On Thu, Jun 01, 2023 at 12:30:50PM +0200, Peter Zijlstra wrote:

On Thu, Jun 01, 2023 at 01:12:56PM +0300, Mike Rapoport wrote:

quoted

+static void __init_or_module do_text_poke(void *addr, const void *opcode, size_t len)
+{
+	if (system_state < SYSTEM_RUNNING) {
+		text_poke_early(addr, opcode, len);
+	} else {
+		mutex_lock(&text_mutex);
+		text_poke(addr, opcode, len);
+		mutex_unlock(&text_mutex);
+	}
+}

So I don't much like do_text_poke(); why?

I believe the idea was to keep memcpy for early boot before the kernel
image is protected without going and adding if (is_module_text_address())
all over the place.

I think this can be used instead without updating all the call sites of
text_poke_early():

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 91057de8e6bc..f994e63e9903 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c

@@ -1458,7 +1458,7 @@ void __init_or_module text_poke_early(void *addr, const void *opcode,
 		 * code cannot be running and speculative code-fetches are
 		 * prevented. Just change the code.
 		 */
-		memcpy(addr, opcode, len);
+		text_poke_copy(addr, opcode, len);
 	} else {
 		local_irq_save(flags);
 		memcpy(addr, opcode, len);
 

quoted

diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index aa99536b824c..d50595f2c1a6 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c

@@ -118,10 +118,13 @@ ftrace_modify_code_direct(unsigned long ip, const char *old_code,
 		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
-		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;
 }

And in the above case it's actively wrong for loosing the _queue()
thing.

-- 
Sincerely yours,
Mike.