diff options
Diffstat (limited to 'kc/core')
| -rw-r--r-- | kc/core/cpu/cpu_task.S | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kc/core/cpu/cpu_task.S b/kc/core/cpu/cpu_task.S index 4f9fd7b..7216d0e 100644 --- a/kc/core/cpu/cpu_task.S +++ b/kc/core/cpu/cpu_task.S @@ -17,6 +17,9 @@ cpu_set_thread: * rsi: pointer to control block of the current thread * rdx: pointer to this cpu's task state segment esp0 field */ + // test for attempt to switch to same thread + cmp %rdi,%rsi + je .Lnothing // test for a NULL origin thread test %rsi,%rsi // skip saving the state for a NULL origin thread @@ -45,6 +48,7 @@ cpu_set_thread: pop %r13 pop %r12 pop %rbx +.Lnothing: // do nothing if the threads are the same ret // leave into the new task .size cpu_set_thread, . - cpu_set_thread |