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* Copyright (C) 2005 Karl Vogel, Giridhar Pemmasani
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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#include <linux/linkage.h>
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# Windows <---> Linux register usage conversion when calling functions
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# NV = Non Volatile (needs to be saved)
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# ---------------------------------------
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# Rax Return V Return V
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# In addition, Linux uses %rax to indicate number of SSE registers used
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# when variadic functions are called. Since there is no way to obtain this
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# from Windows, for now, we just assume this is 0 (hence %rax is cleared).
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# Windows pushes arguments 5 and higher onto stack in case of integer
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# variables and 4 and higher in case of floating point variabes (passed
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In a windows function, the stackframe/registers look like this:
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# 0x0020 shadow/spill space for arg4
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# 0x0018 shadow/spill space for arg3
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# 0x0010 shadow/spill space for arg2
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# 0x0008 shadow/spill space for arg1
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# register spill space is same irrespective of number of arguments - even
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# if Windows function takes less than 4 arguments, 32 bytes above return
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# address is reserved for the function
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In Linux it should look like:
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# setup for Windows to Linux function call
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# when Windows function calls Linux function, the function address is in %r10
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xor %rax, %rax # rax indicates number of SSE regs
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# before prolog, 0(%rsp) is return address, 8(%rsp) would be arg1
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# (but it is in register) and so on, so n'th arg would be at n*8(%rsp)
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# for n > 4. But in prolog, we push 2 registers that are non-volaile in
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# Windows, but volatile in Linux. So after prolog, args are at (n+2)*8(%rsp)
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#define win2lin_win_arg(n) (n+2)*8(%rsp)
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#define win2lin_arg1 mov %rcx, %rdi
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#define win2lin_arg2 mov %rdx, %rsi
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#define win2lin_arg3 mov %r8, %rdx
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#define win2lin_arg4 mov %r9, %rcx
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#define win2lin_arg5 mov win2lin_win_arg(5), %r8
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#define win2lin_arg6 mov win2lin_win_arg(6), %r9
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.type win2lin0, @function
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.size win2lin0, .-win2lin0
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.type win2lin1, @function
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.size win2lin1, .-win2lin1
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.type win2lin2, @function
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.size win2lin2, .-win2lin2
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.type win2lin3, @function
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.size win2lin3, .-win2lin3
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.type win2lin4, @function
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.size win2lin4, .-win2lin4
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.type win2lin5, @function
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.size win2lin5, .-win2lin5
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.type win2lin6, @function
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.size win2lin6, .-win2lin6
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# Allocate stack frame for Linux arguments before calling function.
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# First 6 args are passed through registers, so we need space for 7 and above.
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# The arguments should have been copied onto stack already.
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.macro call_lin_func_args n
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# m is index of Linux arg required, n is total number of args to function
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# After stack frame is allocated, Linux arg 7 should be at 0(%rsp),
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# arg 8 should be at 1*8(%rsp) and so on. So Linux arg m should be at (m-7)*8
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# Stack frame starts at -(n-6)*8(%rsp), so before stack frame is allocated
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# Linux arg m should be at (6-n+m-7)*8(%rsp)
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#define win2lin_lin_arg(m,n) (m-1-n)*8(%rsp)
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.type win2lin7, @function
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# copy windows argument 7 onto stack for Linux function
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mov win2lin_win_arg(7), %r11
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mov %r11, win2lin_lin_arg(7,7)
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call_lin_func_args(7)
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.size win2lin7, .-win2lin7
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.type win2lin8, @function
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# copy windows arguments 7 and 8 onto stack for Linux function
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mov win2lin_win_arg(7), %r11
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mov %r11, win2lin_lin_arg(7,8)
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mov win2lin_win_arg(8), %r11
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mov %r11, win2lin_lin_arg(8,8)
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call_lin_func_args(8)
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.size win2lin8, .-win2lin8
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.type win2lin9, @function
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# since we destroy rsi and rdi here, first copy windows
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# arguments 7 through 12 onto stack for Linux function
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mov %rcx, %r11 # save rcx
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lea win2lin_win_arg(7), %rsi # source (windows arg 7 and up)
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lea win2lin_lin_arg(7,12), %rdi # = destination
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mov $6, %rcx # 6 arguments
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mov %r11, %rcx # restore rcx
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call_lin_func_args(12)
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.size win2lin9, .-win2lin9
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#define win2lin(name, argc) \
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ENTRY(win2lin_ ## name ## _ ## argc) \
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lea name(%rip), %r10 ; \
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#include "win2lin_stubs.h"
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#endif // CONFIG_X86_64
added
removed
ubuntu/ndiswrapper/win2lin_stubs.S
