Hi Larry,
On Mon, May 26, 2014 at 07:56:12PM +0100, Larry Bassel wrote:
To implement the context tracker properly on arm64, a function call needs to be made after debugging and interrupts are turned on, but before the lr is changed to point to ret_to_user(). If the function call is made after the lr is changed the function will not return to the correct place.
For similar reasons, defer the setting of x0 so that it doesn't need to be saved around the function call (save far_el1 in x26 temporarily instead).
Signed-off-by: Larry Bassel larry.bassel@linaro.org
[...]
@@ -476,23 +481,27 @@ el0_undef: // enable interrupts before calling the main handler enable_dbg_and_irq mov x0, sp
- adr lr, ret_to_user b do_undefinstr
el0_dbg: /* * Debug exception handling */ tbnz x24, #0, el0_inv // EL0 only
- mrs x0, far_el1
- mrs x26, far_el1
- mov x0, x26 mov x1, x25 mov x2, sp bl do_debug_exception enable_dbg
- mov x0, x26 b ret_to_user
Why have you added this mov instruction?
Will