[PATCH v4 3/8] ARM: lib: add switch_stack function for safely changing stack

[Will Deacon]

On Wed, Aug 24, 2011 at 02:07:29AM +0100, Nicolas Pitre wrote:
> On Tue, 23 Aug 2011, Will Deacon wrote:
> 
> > When disabling the MMU, it is necessary to take out a 1:1 identity map
> > of the reset code so that it can safely be executed with and without
> > the MMU active. To avoid the situation where the physical address of the
> > reset code aliases with the virtual address of the active stack (which
> > cannot be included in the 1:1 mapping), it is desirable to change to a
> > new stack at a location which is less likely to alias.
> > 
> > This code adds a new lib function, switch_stack:
> > 
> > void switch_stack(void (*fn)(void *), void *arg, void *sp);
> > 
> > which changes the stack to point at the sp parameter, before invoking
> > fn(arg) with the new stack selected.
> > 
> > Signed-off-by: Dave Martin <dave.martin at linaro.org>
> > Signed-off-by: Will Deacon <will.deacon at arm.com>
> 
> For the implementation:
> 
> Reviewed-by: Nicolas Pitre <nicolas.pitre at linaro.org>
> 
> However I think switch_stack() is too vague a name for what this 
> actually does.  Maybe something like call_with_stack(fn, arg, sp) is 
> more precise.

That's a much better name, thanks.

Will