6e121c5427
copy op to shift arguments on the stack instead of transfering each argument one by one through a register. Probably doesn't affect overall operation, but makes the code a little less grotty and easier to update later if I choose to make the wrapper handle more args. Also add comments.
178 lines
6.0 KiB
ArmAsm
178 lines
6.0 KiB
ArmAsm
/*-
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* Copyright (c) 2005
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* Bill Paul <wpaul@windriver.com>. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Bill Paul.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY Bill Paul AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL Bill Paul OR THE VOICES IN HIS HEAD
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*
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* The x86_64 callback routines were written and graciously submitted
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* by Ville-Pertti Keinonen <will@exomi.com>.
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*
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* $FreeBSD$
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*/
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#include <machine/asmacros.h>
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/*
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* Wrapper for handling up to 16 arguments. We can't really
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* know how many arguments the caller will pass us. I'm taking an
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* educated guess that we'll never get over 16. Handling too
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* few arguments is bad. Handling too many is inefficient, but
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* not fatal. If someone can think of a way to handle an arbitrary
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* number of arguments with more elegant code, freel free to let
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* me know.
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*
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* Standard amd64 calling conventions specify the following registers
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* to be used for passing the first 6 arguments:
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*
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* %rdi, %rsi, %rdx, %rcx, %r8, %r9
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*
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* Further arguments are passed on the stack (the 7th argument is
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* located immediately after the return address).
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*
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* Windows x86_64 calling conventions only pass the first 4
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* arguments in registers:
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*
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* %rcx, %rdx, %r8, %r9
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*
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* Even when arguments are passed in registers, the stack must have
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* space reserved for those arguments. Thus the 5th argument (the
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* first non-register argument) is placed 32 bytes after the return
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* address. Additionally, %rdi and %rsi must be preserved. (These
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* two registers are not scratch registers in the standard convention.)
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*
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* Note that in this template, we load a contrived 64 bit address into
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* %r11 to represent our jump address. This is to guarantee that the
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* assembler leaves enough room to patch in an absolute 64-bit address
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* later. The idea behind this code is that we want to avoid having to
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* manually create all the wrapper functions at compile time with
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* a bunch of macros. This is doable, but a) messy and b) requires
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* us to maintain two separate tables (one for the UNIX function
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* pointers and another with the wrappers). This means I'd have to
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* update two different tables each time I added a function.
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*
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* To avoid this, we create the wrappers at runtime instead. The
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* image patch tables now contain two pointers: one two the normal
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* routine, and a blank one for the wrapper. To construct a wrapper,
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* we allocate some memory and copy the template function into it,
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* then patch the function pointer for the routine we want to wrap
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* into the newly created wrapper. The subr_pe module can then
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* simply patch the wrapper routine into the jump table into the
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* windows image. As a bonus, the wrapper pointer not only serves
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* as the wrapper entry point address, it's also a data pointer
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* that we can pass to free() later when we unload the module.
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*/
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.globl x86_64_wrap_call
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.globl x86_64_wrap_end
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ENTRY(x86_64_wrap)
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subq $96,%rsp # allocate space on stack
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mov %rsi,96-8(%rsp) # save %rsi
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mov %rdi,96-16(%rsp)# save %rdi
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mov %rcx,%r10 # temporarily save %rcx in scratch
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mov %rsp,%rsi
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add $96+56,%rsi # source == old stack top (stack+56)
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mov %rsp,%rdi # destination == new stack top
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mov $10,%rcx # count == 10 quadwords
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rep
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movsq # copy old stack contents to new location
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mov %r10,%rdi # set up arg0 (%rcx -> %rdi)
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mov %rdx,%rsi # set up arg1 (%rdx -> %rsi)
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mov %r8,%rdx # set up arg2 (%r8 -> %rdx)
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mov %r9,%rcx # set up arg3 (%r9 -> %rcx)
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mov 96+40(%rsp),%r8 # set up arg4 (stack+40 -> %r8)
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mov 96+48(%rsp),%r9 # set up arg5 (stack+48 -> %r9)
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xor %rax,%rax # clear return value
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x86_64_wrap_call:
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mov $0xFF00FF00FF00FF00,%r11
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callq *%r11 # call routine
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mov 96-16(%rsp),%rdi# restore %rdi
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mov 96-8(%rsp),%rsi # restore %rsi
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addq $96,%rsp # delete space on stack
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ret
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x86_64_wrap_end:
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/*
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* Functions for invoking x86_64 callbacks. In each case, the first
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* argument is a pointer to the function.
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*/
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ENTRY(x86_64_call1)
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subq $8,%rsp
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mov %rsi,%rcx
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call *%rdi
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addq $8,%rsp
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ret
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ENTRY(x86_64_call2)
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subq $24,%rsp
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mov %rsi,%rcx
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/* %rdx is already correct */
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call *%rdi
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addq $24,%rsp
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ret
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ENTRY(x86_64_call3)
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subq $24,%rsp
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mov %rcx,%r8
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mov %rsi,%rcx
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call *%rdi
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addq $24,%rsp
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ret
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ENTRY(x86_64_call4)
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subq $40,%rsp
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mov %r8,%r9
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mov %rcx,%r8
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mov %rsi,%rcx
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call *%rdi
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addq $40,%rsp
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ret
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ENTRY(x86_64_call5)
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subq $40,%rsp
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mov %r9,32(%rsp)
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mov %r8,%r9
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mov %rcx,%r8
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mov %rsi,%rcx
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call *%rdi
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addq $40,%rsp
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ret
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ENTRY(x86_64_call6)
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subq $56,%rsp
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mov 56+8(%rsp),%rax
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mov %r9,32(%rsp)
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mov %rax,40(%rsp)
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mov %r8,%r9
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mov %rcx,%r8
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mov %rsi,%rcx
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call *%rdi
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addq $56,%rsp
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ret
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