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06883ed8a3
The System V ABI for both x86 and x86_64 requires that the stack pointer is 16-byte aligned on entry. Previously we did not align the stack pointer properly. As far as "main" was concerned the stack alignment was correct even without this patch due to how the C++ _start function and the kernel interacted, i.e. the kernel misaligned the stack as far as the ABI was concerned but that misalignment (read: it was properly aligned for a regular function call - but misaligned in terms of what the ABI dictates) was actually expected by our _start function.
28 lines
765 B
ArmAsm
28 lines
765 B
ArmAsm
/*
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* Copyright (c) 2021, Gunnar Beutner <gbeutner@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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.align 4
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.globl _invoke_entry
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.hidden _invoke_entry
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.type _invoke_entry,@function
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_invoke_entry: # (argc, argv, envp, entry)
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addl $4, %esp # return address
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popl %edi # argc
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popl %esi # argv
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popl %edx # envp
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popl %ecx # entry
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// The System V ABI for x86 and x86_64 prescribes that the stack pointer is 16-byte aligned
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andl $~15, %esp
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// We're going to push three arguments so we need to align the stack for that
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subl $4, %esp
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// FIXME: The way we're setting up the stack and passing arguments to the entry point isn't ABI-compliant
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pushl %edx
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pushl %esi
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pushl %edi
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jmp *%ecx
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