Commit Graph

15 Commits

Author SHA1 Message Date
Simon Glass
0b2fa98aa5 linker_lists: Fix alignment issue
The linker script uses alphabetic sorting to group the different linker
lists together. Each group has its own struct and potentially its own
alignment. But when the linker packs the structs together it cannot ensure
that a linker list starts on the expected alignment boundary.

For example, if the first list has a struct size of 8 and we place 3 of
them in the image, that means that the next struct will start at offset
0x18 from the start of the linker_list section. If the next struct has
a size of 16 then it will start at an 8-byte aligned offset, but not a
16-byte aligned offset.

With sandbox on x86_64, a reference to a linker list item using
ll_entry_get() can force alignment of that particular linker_list item,
if it is in the same file as the linker_list item is declared.

Consider this example, where struct driver is 0x80 bytes:

	ll_entry_declare(struct driver, fred, driver)

...

	void *p = ll_entry_get(struct driver, fred, driver)

If these two lines of code are in the same file, then the entry is forced
to be aligned at the 'struct driver' alignment, which is 16 bytes. If the
second line of code is in a different file, then no action is taken, since
the compiler cannot update the alignment of the linker_list item.

In the first case, an 8-byte 'fill' region is added:

 .u_boot_list_2_driver_2_testbus_drv
                0x0000000000270018       0x80 test/built-in.o
                0x0000000000270018                _u_boot_list_2_driver_2_testbus_drv
 .u_boot_list_2_driver_2_testfdt1_drv
                0x0000000000270098       0x80 test/built-in.o
                0x0000000000270098                _u_boot_list_2_driver_2_testfdt1_drv
 *fill*         0x0000000000270118        0x8
 .u_boot_list_2_driver_2_testfdt_drv
                0x0000000000270120       0x80 test/built-in.o
                0x0000000000270120                _u_boot_list_2_driver_2_testfdt_drv
 .u_boot_list_2_driver_2_testprobe_drv
                0x00000000002701a0       0x80 test/built-in.o
                0x00000000002701a0                _u_boot_list_2_driver_2_testprobe_drv

With this, the linker_list no-longer works since items after testfdt1_drv
are not at the expected address.

Ideally we would have a way to tell gcc not to align structs in this way.
It is not clear how we could do this, and in any case it would require us
to adjust every struct used by the linker_list feature.

One possible fix is to force each separate linker_list to start on the
largest possible boundary that can be required by the compiler. However
that does not seem to work on x86_64, which uses 16-byte alignment in this
case but needs 32-byte alignment.

So add a Kconfig option to handle this. Set the default value to 4 so
as to avoid changing platforms that don't need it.

Update the ll_entry_start() accordingly.

Signed-off-by: Simon Glass <sjg@chromium.org>
2020-12-18 20:32:21 -07:00
Mario Six
78a88f7930 doc: Replace DocBook with sphinx-based docs
The Linux kernel moved to sphinx-based documentation and got rid of the
DocBook based documentation quite a while ago. Hence, the DocBook
documentation for U-Boot should be converted as well.

To achieve this, import the necessary files from Linux v4.17, and
convert the current DocBook documentation (three files altogether) to
sphinx/reStructuredText.

For now, all old DocBook documentation was merged into a single
handbook, tentatively named "U-Boot Hacker Manual".

For some source files, the documentation style was changed to comply
with kernel-doc; no functional changes were applied.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
2018-07-23 14:33:21 -04:00
Tom Rini
83d290c56f SPDX: Convert all of our single license tags to Linux Kernel style
When U-Boot started using SPDX tags we were among the early adopters and
there weren't a lot of other examples to borrow from.  So we picked the
area of the file that usually had a full license text and replaced it
with an appropriate SPDX-License-Identifier: entry.  Since then, the
Linux Kernel has adopted SPDX tags and they place it as the very first
line in a file (except where shebangs are used, then it's second line)
and with slightly different comment styles than us.

In part due to community overlap, in part due to better tag visibility
and in part for other minor reasons, switch over to that style.

This commit changes all instances where we have a single declared
license in the tag as both the before and after are identical in tag
contents.  There's also a few places where I found we did not have a tag
and have introduced one.

Signed-off-by: Tom Rini <trini@konsulko.com>
2018-05-07 09:34:12 -04:00
Heinrich Schuchardt
d72fd7b340 linker_lists: remove incorrect comment
Remove a comment line refering to a non-existent file.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
2017-09-07 10:44:37 -04:00
Bin Meng
7e378b8bfc Fix incorrect comments in linker_lists.h
This corrects several typos in the comment block as well as some
indentions and nits in the linker_lists.h.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
2015-07-28 10:36:23 -06:00
Simon Glass
72538f4c3e linker_lists: Add a function to access a linker list entry
Once declared, you cannot access a linker_list entry since you do not have
a symbol name for it. Add llsym() macro to provide this. This avoids
searching for the symbol at run-time based on name.

An example usage is to declare a driver with U_BOOT_DRIVER(), then obtain
a pointer to that driver later.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de>
2015-04-18 11:11:18 -06:00
Guilherme Maciel Ferreira
44f145fd81 linker_lists: fix misspellings
Signed-off-by: Guilherme Maciel Ferreira <guilherme.maciel.ferreira@gmail.com>
2015-01-29 13:38:40 -05:00
Simon Glass
3fcc3af4d2 dm: linker_lists: Add a way to declare multiple objects
The existing ll_entry_declare() permits a single element of the list to
be added to a linker list. Sometimes we want to add several objects at
once. To avoid lots of messy declarations, add a macro to support this.

Signed-off-by: Simon Glass <sjg@chromium.org>
2014-10-22 10:36:53 -06:00
Masahiro Yamada
dc7cb46f97 linker_lists: include <linux/compiler.h>
The header file include/linker_lists.h uses __aligned();
therefore it depends on include/linux/compiler.h

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Acked-by: Simon Glass <sjg@chromium.org>
2014-10-22 10:32:16 -06:00
Masahiro Yamada
97d5e9d149 linker_lists: fix comment
The section name and the C variable name seem to be opposite.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Cc: Marek Vasut <marex@denx.de>
Acked-by: Marek Vasut <marex@denx.de>
2014-09-24 18:30:29 -04:00
Mateusz Zalega
af41d6b4cb common: fixed linker-list example
Last argument shouldn't be there.

Signed-off-by: Mateusz Zalega <m.zalega@samsung.com>
Acked-by: Marek Vasut <marex@denx.de>
Cc: Tom Rini <trini@ti.com>
2014-05-05 10:24:13 +02:00
Masahiro Yamada
babb4440cf kernel-doc: fix some errors
- Delete fs.xml from DOCBOOKS to fix an error.
     Commit e3ff797c added fs.xml to DOCBOOKS
     but missed to add doc/DocBook/fs.tmpl.
  - Fix the location of include guard in include/linker_lists.h.

Signed-off-by: Masahiro Yamada <yamada.m@jp.panasonic.com>
Reported-by: Abraham Varricatt <abraham.varricatt@vvdntech.com>
Acked-by: Simon Glass <sjg@chromium.org>
2014-02-19 11:10:04 -05:00
Wolfgang Denk
1a4596601f Add GPL-2.0+ SPDX-License-Identifier to source files
Signed-off-by: Wolfgang Denk <wd@denx.de>
[trini: Fixup common/cmd_io.c]
Signed-off-by: Tom Rini <trini@ti.com>
2013-07-24 09:44:38 -04:00
Albert ARIBAUD
ef123c5253 Refactor linker-generated arrays
Refactor linker-generated array code so that symbols
which were previously linker-generated are now compiler-
generated. This causes relocation records of type
R_ARM_ABS32 to become R_ARM_RELATIVE, which makes
code which uses LGA able to run before relocation as
well as after.

Note: this affects more than ARM targets, as linker-
lists span possibly all target architectures, notably
PowerPC.

Conflicts:
	arch/arm/cpu/arm926ejs/mxs/u-boot-spl.lds
	arch/arm/cpu/arm926ejs/spear/u-boot-spl.lds
	arch/arm/cpu/armv7/omap-common/u-boot-spl.lds
	board/ait/cam_enc_4xx/u-boot-spl.lds
	board/davinci/da8xxevm/u-boot-spl-da850evm.lds
	board/davinci/da8xxevm/u-boot-spl-hawk.lds
	board/vpac270/u-boot-spl.lds

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
2013-03-12 23:28:40 +01:00
Marek Vasut
42ebaae3a3 common: Implement support for linker-generated arrays
This patch adds support for linker-generated array. These arrays
are a generalization of the U-Boot command declaration approach.

Basically, the idea is to generate an array, where elements of the
array are statically initialized at compile time and each element
is declared separatelly at different place. Such array is assembled
together into continuous piece of memory by linker and a pointer to
it's first entry can then be retrieved via accessor.

The actual implementation relies on placing any variable that is to
represent an element of LG-array into particular subsection of the
.u_boot_list linker section . The subsection is determined by user
options. Once compiled, it is possible to dump all symbols placed
in .u_boot_list section and the subsections in which they should be
and generate appropriate bounds for each requested subsection of the
.u_boot_list section. Each such subsection thus contains __start and
__end entries at the begining and end respecitively.

This allows for simple run-time traversing of the array, since the
symbols are properly defined.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Joe Hershberger <joe.hershberger@gmail.com>
Cc: Mike Frysinger <vapier@gentoo.org>
2012-10-22 08:29:29 -07:00