From: Peter Zijlstra <peterz@infradead.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: nicolas.pitre@linaro.org, linux-mips@linux-mips.org,
linux-sh@vger.kernel.org, benh@kernel.crashing.org,
Will Deacon <will.deacon@arm.com>,
paulus@samba.org, mpe@ellerman.id.au, jejb@parisc-linux.org,
Geert Uytterhoeven <geert@linux-m68k.org>,
Catalin Marinas <catalin.marinas@arm.com>,
gor@linux.vnet.ibm.com, mattst88@gmail.com,
uclinux-h8-devel@lists.sourceforge.jp,
Marc Zyngier <marc.zyngier@arm.com>,
linuxram@us.ibm.com, linux-um@lists.infradead.org,
Nicholas Piggin <npiggin@gmail.com>,
luto@kernel.org, shannon.nelson@oracle.com,
Thomas Gleixner <tglx@linutronix.de>,
alex.bennee@linaro.org, rth@twiddle.net, jkosina@suse.cz,
LKML <linux-kernel@vger.kernel.org>,
ralf@linux-mips.org, rkuo@codeaurora.org, paul.burton@mips.com,
aneesh.kumar@linux.vnet.ibm.com,
Greg KH <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-f>
Subject: Re: [PATCH] treewide: remove current_text_addr
Date: Mon, 27 Aug 2018 09:33:58 +0200 [thread overview]
Message-ID: <20180827073358.GV24124@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <CAKwvOd=wAaPBkFHAcWxgMW91a--9gbvu7xrt3j-q8c+-mT=7Lw@mail.gmail.com>
On Sun, Aug 26, 2018 at 07:52:59PM -0700, Nick Desaulniers wrote:
> On Sun, Aug 26, 2018 at 1:25 PM Linus Torvalds
> > Instead, maybe we could encourage something like
> >
> > struct kernel_loc { const char *file; const char *fn; int line; };
> >
> > #define __GEN_LOC__(n) \
> > ({ static const struct kernel_loc n = { \
> > __FILE__, __FUNCTION__, __LINE__ \
> > }; &n; })
> >
> > #define _THIS_LOC_ __GEN_LOC__(__UNIQUE_ID(loc))
> >
> > which is a hell of a lot nicer to use, and actually allows gcc to
> > optimize things (try it: if you pass a _THIS_LOC_ off to an inline
> > function, and that inline function uses the name and line number, gcc
> > will pick them up directly, without the extra structure dereference.
> >
> > Wouldn't it be much nicer to pass these kinds of "location pointer"
> > around, rather than the nasty _THIS_IP_ thing?
> >
> > Certainly lockdep looks like it could easily take that "const struct
> > kernel_loc *" instead of "unsigned long ip". Makes it easy to print
> > out the lockdep info.
> This is extremely reasonable. I can follow up with the lockdep folks
> to see if they really need _THIS_IP_ to solve their problem, or if
> there's a simpler solution that can solve their needs. Sometimes
> taking a step back and asking for clarity around the big picture
> allows simpler solutions to shake out.
What problem are we trying to solve? _THIS_IP_ and _RET_IP_ work fine.
We're 'good' at dealing with text addresses, we use them for call stacks
and all sorts. Why does this need changing?
next prev parent reply other threads:[~2018-08-27 7:33 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAKwvOdkWL_2yTnJqM6n6R9UCPwY4iz-9BQYGN2MDAk9EzumUvA@mail.gmail.com>
[not found] ` <20180821202900.208417-1-ndesaulniers@google.com>
[not found] ` <207784db-4fcc-85e7-a0b2-fec26b7dab81@gmx.de>
2018-08-26 2:38 ` [PATCH] treewide: remove current_text_addr H. Peter Anvin
2018-08-26 3:16 ` H. Peter Anvin
2018-08-26 4:56 ` H. Peter Anvin
2018-08-26 19:30 ` H. Peter Anvin
2018-08-26 20:25 ` Linus Torvalds
2018-08-27 2:52 ` Nick Desaulniers
2018-08-27 7:33 ` Peter Zijlstra [this message]
2018-08-27 12:26 ` H. Peter Anvin
2018-08-27 13:11 ` Peter Zijlstra
2018-08-27 13:33 ` H. Peter Anvin
2018-08-31 16:48 ` Nick Desaulniers
2018-08-27 7:43 ` Nicholas Piggin
2018-08-26 23:20 ` H. Peter Anvin
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