mirror of
https://github.com/reactos/reactos.git
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67 lines
1.3 KiB
ArmAsm
67 lines
1.3 KiB
ArmAsm
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/* $Id$
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*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS kernel
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* PURPOSE: Stack checker
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* FILE: lib/ntdll/rtl/i386/chkstk.s
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* PROGRAMER: KJK::Hyperion <noog@libero.it>
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*/
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.globl __chkstk
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.globl __alloca_probe
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/*
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_chkstk() is called by all stack allocations of more than 4 KB. It grows the
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stack in areas of 4 KB each, trying to access each area. This ensures that the
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guard page for the stack is hit, and the stack growing triggered
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*/
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__chkstk:
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__alloca_probe:
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/* EAX = size to be allocated */
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/* save the ECX register */
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pushl %ecx
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/* ECX = top of the previous stack frame */
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leal 8(%esp), %ecx
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/* probe the desired memory, page by page */
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cmpl $0x1000, %eax
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jge .l_MoreThanAPage
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jmp .l_LessThanAPage
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.l_MoreThanAPage:
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/* raise the top of the stack by a page and probe */
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subl $0x1000, %ecx
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testl %eax, 0(%ecx)
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/* loop if still more than a page must be probed */
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subl $0x1000, %eax
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cmpl $0x1000, %eax
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jge .l_MoreThanAPage
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.l_LessThanAPage:
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/* raise the top of the stack by EAX bytes (size % 4096) and probe */
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subl %eax, %ecx
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testl %eax, 0(%ecx)
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/* EAX = top of the stack */
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movl %esp, %eax
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/* allocate the memory */
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movl %ecx, %esp
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/* restore ECX */
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movl 0(%eax), %ecx
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/* restore the return address */
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movl 4(%eax), %eax
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pushl %eax
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/* return */
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ret
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/* EOF */
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