On Mon, Oct 21, 2019 at 10:48:02AM +0200, Ingo Molnar wrote: > > * Peter Zijlstra <[email protected]> wrote: > > > --- a/arch/x86/kernel/jump_label.c > > +++ b/arch/x86/kernel/jump_label.c > > @@ -35,18 +35,19 @@ static void bug_at(unsigned char *ip, in > > BUG(); > > } > > > > -static void __jump_label_set_jump_code(struct jump_entry *entry, > > - enum jump_label_type type, > > - union jump_code_union *code, > > - int init) > > +static const void * > > +__jump_label_set_jump_code(struct jump_entry *entry, enum jump_label_type > > type, int init) > > { > > + static union jump_code_union code; /* relies on text_mutex */ > > const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP }; > > const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5]; > > const void *expect; > > int line; > > > > - code->jump = 0xe9; > > - code->offset = jump_entry_target(entry) - > > + lockdep_assert_held(&text_mutex); > > + > > + code.jump = JMP32_INSN_OPCODE; > > + code.offset = jump_entry_target(entry) - > > (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE); > > > > if (init) { > > @@ -54,23 +55,23 @@ static void __jump_label_set_jump_code(s > > } else if (type == JUMP_LABEL_JMP) { > > expect = ideal_nop; line = __LINE__; > > } else { > > - expect = code->code; line = __LINE__; > > + expect = code.code; line = __LINE__; > > Side note: the whole 'line' logic looked weird to me and it obsfuscates > the logic a bit, and I had to look it up to see what it's about: > improving the debug output of text-patching crashes. > > How about something like the below on top of your queue? We have %phD > that can nicely print instructions in hex.
I have a patch like that somewhere; see here: https://lkml.kernel.org/r/[email protected] But yes, the __LINE__ thing is mostly about identifying which case it is and I suppose we can infer that when we have the expected text printed too.
