src/bin/debug/ltrace/arch/x86/arch_ltrace_stub.S

   1 /*
   2  * Copyright 2008, Ingo Weinhold, ingo_weinhold@gmx.de.
   3  * Distributed under the terms of the MIT License.
   4  */
   5
   6 #include <asm_defs.h>
   7
   8
   9 call_stub:
  10         // push a pointer to arguments and a pointer to ourselves on the stack
  11         lea             4(%esp), %eax
  12         push    %eax
  13         call    1f
  14 1:
  15         pop             %eax
  16         subl    $(1b - call_stub), %eax
  17         push    %eax
  18
  19         // call the wrapper function
  20         movl    (call_stub_callback_address - call_stub)(%eax), %eax
  21         call    *%eax
  22                                 // returns a pointer to the actual function
  23         lea             8(%esp), %esp
  24
  25         jmp             *%eax
  26
  27 .align 4
  28 call_stub_callback_address:
  29         .long   0
  30 call_stub_end:
  31
  32
  33 // size_t arch_call_stub_size();
  34 FUNCTION(arch_call_stub_size):
  35         movl    $(call_stub_end - call_stub), %eax
  36         ret
  37 FUNCTION_END(arch_call_stub_size)
  38
  39
  40
  41 // void arch_init_call_stub(void* stub,
  42 //              void* (*callback)(const void* stub, const void* args),
  43 //              void* function);
  44 FUNCTION(arch_init_call_stub):
  45         push    %ebp
  46         movl    %esp, %ebp
  47
  48         // stub address to %edi
  49         push    %edi
  50         movl    8(%ebp), %edi
  51
  52         // copy the stub
  53         movl    $(call_stub_end - call_stub), %eax
  54         push    %eax
  55         movl    $call_stub, %eax
  56         push    %eax
  57         push    %edi
  58         call    memcpy
  59         lea             12(%esp), %esp
  60
  61         // set the callback address in the stub
  62         movl    12(%ebp), %eax
  63         movl    %eax, (call_stub_callback_address - call_stub)(%edi)
  64
  65         // restore %edi
  66         pop             %edi
  67
  68         movl    %ebp, %esp
  69         pop             %ebp
  70         ret
  71 FUNCTION_END(arch_init_call_stub)