switcher: remove some redundant instructions
Force unwind clobbers a0 and a1; there's no need to be paranoid about
their values before possibly trapping or manually invoking force unwind
behavior.
diff --git a/sdk/core/switcher/entry.S b/sdk/core/switcher/entry.S
index 36ac11f..e073cb9 100644
--- a/sdk/core/switcher/entry.S
+++ b/sdk/core/switcher/entry.S
@@ -614,12 +614,6 @@
// We're now out of the exception path, so make sure that mtdc contains
// the trusted stack pointer.
cspecialw mtdc, csp
- // Store an error value in return registers, which will be passed to the
- // caller on unwind. They are currently undefined, if we leave this path
- // for a forced unwind then we will return whatever is in ca0 and ca1 to
- // the caller so must ensure that we don't leak anything.
- li a0, -1
- li a1, 0
// We want to make sure we can't leak any switcher state into error
// handlers, so if we're faulting in the switcher then we should force
@@ -790,17 +784,10 @@
*/
csrci mstatus, 0x8
- // Move the return value to a register that will be cleared in a forced
- // unwind and zero the return registers.
- move s0, a0
- // Store an error value in return registers, which will be passed to the
- // caller on unwind.
- li a0, -1
- li a1, 0
// Return values are 0 for install context, 1 for forced unwind. Anything
// that is not either of these is invalid and so we should do a forced
// unwind anyway.
- bne s0, zero, .Lforce_unwind
+ bnez a0, .Lforce_unwind
// We have been asked to install the new register context and resume.
// We do this by copying the register frame over the save area and entering
