Re: [PATCH] inet/connection_sock: prefer _THIS_IP_ to current_text_addr

From: Nathan Chancellor
Date: Thu Aug 02 2018 - 00:58:36 EST

On Wed, Aug 01, 2018 at 06:42:08PM -0700, David Miller wrote:
> From: Nick Desaulniers <ndesaulniers@xxxxxxxxxx>
> Date: Wed, 1 Aug 2018 14:57:59 -0700
> > - sk, what, when, current_text_addr());
> > + sk, what, when, (void *)_THIS_IP_);
> Is a fugly macro in all caps really better than a function()?
> I'm really surprised that _THIS_IP_ is being chosen over
> current_text_addr(), seriously.

Hi Dave,

current_text_addr is only used in five places in the entire kernel and
this is the only non-architecture specific use.

include/net/inet_connection_sock.h:227: sk, what, when, current_text_addr());
arch/sh/include/asm/kexec.h:64: newregs->pc = (unsigned long)current_text_addr();
arch/sh/kernel/dwarf.c:602: pc = (unsigned long)current_text_addr();
arch/x86/include/asm/kexec.h:135: newregs->ip = (unsigned long)current_text_addr();
arch/parisc/kernel/unwind.c:442: r.iaoq[0] = (unsigned long) current_text_addr();

We're trying to merge it with _THIS_IP_ before for most architectures,
it is defined nearly identically to _THIS_IP_:

#define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; })

#define current_text_addr() ({ __label__ _l; _l: &&_l; })

* arc
* arm
* arm64
* h8300
* hexagon
* m68k
* mips
* nds32
* nios2
* openrisc
* powerpc
* riscv
* unicore32
* xtensa

Ultimately, we're trying to turn off a new Clang warning in _THIS_IP_
which requires some changes to work around what is believed to be a GCC
bug (see

I guess the alternative to this patch is to just define current_text_addr
as _THIS_IP_ for all of those architectures, I am not sure how that
filters into Nick's plan (I think the goal of this was to try and avoid
getting all of the architecture folks involved).

Thanks for your time!