[RFC][PATCH] x86 transition to 4k stacks (0/3)

Dave Hansen
2002-10-15T05:54:15Z

The kernel currently uses an 8k stack, per task. Here is the
infrastructure needed to allow us to halve that at some point in the
future.

This is a port of work Ben LaHaise did around 2.5.20 time. I split it
up and updated it for the new preempt_count semantics.

I split the original patch up into 3 pieces (apply in this order):
* clean thread info infrastructure (1/3)
- take out all instances of things like (8191&addr) to get
current stack address.
* stack checking (3/3)
- use gcc's profiling features to check for stack overflows upon
entry to functions.
- Warn if the task goes over 4k.
- Panic if the stack gets within 512 bytes of overflowing.
* interrupt stacks (3/3)
- allocate per-cpu interrupt stacks. upon entry to
common_interrupt, switch to the current cpu's stack.
- inherit the interrupted task's preempt count

Any suggestions on how to deal with "gcc -p" and old, buggy versions
of gcc would be appreciated.
--
Dave Hansen
haveblue@us.ibm.com