Re: [PATCH v6 1/9] ppc64 (le): prepare for -mprofile-kernel

From: Petr Mladek
Date: Fri Feb 05 2016 - 05:22:47 EST


On Fri 2016-02-05 15:40:27, Balbir Singh wrote:
> On Thu, Feb 4, 2016 at 10:02 PM, Petr Mladek <pmladek@xxxxxxxx> wrote:
> For big endian builds I saw
>
> Dump of assembler code for function alloc_pages_current:
> 0xc000000000256f00 <+0>: mflr r0
> 0xc000000000256f04 <+4>: std r0,16(r1)
> 0xc000000000256f08 <+8>: bl 0xc000000000009e5c <.mcount>
> 0xc000000000256f0c <+12>: mflr r0
>
> The offset is 8 bytes. Your earlier patch handled this by adding 16, I
> suspect it needs revisiting

It seems to be one of the funcitons that do not access any global
symbol. gcc does not produce TOC handling in this case when
compiled with -mprofile-kernel. I believe that it is a gcc bug.
More details can be found in the thread starting at
http://thread.gmane.org/gmane.linux.kernel/2134759/focus=2141996

Best Regards,
Petr