Commit 38c93587 authored Mar 18, 2021 by Peter Zijlstra

static_call: Fix static_call_update() sanity check



Sites that match init_section_contains() get marked as INIT. For
built-in code init_sections contains both __init and __exit text. OTOH
kernel_text_address() only explicitly includes __init text (and there
are no __exit text markers).

Match what jump_label already does and ignore the warning for INIT
sites. Also see the excellent changelog for commit: 8f35eaa5
("jump_label: Don't warn on __exit jump entries")

Fixes: 9183c3f9 ("static_call: Add inline static call infrastructure")
Reported-by: Sumit Garg <sumit.garg@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Jarkko Sakkinen <jarkko@kernel.org>
Tested-by: Sumit Garg <sumit.garg@linaro.org>
Link: https://lkml.kernel.org/r/20210318113610.739542434@infradead.org

parent 698bacef

kernel/jump_label.c

+8 −0

Original line number	Diff line number	Diff line
		@@ -407,6 +407,14 @@ static bool jump_label_can_update(struct jump_entry *entry, bool init)
		return false;

		if (!kernel_text_address(jump_entry_code(entry))) {
		/*
		* This skips patching built-in __exit, which
		* is part of init_section_contains() but is
		* not part of kernel_text_address().
		*
		* Skipping built-in __exit is fine since it
		* will never be executed.
		*/
		WARN_ONCE(!jump_entry_is_init(entry),
		"can't patch jump_label at %pS",
		(void *)jump_entry_code(entry));

kernel/static_call.c

+10 −1

Original line number	Diff line number	Diff line
		@@ -181,7 +181,16 @@ void __static_call_update(struct static_call_key key, void tramp, void *func)
		continue;

		if (!kernel_text_address((unsigned long)site_addr)) {
		WARN_ONCE(1, "can't patch static call site at %pS",
		/*
		* This skips patching built-in __exit, which
		* is part of init_section_contains() but is
		* not part of kernel_text_address().
		*
		* Skipping built-in __exit is fine since it
		* will never be executed.
		*/
		WARN_ONCE(!static_call_is_init(site),
		"can't patch static call site at %pS",
		site_addr);
		continue;
		}