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| author | Ada Christine <adachristine18@gmail.com> | 2022-02-18 17:23:04 +0000 |
|---|---|---|
| committer | Ada Christine <adachristine18@gmail.com> | 2022-02-18 17:23:04 +0000 |
| commit | 7ad9d2715a737b1a1b9dd7ff411ffa6d27fb549e (patch) | |
| tree | 7c0c313352591d0d4cb68d579040655304e60459 /kc/core/cpu/cpu_task.S | |
| parent | 606b7dc226cb51077c016a8ea5fa862ac6ce1db4 (diff) | |
do nothing if the origin and target threads are the same
Diffstat (limited to 'kc/core/cpu/cpu_task.S')
| -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 |