-elf/loadaddr2.d
View File

@ -1,5 +1,5 @@
#source: loadaddr.s
#ld: -T loadaddr2.t -T loadaddr.t -z max-page-size=0x200000
#ld: -T loadaddr2.t -T loadaddr.t -z max-page-size=0x200000 -z noseparate-code
#readelf: -l --wide
#target: *-*-linux* *-*-gnu* arm*-*-uclinuxfdpiceabi

2
ld/testsuite/ld-elf/overlay.d
View File

@ -1,7 +1,5 @@
# ld: -T overlay.t -u __load_start_text1 -u __load_start_text2 -u __load_stop_text1 -u __load_stop_text2
#readelf: -s
#xfail: spu-*-*
# The SPU adds its own LOAD segments, out of order, at the start of the program header table.
#...
[ ]+[0-9]+:[ ]+0*4000[ ]+0[ ]+NOTYPE[ ]+GLOBAL[ ]+DEFAULT[ ]+ABS __load_start_text1

7
ld/testsuite/ld-i386/vxworks2.sd
View File

@ -2,12 +2,7 @@
Elf file type is EXEC \(Executable file\)
Entry point 0x80400
#...
Program Headers:
Type .*
PHDR .*
#...
LOAD .* 0x0007f000 0x0007f000 .* R E 0x1000
LOAD .* 0x00080000 0x00080000 .* R E 0x1000
LOAD .* 0x00081000 0x00081000 .* RW 0x1000
DYNAMIC .*
#...

5
ld/testsuite/ld-powerpc/vxworks2.sd
View File

@ -1,13 +1,8 @@
#...
Elf file type is EXEC \(Executable file\)
Entry point 0x80400
#...
Program Headers:
Type .*
PHDR .*
#...
LOAD .* 0x00070000 0x00070000 .* R E 0x10000
LOAD .* 0x00090000 0x00090000 .* RW 0x10000
DYNAMIC .*
#...

2
ld/testsuite/ld-spu/ovl.lnk
View File

@ -1,6 +1,6 @@
SECTIONS
{
. = SIZEOF_HEADERS;
. = 0x100;
.text : { *(.text) *(.stub) }
.data : { *(.data) *(.ovtab) }
.bss : { *(.bss) }

1
ld/testsuite/ld-tic6x/dsbt-be.ld
View File

@ -3,7 +3,6 @@ OUTPUT_FORMAT("elf32-tic6x-be", "elf32-tic6x-be",
EXTERN (__c6xabi_DSBT_BASE);
SECTIONS
{
PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x0)); . = SEGMENT_START("text-segment", 0x0) + SIZEOF_HEADERS;
. = 0x8000;
.hash : { *(.hash) }
.gnu.hash : { *(.gnu.hash) }

1
ld/testsuite/ld-tic6x/dsbt-inrange.ld
View File

@ -1,7 +1,6 @@
EXTERN (__c6xabi_DSBT_BASE);
SECTIONS
{
PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x0)); . = SEGMENT_START("text-segment", 0x0) + SIZEOF_HEADERS;
. = 0x8000;
.hash : { *(.hash) }
.gnu.hash : { *(.gnu.hash) }

1
ld/testsuite/ld-tic6x/dsbt-overflow.ld
View File

@ -1,7 +1,6 @@
EXTERN (__c6xabi_DSBT_BASE);
SECTIONS
{
PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x0)); . = SEGMENT_START("text-segment", 0x0) + SIZEOF_HEADERS;
. = 0x8000;
.hash : { *(.hash) }
.gnu.hash : { *(.gnu.hash) }

1
ld/testsuite/ld-tic6x/dsbt.ld
View File

@ -3,7 +3,6 @@ OUTPUT_FORMAT("elf32-tic6x-le", "elf32-tic6x-le",
EXTERN (__c6xabi_DSBT_BASE);
SECTIONS
{
PROVIDE (__executable_start = SEGMENT_START("text-segment", 0x0)); . = SEGMENT_START("text-segment", 0x0) + SIZEOF_HEADERS;
. = 0x8000;
.hash : { *(.hash) }
.gnu.hash : { *(.gnu.hash) }