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https://github.com/RGBCube/serenity
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c87aa6d908
Calling sigprocmask() through the PLT requires setting the ebx register to the address of the global offset table, otherwise chaos ensues. Also the value of the ecx register was assumed to be preserved across that function call despite the fact that it is caller-saved in the x86 calling convention.
82 lines
2 KiB
ArmAsm
82 lines
2 KiB
ArmAsm
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <bits/sighow.h>
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//
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// /!\ Read setjmp.h before modifying this file!
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//
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.Lget_pc:
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mov (%esp), %ebx
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ret
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.global setjmp
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setjmp:
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xor %eax, %eax // Grab val argument (hardcoded to zero)
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jmp .Lsigset_common
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.global sigsetjmp
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sigsetjmp:
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mov 8(%esp), %eax // Grab val argument
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.Lsigset_common:
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mov 4(%esp), %ecx // Grab jmp_buf argument
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mov %eax, 24(%ecx) // Store val into did_save_signal_mask
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movl $0, 28(%ecx) // Clear saved_signal_mask
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test %eax, %eax
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jz .Lsaveregs
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push %ebp // Prepare ABI-compliant call to sigprocmask
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mov %esp, %ebp
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push %ebx
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call .Lget_pc // Grab the GOT pointer
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addl $_GLOBAL_OFFSET_TABLE_, %ebx
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lea 28(%ecx), %eax // Set argument oldset
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push %eax
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push $0 // Set argument set
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push $0 // Set argument how
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call sigprocmask@plt
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add $12, %esp
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pop %ebx
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pop %ebp
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.Lsaveregs:
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mov 4(%esp), %ecx // Grab jmp_buf argument
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mov (%esp), %edx // Grab return address
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mov %ebx, (0 * 4)(%ecx) // Save registers
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mov %esi, (1 * 4)(%ecx)
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mov %edi, (2 * 4)(%ecx)
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mov %ebp, (3 * 4)(%ecx)
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mov %esp, (4 * 4)(%ecx)
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mov %edx, (5 * 4)(%ecx)
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xor %eax, %eax
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ret
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.global longjmp
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longjmp:
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mov 4(%esp), %ecx // Grab jmp_buf argument
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mov 8(%esp), %eax // Grab val argument
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test %eax, %eax
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jnz .Lnonzero
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mov $1, %eax
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.Lnonzero:
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mov (0 * 4)(%ecx), %ebx // Restore registers
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mov (1 * 4)(%ecx), %esi
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mov (2 * 4)(%ecx), %edi
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mov (3 * 4)(%ecx), %ebp
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//
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// Until this point, the stack is still from the caller.
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//
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mov (4 * 4)(%ecx), %esp
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mov (5 * 4)(%ecx), %edx
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mov %edx, (%esp) // Patch return address
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//
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// From this point on, the former stack has been restored.
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//
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ret
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