setcontext and makecontext to call a generic function pointer
- by Simone Margaritelli
In another question i had the problem to port the code
unsigned long stack[] = { 1, 23, 33, 43 };
/* save all the registers and the stack pointer */
unsigned long esp;
asm __volatile__ ( "pusha" );
asm __volatile__ ( "mov %%esp, %0" :"=m" (esp));
for( i = 0; i < sizeof(stack); i++ ){
unsigned long val = stack[i];
asm __volatile__ ( "push %0" :: "m"(val) );
}
unsigned long ret = function_pointer();
/* restore registers and stack pointer */
asm __volatile__ ( "mov %0, %%esp" :: "m" (esp) );
asm __volatile__ ( "popa" );
To a 64bit platform and many guys told me i should use the setcontext and makecontext functions set instead due to the calling conversion differences between 32 and 64 bits and portability issues.
Well, i really can't find any useful documentation online, or at least not the kind i need to implement this, so, how can i use those functions to push arguments onto the stack, call a generic function pointer, obtain the return value and then restore the registers?
