Check this GCC function out

[Neo]

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void   dump_registers()
{
???unsigned int _EAX,_EBX,_ECX,_EDX;
  ???printf("\n\tDump Registers here");
???__asm__ __volatile__ ( "movl %%eax,%w0" : "=g"(_EAX): "a"(_EAX) );
???__asm__ __volatile__ ( "movl %%ebx,%w0" : "=g"(_EBX): "b"(_EBX) );
???__asm__ __volatile__ ( "movl %%ecx,%w0" : "=g"(_ECX): "c"(_ECX) );
???__asm__ __volatile__ ( "movl %%edx,%w0" : "=g"(_EDX): "d"(_EDX) );
???printf("\nEAX = %x\nEBX = %x\nECX = %x\nEDX = %x",_EAX,_EBX,_ECX,_EDX);
}

IS this function right? I get errors when i replace %w0 with %w1 etc..
Also does this give the actual register values or is there something more.I'm a beginer ya know
btw does anyone have a better dump registers function.
Also which is the best choice for an executable file format ?

[kaos]

Code: Select all

void   dump_registers()
{
   unsigned int _EAX,_EBX,_ECX,_EDX;
     printf("\n\tDump Registers here");

The previous line will mung the registers. The compiler-generated function setup code might too.

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   __asm__ __volatile__ ( "movl %%eax,%w0" : "=g"(_EAX): "a"(_EAX) );
   __asm__ __volatile__ ( "movl %%ebx,%w0" : "=g"(_EBX): "b"(_EBX) );
   __asm__ __volatile__ ( "movl %%ecx,%w0" : "=g"(_ECX): "c"(_ECX) );
   __asm__ __volatile__ ( "movl %%edx,%w0" : "=g"(_EDX): "d"(_EDX) );
   printf("\nEAX = %x\nEBX = %x\nECX = %x\nEDX = %x",_EAX,_EBX,_ECX,_EDX);
}

IS this function right? I get errors when i replace %w0 with %w1 etc..
Also does this give the actual register values or is there something more.I'm a beginer ya know

You might try compiling with the -S flag so that you can see gcc's assembly output.

btw does anyone have a better dump registers function.
Also which is the best choice for an executable file format ?

Here's what I would use to dump registers:

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#define I386_DUMP_REGISTERS() \
{ \
  __asm__ __volatile__ ("pushl %edx"); \
  __asm__ __volatile__ ("pushl %ecx"); \
  __asm__ __volatile__ ("pushl %ebx"); \
  __asm__ __volatile__ ("pushl %eax"); \
  __asm__ __volatile__ ("call __dumpregs"); \
  __asm__ __volatile__ ("pop %eax"); \
  __asm__ __volatile__ ("pop %eax"); \
  __asm__ __volatile__ ("pop %eax"); \
  __asm__ __volatile__ ("pop %eax"); \
}

void _dumpregs(int eax, int ebx, int ecx, int edx)
{
  printf("\nEAX = %x\nEBX = %x\nECX = %x\nEDX = %x\n", eax, ebx, ecx, edx);
}

Elf is supposedly the best executable format; it does have a lot of options, but it is rather complex. Coff is simple.

[df]

elf wastes a register on PIC... its a shame PE is so complex and coff is lacking that little extra

[Pype.Clicker]

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   __asm__ __volatile__ ( "movl %%eax,%w0" : "=g"(_EAX): "a"(_EAX) );

will hardly do what you want it to do! you're trying to tell the compiler that it must execute "mov [_EAX],eax" under the constraint that "eax must hold the content of _EAX" before execution of the command.

the resulting assembler code will look like

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    mov eax,[ebp-4]
    mov [ebp-4],eax