On Mon, Nov 18, 2024 at 01:25:01PM -0500, Steven Rostedt wrote:
On Wed, 23 Oct 2024 19:27:03 +0300
Mike Rapoport <rppt@xxxxxxxxxx> wrote:
From: "Mike Rapoport (Microsoft)" <rppt@xxxxxxxxxx>
Hi,
This is an updated version of execmem ROX caches.
FYI, I booted a kernel before and after applying these patches with my
change:
https://lore.kernel.org/20241017113105.1edfa943@xxxxxxxxxxxxxxxxxx
Before these patches:
# cat /sys/kernel/tracing/dyn_ftrace_total_info
57695 pages:231 groups: 9
ftrace boot update time = 14733459 (ns)
ftrace module total update time = 449016 (ns)
After:
# cat /sys/kernel/tracing/dyn_ftrace_total_info
57708 pages:231 groups: 9
ftrace boot update time = 47195374 (ns)
ftrace module total update time = 592080 (ns)
Which caused boot time to slowdown by over 30ms. That may not seem like
much, but we are very concerned about boot time and are fighting every ms
we can get.
Hmm, looks like this change was lost in rebase :/
@Andrew, should I send it as a patch on top of mm-stable?
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 8da0e66ca22d..859902dd06fc 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -111,17 +111,22 @@ static int ftrace_verify_code(unsigned long ip, const char *old_code)
*/
static int __ref
ftrace_modify_code_direct(unsigned long ip, const char *old_code,
- const char *new_code)
+ const char *new_code, struct module *mod)
{
int ret = ftrace_verify_code(ip, old_code);
if (ret)
return ret;
/* replace the text with the new text */
- if (ftrace_poke_late)
+ if (ftrace_poke_late) {
text_poke_queue((void *)ip, new_code, MCOUNT_INSN_SIZE, NULL);
- else
+ } else if (!mod) {
text_poke_early((void *)ip, new_code, MCOUNT_INSN_SIZE);
+ } else {
+ mutex_lock(&text_mutex);
+ text_poke((void *)ip, new_code, MCOUNT_INSN_SIZE);
+ mutex_unlock(&text_mutex);
+ }
return 0;
}
@@ -142,7 +147,7 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long ad
* just modify the code directly.
*/
if (addr == MCOUNT_ADDR)
- return ftrace_modify_code_direct(ip, old, new);
+ return ftrace_modify_code_direct(ip, old, new, mod);
/*
* x86 overrides ftrace_replace_code -- this function will never be used
@@ -161,7 +166,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
new = ftrace_call_replace(ip, addr);
/* Should only be called when module is loaded */
- return ftrace_modify_code_direct(rec->ip, old, new);
+ return ftrace_modify_code_direct(rec->ip, old, new, NULL);
}
/*
-- Steve
--
Sincerely yours,
Mike.
