[PATCH] treewide: remove current_text_addr

[H. Peter Anvin]

On 08/27/18 06:11, Peter Zijlstra wrote:
> On Mon, Aug 27, 2018 at 05:26:53AM -0700, H. Peter Anvin wrote:
> 
>> _THIS_IP_, however, is completely ill-defined, other than being an
>> address *somewhere* in the same global function (not even necessarily
>> the same function if the function is static!)  As my experiment show, in
>> many (nearly) cases gcc will hoist the address all the way to the top of
>> the function, at least for the current generic implementation.
> 
> It seems to have mostly worked so far... did anything change?
> 

Most likely because the major architectures contain a arch-specific
assembly implementation.  The generic implementation used in some places
is completely broken, as my experiments show.

>> For the case where _THIS_IP_ is passed to an out-of-line function in all
>> cases, it is extra pointless because all it does is increase the
>> footprint of every caller: _RET_IP_ is inherently passed to the function
>> anyway, and with tailcall protection it will uniquely identify a callsite.
> 
> So I think we can convert many of the lockdep _THIS_IP_ calls to
> _RET_IP_ on the other side, with a wee bit of care.
> 
> A little something like so perhaps...

I don't have time to look at this right now (I'm on sabbatical, and I'm
dealing with personal legal stuff right at the moment), but I think it
is the right direction.

	-hpa