121 lines
3.2 KiB
NASM
121 lines
3.2 KiB
NASM
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TITLE "Runtime Stack Checking"
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;++
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;
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; Copyright (c) 2000 Microsoft Corporation
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;
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; Module Name:
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;
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; chkstk.s
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;
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; Abstract:
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;
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; This module implements runtime stack checking.
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;
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; Author:
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;
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; David N. Cutler (davec) 20-Oct-2000
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;
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; Environment:
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;
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; Any mode.
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;
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;--
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include ksamd64.inc
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subttl "Check Stack"
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;++
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;
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; ULONG64
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; __chkstk (
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; VOID
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; )
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;
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; Routine Description:
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;
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; This function provides runtime stack checking for local allocations
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; that are more than a page and for storage dynamically allocated with
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; the alloca function. Stack checking consists of probing downward in
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; the stack a page at a time. If the current stack commitment is exceeded,
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; then the system will automatically attempts to expand the stack. If the
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; attempt succeeds, then another page is committed. Otherwise, a stack
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; overflow exception is raised. It is the responsibility of the caller to
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; handle this exception.
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;
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; N.B. This routine is called using a non-standard calling sequence since
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; it is typically called from within the prologue. The allocation size
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; argument is in register rax and it must be preserved. Registers r10
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; and r11 used by this function and are not preserved.
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;
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; The typical calling sequence from the prologue is:
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;
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; mov rax, allocation-size ; set requested stack frame size
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; call __chkstk ; check stack page allocation
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; sub rsp, rax ; allocate stack frame
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;
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; Arguments:
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;
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; None.
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;
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; Implicit Arguments:
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;
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; Allocation (rax) - Supplies the size of the allocation on the stack.
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;
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; Return Value:
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;
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; The allocation size is returned as the function value.
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;
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;--
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LEAF_ENTRY __chkstk, _TEXT$00
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ifdef NTOS_KERNEL_RUNTIME
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;
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; Kernel components should never allocate more than 512 bytes on the kernel
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; stack.
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;
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if DBG
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cmp rax, 512 ; check if less than 512 bytes
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jbe short cs05 ; if be, less than 512 bytes
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int 3 ; break into debugger
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endif
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cs05: ret ; return
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else
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lea r10, 8[rsp] ; compute requested stack address
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sub r10, rax ;
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;
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; If the new stack address is greater than the current stack limit, then the
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; pages have already been allocated and nothing further needs to be done.
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;
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mov r11, gs:[TeStackLimit] ; get current stack limit
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cmp r10, r11 ; check if stack within limits
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jae short cs20 ; if ae, stack within limits
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;
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; The new stack address is not within the currently allocated stack. Probe
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; pages downward in the stack until all pages have been allocated or a stack
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; overflow occurs in which case an exception will be raised.
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;
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and r10w, not (PAGE_SIZE - 1) ; round down new stack address
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cs10: lea r11, (-PAGE_SIZE)[r11] ; get next lower page address
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mov byte ptr [r11], 0 ; probe stack address
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cmp r10, r11 ; check if end of probe range
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jne short cs10 ; if ne, not end of probe range
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cs20: ret ; return
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endif
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LEAF_END __chkstk, _TEXT$00
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end
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