coreboot-kgpe-d16/payloads/libpayload/arch/arm/head.S

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/*
* This file is part of the libpayload project.
*
* Copyright (C) 2008 Advanced Micro Devices, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <arch/asm.h>
/*
* Our entry point
*/
ENTRY(_entry)
/* TODO: disable interrupts */
/* Clear BSS */
mov r12, #0
ldr r2, bss_boundaries
ldr r3, bss_boundaries + 4
cmp r2, r3
beq no_bss
sub r3, #4 /* Account for late condition check. */
loop:
cmp r2, r3
str r12, [r2], #4
blt loop
no_bss:
libpayload: arm: Pass the coreboot table location to the payload. To find the coreboot tables, the payload has historically searched for their signature in a predefined region of memory. This is a little clumsy on x86, but it works because you can assume certain regions are RAM. Also, there are areas which are set aside for the firmware by convention. On x86 there's a forwarding entry which goes in one of those fairly small conventional areas and which points to the CBMEM area at the end of memory. On ARM there aren't areas like that, so we've left out the forwarding entry and gone directly to CBMEM. RAM may not start at the beginning of the address space or go to its end, and that means there isn't really anywhere fixed you can put the coreboot tables. That's meant that libpayload has to be configured on a per board basis to know where to look for CBMEM. Now that we have boards that don't have fixed amounts of memory, the location of the end of RAM isn't fixed even on a per board level which means even that workaround will no longer cut it. This change makes coreboot pass the location of the coreboot tables to libpayload using r0, the first argument register. That means we'll be able to find them no matter where CBMEM is, and we can get rid of the per board search ranges. We can extend this mechanism to x86 as well, but there may be more complications and it's less necessary there. It would be a good thing to do eventually though. BUG=None TEST=Built and booted on nyan. Changed the size of memory and saw that the payload could still find the coreboot tables where before it couldn't. Built for pit, snow, and big. BRANCH=None Original-Change-Id: I7218afd999da1662b0db8172fd8125670ceac471 Original-Signed-off-by: Gabe Black <gabeblack@google.com> Original-Reviewed-on: https://chromium-review.googlesource.com/185572 Original-Reviewed-by: Julius Werner <jwerner@chromium.org> Original-Commit-Queue: Gabe Black <gabeblack@chromium.org> Original-Tested-by: Gabe Black <gabeblack@chromium.org> (cherry picked from commit ca88f39c21158b59abe3001f986207a292359cf5) Signed-off-by: Marc Jones <marc.jones@se-eng.com> Change-Id: Iab14e9502b6ce7a55f0a72e190fa582f89f11a1e Reviewed-on: http://review.coreboot.org/7655 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Patrick Georgi <pgeorgi@google.com>
2014-02-08 15:30:49 +01:00
/* Save off the location of the coreboot tables */
ldr r1, 1f
str r0, [r1]
/* Setup new stack */
libpayload: arm: Pass the coreboot table location to the payload. To find the coreboot tables, the payload has historically searched for their signature in a predefined region of memory. This is a little clumsy on x86, but it works because you can assume certain regions are RAM. Also, there are areas which are set aside for the firmware by convention. On x86 there's a forwarding entry which goes in one of those fairly small conventional areas and which points to the CBMEM area at the end of memory. On ARM there aren't areas like that, so we've left out the forwarding entry and gone directly to CBMEM. RAM may not start at the beginning of the address space or go to its end, and that means there isn't really anywhere fixed you can put the coreboot tables. That's meant that libpayload has to be configured on a per board basis to know where to look for CBMEM. Now that we have boards that don't have fixed amounts of memory, the location of the end of RAM isn't fixed even on a per board level which means even that workaround will no longer cut it. This change makes coreboot pass the location of the coreboot tables to libpayload using r0, the first argument register. That means we'll be able to find them no matter where CBMEM is, and we can get rid of the per board search ranges. We can extend this mechanism to x86 as well, but there may be more complications and it's less necessary there. It would be a good thing to do eventually though. BUG=None TEST=Built and booted on nyan. Changed the size of memory and saw that the payload could still find the coreboot tables where before it couldn't. Built for pit, snow, and big. BRANCH=None Original-Change-Id: I7218afd999da1662b0db8172fd8125670ceac471 Original-Signed-off-by: Gabe Black <gabeblack@google.com> Original-Reviewed-on: https://chromium-review.googlesource.com/185572 Original-Reviewed-by: Julius Werner <jwerner@chromium.org> Original-Commit-Queue: Gabe Black <gabeblack@chromium.org> Original-Tested-by: Gabe Black <gabeblack@chromium.org> (cherry picked from commit ca88f39c21158b59abe3001f986207a292359cf5) Signed-off-by: Marc Jones <marc.jones@se-eng.com> Change-Id: Iab14e9502b6ce7a55f0a72e190fa582f89f11a1e Reviewed-on: http://review.coreboot.org/7655 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Patrick Georgi <pgeorgi@google.com>
2014-02-08 15:30:49 +01:00
ldr sp, 2f
/* TODO: Save old stack pointer and link register */
/* Let's rock. */
bl start_main
/* %r0 has the return value - pass it on unmolested */
/* TODO: restore old stack pointer and link register */
/* Return to the original context. */
bx lr
ENDPROC(_entry)
.align 4
bss_boundaries:
.word _edata
.word _end
1:
libpayload: arm: Pass the coreboot table location to the payload. To find the coreboot tables, the payload has historically searched for their signature in a predefined region of memory. This is a little clumsy on x86, but it works because you can assume certain regions are RAM. Also, there are areas which are set aside for the firmware by convention. On x86 there's a forwarding entry which goes in one of those fairly small conventional areas and which points to the CBMEM area at the end of memory. On ARM there aren't areas like that, so we've left out the forwarding entry and gone directly to CBMEM. RAM may not start at the beginning of the address space or go to its end, and that means there isn't really anywhere fixed you can put the coreboot tables. That's meant that libpayload has to be configured on a per board basis to know where to look for CBMEM. Now that we have boards that don't have fixed amounts of memory, the location of the end of RAM isn't fixed even on a per board level which means even that workaround will no longer cut it. This change makes coreboot pass the location of the coreboot tables to libpayload using r0, the first argument register. That means we'll be able to find them no matter where CBMEM is, and we can get rid of the per board search ranges. We can extend this mechanism to x86 as well, but there may be more complications and it's less necessary there. It would be a good thing to do eventually though. BUG=None TEST=Built and booted on nyan. Changed the size of memory and saw that the payload could still find the coreboot tables where before it couldn't. Built for pit, snow, and big. BRANCH=None Original-Change-Id: I7218afd999da1662b0db8172fd8125670ceac471 Original-Signed-off-by: Gabe Black <gabeblack@google.com> Original-Reviewed-on: https://chromium-review.googlesource.com/185572 Original-Reviewed-by: Julius Werner <jwerner@chromium.org> Original-Commit-Queue: Gabe Black <gabeblack@chromium.org> Original-Tested-by: Gabe Black <gabeblack@chromium.org> (cherry picked from commit ca88f39c21158b59abe3001f986207a292359cf5) Signed-off-by: Marc Jones <marc.jones@se-eng.com> Change-Id: Iab14e9502b6ce7a55f0a72e190fa582f89f11a1e Reviewed-on: http://review.coreboot.org/7655 Tested-by: build bot (Jenkins) Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net> Reviewed-by: Patrick Georgi <pgeorgi@google.com>
2014-02-08 15:30:49 +01:00
.word cb_header_ptr
2:
.word _stack