> On Jan 11, 2022, at 4:13 AM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote: > > On Wed, Jan 05, 2022 at 06:25:31PM -0800, Song Liu wrote: > >> diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c >> index 23fb4d51a5da..02c35725cc62 100644 >> --- a/arch/x86/kernel/alternative.c >> +++ b/arch/x86/kernel/alternative.c >> @@ -1102,6 +1102,34 @@ void *text_poke_kgdb(void *addr, const void *opcode, size_t len) >> return __text_poke(addr, opcode, len); >> } >> >> +/** >> + * text_poke_jit - Update instructions on a live kernel by jit engine >> + * @addr: address to modify >> + * @opcode: source of the copy >> + * @len: length to copy, could be more than 2x PAGE_SIZE >> + * >> + * Only module memory taking jit text (e.g. for bpf) should be patched. >> + */ > > Maybe: > > text_poke_copy() - Copy instructions into (an unused part of) RX memory > @args... > > Not safe against concurrent execution; useful for JITs to dump > new code blocks into unused regions of RX memory. Can be used in > conjunction with synchronize_rcu_tasks() to wait for existing > execution to quiesce after having made sure no existing > functions pointers are life. > > or something along those lines? This sounds good! Thanks! Song
