coreboot-kgpe-d16/payloads/libpayload/arch/arm64/head.S
Julius Werner 5c0e72ff99 libpayload: arm64: Make exception handling closer to arm32
This patch reworks the arm64 exception handling to be more similar to
how it works on arm32. This includes a bunch of features like actually
saving and restoring more exception state in the exception_state
structure and supporting the same sort of partial reentrancy that is
useful for GDB. Since there's no instruction to directly load into or
store out of SP on arm64, we can't do quite the same thing where we use
that to read an exception_state_ptr variable right after exception entry
when no other register is available. But we can do something very
similar by (ab-)using the "high" stack pointer (SP_EL2) as a pointer to
the exception_state struct and providing a function to change it.

Change-Id: Ia16a1124be1824392a309ae1f4cb031547d184c1
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/29018
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
2018-10-12 20:17:28 +00:00

55 lines
1.8 KiB
ArmAsm

/*
* 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)
/* Save off the location of the coreboot tables */
ldr x1, 1f
str x0, [x1]
/* Setup new stack */
ldr x1, 2f
mov sp, x1
/* Let's rock. */
bl start_main
ret
ENDPROC(_entry)
.align 4
1:
.quad cb_header_ptr
2:
.quad _stack