Re: [patch V4 part 1 20/36] vmlinux.lds.h: Create section for protection against instrumentation

[Thomas Gleixner]

Peter Zijlstra <peterz@xxxxxxxxxxxxx> writes:
> On Wed, May 06, 2020 at 09:08:31AM -0700, Sean Christopherson wrote:
>> On Tue, May 05, 2020 at 03:16:22PM +0200, Thomas Gleixner wrote:
>> > Provide also a set of markers: instr_begin()/end()
>> > 
>> > These are used to mark code inside a noinstr function which calls
>> > into regular instrumentable text section as safe.
>> 
>> ...
>> 
>> > --- a/include/linux/compiler.h
>> > +++ b/include/linux/compiler.h
>> > @@ -120,10 +120,27 @@ void ftrace_likely_update(struct ftrace_
>> >  /* Annotate a C jump table to allow objtool to follow the code flow */
>> >  #define __annotate_jump_table __section(.rodata..c_jump_table)
>> >  
>> > +/* Begin/end of an instrumentation safe region */
>> > +#define instr_begin() ({						\
>> > +	asm volatile("%c0:\n\t"						\
>> > +		     ".pushsection .discard.instr_begin\n\t"		\
>> > +		     ".long %c0b - .\n\t"				\
>> > +		     ".popsection\n\t" : : "i" (__COUNTER__));		\
>> > +})
>> > +
>> > +#define instr_end() ({							\
>> > +	asm volatile("%c0:\n\t"						\
>> > +		     ".pushsection .discard.instr_end\n\t"		\
>> > +		     ".long %c0b - .\n\t"				\
>> > +		     ".popsection\n\t" : : "i" (__COUNTER__));		\
>> > +})
>> 
>> Any chance we could spell these out, i.e. instrumentation_begin/end()?  I
>> can't help but read these as "instruction_begin/end".  At a glance, the
>> long names shouldn't cause any wrap/indentation issues.
>
> The kernel naming convention is insn for instruction, not instr. That
> said, you're not the first to be confused by this.

I'm happy to spell it out. Was just lazy I guess.