* [RFC][PATCH] x86 transition to 4k stacks (0/3)
@ 2002-10-15 5:59 Dave Hansen
2002-10-15 15:10 ` Daniel Jacobowitz
0 siblings, 1 reply; 2+ messages in thread
From: Dave Hansen @ 2002-10-15 5:59 UTC (permalink / raw)
To: linux-kernel
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
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [RFC][PATCH] x86 transition to 4k stacks (0/3)
2002-10-15 5:59 [RFC][PATCH] x86 transition to 4k stacks (0/3) Dave Hansen
@ 2002-10-15 15:10 ` Daniel Jacobowitz
0 siblings, 0 replies; 2+ messages in thread
From: Daniel Jacobowitz @ 2002-10-15 15:10 UTC (permalink / raw)
To: Dave Hansen; +Cc: linux-kernel
On Mon, Oct 14, 2002 at 10:59:55PM -0700, Dave Hansen wrote:
> 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.
You might have better luck with -finstrument-functions; I don't know if
it is supported as far back but I don't believe it was buggy. It has a
few fewer quirks than mcount profiling.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
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