Re: [PATCH v7 4/5] x86: perf: Refactor misc flag assignments

[Peter Zijlstra]

On Fri, Nov 08, 2024 at 08:20:44PM +0100, Peter Zijlstra wrote:

> Isn't the below more or less what you want?
> 
> static unsigned long misc_flags(struct pt_regs *regs)
> {
>       unsigned long flags = 0;
> 
>       if (regs->flags & PERF_EFLAGS_EXACT)
>               flags |= PERF_RECORD_MISC_EXACT_IP;
> 
>       return flags;
> }
> 
> static unsigned long native_flags(struct pt_regs *regs)
> {
>       unsigned long flags = 0;
> 
>       if (user_mode(regs))
>               flags |= PERF_RECORD_MISC_USER;
>       else
>               flags |= PERF_RECORD_MISC_KERNEL;
> 
>       return flags;
> }
> 
> static unsigned long guest_flags(struct pt_regs *regs)
> {
>       unsigned long guest_state = perf_guest_state();
>       unsigned long flags = 0;
> 
>       if (guest_state & PERF_GUEST_ACTIVE) {
>               if (guest_state & PERF_GUEST_USER)
>                       flags |= PERF_RECORD_MISC_GUEST_USER;
>               else
>                       flags |= PERF_RECORD_MISC_GUEST_KERNEL;
>       }
> 
>       return flags;
> }
> 
> unsigned long perf_arch_guest_misc_flags(struct pt_regs *regs)
> {
>       unsigned long flags;
> 
>       flags = misc_flags(regs);
>       flags |= guest_flags(regs);
> 
>       return flags;
> }
> 
> unsigned long perf_arch_misc_flags(struct pt_regs *regs)
> {
>       unsigned long flags;
>       unsigned long guest;
> 
>       flags = misc_flags(regs);
>       guest = guest_flags(regs);
>       if (guest)
>               flags |= guest;
>       else
>               flags |= native_flags(regs);
> 
>       return flags;
> }

This last can be written more concise:

unsigned long perf_arch_misc_flags(struct pt_regs *regs)
{
        unsigned long flags;

        flags = guest_flags(regs);
        if (!flags)
                flags |= native_flags(regs);

        flgs |= misc_flags(regs);

        return flags;
}