[PATCH 01/19] nptl: Fix testcases for new pthread cancellation mechanism

[Florian Weimer]

On 12/11/2017 08:06 PM, Adhemerval Zanella wrote:
> It also changes how to call the read syscall on tst-backtrace{5,6}
> to use syscall instead of read cancelable syscall to avoid need to
> handle the cancelable bridge function calls.  It requires a change
> on powerpc syscall implementation to create a stackframe, since
> powerpc backtrace rely on such information.

The powerpc is a separate change and should go in separately, with a 
separate bug number, IMHO.

The existence of this bug also suggests to me that you're patching the 
test to check something else, so maybe we need better backtrace testing 
coverage for more syscall implementation variants.  But that's just an 
aside.

 > +	/* Creates a minimum stack frame so backtrace.  */

“so backtrace works”?

> +#ifdef __powerpc64__
> +	addi r1, r1, FRAME_MIN_SIZE
> +#else
> +	addi r1,r1,16
> +#endif
> +        cfi_def_cfa_offset (0)
>  	sc

I find the extent of this pseudo-stack frame rather puzzling.

Thanks,
Florian