lkml.org 
[lkml]   [2005]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: Why system call need to copy the date from the userspace before using it
Date
From
Sorry if this bugs anyone, but I'm learning things here.

What I would expect the kernel to do is this:

system_call_data_prep (userdata, size){

if !4G/4G {
for each page from userdata to userdata+size
{
if the page is swapped out, swap it in
if the page is not owned by the user process, return -ENOWAYMAN
otherwise, lock the page
}
return userdata;
}
else { //kernel land and userland are mutually exclusive
copy the data into kernel land
return kernelland_copy_of_userdata;
}
}

(And then the syscall would need to run the opposite function
sys_call_data_unprep to unlock pages.)

Hmm, maybe that interface sucks.

Is it anything close to that?

--
The best is the enemy of the good -- Voltaire
The Good Enough is the enemy of the Great -- Me
http://www.hacksaw.org -- http://www.privatecircus.com -- KB1FVD


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-04-16 06:55    [W:0.066 / U:1.308 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site