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Update objcopy's --section-alignment option so that it sets the alignment flag on PE sections. Add a check for aligned sections not matching their VMAs.

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This commit is contained in:
Nick Clifton
2024-04-02 15:08:07 +01:00
parent b35013e29f
commit 121a3f4b4f
5 changed files with 182 additions and 20 deletions
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27
binutils/doc/binutils.texi
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@@ -1737,6 +1737,10 @@ above. If @var{sectionpattern} does not match any sections in the
input file, a warning will be issued, unless
@option{--no-change-warnings} is used.
Note - changing the VMA of sections in a fully linked binary can be
dangerous since there may be code that expects the sections to be
located at their old address.
@item --change-warnings
@itemx --adjust-warnings
If @option{--change-section-address} or @option{--change-section-lma} or
@@ -1768,6 +1772,13 @@ Set the alignment for any sections matching @var{sectionpattern}.
@var{align} specifies the alignment in bytes and must be a power of
two, i.e. 1, 2, 4, 8@dots{}.
Note - setting a section's alignment will not automatically align its
LMA or VMA addresses. If those need to be changed as well then the
@option{--change-section-lma} and/or @option{--change-section-vma}
options should be used. Also note that changing VMAs can cause
problems in fully linked binaries where there may be code that expects
the contents of the sections to be located at their old address.
@item --add-section @var{sectionname}=@var{filename}
Add a new section named @var{sectionname} while copying the file. The
contents of the new section are taken from the file @var{filename}. The
@@ -2129,11 +2140,21 @@ for dlls.
[This option is specific to PE targets.]
@item --section-alignment @var{num}
Sets the section alignment field in the PE header. Sections in memory
will always begin at addresses which are a multiple of this number.
Defaults to 0x1000.
[This option is specific to PE targets.]
Sets the section alignment field in the PE header - if one is present
in the binary. Sections in memory will always begin at addresses
which are a multiple of this number. Defaults to 0x1000.
Note - this option will also set the alignment field in each section's
flags.
Note - if a section's LMA or VMA addresses are no longer aligned, and
those addresses have not been set via the @option{--set-section-lma} or
@option{--set-section-vma} options, and the file has been fully
relocated then a warning message will be issued. It will then be up
to the user to decide if the LMA and VMA need updating.
@item --stack @var{reserve}
@itemx --stack @var{reserve},@var{commit}
Specify the number of bytes of memory to reserve (and optionally commit)

110
binutils/objcopy.c
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@@ -4100,6 +4100,50 @@ setup_bfd_headers (bfd *ibfd, bfd *obfd)
return;
}
static inline signed int
power_of_two (bfd_vma val)
{
signed int result = 0;
if (val == 0)
return 0;
while ((val & 1) == 0)
{
val >>= 1;
++result;
}
if (val != 1)
/* Number has more than one 1, i.e. wasn't a power of 2. */
return -1;
return result;
}
static unsigned int
image_scn_align (unsigned int alignment)
{
switch (alignment)
{
case 8192: return IMAGE_SCN_ALIGN_8192BYTES;
case 4096: return IMAGE_SCN_ALIGN_4096BYTES;
case 2048: return IMAGE_SCN_ALIGN_2048BYTES;
case 1024: return IMAGE_SCN_ALIGN_1024BYTES;
case 512: return IMAGE_SCN_ALIGN_512BYTES;
case 256: return IMAGE_SCN_ALIGN_256BYTES;
case 128: return IMAGE_SCN_ALIGN_128BYTES;
case 64: return IMAGE_SCN_ALIGN_64BYTES;
case 32: return IMAGE_SCN_ALIGN_32BYTES;
case 16: return IMAGE_SCN_ALIGN_16BYTES;
case 8: return IMAGE_SCN_ALIGN_8BYTES;
case 4: return IMAGE_SCN_ALIGN_4BYTES;
case 2: return IMAGE_SCN_ALIGN_2BYTES;
case 1: return IMAGE_SCN_ALIGN_1BYTES;
default: return 0;
}
}
/* Create a section in OBFD with the same
name and attributes as ISECTION in IBFD. */
@@ -4224,6 +4268,8 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
if (!bfd_set_section_size (osection, size))
err = _("failed to set size");
bool vma_set_by_user = false;
vma = bfd_section_vma (isection);
p = find_section_list (bfd_section_name (isection), false,
SECTION_CONTEXT_ALTER_VMA | SECTION_CONTEXT_SET_VMA);
@@ -4233,6 +4279,7 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
vma = p->vma_val;
else
vma += p->vma_val;
vma_set_by_user = true;
}
else
vma += change_section_address;
@@ -4240,6 +4287,8 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
if (!bfd_set_section_vma (osection, vma))
err = _("failed to set vma");
bool lma_set_by_user = false;
lma = isection->lma;
p = find_section_list (bfd_section_name (isection), false,
SECTION_CONTEXT_ALTER_LMA | SECTION_CONTEXT_SET_LMA);
@@ -4249,6 +4298,7 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
lma += p->lma_val;
else
lma = p->lma_val;
lma_set_by_user = true;
}
else
lma += change_section_address;
@@ -4259,6 +4309,24 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
SECTION_CONTEXT_SET_ALIGNMENT);
if (p != NULL)
alignment = p->alignment;
else if (pe_section_alignment != (bfd_vma) -1
&& bfd_get_flavour (obfd) == bfd_target_coff_flavour)
{
alignment = power_of_two (pe_section_alignment);
if (coff_section_data (ibfd, isection))
{
struct pei_section_tdata * pei_data = pei_section_data (ibfd, isection);
if (pei_data != NULL)
{
/* Set the alignment flag of the input section, which will
be copied to the output section later on. */
pei_data->pe_flags &= ~IMAGE_SCN_ALIGN_POWER_BIT_MASK;
pei_data->pe_flags |= image_scn_align (pe_section_alignment);
}
}
}
else
alignment = bfd_section_alignment (isection);
@@ -4267,6 +4335,32 @@ setup_section (bfd *ibfd, sec_ptr isection, void *obfdarg)
if (!bfd_set_section_alignment (osection, alignment))
err = _("failed to set alignment");
/* If the output section's VMA is not aligned
and the alignment has changed
and the VMA was not set by the user
and the section does not have relocations associated with it
then warn the user. */
if (osection->vma & ((1 << alignment) - 1)
&& alignment != bfd_section_alignment (isection)
&& change_section_address == 0
&& ! vma_set_by_user
&& bfd_get_reloc_upper_bound (ibfd, isection) < 1)
{
non_fatal (_("output section %s's alignment does not match its VMA"), name);
}
/* Similar check for a non-aligned LMA.
FIXME: Since this is only an LMA, maybe it does not matter if
it is not aligned ? */
if (osection->lma & ((1 << alignment) - 1)
&& alignment != bfd_section_alignment (isection)
&& change_section_address == 0
&& ! lma_set_by_user
&& bfd_get_reloc_upper_bound (ibfd, isection) < 1)
{
non_fatal (_("output section %s's alignment does not match its LMA"), name);
}
/* Copy merge entity size. */
osection->entsize = isection->entsize;
@@ -5713,15 +5807,8 @@ copy_main (int argc, char *argv[])
fatal (_("bad format for --set-section-alignment: numeric argument needed"));
/* Convert integer alignment into a power-of-two alignment. */
palign = 0;
while ((align & 1) == 0)
{
align >>= 1;
++palign;
}
if (align != 1)
/* Number has more than on 1, i.e. wasn't a power of 2. */
palign = power_of_two (align);
if (palign == -1)
fatal (_("bad format for --set-section-alignment: alignment is not a power of two"));
/* Add the alignment setting to the section list. */
@@ -5938,6 +6025,11 @@ copy_main (int argc, char *argv[])
case OPTION_PE_SECTION_ALIGNMENT:
pe_section_alignment = parse_vma (optarg,
"--section-alignment");
if (power_of_two (pe_section_alignment) == -1)
{
non_fatal (_("--section-alignment argument is not a power of two: %s - ignoring"), optarg);
pe_section_alignment = (bfd_vma) -1;
}
break;
case OPTION_SUBSYSTEM:

47
binutils/od-pe.c
View File

@@ -591,7 +591,44 @@ dump_pe_file_header (bfd * abfd,
printf (_("\n Optional header not present\n"));
}
/* Dump the sections header. */
static void
dump_alignment (unsigned int flags)
{
flags &= IMAGE_SCN_ALIGN_POWER_BIT_MASK;
if (flags == IMAGE_SCN_ALIGN_8192BYTES)
printf (_("Align: 8192 "));
else if (flags == IMAGE_SCN_ALIGN_4096BYTES)
printf (_("Align: 4096 "));
else if (flags == IMAGE_SCN_ALIGN_2048BYTES)
printf (_("Align: 2048 "));
else if (flags == IMAGE_SCN_ALIGN_1024BYTES)
printf (_("Align: 1024 "));
else if (flags == IMAGE_SCN_ALIGN_512BYTES)
printf (_("Align: 512 "));
else if (flags == IMAGE_SCN_ALIGN_256BYTES)
printf (_("Align: 256 "));
else if (flags == IMAGE_SCN_ALIGN_128BYTES)
printf (_("Align: 128 "));
else if (flags == IMAGE_SCN_ALIGN_64BYTES)
printf (_("Align: 64 "));
else if (flags == IMAGE_SCN_ALIGN_32BYTES)
printf (_("Align: 32 "));
else if (flags == IMAGE_SCN_ALIGN_16BYTES)
printf (_("Align: 16 "));
else if (flags == IMAGE_SCN_ALIGN_8BYTES)
printf (_("Align: 8 "));
else if (flags == IMAGE_SCN_ALIGN_4BYTES)
printf (_("Align: 4 "));
else if (flags == IMAGE_SCN_ALIGN_2BYTES)
printf (_("Align: 2 "));
else if (flags == IMAGE_SCN_ALIGN_1BYTES)
printf (_("Align: 1 "));
else
printf (_("Align: *unknown* "));
}
/* Dump the section's header. */
static void
dump_pe_sections_header (bfd * abfd,
@@ -656,13 +693,15 @@ dump_pe_sections_header (bfd * abfd,
else
printf (_("\n Flags: %08x: "), flags);
if (flags != 0)
if (flags & IMAGE_SCN_ALIGN_POWER_BIT_MASK)
{
/* Skip the alignment bits. */
dump_alignment (flags);
flags &= ~ IMAGE_SCN_ALIGN_POWER_BIT_MASK;
dump_flags (section_flag_xlat, flags);
}
if (flags != 0)
dump_flags (section_flag_xlat, flags);
putchar ('\n');
}
}

1
binutils/testsuite/binutils-all/objcopy.exp
View File

@@ -1463,6 +1463,7 @@ if [is_elf_format] {
run_dump_test "pr23633"
run_dump_test "set-section-alignment"
run_dump_test "section-alignment"
setup_xfail "hppa*-*-*"
setup_xfail "spu-*-*"

9
binutils/testsuite/binutils-all/section-alignment.d Normal file
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@@ -0,0 +1,9 @@
#source: pr23633.s
#PROG: objcopy
#objcopy: --section-alignment=512
#objdump: -P sections
#target: [is_pecoff_format]
#...
.* Align: 512.*
#pass