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Merge branch 'elf_reloc'

Browse Source 
Conflicts:
	arch/arm/include/asm/config.h
	board/LaCie/edminiv2/config.mk
	board/karo/tx25/config.mk
	board/logicpd/imx27lite/config.mk
	doc/README.arm-relocation

Signed-off-by: Wolfgang Denk <wd@denx.de>
This commit is contained in:
Wolfgang Denk
2010-10-19 21:07:52 +02:00
parent 083d506937 bafe7437a4
commit 6d8d4ef994
18 changed files with 378 additions and 424 deletions
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222
doc/README.arm-relocation
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@@ -1,49 +1,54 @@
To make relocation on arm working, the following changes are done:
Add new compilerflag:
At arch level: add linker flag -pie
-fPIC
This causes the linker to generate fixup tables .rel.dyn and .dynsym,
which must be applied to the relocated image before transferring
control to it.
-> compiler generates position independent code
These fixups are described in the ARM ELF documentation as type 23
(program-base-relative) and 2 (symbol-relative)
changes in board code:
At cpu level: modify linker file and add a relocation and fixup loop
- dram_init:
- bd pointer is now at this point not accessible, so only
detect the real dramsize, and store it in gd->ram_size.
best detected with get_ram_size();
ToDo: move there also the dram initialization on boards where
it is possible.
- setup the bd_t dram bank info in the new function
dram_init_banksize().
the linker file must be modified to include the .rel.dyn and .dynsym
tables in the binary image, and to provide symbols for the relocation
code to access these tables
- board.c code is adapted from ppc code
The relocation and fixup loop must be executed after executing
board_init_f at initial location and before executing board_init_r
at final location.
- undef CONFIG_RELOC_FIXUP_WORKS
At board level:
-> cmdtabl, and subcommand table must be handled from "hand"
collected in section "__datarellocal_start".
dram_init(): bd pointer is now at this point not accessible, so only
detect the real dramsize, and store it in gd->ram_size. Bst detected
with get_ram_size().
- How To fixup the sections:
TODO: move also dram initialization there on boards where it is possible.
__datarel_start, __datarelrolocal_start, __datarellocal_start and
__datarelro_start
Setup of the the bd_t dram bank info is done in the new function
dram_init_banksize() called after bd is accessible.
automatically? Then it should be possible to define again
CONFIG_RELOC_FIXUP_WORKS
At lib level:
- irq stack setup is now not longer on a fix position, instead it is
calculated in board_init_f, and stored in gd->irq_sp
Board.c code is adapted from ppc code
-------------------------------------------------------------------------------------
At config level:
To compile a board without relocation, define CONFIG_SYS_ARM_WITHOUT_RELOC
This possibility will removed!! So please fix your board to compile without
CONFIG_SYS_ARM_WITHOUT_RELOC defined!!!
Define CONFIG_RELOC_FIXUP_WORKS.
Undefine CONFIG_SYS_ARM_WITHOUT_RELOC
-------------------------------------------------------------------------------------
* WARNING ** WARNING ** WARNING ** WARNING ** WARNING ** WARNING ** WARNING *
For boards which boot from nand_spl, it is possible to save a copy
Boards which are not fixed to support relocation will be REMOVED!
Eventually, CONFIG_SYS_ARM_WITHOUT_RELOC and CONFIG_RELOC_FIXUP_WORKS will
disappear and boards which have to migrated to relocation will disappear too.
-----------------------------------------------------------------------------
For boards which boot from nand_spl, it is possible to save one copy
if CONFIG_SYS_TEXT_BASE == relocation address! This prevents that uboot code
is copied again in relocate_code().
@@ -64,9 +69,9 @@ f) u-boot code steps through board_init_f() and calculates
If CONFIG_SYS_TEXT_BASE == relocation address, the copying of u-boot
in f) could be saved.
-------------------------------------------------------------------------------------
-----------------------------------------------------------------------------
ToDo:
TODO
- fill in bd_t infos (check)
- adapt all boards
@@ -80,7 +85,7 @@ ToDo:
- new function dram_init_banksize() is actual board specific. Maybe
we make a weak default function in arch/arm/lib/board.c ?
-------------------------------------------------------------------------------------
-----------------------------------------------------------------------------
Relocation with NAND_SPL (example for the tx25):
@@ -98,158 +103,11 @@ Relocation with NAND_SPL (example for the tx25):
from the nand_spl code), no need to copy, just go on with bss clear
and jump to board_init_r.
-------------------------------------------------------------------------------------
-----------------------------------------------------------------------------
Relocation:
How to translate flash addresses in GOT to ram addresses.
This is automagically done from code, but this example
shows, how this magic code works ;-)
(example on the qong board)
How ELF relocations 23 and 2 work.
Find a variable:
a) search it in System.map
(for example flash_info)
a005b4c0 B BootpID
a005b4c4 B BootpTry
a005b4c8 b slave
a005b4cc B flash_info
^^^^^^^^
a005c908 b saved_sector.4002
a005c910 b cfi_mtd_info
a005c9c0 b cfi_mtd_names
a005c9d0 B mtd_table
---------------------------------------
b) create hexdump from u-boot code:
hexdump -C u-boot > gnlmpfhex
---------------------------------------
c) search the variables address in the hexdump
*
0005fc80 00 00 00 00 00 00 00 00 2c 06 01 a0 18 cd 05 a0 |........,.......|
0005fc90 9c d4 05 a0 bc b4 05 a0 1c 7f 05 a0 f0 05 01 a0 |................|
0005fca0 08 5a 04 a0 1c ab 05 a0 ec a4 05 a0 98 c3 01 a0 |.Z..............|
0005fcb0 a0 d6 05 a0 04 71 05 a0 c0 f9 00 a0 3c cd 05 a0 |.....q......<...|
0005fcc0 cc b4 05 a0 f0 fa 00 a0 f0 d6 05 a0 10 86 05 a0 |................|
^^^^^^^^^^^
0005fcd0 a4 16 06 a0 dc 64 05 a0 18 86 05 a0 52 48 05 a0 |.....d......RH..|
0005fce0 c0 86 05 a0 24 6e 02 a0 b4 6c 05 a0 b0 94 01 a0 |....$n...l......|
0005fcf0 1c 86 05 a0 50 85 05 a0 d4 0c 06 a0 bc 0b 06 a0 |....P...........|
-> 0005fcc0
----------------------------------------
d) know we calculate this address in RAM
8ff08000 (new address of code in RAM *1)
+ 0005fcc0
- 00008000 (offset of text *2)
----------
8ff5fcc0 -> Addr GOT in RAM
*1:
activate debug and look for the line:
Now running in RAM - U-Boot at: 8ff08000
^^^^^^^^
new address of u-boot code in RAM
*2:
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 a0000000 008000 04599c 00 AX 0 0 32
^^^^^^
Offset of text
----------------------------------------
e) now we look in 8ff5fcc0 (RAM)
QongEVB>md 0x8ff5fcc0
8ff5fcc0 : a005b4cc a000faf0 a005d6f0 a0058610 ................
^^^^^^^^
Bingo, here we have the old flash address (when relocation
is working, here is the fixed ram address. see @ f, how
it gets calculated)
----------------------------------------
f) now translate it in the new RAM address
a005b4cc
- a0000000 TextBase
+ 8ff08000 new address of u-boot in ram
----------
8ff634cc
QongEVB>mm 0x8ff5fcc0 0x8ff634cc 1
QongEVB>md 0x8ff5fcc0
8ff5fcc0 : 8ff634cc a000faf0 a005d6f0 a0058610 .4..............
8ff5fcd0 : a00616a4 a00564dc a0058618 a0054852 .....d......RH..
As this must be done for all address in the GOT, the u-boot
code did this automagically ... :-)
----------------------------------------------
g) check if the new address is really in the bss section:
bss start:
8ff6054c (8ff08000 + 0005854C monitorlen)
bss end:
8ff698ac (8ff08000 + 618AC)
8ff634cc is in bss :-)
----------------------------------------------
h) u-boot prints:
important addresses:
U-Boot code: A0000000 -> A005854C BSS: -> A00618AC TextBase 0xa0000000
Now running in RAM - U-Boot at: 8ff08000 relocBase 0x8ff08000
---------
U-Boot 2010.06-rc2-00002-gf8fbb25-dirty (Jun 18 2010 - 17:07:19)
U-Boot code: A0000000 -> A005854C BSS: -> A00618AC
CPU: Freescale i.MX31 at 398 MHz
Board: DAVE/DENX Qong
mon: FFFFFFFF gd->monLen: 000618AC
Top of RAM usable for U-Boot at: 90000000
LCD panel info: 640 x 480, 16 bit/pix
Reserving 600k for LCD Framebuffer at: 8ff6a000
Reserving 390k for U-Boot at: 8ff08000
Reserving 1280k for malloc() at: 8fdc8000
Reserving 28 Bytes for Board Info at: 8fdc7fe4
Reserving 48 Bytes for Global Data at: 8fdc7fb4
New Stack Pointer is: 8fdc7fb0
RAM Configuration:
Bank #0: 80000000 256 MiB
mon: 0005854C gd->monLen: 000618AC
Now running in RAM - U-Boot at: 8ff08000
TBC
-------------------------------------------------------------------------------------