Subject: Re: [PATCH] tools/perf: Fix the mask in regs_dump__printf

From: Jiri Olsa <[email-masked]>
Date: Fri, 17 Jun 2016 13:24:01 +0200

On Fri, Jun 17, 2016 at 02:43:31PM +0530, Madhavan Srinivasan wrote:

SNIP

> 
>  
>                 if (data->user_regs.abi) {
> -                       u64 mask = evsel->attr.sample_regs_user;
> +                       u.val64 = evsel->attr.sample_regs_user;
>  
> -                       sz = hweight_long(mask) * sizeof(u64);
> +                       if (sizeof(u64) > sizeof(unsigned long)) {
> +                               u64 mask = u.val64;
> +                               u.val32[1] = mask >> 32;
> +                               u.val32[0] = mask & ULONG_MAX;
> +                       }
> +
> +                       sz = hweight_long(u.val64) * sizeof(u64);
>                         OVERFLOW_CHECK(array, sz, max_size);
> -                       data->user_regs.mask = mask;
> +                       data->user_regs.mask = u.val64;
>                         data->user_regs.regs = (u64 *)array;
> 
> Issue I see is when printing the mask value in a 32bit perf
> on a 64bit kernel (big endian).
> 
> 442044948492 0xdc0 [0x188]: PERF_RECORD_SAMPLE(IP, 0x1): 7299/7299:
> 0xc000000000059200 period: 12599 addr: 0
> ... intr regs: mask 0xffffffff000007ff ABI 32-bit
>                             ^^^ shld have been 0x7ffffffffff
> 
> I agree it is better to fix this when reading, but
> we need to swap again when printing?

hum, sample data should be swap at this point already..
see perf_session__process_event

jirka