57dc93c967
Simplify the code by directly using the arguments on the stack as base pointer relative memory references, instead of loading them into intermediate registers first. Make it more robust by preserving all callee saved registers mandated by the C calling convention (and only those), namely EBP, EBX, ESI and EDI. Don't assume anything about the register state when the called function returns -- beside the segment registers and the stack pointer to be still the same as before the call. Change-Id: I383d6ccefc5b3d5cca37a1c9b638c231bbc48aa8 Signed-off-by: Mathias Krause <minipli@googlemail.com> Reviewed-on: https://review.coreboot.org/18335 Reviewed-by: Aaron Durbin <adurbin@chromium.org> Tested-by: build bot (Jenkins)
84 lines
2.6 KiB
ArmAsm
84 lines
2.6 KiB
ArmAsm
/*
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* This file is part of the libpayload project.
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*
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* Copyright (C) 2008 Advanced Micro Devices, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/* calling syntax: i386_do_exec(long addr, int argc, char **argv, int *ret) */
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/* This implements the payload API detailed here:
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* http://www.coreboot.org/Payload_API
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*/
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.align 4
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.text
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.global i386_do_exec
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.type i386_do_exec,@function
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i386_do_exec:
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pushl %ebp
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movl %esp, %ebp
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/* Save the remaining callee preserved registers */
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pushl %ebx
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pushl %esi
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pushl %edi
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/* Push argc and argv on to the stack.
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*
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* We need to put a dummy value inbetween, as argc should be at offset
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* 0x10, according to the payload API.
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*/
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pushl 12(%ebp)
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pushl $0
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pushl 16(%ebp)
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/* Push a "magic" number on the stack - the other payload will use this
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* as a clue that the argc and argv values on the stack are sane.
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*/
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pushl $0x12345678
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/* Jump to the code */
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call *8(%ebp)
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/* %eax has the return value */
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/* Skip over the argc/argv stuff still on the stack.
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* Don't assume %ebp is sane, here. Restore it from the stack.
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*/
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addl $0x10, %esp
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/* Restore the saved registers */
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popl %edi
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popl %esi
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popl %ebx
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popl %ebp
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/* Get pointer to return value and save the return value in it. */
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movl 16(%esp), %ecx
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movl %eax, (%ecx)
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ret
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