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authorJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2011-10-03 11:01:46 -0700
committerJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>2011-10-25 11:54:31 -0700
commit20284aa77c0f6227da4783a920b72dc61d4bcc09 (patch)
tree46fb708a9508e3d718be7eb432367547e71208d3 /kernel/jump_label.c
parent92e02396d7214fdc7c25239eb647eb48e6fe6ba9 (diff)
downloadlinux-sh-20284aa77c0f6227da4783a920b72dc61d4bcc09.tar.gz
jump_label: add arch_jump_label_transform_static() to optimise non-live code updates
When updating a newly loaded module, the code is definitely not yet executing on any processor, so it can be updated with no need for any heavyweight synchronization. This patch adds arch_jump_label_static() which is implemented as arch_jump_label_transform() by default, but architectures can override it if it avoids, say, a call to stop_machine(). Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> Acked-by: Jason Baron <jbaron@redhat.com> Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Diffstat (limited to 'kernel/jump_label.c')
-rw-r--r--kernel/jump_label.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 059202d5b77a..ff2028f35aa8 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -104,6 +104,18 @@ static int __jump_label_text_reserved(struct jump_entry *iter_start,
return 0;
}
+/*
+ * Update code which is definitely not currently executing.
+ * Architectures which need heavyweight synchronization to modify
+ * running code can override this to make the non-live update case
+ * cheaper.
+ */
+void __weak arch_jump_label_transform_static(struct jump_entry *entry,
+ enum jump_label_type type)
+{
+ arch_jump_label_transform(entry, type);
+}
+
static void __jump_label_update(struct jump_label_key *key,
struct jump_entry *entry,
struct jump_entry *stop, int enable)
@@ -135,8 +147,8 @@ static __init int jump_label_init(void)
struct jump_label_key *iterk;
iterk = (struct jump_label_key *)(unsigned long)iter->key;
- arch_jump_label_transform(iter, jump_label_enabled(iterk) ?
- JUMP_LABEL_ENABLE : JUMP_LABEL_DISABLE);
+ arch_jump_label_transform_static(iter, jump_label_enabled(iterk) ?
+ JUMP_LABEL_ENABLE : JUMP_LABEL_DISABLE);
if (iterk == key)
continue;
@@ -208,7 +220,7 @@ void jump_label_apply_nops(struct module *mod)
return;
for (iter = iter_start; iter < iter_stop; iter++)
- arch_jump_label_transform(iter, JUMP_LABEL_DISABLE);
+ arch_jump_label_transform_static(iter, JUMP_LABEL_DISABLE);
}
static int jump_label_add_module(struct module *mod)