allocate memory in userspace

I am a kernel newbie and i am writing a module. I need to allocate some memory in userspace because i want to access syscalls like open(), lstat() etc. I need to call these methods in the kernel, and in my special case there is no other way, but i do not want to reimplement all the syscalls.

I read that it should be possible, but i cannot find any example or recipe on how to do it.

Quoted 7 lines · Timo Benk

I am a kernel newbie and i am writing a module. I need to allocate some memory in userspace because i want to access syscalls like open(), lstat() etc. I need to call these methods in the kernel, and in my special case there is no other way, but i do not want to reimplement all the syscalls.

Quoted 2 lines

I read that it should be possible, but i cannot find any example or recipe on how to do it.

mm_segment_t oldfs = get_fs();
set_fs(KERNEL_DS);
ret = sys_yoursyscall(kernelargs ...)
set_fs(oldfs);

Do not even think about using mmap or accessing sys_call_table for this. Your other post was so tasteless that it would be good if you retracted it with a followup because it would be very bad to have such an bad example in the l-k archives open to innocent search machine users uncommented.