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

On Wed, Aug 24, 2011 at 02:07:29AM +0100, Nicolas Pitre wrote:

On Tue, 23 Aug 2011, Will Deacon wrote:

quoted

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 <redacted>
Signed-off-by: Will Deacon <redacted>

For the implementation:

Reviewed-by: Nicolas Pitre <redacted>

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