Messages in this thread | | | Date | Wed, 6 May 2020 18:28:48 +0200 | From | Peter Zijlstra <> | Subject | Re: [patch V4 part 1 20/36] vmlinux.lds.h: Create section for protection against instrumentation |
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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.
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