Commit-ID: 3950746d9d8ef981c1cb842384e0e86e8d1aad76 Gitweb: https://git.kernel.org/tip/3950746d9d8ef981c1cb842384e0e86e8d1aad76 Author: Nadav Amit <[email protected]> AuthorDate: Thu, 25 Apr 2019 17:11:41 -0700 Committer: Ingo Molnar <[email protected]> CommitDate: Tue, 30 Apr 2019 12:38:01 +0200
x86/alternatives: Add comment about module removal races Add a comment to clarify that users of text_poke() must ensure that no races with module removal take place. Signed-off-by: Nadav Amit <[email protected]> Signed-off-by: Rick Edgecombe <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Cc: <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Borislav Petkov <[email protected]> Cc: Dave Hansen <[email protected]> Cc: H. Peter Anvin <[email protected]> Cc: Linus Torvalds <[email protected]> Cc: Masami Hiramatsu <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Thomas Gleixner <[email protected]> Link: https://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]> --- arch/x86/kernel/alternative.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 18f959975ea0..7b9b49dfc05a 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -810,6 +810,11 @@ static void *__text_poke(void *addr, const void *opcode, size_t len) * It means the size must be writable atomically and the address must be aligned * in a way that permits an atomic write. It also makes sure we fit on a single * page. + * + * Note that the caller must ensure that if the modified code is part of a + * module, the module would not be removed during poking. This can be achieved + * by registering a module notifier, and ordering module removal and patching + * trough a mutex. */ void *text_poke(void *addr, const void *opcode, size_t len) {
