Accessing sysenter page by kernel syscalls

[Petr Vandrovec]

Hi,
  is there any reason why copy_from_user does not punch hole in
kernel space to get it possible to access sysenter page? I do not think
that it would add too big overhead to copy_*_user (which is already long),
but I cannot think about any other reason why sysenter page is not
accessible through write().

  Today I wanted to confirm whether my kernel uses sysenter or int 0x80, 
and I found that simple program below does not work and I had to copy page 
first to some temporary location, and then write it from this temporary 
location to stdout.
  
void main(void) {
  write(1, (void*)0xFFFFE000, 4096);
}
                                                    Thanks,
                                                        Petr Vandrovec
                                                

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