On Thu, Aug 22, 2019 at 04:32:37PM +0100, Mark Rutland wrote:

On Mon, Aug 12, 2019 at 03:36:21PM +0100, Andrew Murray wrote:

quoted

On architectures that discard .exit.* sections at runtime, a
warning is printed for each jump label that is used within an
in-kernel __exit annotated function:

can't patch jump_label at ehci_hcd_cleanup+0x8/0x3c
WARNING: CPU: 0 PID: 1 at kernel/jump_label.c:410 __jump_label_update+0x12c/0x138

As these functions will never get executed (they are free'd along
with the rest of initmem) - we do not need to patch them and should
not display any warnings.

The warning is displayed because the test required to satisfy
jump_entry_is_init is based on init_section_contains (__init_begin to
__init_end) whereas the test in __jump_label_update is based on
init_kernel_text (_sinittext to _einittext) via kernel_text_address).

In addition to fixing this, we also remove an out-of-date comment
and use a WARN instead of a WARN_ONCE.

This last sentence is stale -- it was true in v1 but not since then.

With that droppped:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks.

Andrew Murray

Mark.
 

quoted

Fixes: 19483677684b ("jump_label: Annotate entries that operate on __init code earlier")
Signed-off-by: Andrew Murray <redacted>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/jump_label.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index df3008419a1d..cdb3ffab128b 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c

@@ -407,7 +407,9 @@ static bool jump_label_can_update(struct jump_entry *entry, bool init)
 		return false;
 
 	if (!kernel_text_address(jump_entry_code(entry))) {
-		WARN_ONCE(1, "can't patch jump_label at %pS", (void *)jump_entry_code(entry));
+		WARN_ONCE(!jump_entry_is_init(entry),
+			  "can't patch jump_label at %pS",
+			  (void *)jump_entry_code(entry));
 		return false;
 	}
 

-- 
2.21.0

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