From 53910ef7ba04fbf1ea74037fa997d3aa1ae3e0bd Mon Sep 17 00:00:00 2001 From: Zhen Lei Date: Fri, 30 Sep 2022 09:54:46 +0800 Subject: livepatch: Move the result-invariant calculation out of the loop The calculation results of the variables 'func_addr' and 'func_size' are not affected by the for loop and do not change due to the changes of entries[i]. The performance can be improved by moving it outside the loop. No functional change. Signed-off-by: Zhen Lei Reviewed-by: Petr Mladek Signed-off-by: Jiri Kosina --- kernel/livepatch/transition.c | 54 +++++++++++++++++++++---------------------- 1 file changed, 27 insertions(+), 27 deletions(-) diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c index 30187b1d8275..f1b25ec581e0 100644 --- a/kernel/livepatch/transition.c +++ b/kernel/livepatch/transition.c @@ -196,36 +196,36 @@ static int klp_check_stack_func(struct klp_func *func, unsigned long *entries, struct klp_ops *ops; int i; - for (i = 0; i < nr_entries; i++) { - address = entries[i]; + if (klp_target_state == KLP_UNPATCHED) { + /* + * Check for the to-be-unpatched function + * (the func itself). + */ + func_addr = (unsigned long)func->new_func; + func_size = func->new_size; + } else { + /* + * Check for the to-be-patched function + * (the previous func). + */ + ops = klp_find_ops(func->old_func); - if (klp_target_state == KLP_UNPATCHED) { - /* - * Check for the to-be-unpatched function - * (the func itself). - */ - func_addr = (unsigned long)func->new_func; - func_size = func->new_size; + if (list_is_singular(&ops->func_stack)) { + /* original function */ + func_addr = (unsigned long)func->old_func; + func_size = func->old_size; } else { - /* - * Check for the to-be-patched function - * (the previous func). - */ - ops = klp_find_ops(func->old_func); - - if (list_is_singular(&ops->func_stack)) { - /* original function */ - func_addr = (unsigned long)func->old_func; - func_size = func->old_size; - } else { - /* previously patched function */ - struct klp_func *prev; - - prev = list_next_entry(func, stack_node); - func_addr = (unsigned long)prev->new_func; - func_size = prev->new_size; - } + /* previously patched function */ + struct klp_func *prev; + + prev = list_next_entry(func, stack_node); + func_addr = (unsigned long)prev->new_func; + func_size = prev->new_size; } + } + + for (i = 0; i < nr_entries; i++) { + address = entries[i]; if (address >= func_addr && address < func_addr + func_size) return -EAGAIN; -- cgit v1.2.3