elf: Set p_align to the minimum page size if possible
Currently, on 32-bit and 64-bit ARM, it seems that ld generates p_align
values of 0x10000 even if no section alignment is greater than 0x1000.
The issue is more general and probably affects other targets with multiple
page sizes.
While file layout absolutely must take 64K page size into account, that
does not have to be reflected in the p_align value. If running on a 64K
kernel, the file will be loaded at a 64K page boundary by necessity. On
a 4K kernel, 64K alignment is not needed.
The glibc loader has been fixed to honor p_align:
https://sourceware.org/bugzilla/show_bug.cgi?id=28676
similar to kernel:
commit ce81bb256a224259ab686742a6284930cbe4f1fa
Author: Chris Kennelly <ckennelly@google.com>
Date: Thu Oct 15 20:12:32 2020 -0700
fs/binfmt_elf: use PT_LOAD p_align values for suitable start address
This means that on 4K kernels, we will start to do extra work for 64K
p_align, but this pointless for pretty much all binaries (whose section
alignment rarely exceeds 16).
The minimum page size is used, instead of the maximum section alignment
due to this glibc bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=28688
It has been fixed in glibc 2.35. But linker output must work on existing
glibc binaries.
1. Set p_align to the minimum page size while laying out segments aligning
to the maximum page size or section alignment. The run-time loader can
align segments to the minimum page size or above, depending on system page
size.
2. If -z max-page-size=NNN is used, p_align will be set to the maximum
page size or the largest section alignment.
3. If a section requires alignment higher than the minimum page size,
don't set p_align to the minimum page size.
4. If a section requires alignment higher than the maximum page size,
set p_align to the section alignment.
5. For objcopy, when the minimum page size != the maximum page size,
p_align may be set to the minimum page size while segments are aligned
to the maximum page size. In this case, the input p_align will be
ignored and the maximum page size will be used to align the ouput
segments.
6. Update linker to disallow the common page size > the maximum page size.
7. Update linker to avoid the common page size > the maximum page size.
8. Adjust pru_irq_map-1.d to expect p_align == sh_addralign:
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000 00 0 0 0
[ 1] .text PROGBITS 20000000 00007c 000004 00 AX 0 0 4
...
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000074 0x00000000 0x00000000 0x00008 0x00008 RW 0x1
LOAD 0x00007c 0x20000000 0x20000000 0x00004 0x00004 R E 0x4
vs.
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000 00 0 0 0
[ 1] .text PROGBITS 20000000 00007c 000004 00 AX 0 0 4
...
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000074 0x00000000 0x00000000 0x00008 0x00008 RW 0x1
LOAD 0x00007c 0x20000000 0x20000000 0x00004 0x00004 R E 0x1
To enable this linker optimization, the backend should define ELF_P_ALIGN
to ELF_MINPAGESIZE.
bfd/
PR ld/28689
PR ld/28695
* elf-bfd.h (elf_backend_data): Add p_align.
* elf.c (assign_file_positions_for_load_sections): Set p_align
to the default p_align value while laying out segments aligning
to maximum page size or section alignment.
(elf_is_p_align_valid): New function.
(copy_elf_program_header): Call elf_is_p_align_valid to determine
if p_align is valid.
* elfxx-target.h (ELF_P_ALIGN): New. Default to 0.
(elfNN_bed): Add ELF_P_ALIGN.
* elfxx-x86.h (ELF_P_ALIGN): New. Set to ELF_MINPAGESIZE.
include/
PR ld/28689
PR ld/28695
* bfdlink.h (bfd_link_info): Add maxpagesize_is_set.
ld/
PR ld/28689
PR ld/28695
* emultempl/elf.em (gld${EMULATION_NAME}_handle_option): Set
link_info.maxpagesize_is_set for -z max-page-size=NNN.
* ldelf.c (ldelf_after_parse): Disallow link_info.commonpagesize
> link_info.maxpagesize.
* testsuite/ld-elf/elf.exp: Pass -z max-page-size=0x4000 to
linker to build mbind2a and mbind2b.
* testsuite/ld-elf/header.d: Add -z common-page-size=0x100.
* testsuite/ld-elf/linux-x86.exp: Add PR ld/28689 tests.
* testsuite/ld-elf/p_align-1.c: New file.
* testsuite/ld-elf/page-size-1.d: New test.
* testsuite/ld-elf/pr26936.d: Add -z common-page-size=0x1000.
* testsuite/ld-elf/seg.d: Likewise.
* testsuite/ld-scripts/rgn-at5.d: Likewise.
* testsuite/ld-pru/pru_irq_map-1.d: Append 1 to name. Adjust
expected PT_LOAD segment alignment.
* testsuite/ld-pru/pru_irq_map-2.d: Append 2 to name.
* testsuite/ld-scripts/pr23571.d: Add -z max-page-size=0x1000.
ld: Allow symbols from PROVIDE to be use in MEMORY regions
I wanted to write a linker script like this:
PROVIDE(mem_origin = 0x1000);
PROVIDE(mem_length = 0x1000);
MEMORY
{
REGION : ORIGIN = mem_origin, LENGTH = mem_length
}
....
Then when I link using this script I can optionally supply:
--defsym=mem_origin=..... --defsym=mem_length=....
to override the defaults.
And though passing `--defsym' does work, if I remove the use of
`--defsym' and just rely on the defaults I get an error:
ld-new: invalid origin for memory region REGION
Interestingly, if I make the above error non-fatal and dump a linker
map file I see that (a) REGION has origin 0x0, and length 0xffff...,
and (b) the symbol from the PROVIDE is provided.
An examination of ldlang.c:lang_process shows us what the issue is,
the origin and length of all memory regions are set as a result of a
single call to lang_do_memory_regions, this call is done after calling
open_input_bfds.
During the open_input_bfds call provide statements can be converted to
provided statements if we know that the assigned symbol is needed, but
for symbols that are only used in the memory regions we are unaware
that we need these symbols.
What I propose in this patch is to make two calls to
lang_do_memory_regions, in the first call we process the expressions
for the origin and length fields of each region, however, errors,
especially undefined symbols, will be ignored. The origin and length
values are not updated. However, by evaluating the expressions any
symbols we need will be added to the symbol table.
Now when we call open_input_bfds, when we process the provide
statements, we will see that the assigned symbol is needed add its new
value to the symbol table.
Finally we reach the original call to lang_do_memory_regions, in
this (now second) call we again process the expressions, and this time
update the origin and length values. Any errors encountered now are
reported to the user.
ld/ChangeLog:
* ldlang.c (lang_process): Add extra call to
lang_do_memory_regions, and pass parameter.
(lang_do_memory_regions): Add parameter, only define origin and
length when requested. Reindent.
* testsuite/ld-scripts/provide-10.d: New file.
* testsuite/ld-scripts/provide-10.map: New file.
* testsuite/ld-scripts/provide-11.d: New file.
* testsuite/ld-scripts/provide-11.map: New file.
* testsuite/ld-scripts/provide-12.d: New file.
* testsuite/ld-scripts/provide-12.map: New file.
* testsuite/ld-scripts/provide-9.d: New file.
* testsuite/ld-scripts/provide-9.map: New file.
* testsuite/ld-scripts/provide-9.t: New file.
ld: Allow symbols from PROVIDE to be use in MEMORY regions
I wanted to write a linker script like this:
PROVIDE(mem_origin = 0x1000);
PROVIDE(mem_length = 0x1000);
MEMORY
{
REGION : ORIGIN = mem_origin, LENGTH = mem_length
}
....
Then when I link using this script I can optionally supply:
--defsym=mem_origin=..... --defsym=mem_length=....
to override the defaults.
And though passing `--defsym' does work, if I remove the use of
`--defsym' and just rely on the defaults I get an error:
ld-new: invalid origin for memory region REGION
Interestingly, if I make the above error non-fatal and dump a linker
map file I see that (a) REGION has origin 0x0, and length 0xffff...,
and (b) the symbol from the PROVIDE is provided.
An examination of ldlang.c:lang_process shows us what the issue is,
the origin and length of all memory regions are set as a result of a
single call to lang_do_memory_regions, this call is done after calling
open_input_bfds.
During the open_input_bfds call provide statements can be converted to
provided statements if we know that the assigned symbol is needed, but
for symbols that are only used in the memory regions we are unaware
that we need these symbols.
What I propose in this patch is to make two calls to
lang_do_memory_regions, in the first call we process the expressions
for the origin and length fields of each region, however, errors,
especially undefined symbols, will be ignored. The origin and length
values are not updated. However, by evaluating the expressions any
symbols we need will be added to the symbol table.
Now when we call open_input_bfds, when we process the provide
statements, we will see that the assigned symbol is needed add its new
value to the symbol table.
Finally we reach the original call to lang_do_memory_regions, in
this (now second) call we again process the expressions, and this time
update the origin and length values. Any errors encountered now are
reported to the user.
ld/ChangeLog:
* ldlang.c (lang_process): Add extra call to
lang_do_memory_regions, and pass parameter.
(lang_do_memory_regions): Add parameter, only define origin and
length when requested. Reindent.
* testsuite/ld-scripts/provide-10.d: New file.
* testsuite/ld-scripts/provide-10.map: New file.
* testsuite/ld-scripts/provide-11.d: New file.
* testsuite/ld-scripts/provide-11.map: New file.
* testsuite/ld-scripts/provide-12.d: New file.
* testsuite/ld-scripts/provide-12.map: New file.
* testsuite/ld-scripts/provide-9.d: New file.
* testsuite/ld-scripts/provide-9.map: New file.
* testsuite/ld-scripts/provide-9.t: New file.
ld: Allow symbols from PROVIDE to be use in MEMORY regions
I wanted to write a linker script like this:
PROVIDE(mem_origin = 0x1000);
PROVIDE(mem_length = 0x1000);
MEMORY
{
REGION : ORIGIN = mem_origin, LENGTH = mem_length
}
....
Then when I link using this script I can optionally supply:
--defsym=mem_origin=..... --defsym=mem_length=....
to override the defaults.
And though passing `--defsym' does work, if I remove the use of
`--defsym' and just rely on the defaults I get an error:
ld-new: invalid origin for memory region REGION
Interestingly, if I make the above error non-fatal and dump a linker
map file I see that (a) REGION has origin 0x0, and length 0xffff...,
and (b) the symbol from the PROVIDE is provided.
An examination of ldlang.c:lang_process shows us what the issue is,
the origin and length of all memory regions are set as a result of a
single call to lang_do_memory_regions, this call is done after calling
open_input_bfds.
During the open_input_bfds call provide statements can be converted to
provided statements if we know that the assigned symbol is needed, but
for symbols that are only used in the memory regions we are unaware
that we need these symbols.
What I propose in this patch is to make two calls to
lang_do_memory_regions, in the first call we process the expressions
for the origin and length fields of each region, however, errors,
especially undefined symbols, will be ignored. The origin and length
values are not updated. However, by evaluating the expressions any
symbols we need will be added to the symbol table.
Now when we call open_input_bfds, when we process the provide
statements, we will see that the assigned symbol is needed add its new
value to the symbol table.
Finally we reach the original call to lang_do_memory_regions, in
this (now second) call we again process the expressions, and this time
update the origin and length values. Any errors encountered now are
reported to the user.
ld/ChangeLog:
* ldlang.c (lang_process): Add extra call to
lang_do_memory_regions, and pass parameter.
(lang_do_memory_regions): Add parameter, only define origin and
length when requested. Reindent.
* testsuite/ld-scripts/provide-10.d: New file.
* testsuite/ld-scripts/provide-10.map: New file.
* testsuite/ld-scripts/provide-11.d: New file.
* testsuite/ld-scripts/provide-11.map: New file.
* testsuite/ld-scripts/provide-12.d: New file.
* testsuite/ld-scripts/provide-12.map: New file.
* testsuite/ld-scripts/provide-9.d: New file.
* testsuite/ld-scripts/provide-9.map: New file.
* testsuite/ld-scripts/provide-9.t: New file.
ld: Allow symbols from PROVIDE to be use in MEMORY regions
I wanted to write a linker script like this:
PROVIDE(mem_origin = 0x1000);
PROVIDE(mem_length = 0x1000);
MEMORY
{
REGION : ORIGIN = mem_origin, LENGTH = mem_length
}
....
Then when I link using this script I can optionally supply:
--defsym=mem_origin=..... --defsym=mem_length=....
to override the defaults.
And though passing `--defsym' does work, if I remove the use of
`--defsym' and just rely on the defaults I get an error:
ld-new: invalid origin for memory region REGION
Interestingly, if I make the above error non-fatal and dump a linker
map file I see that (a) REGION has origin 0x0, and length 0xffff...,
and (b) the symbol from the PROVIDE is provided.
An examination of ldlang.c:lang_process shows us what the issue is,
the origin and length of all memory regions are set as a result of a
single call to lang_do_memory_regions, this call is done after calling
open_input_bfds.
During the open_input_bfds call provide statements can be converted to
provided statements if we know that the assigned symbol is needed, but
for symbols that are only used in the memory regions we are unaware
that we need these symbols.
What I propose in this patch is to make two calls to
lang_do_memory_regions, in the first call we process the expressions
for the origin and length fields of each region, however, errors,
especially undefined symbols, will be ignored. The origin and length
values are not updated. However, by evaluating the expressions any
symbols we need will be added to the symbol table.
Now when we call open_input_bfds, when we process the provide
statements, we will see that the assigned symbol is needed add its new
value to the symbol table.
Finally we reach the original call to lang_do_memory_regions, in
this (now second) call we again process the expressions, and this time
update the origin and length values. Any errors encountered now are
reported to the user.
ld/ChangeLog:
* ldlang.c (lang_process): Add extra call to
lang_do_memory_regions, and pass parameter.
(lang_do_memory_regions): Add parameter, only define origin and
length when requested. Reindent.
* testsuite/ld-scripts/provide-10.d: New file.
* testsuite/ld-scripts/provide-10.map: New file.
* testsuite/ld-scripts/provide-11.d: New file.
* testsuite/ld-scripts/provide-11.map: New file.
* testsuite/ld-scripts/provide-12.d: New file.
* testsuite/ld-scripts/provide-12.map: New file.
* testsuite/ld-scripts/provide-9.d: New file.
* testsuite/ld-scripts/provide-9.map: New file.
* testsuite/ld-scripts/provide-9.t: New file.
ld: Allow symbols from PROVIDE to be use in MEMORY regions
I wanted to write a linker script like this:
PROVIDE(mem_origin = 0x1000);
PROVIDE(mem_length = 0x1000);
MEMORY
{
REGION : ORIGIN = mem_origin, LENGTH = mem_length
}
....
Then when I link using this script I can optionally supply:
--defsym=mem_origin=..... --defsym=mem_length=....
to override the defaults.
And though passing `--defsym' does work, if I remove the use of
`--defsym' and just rely on the defaults I get an error:
ld-new: invalid origin for memory region REGION
Interestingly, if I make the above error non-fatal and dump a linker
map file I see that (a) REGION has origin 0x0, and length 0xffff...,
and (b) the symbol from the PROVIDE is provided.
An examination of ldlang.c:lang_process shows us what the issue is,
the origin and length of all memory regions are set as a result of a
single call to lang_do_memory_regions, this call is done after calling
open_input_bfds.
During the open_input_bfds call provide statements can be converted to
provided statements if we know that the assigned symbol is needed, but
for symbols that are only used in the memory regions we are unaware
that we need these symbols.
What I propose in this patch is to make two calls to
lang_do_memory_regions, in the first call we process the expressions
for the origin and length fields of each region, however, errors,
especially undefined symbols, will be ignored. The origin and length
values are not updated. However, by evaluating the expressions any
symbols we need will be added to the symbol table.
Now when we call open_input_bfds, when we process the provide
statements, we will see that the assigned symbol is needed add its new
value to the symbol table.
Finally we reach the original call to lang_do_memory_regions, in
this (now second) call we again process the expressions, and this time
update the origin and length values. Any errors encountered now are
reported to the user.
ld/ChangeLog:
* ldlang.c (lang_process): Add extra call to
lang_do_memory_regions, and pass parameter.
(lang_do_memory_regions): Add parameter, only define origin and
length when requested. Reindent.
* testsuite/ld-scripts/provide-10.d: New file.
* testsuite/ld-scripts/provide-10.map: New file.
* testsuite/ld-scripts/provide-11.d: New file.
* testsuite/ld-scripts/provide-11.map: New file.
* testsuite/ld-scripts/provide-12.d: New file.
* testsuite/ld-scripts/provide-12.map: New file.
* testsuite/ld-scripts/provide-9.d: New file.
* testsuite/ld-scripts/provide-9.map: New file.
* testsuite/ld-scripts/provide-9.t: New file.
ld: Allow symbols from PROVIDE to be use in MEMORY regions
I wanted to write a linker script like this:
PROVIDE(mem_origin = 0x1000);
PROVIDE(mem_length = 0x1000);
MEMORY
{
REGION : ORIGIN = mem_origin, LENGTH = mem_length
}
....
Then when I link using this script I can optionally supply:
--defsym=mem_origin=..... --defsym=mem_length=....
to override the defaults.
And though passing `--defsym' does work, if I remove the use of
`--defsym' and just rely on the defaults I get an error:
ld-new: invalid origin for memory region REGION
Interestingly, if I make the above error non-fatal and dump a linker
map file I see that (a) REGION has origin 0x0, and length 0xffff...,
and (b) the symbol from the PROVIDE is provided.
An examination of ldlang.c:lang_process shows us what the issue is,
the origin and length of all memory regions are set as a result of a
single call to lang_do_memory_regions, this call is done after calling
open_input_bfds.
During the open_input_bfds call provide statements can be converted to
provided statements if we know that the assigned symbol is needed, but
for symbols that are only used in the memory regions we are unaware
that we need these symbols.
What I propose in this patch is to make two calls to
lang_do_memory_regions, in the first call we process the expressions
for the origin and length fields of each region, however, errors,
especially undefined symbols, will be ignored. The origin and length
values are not updated. However, by evaluating the expressions any
symbols we need will be added to the symbol table.
Now when we call open_input_bfds, when we process the provide
statements, we will see that the assigned symbol is needed add its new
value to the symbol table.
Finally we reach the original call to lang_do_memory_regions, in
this (now second) call we again process the expressions, and this time
update the origin and length values. Any errors encountered now are
reported to the user.
ld/ChangeLog:
* ldlang.c (lang_process): Add extra call to
lang_do_memory_regions, and pass parameter.
(lang_do_memory_regions): Add parameter, only define origin and
length when requested. Reindent.
* testsuite/ld-scripts/provide-10.d: New file.
* testsuite/ld-scripts/provide-10.map: New file.
* testsuite/ld-scripts/provide-11.d: New file.
* testsuite/ld-scripts/provide-11.map: New file.
* testsuite/ld-scripts/provide-12.d: New file.
* testsuite/ld-scripts/provide-12.map: New file.
* testsuite/ld-scripts/provide-9.d: New file.
* testsuite/ld-scripts/provide-9.map: New file.
* testsuite/ld-scripts/provide-9.t: New file.
ld: Don't evaluate unneeded PROVIDE expressions.
When creating a linker mapfile (using -Map=MAPFILE), we previously would
always try to evaluate the expression from a PROVIDE statement.
However, this is not always safe, consider:
PROVIDE (foo = 0x10);
PROVIDE (bar = foo);
In this example, if neither 'foo' or 'bar' is needed, then while
generating the linker mapfile evaluating the expression for 'foo' is
harmless (just the value 0x10). However, evaluating the expression for
'bar' requires the symbol 'foo', which is undefined. This used to cause
a fatal error.
This patch changes the behaviour, so that when the destination of the
PROVIDE is not defined (that is the PROVIDE is not going to provide
anything) the expression is not evaluated, and instead a special string
is displayed to indicate that the linker is discarding the PROVIDE
statement.
This change not only fixes the spurious undefined symbol error, but also
means that a user can now tell if a PROVIDE statement has provided
anything by inspecting the linker mapfile, something that could not be
done before.
ld/ChangeLog:
* ldlang.c (print_assignment): Only evaluate the expression for a
PROVIDE'd assignment when the destination is being defined.
Display a special message for PROVIDE'd symbols that are not being
provided.
ld/testsuite/ChangeLog:
* ld-scripts/provide-4.d: New file.
* ld-scripts/provide-4-map.d: New file.
* ld-scripts/provide-4.t: New file.
* ld-scripts/provide-5.d: New file.
* ld-scripts/provide-5.s: New file.
* ld-scripts/provide-5-map.d: New file.
* ld-scripts/provide-5.t: New file.
* ld-scripts/provide.exp: Run the provide-4.d and provide-5.d
tests.
ld: Allow symbols from PROVIDE to be use in MEMORY regions
I wanted to write a linker script like this:
PROVIDE(mem_origin = 0x1000);
PROVIDE(mem_length = 0x1000);
MEMORY
{
REGION : ORIGIN = mem_origin, LENGTH = mem_length
}
....
Then when I link using this script I can optionally supply:
--defsym=mem_origin=..... --defsym=mem_length=....
to override the defaults.
And though passing `--defsym' does work, if I remove the use of
`--defsym' and just rely on the defaults I get an error:
ld-new: invalid origin for memory region REGION
Interestingly, if I make the above error non-fatal and dump a linker
map file I see that (a) REGION has origin 0x0, and length 0xffff...,
and (b) the symbol from the PROVIDE is provided.
An examination of ldlang.c:lang_process shows us what the issue is,
the origin and length of all memory regions are set as a result of a
single call to lang_do_memory_regions, this call is done after calling
open_input_bfds.
During the open_input_bfds call provide statements can be converted to
provided statements if we know that the assigned symbol is needed, but
for symbols that are only used in the memory regions we are unaware
that we need these symbols.
What I propose in this patch is to make two calls to
lang_do_memory_regions, in the first call we process the expressions
for the origin and length fields of each region, however, errors,
especially undefined symbols, will be ignored. The origin and length
values are not updated. However, by evaluating the expressions any
symbols we need will be added to the symbol table.
Now when we call open_input_bfds, when we process the provide
statements, we will see that the assigned symbol is needed add its new
value to the symbol table.
Finally we reach the original call to lang_do_memory_regions, in
this (now second) call we again process the expressions, and this time
update the origin and length values. Any errors encountered now are
reported to the user.
ld/ChangeLog:
* ldlang.c (lang_process): Add extra call to
lang_do_memory_regions, and pass parameter.
(lang_do_memory_regions): Add parameter, only define origin and
length when requested. Reindent.
* testsuite/ld-scripts/provide-10.d: New file.
* testsuite/ld-scripts/provide-10.map: New file.
* testsuite/ld-scripts/provide-11.d: New file.
* testsuite/ld-scripts/provide-11.map: New file.
* testsuite/ld-scripts/provide-12.d: New file.
* testsuite/ld-scripts/provide-12.map: New file.
* testsuite/ld-scripts/provide-9.d: New file.
* testsuite/ld-scripts/provide-9.map: New file.
* testsuite/ld-scripts/provide-9.t: New file.
ld: Allow symbols from PROVIDE to be use in MEMORY regions
I wanted to write a linker script like this:
PROVIDE(mem_origin = 0x1000);
PROVIDE(mem_length = 0x1000);
MEMORY
{
REGION : ORIGIN = mem_origin, LENGTH = mem_length
}
....
Then when I link using this script I can optionally supply:
--defsym=mem_origin=..... --defsym=mem_length=....
to override the defaults.
And though passing `--defsym' does work, if I remove the use of
`--defsym' and just rely on the defaults I get an error:
ld-new: invalid origin for memory region REGION
Interestingly, if I make the above error non-fatal and dump a linker
map file I see that (a) REGION has origin 0x0, and length 0xffff...,
and (b) the symbol from the PROVIDE is provided.
An examination of ldlang.c:lang_process shows us what the issue is,
the origin and length of all memory regions are set as a result of a
single call to lang_do_memory_regions, this call is done after calling
open_input_bfds.
During the open_input_bfds call provide statements can be converted to
provided statements if we know that the assigned symbol is needed, but
for symbols that are only used in the memory regions we are unaware
that we need these symbols.
What I propose in this patch is to make two calls to
lang_do_memory_regions, in the first call we process the expressions
for the origin and length fields of each region, however, errors,
especially undefined symbols, will be ignored. The origin and length
values are not updated. However, by evaluating the expressions any
symbols we need will be added to the symbol table.
Now when we call open_input_bfds, when we process the provide
statements, we will see that the assigned symbol is needed add its new
value to the symbol table.
Finally we reach the original call to lang_do_memory_regions, in
this (now second) call we again process the expressions, and this time
update the origin and length values. Any errors encountered now are
reported to the user.
ld/ChangeLog:
* ldlang.c (lang_process): Add extra call to
lang_do_memory_regions, and pass parameter.
(lang_do_memory_regions): Add parameter, only define origin and
length when requested. Reindent.
* testsuite/ld-scripts/provide-10.d: New file.
* testsuite/ld-scripts/provide-10.map: New file.
* testsuite/ld-scripts/provide-11.d: New file.
* testsuite/ld-scripts/provide-11.map: New file.
* testsuite/ld-scripts/provide-12.d: New file.
* testsuite/ld-scripts/provide-12.map: New file.
* testsuite/ld-scripts/provide-9.d: New file.
* testsuite/ld-scripts/provide-9.map: New file.
* testsuite/ld-scripts/provide-9.t: New file.
elf: Set p_align to the minimum page size if possible
Currently, on 32-bit and 64-bit ARM, it seems that ld generates p_align
values of 0x10000 even if no section alignment is greater than 0x1000.
The issue is more general and probably affects other targets with multiple
page sizes.
While file layout absolutely must take 64K page size into account, that
does not have to be reflected in the p_align value. If running on a 64K
kernel, the file will be loaded at a 64K page boundary by necessity. On
a 4K kernel, 64K alignment is not needed.
The glibc loader has been fixed to honor p_align:
https://sourceware.org/bugzilla/show_bug.cgi?id=28676
similar to kernel:
commit ce81bb256a224259ab686742a6284930cbe4f1fa
Author: Chris Kennelly <ckennelly@google.com>
Date: Thu Oct 15 20:12:32 2020 -0700
fs/binfmt_elf: use PT_LOAD p_align values for suitable start address
This means that on 4K kernels, we will start to do extra work for 64K
p_align, but this pointless for pretty much all binaries (whose section
alignment rarely exceeds 16).
The minimum page size is used, instead of the maximum section alignment
due to this glibc bug:
https://sourceware.org/bugzilla/show_bug.cgi?id=28688
It has been fixed in glibc 2.35. But linker output must work on existing
glibc binaries.
1. Set p_align to the minimum page size while laying out segments aligning
to the maximum page size or section alignment. The run-time loader can
align segments to the minimum page size or above, depending on system page
size.
2. If -z max-page-size=NNN is used, p_align will be set to the maximum
page size or the largest section alignment.
3. If a section requires alignment higher than the minimum page size,
don't set p_align to the minimum page size.
4. If a section requires alignment higher than the maximum page size,
set p_align to the section alignment.
5. For objcopy, when the minimum page size != the maximum page size,
p_align may be set to the minimum page size while segments are aligned
to the maximum page size. In this case, the input p_align will be
ignored and the maximum page size will be used to align the ouput
segments.
6. Update linker to disallow the common page size > the maximum page size.
7. Update linker to avoid the common page size > the maximum page size.
8. Adjust pru_irq_map-1.d to expect p_align == sh_addralign:
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000 00 0 0 0
[ 1] .text PROGBITS 20000000 00007c 000004 00 AX 0 0 4
...
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000074 0x00000000 0x00000000 0x00008 0x00008 RW 0x1
LOAD 0x00007c 0x20000000 0x20000000 0x00004 0x00004 R E 0x4
vs.
Section Headers:
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 0] NULL 00000000 000000 000000 00 0 0 0
[ 1] .text PROGBITS 20000000 00007c 000004 00 AX 0 0 4
...
Program Headers:
Type Offset VirtAddr PhysAddr FileSiz MemSiz Flg Align
LOAD 0x000074 0x00000000 0x00000000 0x00008 0x00008 RW 0x1
LOAD 0x00007c 0x20000000 0x20000000 0x00004 0x00004 R E 0x1
To enable this linker optimization, the backend should define ELF_P_ALIGN
to ELF_MINPAGESIZE.
bfd/
PR ld/28689
PR ld/28695
* elf-bfd.h (elf_backend_data): Add p_align.
* elf.c (assign_file_positions_for_load_sections): Set p_align
to the default p_align value while laying out segments aligning
to maximum page size or section alignment.
(elf_is_p_align_valid): New function.
(copy_elf_program_header): Call elf_is_p_align_valid to determine
if p_align is valid.
* elfxx-target.h (ELF_P_ALIGN): New. Default to 0.
(elfNN_bed): Add ELF_P_ALIGN.
* elfxx-x86.h (ELF_P_ALIGN): New. Set to ELF_MINPAGESIZE.
include/
PR ld/28689
PR ld/28695
* bfdlink.h (bfd_link_info): Add maxpagesize_is_set.
ld/
PR ld/28689
PR ld/28695
* emultempl/elf.em (gld${EMULATION_NAME}_handle_option): Set
link_info.maxpagesize_is_set for -z max-page-size=NNN.
* ldelf.c (ldelf_after_parse): Disallow link_info.commonpagesize
> link_info.maxpagesize.
* testsuite/ld-elf/elf.exp: Pass -z max-page-size=0x4000 to
linker to build mbind2a and mbind2b.
* testsuite/ld-elf/header.d: Add -z common-page-size=0x100.
* testsuite/ld-elf/linux-x86.exp: Add PR ld/28689 tests.
* testsuite/ld-elf/p_align-1.c: New file.
* testsuite/ld-elf/page-size-1.d: New test.
* testsuite/ld-elf/pr26936.d: Add -z common-page-size=0x1000.
* testsuite/ld-elf/seg.d: Likewise.
* testsuite/ld-scripts/rgn-at5.d: Likewise.
* testsuite/ld-pru/pru_irq_map-1.d: Append 1 to name. Adjust
expected PT_LOAD segment alignment.
* testsuite/ld-pru/pru_irq_map-2.d: Append 2 to name.
* testsuite/ld-scripts/pr23571.d: Add -z max-page-size=0x1000.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
* ldlang.c (lang_check_section_addresses): Also report size of
overflow for any overflowed memory regions.
(os_region_check): Diagnose an overflowed region only once per
region. Do not reset region->current on overflow.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
Daniel Jacobowitz <dan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
Joseph Myers <joseph@codesourcery.com>
* ld-scripts/rgn-over.exp: New driver.
* ld-scripts/rgn-over.s: New file.
* ld-scripts/rgn-over1.d, ld-scripts/rgn-over1.t,
ld-scripts/rgn-over2.d, ld-scripts/rgn-over2.t,
ld-scripts/rgn-over3.d, ld-scripts/rgn-over3.t,
ld-scripts/rgn-over4.d, ld-scripts/rgn-over4.t,
ld-scripts/rgn-over5.d, ld-scripts/rgn-over5.t,
ld-scripts/rgn-over6.d, ld-scripts/rgn-over6.t,
ld-scripts/rgn-over7.d, ld-scripts/rgn-over7.t:
New test cases.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
* ldlang.c (lang_check_section_addresses): Also report size of
overflow for any overflowed memory regions.
(os_region_check): Diagnose an overflowed region only once per
region. Do not reset region->current on overflow.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
Daniel Jacobowitz <dan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
Joseph Myers <joseph@codesourcery.com>
* ld-scripts/rgn-over.exp: New driver.
* ld-scripts/rgn-over.s: New file.
* ld-scripts/rgn-over1.d, ld-scripts/rgn-over1.t,
ld-scripts/rgn-over2.d, ld-scripts/rgn-over2.t,
ld-scripts/rgn-over3.d, ld-scripts/rgn-over3.t,
ld-scripts/rgn-over4.d, ld-scripts/rgn-over4.t,
ld-scripts/rgn-over5.d, ld-scripts/rgn-over5.t,
ld-scripts/rgn-over6.d, ld-scripts/rgn-over6.t,
ld-scripts/rgn-over7.d, ld-scripts/rgn-over7.t:
New test cases.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
* ldlang.c (lang_check_section_addresses): Also report size of
overflow for any overflowed memory regions.
(os_region_check): Diagnose an overflowed region only once per
region. Do not reset region->current on overflow.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
Daniel Jacobowitz <dan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
Joseph Myers <joseph@codesourcery.com>
* ld-scripts/rgn-over.exp: New driver.
* ld-scripts/rgn-over.s: New file.
* ld-scripts/rgn-over1.d, ld-scripts/rgn-over1.t,
ld-scripts/rgn-over2.d, ld-scripts/rgn-over2.t,
ld-scripts/rgn-over3.d, ld-scripts/rgn-over3.t,
ld-scripts/rgn-over4.d, ld-scripts/rgn-over4.t,
ld-scripts/rgn-over5.d, ld-scripts/rgn-over5.t,
ld-scripts/rgn-over6.d, ld-scripts/rgn-over6.t,
ld-scripts/rgn-over7.d, ld-scripts/rgn-over7.t:
New test cases.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
* ldlang.c (lang_check_section_addresses): Also report size of
overflow for any overflowed memory regions.
(os_region_check): Diagnose an overflowed region only once per
region. Do not reset region->current on overflow.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
Daniel Jacobowitz <dan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
Joseph Myers <joseph@codesourcery.com>
* ld-scripts/rgn-over.exp: New driver.
* ld-scripts/rgn-over.s: New file.
* ld-scripts/rgn-over1.d, ld-scripts/rgn-over1.t,
ld-scripts/rgn-over2.d, ld-scripts/rgn-over2.t,
ld-scripts/rgn-over3.d, ld-scripts/rgn-over3.t,
ld-scripts/rgn-over4.d, ld-scripts/rgn-over4.t,
ld-scripts/rgn-over5.d, ld-scripts/rgn-over5.t,
ld-scripts/rgn-over6.d, ld-scripts/rgn-over6.t,
ld-scripts/rgn-over7.d, ld-scripts/rgn-over7.t:
New test cases.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
* ldlang.c (lang_check_section_addresses): Also report size of
overflow for any overflowed memory regions.
(os_region_check): Diagnose an overflowed region only once per
region. Do not reset region->current on overflow.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
Daniel Jacobowitz <dan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
Joseph Myers <joseph@codesourcery.com>
* ld-scripts/rgn-over.exp: New driver.
* ld-scripts/rgn-over.s: New file.
* ld-scripts/rgn-over1.d, ld-scripts/rgn-over1.t,
ld-scripts/rgn-over2.d, ld-scripts/rgn-over2.t,
ld-scripts/rgn-over3.d, ld-scripts/rgn-over3.t,
ld-scripts/rgn-over4.d, ld-scripts/rgn-over4.t,
ld-scripts/rgn-over5.d, ld-scripts/rgn-over5.t,
ld-scripts/rgn-over6.d, ld-scripts/rgn-over6.t,
ld-scripts/rgn-over7.d, ld-scripts/rgn-over7.t:
New test cases.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
* ldlang.c (lang_check_section_addresses): Also report size of
overflow for any overflowed memory regions.
(os_region_check): Diagnose an overflowed region only once per
region. Do not reset region->current on overflow.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
Daniel Jacobowitz <dan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
Joseph Myers <joseph@codesourcery.com>
* ld-scripts/rgn-over.exp: New driver.
* ld-scripts/rgn-over.s: New file.
* ld-scripts/rgn-over1.d, ld-scripts/rgn-over1.t,
ld-scripts/rgn-over2.d, ld-scripts/rgn-over2.t,
ld-scripts/rgn-over3.d, ld-scripts/rgn-over3.t,
ld-scripts/rgn-over4.d, ld-scripts/rgn-over4.t,
ld-scripts/rgn-over5.d, ld-scripts/rgn-over5.t,
ld-scripts/rgn-over6.d, ld-scripts/rgn-over6.t,
ld-scripts/rgn-over7.d, ld-scripts/rgn-over7.t:
New test cases.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
* ldlang.c (lang_check_section_addresses): Also report size of
overflow for any overflowed memory regions.
(os_region_check): Diagnose an overflowed region only once per
region. Do not reset region->current on overflow.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
Daniel Jacobowitz <dan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
Joseph Myers <joseph@codesourcery.com>
* ld-scripts/rgn-over.exp: New driver.
* ld-scripts/rgn-over.s: New file.
* ld-scripts/rgn-over1.d, ld-scripts/rgn-over1.t,
ld-scripts/rgn-over2.d, ld-scripts/rgn-over2.t,
ld-scripts/rgn-over3.d, ld-scripts/rgn-over3.t,
ld-scripts/rgn-over4.d, ld-scripts/rgn-over4.t,
ld-scripts/rgn-over5.d, ld-scripts/rgn-over5.t,
ld-scripts/rgn-over6.d, ld-scripts/rgn-over6.t,
ld-scripts/rgn-over7.d, ld-scripts/rgn-over7.t:
New test cases.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
* ldlang.c (lang_check_section_addresses): Also report size of
overflow for any overflowed memory regions.
(os_region_check): Diagnose an overflowed region only once per
region. Do not reset region->current on overflow.
2007-10-17 Zack Weinberg <zack@codesourcery.com>
Daniel Jacobowitz <dan@codesourcery.com>
Mark Shinwell <shinwell@codesourcery.com>
Joseph Myers <joseph@codesourcery.com>
* ld-scripts/rgn-over.exp: New driver.
* ld-scripts/rgn-over.s: New file.
* ld-scripts/rgn-over1.d, ld-scripts/rgn-over1.t,
ld-scripts/rgn-over2.d, ld-scripts/rgn-over2.t,
ld-scripts/rgn-over3.d, ld-scripts/rgn-over3.t,
ld-scripts/rgn-over4.d, ld-scripts/rgn-over4.t,
ld-scripts/rgn-over5.d, ld-scripts/rgn-over5.t,
ld-scripts/rgn-over6.d, ld-scripts/rgn-over6.t,
ld-scripts/rgn-over7.d, ld-scripts/rgn-over7.t:
New test cases.